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Sample records for bright light exposures

  1. Reduction of human sleep duration after bright light exposure in the morning

    NARCIS (Netherlands)

    Dijk, D.J.; Visscher, C.A.; Bloem, G.M.; Beersma, D.G.M.; Daan, S.

    1987-01-01

    In 8 subjects the spontaneous termination of sleep was determined after repetitive exposure to either bright or dim light, between 6:00 and 9:00 h, on 3 days preceding sleep assessment. Sleep duration was significantly shorter following bright light than following dim light. During sleep the time

  2. Effects of bright light exposure during daytime on peripheral clock gene expression in humans

    Science.gov (United States)

    Sato, Maki; Wakamura, Tomoko; Morita, Takeshi; Okamoto, Akihiko; Akashi, Makoto; Matsui, Takuya; Sato, Motohiko

    2016-12-01

    Light is the strongest synchronizer controlling circadian rhythms. The intensity and duration of light change throughout the year, thereby influencing body weight, food preferences, and melatonin secretion in humans and animals. Although the expression of clock genes has been examined using human samples, it currently remains unknown whether bright light during the daytime affects the expression of these genes in humans. Therefore, we herein investigated the effects of bright light exposure during the daytime on clock gene expression in the hair follicular and root cells of the human scalp. Seven healthy men (20.4 ± 2.2 years old; 172.3 ± 5.8 cm; 64.3 ± 8.5 kg; BMI 21.7 ± 3.1 kg/m2, mean ± SD) participated in this study. Subjects completed 3-day experimental sessions twice in 1 month during which they were exposed to bright and dim light conditions. The mRNA expression of Per1-3, Cry1-2, Rev-erb-α (Nr1d1), Rev-erb-β (Nr1d2), and Dec1 was analyzed using branched DNA probes. No significant changes were observed in the expression of Per1, Per2, Per3, Cry1, Cry2, Rev-erb-α (Nr1d1), or Dec1 following exposure to bright light conditions. However, the expression of Rev-erb-β (Nr1d2) tended to be stronger under bright light than dim light conditions. These results suggest that the bright light stimulus did not influence the expression of clock genes in humans. Long-lasting bright light exposure during the daytime may be required to change the expression of clock genes in humans.

  3. Molecular circadian rhythm shift due to bright light exposure before bedtime is related to subthreshold bipolarity.

    Science.gov (United States)

    Cho, Chul-Hyun; Moon, Joung-Ho; Yoon, Ho-Kyoung; Kang, Seung-Gul; Geum, Dongho; Son, Gi-Hoon; Lim, Jong-Min; Kim, Leen; Lee, Eun-Il; Lee, Heon-Jeong

    2016-08-22

    This study examined the link between circadian rhythm changes due to bright light exposure and subthreshold bipolarity. Molecular circadian rhythms, polysomnography, and actigraphy data were studied in 25 young, healthy male subjects, divided into high and low mood disorder questionnaire (MDQ) score groups. During the first 2 days of the study, the subjects were exposed to daily-living light (150 lux) for 4 hours before bedtime. Saliva and buccal cells were collected 5 times a day for 2 consecutive days. During the subsequent 5 days, the subjects were exposed to bright light (1,000 lux), and saliva and buccal cell samples were collected in the same way. Molecular circadian rhythms were analyzed using sine regression. Circadian rhythms of cortisol (F = 16.956, p < 0.001) and relative PER1/ARNTL gene expression (F = 122.1, p < 0.001) showed a delayed acrophase in both groups after bright light exposure. The high MDQ score group showed a significant delay in acrophase compared to the low MDQ score group only in salivary cortisol (F = 8.528, p = 0.008). The high MDQ score group showed hypersensitivity in cortisol rhythm shift after bright light exposure, suggesting characteristic molecular circadian rhythm changes in the high MDQ score group may be related to biological processes downstream from core circadian clock gene expression.

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

    Science.gov (United States)

    Slama, Hichem; Deliens, Gaétane; Schmitz, Rémy; Peigneux, Philippe; Leproult, Rachel

    2015-01-01

    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 beneficial effects as

  5. 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

  6. [Bright light therapy].

    Science.gov (United States)

    Poirrier, R; Cambron, L

    2007-01-01

    Bright light therapy is a treatment that emerged in the eighties of the last century. It can be used in different pathologies such as seasonal affective disorders, major depressions, and many disorders of the wake-sleep rhythm, whether they are of primary or secondary origin. Important progress made at the basic neuroscience levels, allows today a sound understanding of the bright light mode of action. Moreover, the main indications are now the subject of consensus reports and meta-analyses which show good levels of evidence-based medicine. Bright light therapy constitutes a first choice indication in seasonal affective disorder. It is also perfectly possible to prescribe bright light therapy in the major depression disorders. It has been demonstrated that the effect size is the same as with antidepressants of reference. It is admitted nowadays that bright light therapy may be at least, an adjunct to pharmacotherapy, in order to accelerate the antidepressant effect onset, or to prolong this effect after withdrawal of the drug. Bright light therapy can also be viewed as an alternative to the pharmacological approach especially when this one is impossible, not tolerated or not accepted by the patient. The contraindications are rare.

  7. Bright Light Treatment in Psychiatry

    Directory of Open Access Journals (Sweden)

    Pinar Guzel Ozdemir

    2017-06-01

    Full Text Available Bright light treatment is a treatment modality that leads elevation of mood due to attenuation in depressive symptoms, regulation in circadian rhythm activity, increase the effect of antidepressants and amelioration in sleep quality. Bright light treatment is considered among the first-line treatments for seasonal affective disorder because of high response rates. Additionally, bright light treatment being extended to other conditions, including non-seasonal mood disorders, Alzheimer's disease, circadian rhythm sleep disorders, eating disorders, attention deficit hyperactivity disorder and other behavioral syndromes is likely to have a far reached use. Side effects are often temporary and can generally be overcome by reducing exposure time. The central focus on this paper is to review the action mechanisms, efficacy, usage areas, the ways of administration and side effects of the light treatment. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2017; 9(2.000: 177-188

  8. Morphological changes in the pineal gland of rats under conditions of long-term exposure to bright light.

    Science.gov (United States)

    Gerasimov, A V; Logvinov, S V; Kostyuchenko, V P

    2010-12-01

    Changes in the diurnal light cycle affect the morphofunctional state of the pineal gland. The volume of the nucleus, Golgi apparatus, and mitochondria in pinealocytes decreases after 45-day exposure to bright light. After 90 days, the degree of nuclear polymorphism increased, the specific volume of the Golgi apparatus returned to normal, the volume of the granular endoplasmic reticulum decreased, while the volume of lysosomes, free ribosomes, and polysomes increased. These changes reflect plasticity of pinealocytes and adaptation of the gland to long-term 24-h light exposure.

  9. High Brightness OLED Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Spindler, Jeffrey [OLEDWorks LLC; Kondakova, Marina [OLEDWorks LLC; Boroson, Michael [OLEDWorks LLC; Hamer, John [OLEDWorks LLC

    2016-05-25

    In this work we describe the technology developments behind our current and future generations of high brightness OLED lighting panels. We have developed white and amber OLEDs with excellent performance based on the stacking approach. Current products achieve 40-60 lm/W, while future developments focus on achieving 80 lm/W or higher.

  10. Efficacy of a single sequence of intermittent bright light pulses for delaying circadian phase in humans. : Phase delaying efficacy of intermittent bright light

    OpenAIRE

    2004-01-01

    International audience; It has been shown in animal studies that exposure to brief pulses of bright light can phase shift the circadian pacemaker and that the resetting action of light is most efficient during the first minutes of light exposure. In humans, multiple consecutive days of exposure to brief bright light pulses have been shown to phase shift the circadian pacemaker. The aim of the present study was to determine whether a single sequence of brief bright light pulses administered du...

  11. Efficacy of a single sequence of intermittent bright light pulses for delaying circadian phase in humans

    OpenAIRE

    2004-01-01

    It has been shown in animal studies that exposure to brief pulses of bright light can phase shift the circadian pacemaker, and that the resetting action of light is most efficient during the first minutes of light exposure. In humans, multiple consecutive days of exposure to brief bright light pulses have been shown to phase shift the circadian pacemaker. The aim of the present study was to determine if a single sequence of brief bright light pulses administered during the early biological ni...

  12. Increasing the brightness of light sources

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Ling

    2006-11-16

    In this work the principle of light recycling is applied to artificial light sources in order to achieve brightness enhancement. Firstly, the feasibilities of increasing the brightness of light sources via light recycling are examined theoretically, based on the fundamental laws of thermodynamics including Kirchhoff's law on radiation, Planck's law, Lambert-Beer's law, the etendue conservation and the brightness theorem. From an experimental viewpoint, the radiation properties of three different kinds of light sources including short-arc lamps, incandescent lamps and LEDs characterized by their light-generating mechanisms are investigated. These three types of sources are used in light recycling experiments, for the purpose of 1. validating the intrinsic light recycling effect in light sources, e. g. the intrinsic light recycling effect in incandescent lamps stemming from the coiled filament structure. 2. acquiring the required parameters for establishing physical models, e.g. the emissivity/absorptivity of the short-arc lamps, the intrinsic reflectivity and the external quantum efficiency of LEDs. 3. laying the foundations for designing optics aimed at brightness enhancement according to the characteristics of the sources and applications. Based on the fundamental laws and experiments, two physical models for simulating the radiance distribution of light sources are established, one for thermal filament lamps, the other for luminescent sources, LEDs. As validation of the theoretical and experimental investigation of the light recycling effect, an optical device, the Carambola, is designed for achieving deterministic and multiple light recycling. The Carambola has the function of a concentrator. In order to achieve the maximum possible brightness enhancement with the Carambola, several combinations of sources and Carambolas are modelled in ray-tracing simulations. Sources with different light-emitting mechanisms and different radiation properties

  13. 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 ha

  14. 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

  15. Does bright light have an anxiolytic effect? - an open trial

    Directory of Open Access Journals (Sweden)

    Kripke Daniel F

    2007-10-01

    Full Text Available Abstract Background The aim of this open trial was to examine the influence of acute bright light exposure on anxiety in older and young adults. Methods This study was ancillary to a complex 5-day laboratory experiment testing phase-responses to light at all times of the day. On 3 consecutive days, participants were exposed to bright light (3,000 lux for 3 hours. The Spielberger State-Trait Anxiety Inventory (Form Y1 was administered 5 minutes before and 20 minutes after each treatment. Mean state anxiety before and after treatment were analyzed by age, sex, and time ANOVA. To avoid floor effects, only participants with baseline STAI levels of ≥ 25 were included. Results A significant anxiolytic effect of bright light was found for the mean data, as well as for each of the three days. No significant main effect of age, sex, or interaction of these factors with STAI change were found. Conclusion The results show consistent and significant (albeit modest anxiolytic effects following acute bright light exposure in low anxiety adults. Further randomized, controlled trials in clinically anxious individuals are needed.

  16. 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.

  17. 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 (bright 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.

  18. Hybrid quantum repeater using bright coherent light.

    Science.gov (United States)

    van Loock, P; Ladd, T D; Sanaka, K; Yamaguchi, F; Nemoto, Kae; Munro, W J; Yamamoto, Y

    2006-06-23

    We describe a quantum repeater protocol for long-distance quantum communication. In this scheme, entanglement is created between qubits at intermediate stations of the channel by using a weak dispersive light-matter interaction and distributing the outgoing bright coherent-light pulses among the stations. Noisy entangled pairs of electronic spin are then prepared with high success probability via homodyne detection and postselection. The local gates for entanglement purification and swapping are deterministic and measurement-free, based upon the same coherent-light resources and weak interactions as for the initial entanglement distribution. Finally, the entanglement is stored in a nuclear-spin-based quantum memory. With our system, qubit-communication rates approaching 100 Hz over 1280 km with fidelities near 99% are possible for reasonable local gate errors.

  19. Regulation of lipid peroxidation in the retina under the effect of bright light.

    Science.gov (United States)

    Dzhafarov, A I; Kasimov, E M; Mamedov, Sh Y

    2011-04-01

    Changes in LPO intensity under the effect of exposure to bright light and the possibility of their correction with antioxidants were studied on rabbits with diabetic retinopathy. It was found that enhanced LPO caused by exposure to bright light in rabbits with diabetic retinopathy can be corrected with antioxidants. Phenosan potassium salt, α-tocopherol, and oxypyridine were more effective than SOD and taurine in preventing MDA accumulation. A complex of natural and synthetic antioxidants was most efficient in correcting LPO under conditions of exposure to bright light.

  20. Sleep quality during alcohol withdrawal with bright light therapy.

    Science.gov (United States)

    Schmitz, M; Frey, R; Pichler, P; Röpke, H; Anderer, P; Saletu, B; Rudas, S

    1997-08-01

    1. Alcohol withdrawal is a complex syndrome that ranges from anxiety, insomnia to delirium tremens. Common treatment is the application of sedative medication. Exposure to bright light in the daytime should advance the normal sleep/wake cycle and moreover it should improve the availability of man's adaptive behavior during alcohol withdrawal. 2. This pilot study describes bright light therapy (BL) during alcohol withdrawal in ten alcohol dependent patients (DSM-III-R: 291.80) without any sedative medication. BL (3000 Lux) was administered on day 3 of abstinence between 7.00-9.00 a.m. and 5.00-9.00 p.m. Total-sleep-polysomnography (recordings between 10.30 p.m.-6.00 a.m.) and self-rating scale were performed to compare intraindividual changes during three nights. After one adaptation night (immediately after alcohol withdrawal), one baseline night and one "BL-night" and one "post-BL night" were analysed. 3. At baseline, total sleep time and sleep efficiency were severely deteriorated, but tended to improve in the following nights after BL. Sleep onset latency showed a significant decline after BL. Stages 3 and 4 were reduced at baseline. Latencies to slow wave sleep were significantly shortened after BL. REM increased in the nights after BL. Subjective sleep quality improved after BL. Although the present results, bright light having a possible stabilizing effect on sleep maintenance and sleep architecture during acute alcohol withdrawal, the authors could only derive hypotheses for further ongoing controlled investigations using placebo light, to receive final verification.

  1. The Stimulating Effect of Bright Light on Physical Performance Depends on Internal Time

    NARCIS (Netherlands)

    Kantermann, Thomas; Forstner, Sebastian; Halle, Martin; Schlangen, Luc; Roenneberg, Till; Schmidt-Trucksaess, Arno

    2012-01-01

    The human circadian clock regulates the daily timing of sleep, alertness and performance and is synchronized to the 24-h day by the environmental light-dark cycle. Bright light exposure has been shown to positively affect sleepiness and alertness, yet little is known about its effects on physical pe

  2. Light-emitting nanolattices with enhanced brightness

    Science.gov (United States)

    Ng, Ryan C.; Mandal, Rajib; Anthony, Rebecca J.; Greer, Julia R.

    2017-02-01

    Three-dimensional (3D) photonic crystals have potential in solid state lighting applications due to their advantages over conventional planar thin film devices. Periodicity in a photonic crystal structure enables engineering of the density of states to improve spontaneous light emission according to Fermi's golden rule. Unlike planar thin films, which suffer significantly from total internal reflection, a 3D architectured structure is distributed in space with many non-flat interfaces, which facilitates a substantial enhancement in light extraction. We demonstrate the fabrication of 3D nano-architectures with octahedron geometry that utilize luminescing silicon nanocrystals as active media with an aluminum cathode and indium tin oxide anode towards the realization of a 3D light emitting device. The developed fabrication procedure allows charge to pass through the nanolattice between two contacts for electroluminescence. These initial fabrication efforts suggest that 3D nano-architected devices are realizable and can reach greater efficiencies than planar devices.

  3. Exposure to Bright Light Has Little Effect on Eye Sensitivity and Ultrastructure of Saduria entomon(Crustacea; Isopoda; Valvifera)(Physiology)

    OpenAIRE

    MAGNUS, LINDSTROM; WILHELM, FORIELIUS; V.BENNO, MEYER-ROCNOW; Tvarminne Zoological Station, University of Helsinki; School of Science and Technology, Department of Biological Sciences, University of Waikato

    1991-01-01

    Specimens of the isopod Saduria entomon were caught during late winter nights in Finland and divided into three groups: one was not at all exposed to any light and served as the control; a second was exposed to midday sunlight of 9.1×10^qu/m^2s for 30min; the third was exposed to artificial white light of 4.2×10^ qu/m^2s during the day for 30 min. The visual sensitivity thresholds as well as V/log I curves of 15 exposed animals from 30 min to 456 h postexposure were recorded at random interva...

  4. Effects of Bright Light Treatment on Psychomotor Speed in Athletes

    Directory of Open Access Journals (Sweden)

    Mikko Paavo Tulppo

    2014-05-01

    Full Text Available Purpose: A recent study suggests that transcranial brain targeted light treatment via ear canals may have physiological effects on brain function studied by functional magnetic resonance imaging (fMRI techniques in humans. We tested the hypothesis that bright light treatment could improve psychomotor speed in professional ice hockey players. Methods: Psychomotor speed tests with audio and visual warning signals were administered to a Finnish National Ice Hockey League team before and after 24 days of transcranial bright light or sham treatment. The treatments were given during seasonal darkness in the Oulu region (latitude 65 degrees north when the strain on the players was also very high (10 matches during 24 days. A daily 12-min dose of bright light or sham (n = 11 for both treatment was given every morning between 8–12 am at home with a transcranial bright light device. Mean reaction time and motor time were analyzed separately for both psychomotor tests. Analysis of variance for repeated measures adjusted for age was performed. Results: Time x group interaction for motor time with a visual warning signal was p = 0.024 after adjustment for age. In Bonferroni post-hoc analysis, motor time with a visual warning signal decreased in the bright light treatment group from 127 ± 43 to 94 ± 26 ms (p = 0.024 but did not change significantly in the sham group 121 ± 23 vs. 110 ± 32 ms (p = 0.308. Reaction time with a visual signal did not change in either group. Reaction or motor time with an audio warning signal did not change in either the treatment or sham group. Conclusion: Psychomotor speed, particularly motor time with a visual warning signal, improves after transcranial bright light treatment in professional ice-hockey players during the competition season in the dark time of the year.

  5. Effects of short duration morning bright light in healthy elderly subjects. I: subjective feeling and ophthalmological examinations.

    Science.gov (United States)

    Fukuda, N; Kohsaka, M; Sasamoto, Y; Koyama, E; Kobayashi, R; Honma, H; Matsubara, H; Nakano, T; Sakakibara, S

    1998-04-01

    Seven aged subjects aged 61-78 years were exposed to 6000 lx bright light for 30 min during morning hours at their homes for 1 week. Visual analog scale was recorded before bedtime and after rising to assess subjective feelings. Ophthalmological examinations were made before and after light exposure, to exclude pre-existing ocular disorders and to detect ocular damage. Furthermore, ocular fatigue was self-evaluated immediately before and after exposure. Visual analog scale results indicated that alertness reduced significantly before bedtime. Ophthalmological abnormalities were not found after exposure. These findings suggest that short duration morning bright light exposure reduces night-time vigilance.

  6. Low-intensity treadmill exercise and/or bright light promote neurogenesis in adult rat brain

    Institute of Scientific and Technical Information of China (English)

    Sung Jin Kwon; Jeongsook Park; So Yun Park; Kwang Seop Song; Sun Tae Jung; So Bong Jung; Ik Ryeul Park; Wan Sung Choi; Sun Ok Kwon

    2013-01-01

    The hippocampus is a brain region responsible for learning and memory functions. The purpose of this study was to investigate the effects of low-intensity exercise and bright light exposure on neurogenesis and brain-derived neurotrophic factor expression in adult rat hippocampus. Male Sprague-Dawley rats were randomly assigned to control, exercise, light, or exercise + light groups (n = 9 per group). The rats in the exercise group were subjected to treadmill exercise (5 days per week, 30 minutes per day, over a 4-week period), the light group rats were irradiated (5 days per week, 30 minutes per day, 10 000 lx, over a 4-week period), the exercise + light group rats were subjected to treadmill exercise in combination with bright light exposure, and the control group rats remained sedentary over a 4-week period. Compared with the control group, there was a significant increase in neurogenesis in the hippocampal dentate gyrus of rats in the exercise, light, and exercise + light groups. Moreover, the expression level of brain-derived neurotrophic factor in the rat hippocampal dentate gyrus was significantly higher in the exercise group and light group than that in the control group. Interestingly, there was no significant difference in brain-derived neurotrophic factor expression between the control group and exercise + light group. These results indicate that low-intensity treadmill exercise (first 5 minutes at a speed of 2 m/min, second 5 minutes at a speed of 5 m/min, and the last 20 minutes at a speed of 8 m/min) or bright-light exposure therapy induces positive biochemical changes in the brain. In view of these findings, we propose that moderate exercise or exposure to sunlight during childhood can be beneficial for neural development.

  7. A phase response curve to single bright light pulses in human subjects

    Science.gov (United States)

    Khalsa, Sat Bir S.; Jewett, Megan E.; Cajochen, Christian; Czeisler, Charles A.

    2003-01-01

    The circadian pacemaker is differentially sensitive to the resetting effects of retinal light exposure, depending upon the circadian phase at which the light exposure occurs. Previously reported human phase response curves (PRCs) to single bright light exposures have employed small sample sizes, and were often based on relatively imprecise estimates of circadian phase and phase resetting. In the present study, 21 healthy, entrained subjects underwent pre- and post-stimulus constant routines (CRs) in dim light (approximately 2-7 lx) with maintained wakefulness in a semi-recumbent posture. The 6.7 h bright light exposure stimulus consisted of alternating 6 min fixed gaze (approximately 10 000 lx) and free gaze (approximately 5000-9000 lx) exposures. Light exposures were scheduled across the circadian cycle in different subjects so as to derive a PRC. Plasma melatonin was used to determine the phase of the onset, offset, and midpoint of the melatonin profiles during the CRs. Phase shifts were calculated as the difference in phase between the pre- and post-stimulus CRs. The resultant PRC of the midpoint of the melatonin rhythm revealed a characteristic type 1 PRC with a significant peak-to-trough amplitude of 5.02 h. Phase delays occurred when the light stimulus was centred prior to the critical phase at the core body temperature minimum, phase advances occurred when the light stimulus was centred after the critical phase, and no phase shift occurred at the critical phase. During the subjective day, no prolonged 'dead zone' of photic insensitivity was apparent. Phase shifts derived using the melatonin onsets showed larger magnitudes than those derived from the melatonin offsets. These data provide a comprehensive characterization of the human PRC under highly controlled laboratory conditions.

  8. The acute side effects of bright light therapy: a placebo-controlled investigation.

    Directory of Open Access Journals (Sweden)

    Yevgeny Botanov

    Full Text Available Despite the emergence of numerous clinical and non-clinical applications of bright light therapy (LT in recent decades, the prevalence and severity of LT side effects have not yet been fully explicated. A few adverse LT effects-headache, eye strain, irritability, and nausea-have been consistently reported among depressed individuals and other psychiatric cohorts, but there exists little published evidence regarding LT side effects in non-clinical populations, who often undergo LT treatment of considerably briefer duration. Accordingly, in the present study we examined, in a randomized sample of healthy young adults, the acute side effects of exposure to a single 30-minute session of bright white light (10,000 lux versus dim red light (< 500 lux. Across a broad range of potential side effects, repeated-measures analyses of variance revealed no significant group-by-time (Pre, Post interactions. In other words, bright light exposure was not associated with a significantly higher incidence of any reported side effect than was the placebo control condition. Nevertheless, small but statistically significant increases in both eye strain and blurred vision were observed among both the LT and control groups. Overall, these results suggest that the relatively common occurrence of adverse side effects observed in the extant LT literature may not fully extend to non-clinical populations, especially for healthy young adults undergoing LT for a brief duration.

  9. Highly Bright White Organic Light-Emitting Diode

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ A highly bright white organic light-emitting diode (OLED) was realized by using a highly bright blue emitting layer, 1,7-diphenyl-4-biphenyl-3,5-dimethyl-l,7-dihydrodipyrazolo[3,4-b;4',3'-e]pyridine (PAP-Ph), together with a 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM)-doped Alq [tris(8-hydroxyquinolinato) aluminum (Ⅲ)] layer to provide the blue, red and green emission for color mixing. With appropriate thickness control, the white-light OLED has a performance that reaches 24700 cd/m2 at 15 V, 1.93 lm/W at 6.5 V, and >300 cd/m2 at 7.7 mA/em2. The Commission Internationale de l'Eclairage (CIE) coordinates of the emitted light vary in a very small range, from (0.35, 0.34) to (0.34, 0.35), when forward voltages change from 6 to 12 V.

  10. Highly Bright White Organic Light-Emitting Diode

    Institute of Scientific and Technical Information of China (English)

    KO; C.; W.

    2001-01-01

    A highly bright white organic light-emitting diode (OLED) was realized by using a highly bright blue emitting layer, 1,7-diphenyl-4-biphenyl-3,5-dimethyl-l,7-dihydrodipyrazolo[3,4-b;4',3'-e]pyridine (PAP-Ph), together with a 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM)-doped Alq [tris(8-hydroxyquinolinato) aluminum (Ⅲ)] layer to provide the blue, red and green emission for color mixing. With appropriate thickness control, the white-light OLED has a performance that reaches 24700 cd/m2 at 15 V, 1.93 lm/W at 6.5 V, and >300 cd/m2 at 7.7 mA/em2. The Commission Internationale de l'Eclairage (CIE) coordinates of the emitted light vary in a very small range, from (0.35, 0.34) to (0.34, 0.35), when forward voltages change from 6 to 12 V.  ……

  11. 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%.

  12. Light-induced melatonin suppression at night after exposure to different wavelength composition of morning light.

    Science.gov (United States)

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

    2016-03-11

    Bright nocturnal light has been shown to suppress melatonin secretion. However, bright light exposure during the day might reduce light-induced melatonin suppression at night. The human circadian system is sensitive to short wavelength light. This study evaluated the preventive effect of different wavelengths of daytime light on light-induced melatonin suppression at night. Twelve male subjects were exposed to various light conditions (dim, white, and bluish white light) between the hours of 09:00 and 10:30 (daytime light conditions). They were then exposed to light (300lx) again between 01:00 and 02:30 (night-time light exposure). Subjects provided saliva samples before (00:55) and after night-time light exposure (02:30). A two-tailed paired t-test yielded significant decrements in melatonin concentrations after night-time light exposure under daytime dim and white light conditions. No significant differences were found in melatonin concentrations between pre- and post-night-time light exposure with bluish-white light. Present findings suggest that daytime blue light exposure has an acute preventive impact on light-induced melatonin suppression in individuals with a general life rhythm (sleep/wake schedule). These findings may be useful for implementing artificial light environments for humans in, for example, hospitals and underground shopping malls to reduce health risks.

  13. 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

  14. Bright light-emitting diodes based on organometal halide perovskite.

    Science.gov (United States)

    Tan, Zhi-Kuang; Moghaddam, Reza Saberi; Lai, May Ling; Docampo, Pablo; Higler, Ruben; Deschler, Felix; Price, Michael; Sadhanala, Aditya; Pazos, Luis M; Credgington, Dan; Hanusch, Fabian; Bein, Thomas; Snaith, Henry J; Friend, Richard H

    2014-09-01

    Solid-state light-emitting devices based on direct-bandgap semiconductors have, over the past two decades, been utilized as energy-efficient sources of lighting. However, fabrication of these devices typically relies on expensive high-temperature and high-vacuum processes, rendering them uneconomical for use in large-area displays. Here, we report high-brightness light-emitting diodes based on solution-processed organometal halide perovskites. We demonstrate electroluminescence in the near-infrared, green and red by tuning the halide compositions in the perovskite. In our infrared device, a thin 15 nm layer of CH3NH3PbI(3-x)Cl(x) perovskite emitter is sandwiched between larger-bandgap titanium dioxide (TiO2) and poly(9,9'-dioctylfluorene) (F8) layers, effectively confining electrons and holes in the perovskite layer for radiative recombination. We report an infrared radiance of 13.2 W sr(-1) m(-2) at a current density of 363 mA cm(-2), with highest external and internal quantum efficiencies of 0.76% and 3.4%, respectively. In our green light-emitting device with an ITO/PEDOT:PSS/CH3NH3PbBr3/F8/Ca/Ag structure, we achieved a luminance of 364 cd m(-2) at a current density of 123 mA cm(-2), giving external and internal quantum efficiencies of 0.1% and 0.4%, respectively. We show, using photoluminescence studies, that radiative bimolecular recombination is dominant at higher excitation densities. Hence, the quantum efficiencies of the perovskite light-emitting diodes increase at higher current densities. This demonstration of effective perovskite electroluminescence offers scope for developing this unique class of materials into efficient and colour-tunable light emitters for low-cost display, lighting and optical communication applications.

  15. Bright morning light advances the human circadian system without affecting NREM sleep homeostasis

    NARCIS (Netherlands)

    Dijk, Derk Jan; Beersma, Domien G.M.; Daan, Serge; Lewy, Alfred J.

    1989-01-01

    Eight male subjects were exposed to either bright light or dim light between 0600 and 0900 h for 3 consecutive days each. Relative to the dim light condition, the bright light treatment advanced the evening rise in plasma melatonin and the time of sleep termination (sleep onset was held constant) fo

  16. 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...... patients, as an awakening profile, before medication and light therapy started. The CAR was calculated by using three time-points: awakening and 20 and 60 min after awakening. RESULTS: Patients with low CAR had a very substantial effect of bright light therapy compared with dim light therapy, whereas...... patients with a high CAR had no effect of bright light therapy compared with dim light therapy. CONCLUSION: High CAR was associated with an impairment of the effect of bright light therapy. This result raises the question of whether bright light acts through a mechanism different from...

  17. The plastoquinone pool of Nannochloropsis oceanica is not completely reduced during bright light pulses.

    Science.gov (United States)

    Røkke, Gunvor; Melø, Thor Bernt; Hohmann-Marriott, Martin Frank

    2017-01-01

    The lipid-producing model alga Nannochloropsis oceanica has a distinct photosynthetic machinery. This organism possesses chlorophyll a as its only chlorophyll species, and has a high ratio of PSI to PSII. This high ratio of PSI to PSII may affect the redox state of the plastoquinone pool during exposure to light, and consequently may play a role in activating photoprotection mechanisms. We utilized pulse-amplitude modulated fluorometry to investigate the redox state of the plastoquinone pool during and after bright light pulses. Our data indicate that even very intense (5910 μmol photons s-1m-2 of blue light having a wavelength of 440 nm) light pulses of 0.8 second duration are not sufficient to completely reduce the plastoquinone pool in Nannochloropsis. In order to achieve extensive reduction of the plastoquinone pool by bright light pulses, anaerobic conditions or an inhibitor of the photosynthetic electron transport chain has to be utilized. The implication of this finding for the application of the widely used saturating pulse method in algae is discussed.

  18. 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

  19. Pioneer 10 observations of zodiacal light brightness near the ecliptic - Changes with heliocentric distance

    Science.gov (United States)

    Hanner, M. S.; Weinberg, J. L.; Beeson, D. E.; Sparrow, J. G.

    1976-01-01

    Sky maps made by the Pioneer 10 Imaging Photopolarimeter (IPP) at sun-spacecraft distances from 1 to 3 AU have been analyzed to derive the brightness of the zodiacal light near the ecliptic at elongations greater than 90 degrees. The change in zodiacal light brightness with heliocentric distance is compared with models of the spatial distribution of the dust. Use of background starlight brightnesses derived from IPP measurements beyond the asteroid belt, where the zodiacal light is not detected, and, especially, use of a corrected calibration lead to considerably lower values for zodiacal light than those reported by us previously.

  20. Effects of light exposure and sleep displacement on dim light melatonin onset

    NARCIS (Netherlands)

    Gordijn, MCM; Beersma, DGM; Korte, HJ; Van den Hoofdakker, RH

    1999-01-01

    The purpose of the study was to induce in two different ways, a phase-angle difference between the circadian pacemaker and the imposed sleep-wake cycle in humans, we intended to: (i) shift the circadian pacemaker by exposure to bright light and keep the timing of the sleep-wake cycle fixed; and (ii)

  1. Lightness, brightness and transparency: a quarter century of new ideas, captivating demonstrations and unrelenting controversy.

    Science.gov (United States)

    Kingdom, Frederick A A

    2011-04-13

    The past quarter century has witnessed considerable advances in our understanding of Lightness (perceived reflectance), Brightness (perceived luminance) and perceived Transparency (LBT). This review poses eight major conceptual questions that have engaged researchers during this period, and considers to what extent they have been answered. The questions concern 1. the relationship between lightness, brightness and perceived non-uniform illumination, 2. the brain site for lightness and brightness perception, 3 the effects of context on lightness and brightness, 4. the relationship between brightness and contrast for simple patch-background stimuli, 5. brightness "filling-in", 6. lightness anchoring, 7. the conditions for perceptual transparency, and 8. the perceptual representation of transparency. The discussion of progress on major conceptual questions inevitably requires an evaluation of which approaches to LBT are likely and which are unlikely to bear fruit in the long term, and which issues remain unresolved. It is concluded that the most promising developments in LBT are (a) models of brightness coding based on multi-scale filtering combined with contrast normalization, (b) the idea that the visual system decomposes the image into "layers" of reflectance, illumination and transparency, (c) that an understanding of image statistics is important to an understanding of lightness errors, (d) Whittle's logW metric for contrast-brightness, (e) the idea that "filling-in" is mediated by low spatial frequencies rather than neural spreading, and (f) that there exist multiple cues for identifying non-uniform illumination and transparency. Unresolved issues include how relative lightness values are anchored to produce absolute lightness values, and the perceptual representation of transparency. Bridging the gap between multi-scale filtering and layer decomposition approaches to LBT is a major task for future research.

  2. Artificial light alters natural regimes of night-time sky brightness

    Science.gov (United States)

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

    2013-04-01

    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.

  3. Compact stacking of diode lasers for pulsed light sources of high brightness.

    Science.gov (United States)

    Alahautala, Taito; Lassila, Erkki; Hernberg, Rolf

    2004-07-20

    A compact stacking architecture for high-power diode-laser arrays is proposed and compared with traditional stacks. The objective of compact stacking is to achieve high brightness values without the use of microlenses. The calculated brightness for a compact stack is over 300 W mm(-2) sr(-1), which is approximately 40 times higher than that of a traditional stack made of similar laser emitters. Even higher brightness values of over 600 W mm(-2) sr(-1) were reached in practice. A laser head was manufactured in which the light from several compact laser stacks could be fiber coupled or the light could be transformed to a highly uniform beam.

  4. Bright Lights: Big Experiments! A public engagement activity for international year of light

    Science.gov (United States)

    Downie, Jonathan; Morton, Jonathan A. S.; McCoustra, Martin R. S.

    2017-01-01

    The Bright Lights: Big Experiments! public engagement project enabled high school students Scottish S2 to prepare a short, 5 min video using their own words and in their own style to present a scientific experiment on the theme of light to their contemporaries via YouTube. This paper describes the various experiments that we chose to deliver and our experiences in delivering them to our partner schools. The results of pre- and post-activity surveys of both the pupils and teachers are presented in an effort to understand the impact of the project on the students, staff and their schools. The quality of the final video product is shown to be a key factor, increasing the pupils’ likelihood of pursuing science courses and participating in further science engagement activities. Analysis of the evaluation methods used indicate the need for more sensitive tools to provide further insight into the impact of this type of engagement activity.

  5. Developing a new supplemental lighting device with ultra-bright white LED for vegetables

    Science.gov (United States)

    Hu, Yongguang; Li, Pingping; Jiang, Jianghai

    2007-02-01

    It has been proved that monochromatic or compound light-emitting diode (LED) or laser diode (LD) can promote the photosynthesis of horticultural crops, but the promotion of polychromatic light like white LED is unclear. A new type of ultra-bright white LED (LUW56843, InGaN, \

  6. Bright Light-Emitting Diodes Based on Organometal Halide Perovskite Nanoplatelets.

    Science.gov (United States)

    Ling, Yichuan; Yuan, Zhao; Tian, Yu; Wang, Xi; Wang, Jamie C; Xin, Yan; Hanson, Kenneth; Ma, Biwu; Gao, Hanwei

    2016-01-13

    Bright light-emitting diodes based on solution-processable organometal halide perovskite nanoplatelets are demonstrated. The nanoplatelets created using a facile one-pot synthesis exhibit narrow-band emissions at 529 nm and quantum yield up to 85%. Using these nanoparticles as emitters, efficient electroluminescence is achieved with a brightness of 10 590 cd m(-2) . These ligand-capped nanoplatelets appear to be quite stable in moisture, allowing out-of-glovebox device fabrication.

  7. Volume-scalable high-brightness three-dimensional visible light source

    Science.gov (United States)

    Subramania, Ganapathi; Fischer, Arthur J; Wang, George T; Li, Qiming

    2014-02-18

    A volume-scalable, high-brightness, electrically driven visible light source comprises a three-dimensional photonic crystal (3DPC) comprising one or more direct bandgap semiconductors. The improved light emission performance of the invention is achieved based on the enhancement of radiative emission of light emitters placed inside a 3DPC due to the strong modification of the photonic density-of-states engendered by the 3DPC.

  8. Phosphorescent organic light emitting diodes with high efficiency and brightness

    Science.gov (United States)

    Forrest, Stephen R; Zhang, Yifan

    2015-11-12

    An organic light emitting device including a) an anode; b) a cathode; and c) an emissive layer disposed between the anode and the cathode, the emissive layer comprising an organic host compound and a phosphorescent compound exhibiting a Stokes Shift overlap greater than 0.3 eV. The organic light emitting device may further include a hole transport layer disposed between the emissive layer and the anode; and an electron transport layer disposed between the emissive layer and the cathode. In some embodiments, the phosphorescent compound exhibits a phosphorescent lifetime of less than 10 .mu.s. In some embodiments, the concentration of the phosphorescent compound ranges from 0.5 wt. % to 10 wt. %.

  9. Contributions of artificial lighting sources on light pollution in Hong Kong measured through a night sky brightness monitoring network

    CERN Document Server

    Pun, Chun Shing Jason; Leung, Wai Yan; Wong, Chung Fai

    2014-01-01

    Light pollution is a form of environmental degradation in which excessive artificial outdoor lighting, such as street lamps, neon signs, and illuminated signboards, affects the natural environment and the ecosystem. Poorly designed outdoor lighting not only wastes energy, money, and valuable Earth resources, but also robs us of our beautiful night sky. Effects of light pollution on the night sky can be evaluated by the skyglow caused by these artificial lighting sources, through measurements of the night sky brightness (NSB). The Hong Kong Night Sky Brightness Monitoring Network (NSN) was established to monitor in detail the conditions of light pollution in Hong Kong. Monitoring stations were set up throughout the city covering a wide range of urban and rural settings to continuously measure the variations of the NSB. Over 4.6 million night sky measurements were collected from 18 distinct locations between May 2010 and March 2013. This huge dataset, over two thousand times larger than our previous survey, for...

  10. Do Wild Great Tits Avoid Exposure to Light at Night?

    Science.gov (United States)

    de Jong, Maaike; Ouyang, Jenny Q; van Grunsven, Roy H A; Visser, Marcel E; Spoelstra, Kamiel

    2016-01-01

    Studies of wild populations have provided important insights into the effects of artificial light at night on organisms, populations and ecosystems. However, in most studies the exact amount of light at night individuals are exposed to remains unknown. Individuals can potentially control their nighttime light exposure by seeking dark spots within illuminated areas. This uncertainty makes it difficult to attribute effects to a direct effect of light at night, or to indirect effects, e.g., via an effect of light at night on food availability. In this study, we aim to quantify the nocturnal light exposure of wild birds in a previously dark forest-edge habitat, experimentally illuminated with three different colors of street lighting, in comparison to a dark control. During two consecutive breeding seasons, we deployed male great tits (Parus major) with a light logger measuring light intensity every five minutes over a 24h period. We found that three males from pairs breeding in brightly illuminated nest boxes close to green and red lamp posts, were not exposed to more artificial light at night than males from pairs breeding further away. This suggests, based on our limited sample size, that these males could have been avoiding light at night by choosing a roosting place with a reduced light intensity. Therefore, effects of light at night previously reported for this species in our experimental set-up might be indirect. In contrast to urban areas where light is omnipresent, bird species in non-urban areas may evade exposure to nocturnal artificial light, thereby avoiding direct consequences of light at night.

  11. Do Wild Great Tits Avoid Exposure to Light at Night?

    Directory of Open Access Journals (Sweden)

    Maaike de Jong

    Full Text Available Studies of wild populations have provided important insights into the effects of artificial light at night on organisms, populations and ecosystems. However, in most studies the exact amount of light at night individuals are exposed to remains unknown. Individuals can potentially control their nighttime light exposure by seeking dark spots within illuminated areas. This uncertainty makes it difficult to attribute effects to a direct effect of light at night, or to indirect effects, e.g., via an effect of light at night on food availability. In this study, we aim to quantify the nocturnal light exposure of wild birds in a previously dark forest-edge habitat, experimentally illuminated with three different colors of street lighting, in comparison to a dark control. During two consecutive breeding seasons, we deployed male great tits (Parus major with a light logger measuring light intensity every five minutes over a 24h period. We found that three males from pairs breeding in brightly illuminated nest boxes close to green and red lamp posts, were not exposed to more artificial light at night than males from pairs breeding further away. This suggests, based on our limited sample size, that these males could have been avoiding light at night by choosing a roosting place with a reduced light intensity. Therefore, effects of light at night previously reported for this species in our experimental set-up might be indirect. In contrast to urban areas where light is omnipresent, bird species in non-urban areas may evade exposure to nocturnal artificial light, thereby avoiding direct consequences of light at night.

  12. 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

    -light intervention led to a dose-dependent increase in risk-taking in the LA/LA group relative to the non-LA/LA group. Further, bright-light intervention enhanced risk-related activity in ventral striatum and head of caudate nucleus in proportion with the individual bright-light dose. The augmentation effect...

  13. 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...

  14. 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 ATD'

  15. 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...

  16. Skylab experiment SO73: Gegenschein/zodiacal light. [electrophotometry of surface brightness and polarization

    Science.gov (United States)

    Weinberg, J. L.

    1976-01-01

    A 10 color photoelectric polarimeter was used to measure the surface brightness and polarization associated with zodiacal light, background starlight, and spacecraft corona during each of the Skylab missions. Fixed position and sky scanning observations were obtained during Skylab missions SL-2 and SL-3 at 10 wavelenghts between 4000A and 8200A. Initial results from the fixed-position data are presented on the spacecraft corona and on the polarized brightness of the zodiacal light. Included among the fixed position regions that were observed are the north celestial pole, south ecliptic pole, two regions near the north galactic pole, and 90 deg from the sun in the ecliptic. The polarized brightness of the zodiacal light was found to have the color of the sun at each of these positions. Because previous observations found the total brightness to have the color of the sun from the near ultraviolet out to 2.4 micrometers, the degree of polarization of the zodiacal light is independent of wavelength from 4000A to 8200A.

  17. 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.

  18. Sleep-wake behavior in the rat: ultradian rhythms in a light-dark cycle and continuous bright light.

    Science.gov (United States)

    Stephenson, Richard; Lim, Joonbum; Famina, Svetlana; Caron, Aimee M; Dowse, Harold B

    2012-12-01

    Ultradian rhythms are a prominent but little-studied feature of mammalian sleep-wake and rest-activity patterns. They are especially evident in long-term records of behavioral state in polyphasic animals such as rodents. However, few attempts have been made to incorporate ultradian rhythmicity into models of sleep-wake dynamics, and little is known about the physiological mechanisms that give rise to ultradian rhythms in sleep-wake state. This study investigated ultradian dynamics in sleep and wakefulness in rats entrained to a 12-h:12-h light-dark cycle (LD) and in rats whose circadian rhythms were suppressed and free-running following long-term exposure to uninterrupted bright light (LL). We recorded sleep-wake state continuously for 7 to 12 consecutive days and used time-series analysis to quantify the dynamics of net cumulative time in each state (wakefulness [WAKE], rapid eye movement sleep [REM], and non-REM sleep [NREM]) in each animal individually. Form estimates and autocorrelation confirmed the presence of significant ultradian and circadian rhythms; maximum entropy spectral analysis allowed high-resolution evaluation of multiple periods within the signal, and wave-by-wave analysis enabled a statistical evaluation of the instantaneous period, peak-trough range, and phase of each ultradian wave in the time series. Significant ultradian periodicities were present in all 3 states in all animals. In LD, ultradian range was approximately 28% of circadian range. In LL, ultradian range was slightly reduced relative to LD, and circadian range was strongly attenuated. Ultradian rhythms were found to be quasiperiodic in both LD and LL. That is, ultradian period varied randomly around a mean of approximately 4 h, with no relationship between ultradian period and time of day.

  19. 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.

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

    CERN Document Server

    Pun, Chun Shing Jason

    2011-01-01

    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 per arcsec square) are on average ~100 times brighter than at the darkest rural sites (20.1 mag per arcsec square), 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 per arcsec square can be over 500 times brighter than the darkest sites in Hong Kong. The observed night-sky brightness is found to be affected by hu...

  1. Comparison of venlafaxine alone versus venlafaxine plus bright light therapy combination for severe major depressive disorder.

    Science.gov (United States)

    Güzel Özdemir, Pınar; Boysan, Murat; Smolensky, Michael H; Selvi, Yavuz; Aydin, Adem; Yilmaz, Ekrem

    2015-05-01

    Phototherapy, ie, bright light therapy, is an effective and safe treatment of major depressive disorder (MDD). It exerts rapid mood-elevating activity, similar to antidepressant medications, most likely mediated through both monoaminergic and circadian system melatonergic mechanisms. We assessed the efficiency of bright light therapy as an adjuvant treatment to antidepressant pharmacotherapy in patients with severe MDD randomized by Hamilton Depression Rating Scale (HDRS) score to either (1) 150 mg venlafaxine hydrochloride daily at 7:00 AM or (2) 150 mg venlafaxine plus 60-minute light of 7000 lux the initial week of clinical management (venlafaxine + bright light therapy) daily at 7:00 AM. 50 inpatients with severe MDD at the Psychiatry Clinic of Yüzüncü Yıl University Training and Education Hospital participated. The study, which was conducted from January 2013 through June 2014, entailed patients diagnosed with severe MDD based on DSM-IV-TR for the first time. Mood states were assessed by the HDRS, Profile of Mood States (POMS), and Beck Depression Inventory (BDI) before treatment and at 1, 2, 4, and 8 weeks of treatment. On the basis of the HDRS score as the primary outcome variable, both strategies significantly improved depression and negative mood states already at the first treatment week (P treatment strategy were remarkable at the second and fourth weeks of clinical management (P = .018 and P = .011, respectively), with beneficial effects continuing until trial conclusion. Those treated with venlafaxine + bright light therapy evidenced significantly lower HDRS depression scores (P depression-dejection, tension-anxiety, anger-hostility, fatigue-inertia, and confusion-bewilderment subscales; all P treatment, a HDRS score ≤ 13, indicative of mild depression, and, although not statistically significant in our small sample study (P = .36), at week 8, 76% of venlafaxine + bright light therapy patients (n = 19) versus just 64% of the venlafaxine patients

  2. Physiological responses to daily light exposure

    Science.gov (United States)

    Yang, Yefeng; Yu, Yonghua; Yang, Bo; Zhou, Hong; Pan, Jinming

    2016-04-01

    Long daylength artificial light exposure associates with disorders, and a potential physiological mechanism has been proposed. However, previous studies have examined no more than three artificial light treatments and limited metabolic parameters, which have been insufficient to demonstrate mechanical responses. Here, comprehensive physiological response curves were established and the physiological mechanism was strengthened. Chicks were illuminated for 12, 14, 16, 18, 20, or 22 h periods each day. A quadratic relationship between abdominal adipose weight (AAW) and light period suggested that long-term or short-term light exposure could decrease the amount of AAW. Quantitative relationships between physiological parameters and daily light period were also established in this study. The relationships between triglycerides (TG), cholesterol (TC), glucose (GLU), phosphorus (P) levels and daily light period could be described by quadratic regression models. TG levels, AAW, and BW positively correlated with each other, suggesting long-term light exposure significantly increased AAW by increasing TG thus resulting in greater BW. A positive correlation between blood triiodothyronine (T3) levels and BW suggested that daily long-term light exposure increased BW by thyroid hormone secretion. Though the molecular pathway remains unknown, these results suggest a comprehensive physiological mechanism through which light exposure affects growth.

  3. 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.

  4. Hybrid quantum repeater based on dispersive CQED interactions between matter qubits and bright coherent light

    CERN Document Server

    Ladd, T D; Nemoto, K; Munro, W J; Yamamoto, Y; Ladd, Thaddeus D.; Loock, Peter van; Nemoto, Kae; Munro, William J.; Yamamoto, Yoshihisa

    2006-01-01

    We describe a system for long-distance distribution of quantum entanglement, in which coherent light with large average photon number interacts dispersively with single, far-detuned atoms or semiconductor impurities in optical cavities. Entanglement is heralded by homodyne detection using a second bright light pulse for phase reference. The use of bright pulses leads to a high success probability for the generation of entanglement, at the cost of a lower initial fidelity. This fidelity may be boosted by entanglement purification techniques, implemented with the same physical resources. The need for more purification steps is well compensated for by the increased probability of success when compared to heralded entanglement schemes using single photons or weak coherent pulses with realistic detectors. The principle cause of the lower initial fidelity is fiber loss; however, spontaneous decay and cavity losses during the dispersive atom/cavity interactions can also impair performance. We show that these effects...

  5. Gamut relativity: a new computational approach to brightness and lightness perception.

    Science.gov (United States)

    Vladusich, Tony

    2013-01-09

    This article deconstructs the conventional theory that "brightness" and "lightness" constitute perceptual dimensions corresponding to the physical dimensions of luminance and reflectance, and builds in its place the theory that brightness and lightness correspond to computationally defined "modes," rather than dimensions, of perception. According to the theory, called gamut relativity, "blackness" and "whiteness" constitute the perceptual dimensions (forming a two-dimensional "blackness-whiteness" space) underlying achromatic color perception (black, white, and gray shades). These perceptual dimensions are postulated to be related to the neural activity levels in the ON and OFF channels of vision. The theory unifies and generalizes a number of extant concepts in the brightness and lightness literature, such as simultaneous contrast, anchoring, and scission, and quantitatively simulates several challenging perceptual phenomena, including the staircase Gelb effect and the effects of task instructions on achromatic color-matching behavior, all with a single free parameter. The theory also provides a new conception of achromatic color constancy in terms of the relative distances between points in blackness-whiteness space. The theory suggests a host of striking conclusions, the most important of which is that the perceptual dimensions of vision should be generically specified according to the computational properties of the brain, rather than in terms of "reified" physical dimensions. This new approach replaces the computational goal of estimating absolute physical quantities ("inverse optics") with the goal of computing object properties relatively.

  6. Quantum emitters coupled to circular nanoantennas for high-brightness quantum light sources

    Science.gov (United States)

    Abudayyeh, Hamza A.; Rapaport, Ronen

    2017-09-01

    Engineering the directionality and emission rate of quantum light sources is essential in the development of modern quantum applications. In this work we use numerical calculations to optimise the brightness of a broadband quantum emitter positioned in a hybrid metal-dielectric circular periodic nanoantenna. The optimised structure features a photon collection efficiency of 74 % (82 % ) and a photon flux enhancement of over 10 (6) into a numerical aperture of 0.22 (0.50), respectively, corresponding to a direct coupling into two types of multi-mode fibres. To enhance the emission rate, we present a new circular nanoantenna design where a quantum emitter is attached to a silver nanocone at the centre of the antenna. After optimisation, we find a collection efficiency of 61 % (78 % ) into a numerical aperture of 0.22 (0.50), giving a brightness enhancement of 1000 (600) for an unpolarised emitter. The enhancements in both structures are broadband due to the low-quality factor of the device and are therefore ideal for room-temperature sources. This type of a scalable design can be utilised towards on-chip, high-brightness quantum light sources operating at room temperature.

  7. A novel high-brightness broadband light-source technology from the VUV to the IR

    Science.gov (United States)

    Horne, Stephen; Smith, Don; Besen, Matthew; Partlow, Matthew; Stolyarov, Daniil; Zhu, Huiling; Holber, William

    2010-04-01

    A novel technology has been developed which enables high-brightness, broadband light output from the VUV to the IR spectral regions. A focused laser is used to sustain a high-pressure xenon discharge inside a bulb, creating a smaller, hotter discharge than can be obtained by using an electrically-driven discharge. This allows for continuous output down to 120 nm wavelength and into the infrared. Application areas include hyperspectral imaging, standoff detection, surveillance, bioanalytical instrumentation, microscopy, and materials studies. Laser-driven optical discharges were first investigated over 30 years ago, providing the initial technical understanding of such discharges. However it took the convergence of two separate elements - the availability of low-cost, high-efficiency CW diode lasers; and a market need for high-brightness, broadband light source - to provide the impetus for further development in this area. Using near-IR CW diode lasers at power levels from 15 W to over 2000 W, we have generated high-pressure xenon discharges having temperatures as high as 10,000 C. The optical brightness of these discharges can be over an order of magnitude higher than those obtainable from the brightest xenon arc lamps, and can be several orders of magnitude brighter than deuterium lamps. Results from modeling of these discharges as well as experimental measurements will be presented.

  8. 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.

  9. Determining contrast sensitivity functions for monochromatic light emitted by high-brightness LEDs

    Science.gov (United States)

    Ramamurthy, Vasudha; Narendran, Nadarajah; Freyssinier, Jean Paul; Raghavan, Ramesh; Boyce, Peter

    2004-01-01

    Light-emitting diode (LED) technology is becoming the choice for many lighting applications that require monochromatic light. However, one potential problem with LED-based lighting systems is uneven luminance patterns. Having a uniform luminance distribution is more important in some applications. One example where LEDs are becoming a viable alternative and luminance uniformity is an important criterion is backlighted monochromatic signage. The question is how much uniformity is required for these applications. Presently, there is no accepted metric that quantifies luminance uniformity. A recent publication proposed a method based on digital image analysis to quantify beam quality of reflectorized halogen lamps. To be able to employ such a technique to analyze colored beams generated by LED systems, it is necessary to have contrast sensitivity functions (CSFs) for monochromatic light produced by LEDs. Several factors including the luminance, visual field size, and spectral power distribution of the light affect the CSFs. Although CSFs exist for a variety of light sources at visual fields ranging from 2 degrees to 20 degrees, CSFs do not exist for red, green, and blue light produced by high-brightness LEDs at 2-degree and 10-degree visual fields and at luminances typical for backlighted signage. Therefore, the goal of the study was to develop a family of CSFs for 2-degree and 10-degree visual fields illuminated by narrow-band LEDs at typical luminances seen in backlighted signs. The details of the experiment and the results are presented in this manuscript.

  10. Aggregation in quads but not pairs of rats exposed to cat odor or bright light.

    Science.gov (United States)

    Bowen, Michael T; Keats, Kirily; Kendig, Michael D; Cakic, Vince; Callaghan, Paul D; McGregor, Iain S

    2012-07-01

    In many prey species aggregation of individuals is a defensive strategy commonly employed in response to predators and predator-related cues. However, very little work has explored this adaptive response in laboratory rats. It is known that individual rats show characteristic defensive responses to predator odors, such as hiding, avoidance, inhibition of foraging, feeding and reproduction, and risk assessment directed toward the odor source. However, whether these species-typical responses in individuals are altered in the presence of other conspecifics is yet to be characterized. The present study therefore examined the defensive response of groups of two rats (dyads) or four rats (quads) to two unconditioned stressors: bright ambient light and cat odor (a 2g ball of cat fur). The dyads and quads were formed from familiar cage mates and test sessions (20 min) occurred in a large open arena (1200 mm(2)) to which the rats had been extensively habituated under dark conditions. The results showed that when quads of rats were exposed to either cat odor or bright light in this arena, they showed characteristic increases in close social proximity, termed "huddling". A tight grouping of 3 (triplet) or 4 (quad) rats was commonly seen in response to cat fur, while triplets were more commonly seen in response to bright light. Interestingly there was no evidence for increased social proximity in dyads exposed to either stressor, only in quads. However, cat odor caused other signs of fear (such as decreased locomotor activity and increased defecation) in both quads and dyads. It is concluded that huddling is a rodent defensive strategy in rats when anxiogenic stimuli are encountered by larger groups of rats. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Bright hybrid white light-emitting quantum dot device with direct charge injection into quantum dot

    Science.gov (United States)

    Cao, Jin; Xie, Jing-Wei; Wei, Xiang; Zhou, Jie; Chen, Chao-Ping; Wang, Zi-Xing; Jhun, Chulgyu

    2016-12-01

    A bright white quantum dot light-emitting device (white-QLED) with 4-[4-(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl]-2- [3-(tri-phenylen-2-yl)phen-3-yl]quinazoline deposited on a thin film of mixed green/red-QDs as a bilayer emitter is fabricated. The optimized white-QLED exhibits a turn-on voltage of 3.2 V and a maximum brightness of 3660 cd/m2@8 V with the Commission Internationale de l’Eclairage (CIE) chromaticity in the region of white light. The ultra-thin layer of QDs is proved to be critical for the white light generation in the devices. Excitation mechanism in the white-QLEDs is investigated by the detailed analyses of electroluminescence (EL) spectral and the fluorescence lifetime of QDs. The results show that charge injection is a dominant mechanism of excitation in the white-QLED. Project supported by the National Natural Science Foundation of China (Grant No. 21302122) and the Science and Technology Commission of Shanghai Municipality, China (Grant No. 13ZR1416600).

  12. 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.

  13. Growth of highly bright-white silica nanowires as diffusive reflection coating in LED lighting.

    Science.gov (United States)

    Xi, Shuang; Shi, Tielin; Zhang, Lei; Liu, Dan; Lai, Wuxing; Tang, Zirong

    2011-12-19

    Large quantities of silica nanowires were synthesized through thermal treatment of silicon wafer in the atmosphere of N(2)/H(2)(5%) under 1200 °C with Cu as catalyst. These nanowires grew to form a natural bright-white mat, which showed highly diffusive reflectivity over the UV-visible range, with more than 60% at the whole range and up to 88% at 350 nm. The utilization of silica nanowires in diffusive coating on the reflector cup of LED is demonstrated, which shows greatly improved light distribution comparing with the specular reflector cup. It is expected that these nanowires can be promising coating material for optoelectronic applications.

  14. Graded Heterojunction of AlGaInP High-brightness Light Emitting Diodes

    Institute of Scientific and Technical Information of China (English)

    LIU Lu; FAN Guang-han; LIAO Chang-jun

    2004-01-01

    A simple model of the graded heterojunction in AlGaInP compound semiconductors was introduced to analyze the band profile. The band profiles are analyzed with the different grading ways but the same grading length and under the different doping densities. The effect of the different grading lengths on the surplus of the potential of the spike to the potential of N region are also analyzed under the different doping densities.Through the experiments,it proves that the performances of high brightness light emitting diodes can be improved by the effects of the graded heterojunction.

  15. 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

  16. Sliding Mode Pulsed Averaging IC Drivers for High Brightness Light Emitting Diodes

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Anatoly Shteynberg, PhD

    2006-08-17

    This project developed new Light Emitting Diode (LED) driver ICs associated with specific (uniquely operated) switching power supplies that optimize performance for High Brightness LEDs (HB-LEDs). The drivers utilize a digital control core with a newly developed nonlinear, hysteretic/sliding mode controller with mixed-signal processing. The drivers are flexible enough to allow both traditional microprocessor interface as well as other options such as “on the fly” adjustment of color and brightness. Some other unique features of the newly developed drivers include • AC Power Factor Correction; • High power efficiency; • Substantially fewer external components should be required, leading to substantial reduction of Bill of Materials (BOM). Thus, the LED drivers developed in this research : optimize LED performance by increasing power efficiency and power factor. Perhaps more remarkably, the LED drivers provide this improved performance at substantially reduced costs compared to the present LED power electronic driver circuits. Since one of the barriers to market penetration for HB-LEDs (in particular “white” light LEDs) is cost/lumen, this research makes important contributions in helping the advancement of SSL consumer acceptance and usage.

  17. Drop-out and mood improvement: a randomised controlled trial with light exposure and physical exercise [ISRCTN36478292

    Directory of Open Access Journals (Sweden)

    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.

  18. Light curve solutions for bright detached eclipsing binaries in SMC: absolute dimensions and distance indicators

    CERN Document Server

    Graczyk, D

    2003-01-01

    This paper presents a careful and detailed light curve analysis of bright detached eclipsing binaries (DEB) in the Small Magellanic Cloud, discovered by OGLE collaboration, on the basis of recently available difference image analysis (DIA) photometry. The 19 binaries brighter than 16.4 mag in I band and with the depth of primary and secondary eclipse greater than 0.25 mag were investigated. The solutions were obtained by a modified version of the Wilson-Devinney program. The quality of DIA light curves - a good phase coverage and relatively small scatter - is enough to calculate realistic estimates for the third light l_3 and the argument of periastron. It was found that solutions of detached, eccentric systems with flat light curve between eclipses usually may suffer from indetermination of l_3 in contrast to those of similar systems having some proximity effects. The physical properties of the stars were estimated on the basis of their photometric elements and indices assuming the distance modulus to SMC ~1...

  19. LCD brightness decay due to particulate contamination of back light unit

    Science.gov (United States)

    Kim, Sanghoon; Lee, Sang-Chul; Yook, Se-Jin; Choi, Jung-Uk; Ahn, Kang-Ho

    2013-01-01

    So far, particulate contamination problems occurring in cleanroom environments have been intensively investigated by considering the product yield in semiconductor manufacturing or liquid crystal display (LCD) manufacturing. This study, however, focused on the particulate contamination problem causing the degradation of LCD TVs run in common environments. A field test was conducted by running a LCD TV in an office room for 60 days in order to collect and analyze the particles contaminating the backlight unit (BLU) of the LCD TV. Based on the field test result, soot particles were generated to simulate the contaminant particles, and an accelerated test was performed by exposing the LCD TV to a soot aerosol of relatively high concentration. As the exposure time was increased, the degree of particulate contamination of the BLU became more severe, and the decay rate of the LCD brightness increased. As a result, the particulate contamination of the BLU was found to greatly affect the decay rate of the LCD brightness. A numerical simulation was performed to elucidate the mechanism of particle influx into the BLU and to predict the particle deposition pattern. The contaminant particles could enter into the BLU through the gaps on the BLU casing due to the air flow induced by natural convection in the BLU. The particles were thought to have been deposited on the walls in the BLU, especially at the corner regions.

  20. Differential regulation of circadian melatonin rhythm and sleep-wake cycle by bright lights and nonphotic time cues in humans.

    Science.gov (United States)

    Yamanaka, Yujiro; Hashimoto, Satoko; Masubuchi, Satoru; Natsubori, Akiyo; Nishide, Shin-Ya; Honma, Sato; Honma, Ken-Ichi

    2014-09-01

    Our previous study demonstrated that physical exercise under dim lights (cycle but not the circadian melatonin rhythm to an 8-h phase-advanced sleep schedule, indicating differential effects of physical exercise on the human circadian system. The present study examined the effects of bright light (>5,000 lux) on exercise-induced acceleration of reentrainment because timed bright lights are known to reset the circadian pacemaker. Fifteen male subjects spent 12 days in temporal isolation. The sleep schedule was advanced from habitual sleep times by 8 h for 4 days, which was followed by a free-run session. In the shift session, bright lights were given during the waking time. Subjects in the exercise group performed 2-h bicycle running twice a day. Subjects in the control kept quiet. As a result, the sleep-wake cycle was fully entrained by the shift schedule in both groups. Bright light may strengthen the resetting potency of the shift schedule. By contrast, the circadian melatonin rhythm was phase-advanced by 6.9 h on average in the exercise group but only by 2.0 h in the control. Thus physical exercise prevented otherwise unavoidable internal desynchronization. Polysomnographical analyses revealed that deterioration of sleep quality by shift schedule was protected by physical exercise under bright lights. These findings indicate differential regulation of sleep-wake cycle and circadian melatonin rhythm by physical exercise in humans. The melatonin rhythm is regulated primarily by bright lights, whereas the sleep-wake cycle is by nonphotic time cues, such as physical exercise and shift schedule.

  1. Controlling an actively-quenched single photon detector with bright light.

    Science.gov (United States)

    Sauge, Sebastien; Lydersen, Lars; Anisimov, Andrey; Skaar, Johannes; Makarov, Vadim

    2011-11-01

    We control using bright light an actively-quenched avalanche single-photon detector. Actively-quenched detectors are commonly used for quantum key distribution (QKD) in the visible and near-infrared range. This study shows that these detectors are controllable by the same attack used to hack passively-quenched and gated detectors. This demonstrates the generality of our attack and its possible applicability to eavsdropping the full secret key of all QKD systems using avalanche photodiodes (APDs). Moreover, the commercial detector model we tested (PerkinElmer SPCM-AQR) exhibits two new blinding mechanisms in addition to the previously observed thermal blinding of the APD, namely: malfunctioning of the bias voltage control circuit, and overload of the DC/DC converter biasing the APD. These two new technical loopholes found just in one detector model suggest that this problem must be solved in general, by incorporating generally imperfect detectors into the security proof for QKD.

  2. The effect of systematic light exposure on sleep and sleep quality in a mixed group of fatigued cancer survivors

    DEFF Research Database (Denmark)

    Wu, Lisa; Amidi, Ali; Valdimarsdottir, Heiddis

    2017-01-01

    Study objectives: Sleep disturbances are commonly reported by cancer survivors. Systematic light exposure using bright light has been used to improve sleep in other populations. In this secondary data analysis, the effect of morning administration of bright light on sleep and sleep quality....... Wrist actigraphy and the Pittsburgh Sleep Quality Index were administered at 4 time points: prior to light treatment (baseline), 2 weeks into the intervention, during the last week of the intervention, and 3 weeks post-intervention. Thirty-seven participants completed the end-of-intervention assessment....... Results: Repeated measures linear mixed models indicated a statistically significant time by treatment group interaction effect with sleep efficiency improving more in the bright light condition over time compared with the dim light condition [F(3,42)=5.55; p=0.003] with a large effect size (eta2...

  3. Bright luminescence from pure DNA-curcumin–based phosphors for bio hybrid light-emitting diodes

    Science.gov (United States)

    Reddy, M. Siva Pratap; Park, Chinho

    2016-08-01

    Recently, significant advances have occurred in the development of phosphors for bio hybrid light-emitting diodes (Bio-HLEDs), which have created brighter, metal-free, rare-earth phosphor-free, eco-friendly, and cost-competitive features for visible light emission. Here, we demonstrate an original approach using bioinspired phosphors in Bio-HLEDs based on natural deoxyribonucleic acid (DNA)-curcumin complexes with cetyltrimethylammonium (CTMA) in bio-crystalline form. The curcumin chromophore was bound to the DNA double helix structure as observed using field emission tunnelling electron microscopy (FE-TEM). Efficient luminescence occurred due to tightly bound curcumin chromophore to DNA duplex. Bio-HLED shows low luminous drop rate of 0.0551 s‑1. Moreover, the solid bio-crystals confined the activating bright luminescence with a quantum yield of 62%, thereby overcoming aggregation-induced quenching effect. The results of this study herald the development of commercially viable large-scale hybrid light applications that are environmentally benign.

  4. Pupillary light reaction during high altitude exposure.

    Directory of Open Access Journals (Sweden)

    Maximilian Schultheiss

    Full Text Available PURPOSE: This study aimed to quantify the pupillary light reaction during high altitude exposure using the state of the art Compact Integrated Pupillograph (CIP and to investigate a potential correlation of altered pupil reaction with severity of acute mountain sickness (AMS. This work is related to the Tübingen High Altitude Ophthalmology (THAO study. METHODS: Parameters of pupil dynamics (initial diameter, amplitude, relative amplitude, latency, constriction velocity were quantified in 14 healthy volunteers at baseline (341 m and high altitude (4559 m over several days using the CIP. Scores of AMS, peripheral oxygen saturation and heart rate were assessed for respective correlations with pupil dynamics. For statistical analysis JMP was used and data are shown in terms of intra-individual normalized values (value during exposure/value at baseline and the 95% confidence interval for each time point. RESULTS: During high altitude exposure the initial diameter size was significantly reduced (p<0.05. In contrast, the amplitude, the relative amplitude and the contraction velocity of the light reaction were significantly increased (p<0.05 on all days measured at high altitude. The latency did not show any significant differences at high altitude compared to baseline recordings. Changes in pupil parameters did not correlate with scores of AMS. CONCLUSIONS: Key parameters of the pupillary light reaction are significantly altered at high altitude. We hypothesize that high altitude hypoxia itself as well as known side effects of high altitude exposure such as fatigue or exhaustion after ascent may account for an altered pupillogram. Interestingly, none of these changes are related to AMS.

  5. Pupillary Light Reaction during High Altitude Exposure

    Science.gov (United States)

    Schatz, Andreas; Wilhelm, Barbara; Peters, Tobias; Fischer, M. Dominik; Zrenner, Eberhart; Bartz-Schmidt, Karl U.; Gekeler, Florian; Willmann, Gabriel

    2014-01-01

    Purpose This study aimed to quantify the pupillary light reaction during high altitude exposure using the state of the art Compact Integrated Pupillograph (CIP) and to investigate a potential correlation of altered pupil reaction with severity of acute mountain sickness (AMS). This work is related to the Tübingen High Altitude Ophthalmology (THAO) study. Methods Parameters of pupil dynamics (initial diameter, amplitude, relative amplitude, latency, constriction velocity) were quantified in 14 healthy volunteers at baseline (341 m) and high altitude (4559 m) over several days using the CIP. Scores of AMS, peripheral oxygen saturation and heart rate were assessed for respective correlations with pupil dynamics. For statistical analysis JMP was used and data are shown in terms of intra-individual normalized values (value during exposure/value at baseline) and the 95% confidence interval for each time point. Results During high altitude exposure the initial diameter size was significantly reduced (p<0.05). In contrast, the amplitude, the relative amplitude and the contraction velocity of the light reaction were significantly increased (p<0.05) on all days measured at high altitude. The latency did not show any significant differences at high altitude compared to baseline recordings. Changes in pupil parameters did not correlate with scores of AMS. Conclusions Key parameters of the pupillary light reaction are significantly altered at high altitude. We hypothesize that high altitude hypoxia itself as well as known side effects of high altitude exposure such as fatigue or exhaustion after ascent may account for an altered pupillogram. Interestingly, none of these changes are related to AMS. PMID:24503770

  6. Gamma-ray Light Curves and Variability of Bright Fermi-Detected Blazars

    CERN Document Server

    Abdo, A A

    2010-01-01

    This paper presents light curves and the first systematic characterization of variability of the 106 objects in the Fermi Large Area Telescope (LAT) Bright AGN Sample (LBAS). Weekly light curves obtained during the first 11 months of survey (August 04, 2008 - July 04, 2009), are tested for variability, and their properties are quantified through autocorrelation and structure function analysis. For the brightest sources power density spectra (PDS) and fit of the temporal structure of major flares is performed. More than 50% of the sources are variable, where high states do not exceed 1/4 of the total observation range. Variation amplitudes are larger for FSRQs and low/intermediate synchrotron peaked (LSP/ISP) BL Lac objects. Autocorrelation time scales vary from 4 to a dozen of weeks. Variable sources of the sample have 1/(f^{a}) PDS and show two modes: (1) rather constant baseline with sporadic flaring activity characterized by flatter PDS slopes resembling flickering and red-noise with occasional intermitten...

  7. 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.

  8. Measurement Duration and Frequency Impact Objective Light Exposure Measures.

    Science.gov (United States)

    Ulaganathan, Sekar; Read, Scott A; Collins, Michael J; Vincent, Stephen J

    2017-05-01

    To determine the measurement duration and frequency required to reliably quantify the typical personal light exposure patterns of children and young adults. Ambient light exposure data were obtained from 31 young adults and 30 children using a wrist-worn light sensor configured to measure ambient light exposure every 30 seconds for 14 days. To examine the influence of measurement duration upon light exposure, the daily time exposed to outdoor light levels (>1000 lux) was initially calculated based upon data from all 14 days and then recalculated from 12, 10, 8, 6, 4, and 2 randomly selected days. To examine the influence of measurement frequency, the outdoor exposure time was calculated for a 30-second sampling rate and again after resampling at 1-, 2-, 3-, 4-, 5-, and 10-minute sampling rates. Children spent significantly greater time outdoors (44 minutes higher [95% CI: 26, 62]) compared to adults (P = .001). Children spent more time outdoors during the weekdays (13 minutes higher [-7, 32]) and adults spent more time outdoors during the weekends (24 minutes higher [7, 40]) (P = .005). Calculating light exposure using a lower number of days and coarser sampling frequencies did not significantly alter the group mean light exposure (P > .05). However, a significant increase in measurement variability occurred for outdoor light exposure derived from less than 8 days and 3 minutes or coarser measurement frequencies in adults, and from less than 8 days and 4 minutes or coarser frequencies in children (all P light exposure measures in children and young adults.

  9. Acute short-term dim light exposure can lower muscle strength endurance

    Institute of Scientific and Technical Information of China (English)

    Arnold G. Nelson; Joke Kokkonen; Megan Mickenberg

    2015-01-01

    Background:Since it has been shown that spending 18 h under dim light conditions can result in reduced handgrip endurance, it was questioned whether or not a shorter exposure to dim light (i.e., 1 h) would have similar influence upon muscular endurance. Therefore this study compared the number of weighted knee extension lifts that could be done after spending 1 h in either dim or bright light. Methods:Participants (5 women, 11 men, college students 19-26 years) performed knee extension lifts to exhaustion with a load approximating 40%of their body weight. The lifts to exhaustion were measured immediately following 1 h of exposure to each of the following three con-ditions:dark (DL), room light (RL), and room light plus 5 mg melatonin (RLM). A minimum of 48 h separated each condition, and all par-ticipants started the exposures in a rested fed condition. Results:Average (±SD) number of knee extension lifts for RL (62.0 ± 22.0) was significantly ( p<0.05) greater than DL (51.4 ± 14.7) and RLM (57.8 ± 22.9). The number of RLM knee extension lifts was not significantly different from DL. Exposure to 1 h of dim light immediately prior to activity can result in a reduction in thigh muscle endurance. The decline in performance to short-term dim light exposure was similar to that found following longer-term exposure. Conclusion: It appears that light intensity can influence muscle endurance, however, at this time this effect cannot be directly related to endogenous melatonin production.

  10. The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder.

    Science.gov (United States)

    Meesters, Ybe; Winthorst, Wim H; Duijzer, Wianne B; Hommes, Vanja

    2016-02-18

    The discovery of a novel photoreceptor in the retinal ganglion cells with a highest sensitivity of 470-490 nm blue light has led to research on the effects of short-wavelength light in humans. Several studies have explored the efficacy of monochromatic blue or blue-enriched light in the treatment of SAD. In this study, a comparison has been made between the effects of broad-wavelength light without ultraviolet (UV) wavelengths compared to narrow-band blue light in the treatment of sub-syndromal seasonal affective disorder (Sub-SAD). In a 15-day design, 48 participants suffering from Sub-SAD completed 20-minute sessions of light treatment on five consecutive days. 22 participants were given bright white-light treatment (BLT, broad-wavelength light without UV 10 000 lux, irradiance 31.7 Watt/m(2)) and 26 participants received narrow-band blue light (BLUE, 100 lux, irradiance 1.0 Watt/m(2)). All participants completed daily and weekly questionnaires concerning mood, activation, sleep quality, sleepiness and energy. Also, mood and energy levels were assessed by means of the SIGH-SAD, the primary outcome measure. On day 15, SIGH-SAD ratings were significantly lower than on day 1 (BLT 54.8 %, effect size 1.7 and BLUE 50.7 %, effect size 1.9). No statistically significant differences were found on the main outcome measures. Light treatment is an effective treatment for Sub-SAD. The use of narrow-band blue-light treatment is equally effective as bright white-light treatment. This study was registered in the Dutch Trial Register (Nederlands Trial Register TC =  4342 ) (20-12-2013).

  11. 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.

  12. Fabrication and property analysis of AIGalnP red light LED with high bright

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The LED with DBR and enhancing transmission film was grown by MOCVD. At 20 mA DC injection current, the LED peak wavelength was 623 nm, the light intensity was 200 mcd, and the output light power was 2.14 mW. The light intensity and output light power have been improved than traditional LED.

  13. 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...

  14. Nonvisual responses to light exposure in the human brain during the circadian night.

    Science.gov (United States)

    Perrin, Fabien; Peigneux, Philippe; Fuchs, Sonia; Verhaeghe, Stéphane; Laureys, Steven; Middleton, Benita; Degueldre, Christian; Del Fiore, Guy; Vandewalle, Gilles; Balteau, Evelyne; Poirrier, Robert; Moreau, Vincent; Luxen, André; Maquet, Pierre; Dijk, Derk-Jan

    2004-10-26

    The brain processes light information to visually represent the environment but also to detect changes in ambient light level. The latter information induces non-image-forming responses and exerts powerful effects on physiology such as synchronization of the circadian clock and suppression of melatonin. In rodents, irradiance information is transduced from a discrete subset of photosensitive retinal ganglion cells via the retinohypothalamic tract to various hypothalamic and brainstem regulatory structures including the hypothalamic suprachiasmatic nuclei, the master circadian pacemaker. In humans, light also acutely modulates alertness, but the cerebral correlates of this effect are unknown. We assessed regional cerebral blood flow in 13 subjects attending to auditory and visual stimuli in near darkness following light exposures (>8000 lux) of different durations (0.5, 17, 16.5, and 0 min) during the biological night. The bright broadband polychromatic light suppressed melatonin and enhanced alertness. Functional imaging revealed that a large-scale occipito-parietal attention network, including the right intraparietal sulcus, was more active in proportion to the duration of light exposures preceding the scans. Activity in the hypothalamus decreased in proportion to previous illumination. These findings have important implications for understanding the effects of light on human behavior.

  15. High Efficiency SEPIC Converter For High Brightness Light Emitting Diodes (LEDs) System

    OpenAIRE

    Qin, Yaxiao

    2012-01-01

    ABSTRACT This thesis presents an investigation into the characteristics of and driving methods for light emitting diode (LED) lamp system. A comprehensive overview on the lighting development is proposed. The characteristic of the light emitting diode (LED) lamp is described and the requirements of the ballast for the light emitting diode (LED) lamp are presented. Although LED lamps have longer lifetime than fluorescent lamps, the short lifetime limitation of LED driver imposed by ele...

  16. Occupational exposure to UV light and mortality from multiple sclerosis.

    Science.gov (United States)

    Westberg, M; Feychting, M; Jonsson, F; Nise, G; Gustavsson, P

    2009-05-01

    The etiology of multiple sclerosis (MS) is largely unknown; low exposure to ultraviolet (UV) light has been a suggested risk factor. The aim of this study was to investigate whether occupational exposure to UV light reduces the risk of death from MS. The cohort was based on all individuals in the Swedish census in 1980. All MS-related deaths were identified in the national registry of causes of death. A job-exposure matrix was developed to classify the occupational exposure to UV light. MS was recorded as a cause of the death for 839 individuals. The risk of MS-related death decreased with increasing occupational exposure to UV light. The relative risk adjusted for age, sex, and socioeconomic status was 0.48 (95% CI 0.28-0.80) in the high-exposure group and 0.88 (95% CI 0.73-1.06) in the intermediate-exposure group. Occupational exposure to UV light was associated with a reduced risk of MS. Our findings are corroborated by previous observations that UV light has a preventive role in the development of MS, although the possibility of reversed causality cannot be completely ruled out. Copyright 2009 Wiley-Liss, Inc.

  17. 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.

  18. A controllable growth-doping approach to synthesize bright white-light-emitting Cd:In2S3 nanocrystals

    Science.gov (United States)

    Feng, Jian; Zhu, Hui; Yang, Xiurong

    2013-06-01

    A new type of doped Cd:In2S3 NC, which exhibits bright white-light emission with a QY of about 18%, synthesized by a one-pot G-doping synthesis approach is presented. The successful realization of temporal separation of nucleation doping and growth doping makes this approach a facile method to synthesize the In2S3/Cd:In2S3 core/shell nanostructure.A new type of doped Cd:In2S3 NC, which exhibits bright white-light emission with a QY of about 18%, synthesized by a one-pot G-doping synthesis approach is presented. The successful realization of temporal separation of nucleation doping and growth doping makes this approach a facile method to synthesize the In2S3/Cd:In2S3 core/shell nanostructure. Electronic supplementary information (ESI) available: Detailed synthetic procedure, ICP-MS, TEM, HRTEM, PL decay curves, CIE coordinates and CCT of Cd:In2S3 NCs, and PL spectra of In2S3 and CdS. See DOI: 10.1039/c3nr00878a

  19. Bright ideas. Some rules of thumb for interior lighting design and selection.

    Science.gov (United States)

    Hunter, Claudia M

    2002-07-01

    Interior lighting design and selection can be a demanding assignment for a health facilities manager or department head. It requires a balance between conflicting needs, such as providing good task lighting for a nursing station while also shielding luminaires that are visible from patients' rooms to avoid glare.

  20. 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.

  1. A Laboratory Study of the Effects of Diet and Bright Light Countermeasures to Jet Lag

    Science.gov (United States)

    1990-03-01

    within a food group using the nutrition handbook for diabetics as a reference (14]. At dinner on the day before the shift occurred (Day 7), a subject in...publication. 34 References [1] Lewy AJ, Wehr TA, Goodwin FK, Newsome DA and Markey SP. Light suppresses melatonin secretion in humans. Science 210:1267-1269... Melatonin Production: Shifting "Dawn" and "Dusk" Shifts the Dim Light Melatonin Onset (DLUMO). Annals New York Academy of Sciences 453:253-259, 1985

  2. Carcinogenesis related to intense pulsed light and UV exposure

    DEFF Research Database (Denmark)

    Hedelund, L; Lerche, C; Wulf, H C;

    2006-01-01

    This study examines whether intense pulsed light (IPL) treatment has a carcinogenic potential itself or may influence ultraviolet (UV)-induced carcinogenesis. Secondly, it evaluates whether UV exposure may influence IPL-induced side effects. Hairless, lightly pigmented mice (n=144) received three...

  3. Timing of light exposure affects mood and brain circuits

    Science.gov (United States)

    Bedrosian, T A; Nelson, R J

    2017-01-01

    Temporal organization of physiology is critical for human health. In the past, humans experienced predictable periods of daily light and dark driven by the solar day, which allowed for entrainment of intrinsic circadian rhythms to the environmental light–dark cycles. Since the adoption of electric light, however, pervasive exposure to nighttime lighting has blurred the boundaries of day and night, making it more difficult to synchronize biological processes. Many systems are under circadian control, including sleep–wake behavior, hormone secretion, cellular function and gene expression. Circadian disruption by nighttime light perturbs those processes and is associated with increasing incidence of certain cancers, metabolic dysfunction and mood disorders. This review focuses on the role of artificial light at night in mood regulation, including mechanisms through which aberrant light exposure affects the brain. Converging evidence suggests that circadian disruption alters the function of brain regions involved in emotion and mood regulation. This occurs through direct neural input from the clock or indirect effects, including altered neuroplasticity, neurotransmission and clock gene expression. Recently, the aberrant light exposure has been recognized for its health effects. This review summarizes the evidence linking aberrant light exposure to mood. PMID:28140399

  4. Investigation of Pattern-Induced Brightness Non-uniformity in Active-Matrix Organic Light-Emitting Diode Displays

    Science.gov (United States)

    Kim, Kyoung-Bo; Park, Hye-Hyang; Kwon, Ohseob; Kim, Moojin; Lee, Ki-Yong; Park, Yongwoo; Choi, JongHyun; Yu, CheolHo; Kim, Hye-Dong; Kim, Sung Chul; Chung, Ho-Kyoon

    2008-01-01

    We recently improved the brightness non-uniformity in active-matrix organic light-emitting diode (AMOLED) regarding non-uniform laser energy distribution by applying a “shot mixing” technique in sequential lateral solidification (SLS) method. Although the new SLS technique was employed, another brightness non-uniformity that appeared as oblique lines on AMOLED panels became a crucial issue. In this work, we attempted to investigate the origins of the non-uniformity. Our systematic analysis on the oblique lines revealed that the line type non-uniformity was attributed to both the SLS process and the thin-film transistor (TFT) fabrication processes. In particular, we found that such oblique patterns might be related to moiré patterns that appear when primary grain boundaries aligned in a repetitive pattern is placed over other repetitive TFT patterns such as metal lines. We adopted a method to diminish the moiré pattern type non-uniformity by applying top emission TFT structure.

  5. Circadian phase resetting by a single short-duration light exposure

    Science.gov (United States)

    Rahman, Shadab A.; St. Hilaire, Melissa A.; Chang, Anne-Marie; Santhi, Nayantara; Duffy, Jeanne F.; Kronauer, Richard E.; Czeisler, Charles A.; Lockley, Steven W.; Klerman, Elizabeth B.

    2017-01-01

    BACKGROUND. In humans, a single light exposure of 12 minutes and multiple-millisecond light exposures can shift the phase of the circadian pacemaker. We investigated the response of the human circadian pacemaker to a single 15-second or 2-minute light pulse administered during the biological night. METHODS. Twenty-six healthy individuals participated in a 9-day inpatient protocol that included assessment of dim light melatonin onset time (DLMO time) before and after exposure to a single 15-second (n = 8) or 2-minute (n = 12) pulse of bright light (9,500 lux; 4,100 K fluorescent) or control background dim light (lux; n = 6). Phase shifts were calculated as the difference in clock time between the two phase estimates. RESULTS. Both 15-second and 2-minute exposures induced phase delay shifts [median (± SD)] of –34.8 ± 47.2 minutes and –45.4 ± 28.4 minutes, respectively, that were significantly (P = 0.04) greater than the control condition (advance shift: +22.3 ± 51.3 minutes) but were not significantly different from each other. Comparisons with historic data collected under the same conditions confirmed a nonlinear relationship between exposure duration and the magnitude of phase shift. CONCLUSIONS. Our results underscore the exquisite sensitivity of the human pacemaker to even short-duration single exposures to light. These findings may have real-world implications for circadian disruption induced by exposure to brief light stimuli at night. TRIAL REGISTRATION. The study was registered as a clinical trial on www.clinicaltrials.org, NCT #01330992. FUNDING. Funding for this study was provided by NSBRI HFP02802 and NIH P01-AG09975, R01-HL114088 (EBK), RC2-HL101340-0 (EBK, SWL, SAR, REK), K02-HD045459 (EBK), K24-HL105664 (EBK), T32-HL07901 (MSH, SAR), HL094654 (CAC), and AG044416 (JFD). The project described was supported by NIH grant 1UL1 TR001102-01, 8UL1TR000170-05, UL1 RR 025758, Harvard Clinical and Translational Science Center, from the National Center for

  6. Exposure of tropical ecosystems to artificial light at night: Brazil as a case study

    Science.gov (United States)

    Bennie, Jon; Mantovani, Waldir; Gaston, Kevin J.

    2017-01-01

    Artificial nighttime lighting from streetlights and other sources has a broad range of biological effects. Understanding the spatial and temporal levels and patterns of this lighting is a key step in determining the severity of adverse effects on different ecosystems, vegetation, and habitat types. Few such analyses have been conducted, particularly for regions with high biodiversity, including the tropics. We used an intercalibrated version of the Defense Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS) images of stable nighttime lights to determine what proportion of original and current Brazilian vegetation types are experiencing measurable levels of artificial light and how this has changed in recent years. The percentage area affected by both detectable light and increases in brightness ranged between 0 and 35% for native vegetation types, and between 0 and 25% for current vegetation (i.e. including agriculture). The most heavily affected areas encompassed terrestrial coastal vegetation types (restingas and mangroves), Semideciduous Seasonal Forest, and Mixed Ombrophilous Forest. The existing small remnants of Lowland Deciduous and Semideciduous Seasonal Forests and of Campinarana had the lowest exposure levels to artificial light. Light pollution has not often been investigated in developing countries but our data show that it is an environmental concern. PMID:28178352

  7. Bright infrared quantum-dot light-emitting diodes through inter-dot spacing control

    KAUST Repository

    Sun, Liangfeng

    2012-05-06

    Infrared light-emitting diodes are currently fabricated from direct-gap semiconductors using epitaxy, which makes them expensive and difficult to integrate with other materials. Light-emitting diodes based on colloidal semiconductor quantum dots, on the other hand, can be solution-processed at low cost, and can be directly integrated with silicon. However, so far, exciton dissociation and recombination have not been well controlled in these devices, and this has limited their performance. Here, by tuning the distance between adjacent PbS quantum dots, we fabricate thin-film quantum-dot light-emitting diodes that operate at infrared wavelengths with radiances (6.4 W sr \\'1 m \\'2) eight times higher and external quantum efficiencies (2.0%) two times higher than the highest values previously reported. The distance between adjacent dots is tuned over a range of 1.3 nm by varying the lengths of the linker molecules from three to eight CH 2 groups, which allows us to achieve the optimum balance between charge injection and radiative exciton recombination. The electroluminescent powers of the best devices are comparable to those produced by commercial InGaAsP light-emitting diodes. By varying the size of the quantum dots, we can tune the emission wavelengths between 800 and 1,850 nm.© 2012 Macmillan Publishers Limited.

  8. Bright infrared quantum-dot light-emitting diodes through inter-dot spacing control.

    Science.gov (United States)

    Sun, Liangfeng; Choi, Joshua J; Stachnik, David; Bartnik, Adam C; Hyun, Byung-Ryool; Malliaras, George G; Hanrath, Tobias; Wise, Frank W

    2012-05-06

    Infrared light-emitting diodes are currently fabricated from direct-gap semiconductors using epitaxy, which makes them expensive and difficult to integrate with other materials. Light-emitting diodes based on colloidal semiconductor quantum dots, on the other hand, can be solution-processed at low cost, and can be directly integrated with silicon. However, so far, exciton dissociation and recombination have not been well controlled in these devices, and this has limited their performance. Here, by tuning the distance between adjacent PbS quantum dots, we fabricate thin-film quantum-dot light-emitting diodes that operate at infrared wavelengths with radiances (6.4 W sr(-1) m(-2)) eight times higher and external quantum efficiencies (2.0%) two times higher than the highest values previously reported. The distance between adjacent dots is tuned over a range of 1.3 nm by varying the lengths of the linker molecules from three to eight CH(2) groups, which allows us to achieve the optimum balance between charge injection and radiative exciton recombination. The electroluminescent powers of the best devices are comparable to those produced by commercial InGaAsP light-emitting diodes. By varying the size of the quantum dots, we can tune the emission wavelengths between 800 and 1,850 nm.

  9. Bright light therapy for depression: a review of its effects on chronobiology and the autonomic nervous system.

    Science.gov (United States)

    Oldham, Mark A; Ciraulo, Domenic A

    2014-04-01

    Bright light therapy (BLT) is considered among the first-line treatments for seasonal affective disorder (SAD), yet a growing body of literature supports its use in other neuropsychiatric conditions including non-seasonal depression. Despite evidence of its antidepressant efficacy, clinical use of BLT remains highly variable internationally. In this article, we explore the autonomic effects of BLT and suggest that such effects may play a role in its antidepressant and chronotherapeutic properties. After providing a brief introduction on the clinical application of BLT, we review the chronobiological effects of BLT on depression and on the autonomic nervous system in depressed and non-depressed individuals with an emphasis on non-seasonal depression. Such a theory of autonomic modulation via BLT could serve to integrate aspects of recent work centered on alleviating allostatic load, the polyvagal theory, the neurovisceral integration model and emerging evidence on the roles of glutamate and gamma-hydroxybutyric acid (GABA).

  10. 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

    2011-12-01

    To evaluate cognitive-behavior therapy plus bright light therapy (CBT plus BLT) for adolescents diagnosed with delayed sleep phase disorder (DSPD). 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. Flinders University Child & Adolescent Sleep Clinic, Adelaide, South Australia. 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). 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. 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 CBT plus BLT for adolescent DSPD is effective for improving multiple sleep and daytime impairments in the immediate and long-term. Studies evaluating the treatment effectiveness of each treatment component are needed. Australia-New Zealand Trials Registry Number: ACTRN12610001041044.

  11. Nature of light rain during presence and absence of bright band

    Indian Academy of Sciences (India)

    Mahen Konwar; R S Maheskumar; S K Das; S B Morwal

    2012-08-01

    This paper reports the evolution of rain drop size distribution (DSD) during bright band (BB) and no-BB (NBB) conditions of low intensity rainfall events as observed by a vertically pointing Micro Rain Radar (MRR) over Pune (18.58°N, 73.92°E), India. The BB is identified by enhanced radar reflectivity factor (dBZ) at the 0°C isotherm. The gradient of hydrometeor fall velocity is found to be a good indicator in identifying the melting layer when enhanced radar reflectivity at melting layer is not prominent. The storm structures as observed by the MRR are compared with CloudSat observations that provide evidence of ice hydrometeor at ∼−60°C with clear indication of BB at 0°C. Storm heights at warmer than 0°C are evident during NBB conditions from CloudSat. This suggests that warm rain processes are responsible for producing rain during NBB conditions. During BB conditions, bimodal DSDs below the melting layer are observed at lower altitudes. The DSDs of shallow warm precipitating systems of NBB conditions are monomodal at all the altitudes. Significantly, normalized DSDs are found to be bimodal for BB conditions, and monomodal for NBB conditions which confirm different dominant microphysical processes. It is found that the observed bimodal DSDs during BB conditions are mainly due to the collision, coalescence and break-up processes. During NBB conditions, number and size of large raindrops grow while reaching the ground without much breakup. The radar reflectivity and rainfall intensity (mmh−1) relationship of the form = b are found out for BB and NBB conditions. Existing different microphysical processes lead to large coefficient in the – relationship with small exponent during BB conditions while during NBB conditions the coefficients are small with large exponents.

  12. 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.

  13. Bright Light Therapy for Treatment of Sleep Problems Following Mild TBI

    Science.gov (United States)

    2015-10-01

    imaging, light therapy, neuropsychological performance, neurocognitive performance, sleep 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18...Correlates of Electroencephalographic Activity During Stage 2 and Slow Wave Sleep : An H215O PET Study: Presented at the Bi- Annual 71F Research...cerebral metabolic correlates of electroencephalographic activity during stage -2 and slow-wave sleep : An H215O PET Study, 18th Associated

  14. The envelope of IRC+10216 reflecting the galactic light: UBV surface brightness photometry and interpretation

    CERN Document Server

    Mauron, N; López, B

    2003-01-01

    We present and analyse new optical images of the dust envelope surrounding the high mass-loss carbon star IRC+10216. This envelope is seen due to external illumination by galactic light. Intensity profiles and colors of the nebula were obtained in the UBV bandpasses. The data are compared with the results of a radiative transfer model calculating multiple scattering of interstellar field photons by dust grains with a single radius. The data show that the observed radial shape of the nebula, especially its half maximum radius, does not depend on wavelength (within experimental errors), suggesting that grains scatter in the grey regime, etc, etc (this abstract has been shortened)

  15. Heralded source of bright multi-mode mesoscopic sub-Poissonian light

    DEFF Research Database (Denmark)

    Iskhakov, Timur; Usenko, V. C.; Andersen, Ulrik Lund

    2016-01-01

    In a direct detection scheme, we observed 7.8 dB of twin-beam squeezing for multi-mode two-color squeezed vacuum generated via parametric downconversion. Applying postselection, we conditionally prepared a sub-Poissonian state of light containing 6.3 . 105 photons per pulse on the average...... with the Fano factor 0.63 +/- 0.01. The scheme can be considered as the heralded preparation of pulses with the mean energy varying between tens and hundreds of fJ and the uncertainty considerably below the shot-noise level. Such pulses can be used in metrology (for instance, for radiometer calibration...

  16. Objectively Measured Light Exposure in Emmetropic and Myopic Adults.

    Science.gov (United States)

    Ostrin, Lisa A

    2017-02-01

    Light exposure has a close link with numerous aspects of human physiology including circadian rhythm, mood disorders, metabolism, and eye growth. Here, a lightweight wrist-worn device was employed to continuously measure light exposure and activity across seasons and between refractive error groups to assess objectively measured differences and compare with subjectively reported data. Subjects, aged 21-65 years (n = 55), wore an actigraph device (Actiwatch Spectrum) continuously for 14 days to quantify light exposure, activity, and sleep. Subjects were classified as emmetropic (n = 18) or myopic (n = 37), and answered an activity questionnaire. Additionally, devices were calibrated against a lux meter and UV sensor for indoor and outdoor settings, and used to measure ambient illumination in various environmental conditions. Subjects spent 1:52 ± 0:56 hours outside per day, as measured objectively. Subjectively reported measures overestimated objective measures by 0:25 ± 1:19 hours per day (range -1:49 to +4:29 hours, P light dose compared to winter (P light at 142 ± 150 lux. Subjects spent more time outdoors and received an increased light dose in summer, with no differences between refractive error groups in this adult population. Various environmental and seasonal measurements revealed significantly different available light in winter versus summer and indoors versus outdoors. Objective devices such as the Actiwatch can be valuable in studies where quantification of environmental factors is critical.

  17. High-brightness organic light-emitting diodes for optogenetic control of Drosophila locomotor behaviour

    Science.gov (United States)

    Morton, Andrew; Murawski, Caroline; Pulver, Stefan R.; Gather, Malte C.

    2016-08-01

    Organic light emitting diodes (OLEDs) are in widespread use in today’s mobile phones and are likely to drive the next generation of large area displays and solid-state lighting. Here we show steps towards their utility as a platform technology for biophotonics, by demonstrating devices capable of optically controlling behaviour in live animals. Using devices with a pin OLED architecture, sufficient illumination intensity (0.3 mW.mm‑2) to activate channelrhodopsins (ChRs) in vivo was reliably achieved at low operating voltages (5 V). In Drosophila melanogaster third instar larvae expressing ChR2(H134R) in motor neurons, we found that pulsed illumination from blue and green OLEDs triggered robust and reversible contractions in animals. This response was temporally coupled to the timing of OLED illumination. With blue OLED illumination, the initial rate and overall size of the behavioural response was strongest. Green OLEDs achieved roughly 70% of the response observed with blue OLEDs. Orange OLEDs did not produce contractions in larvae, in agreement with the spectral response of ChR2(H134R). The device configuration presented here could be modified to accommodate other small model organisms, cell cultures or tissue slices and the ability of OLEDs to provide patterned illumination and spectral tuning can further broaden their utility in optogenetics experiments.

  18. High brightness three-dimensional light field display based on the aspheric substrate Fresnel-lens-array with eccentric pupils

    Science.gov (United States)

    Gao, Xin; Sang, Xinzhu; Yu, Xunbo; Cao, Xuemei; Chen, Zhidong; Yan, Binbin; Yuan, Jinhui; Wang, Kuiru; Yu, Chongxiu; Dou, Wenhua; Xiao, Liquan

    2016-02-01

    The brightness and viewing field of the reproductive three-dimensional (3D) image are crucial factors to realize a comfortable 3D perception for the light field display based on the liquid crystal device (LCD). To improve the illuminance of 3D image with sub-image-units with small aperture angles and enlarge the viewing field, the illuminance of the Fresnel-lens combining with the sub-images on LCD is analyzed and designed. Theoretical and experimental results show that the Fresnel-lens-array with eccentric pupil(FAEP) can address above problems. A 3D light field display based on LCD with FAEP and directional diffuser screen are used to reconstruct the target 3D field. 25 parallax sub-images are projected to the directional diffuser screen to verify the improvement of illuminance and viewing field. To reduce eccentric aberration introduced by eccentric pupil, a novel structure of Fresnel-lens-array is presented to reduce the aberration. The illuminance and viewing field are well promoted at the same time. 3D image with the high quality can be achieved.

  19. Protecting the Melatonin Rhythm through Circadian Healthy Light Exposure

    Directory of Open Access Journals (Sweden)

    Maria Angeles Bonmati-Carrion

    2014-12-01

    Full Text Available Currently, in developed countries, nights are excessively illuminated (light at night, whereas daytime is mainly spent indoors, and thus people are exposed to much lower light intensities than under natural conditions. In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD, including perturbations in melatonin rhythm. Epidemiological studies show that CD is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer. Knowledge of retinal photoreceptors and the discovery of melanopsin in some ganglion cells demonstrate that light intensity, timing and spectrum must be considered to keep the biological clock properly entrained. Importantly, not all wavelengths of light are equally chronodisrupting. Blue light, which is particularly beneficial during the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition. Nocturnal blue light exposure is currently increasing, due to the proliferation of energy-efficient lighting (LEDs and electronic devices. Thus, the development of lighting systems that preserve the melatonin rhythm could reduce the health risks induced by chronodisruption. This review addresses the state of the art regarding the crosstalk between light and the circadian system.

  20. Protecting the Melatonin Rhythm through Circadian Healthy Light Exposure

    Science.gov (United States)

    Bonmati-Carrion, Maria Angeles; Arguelles-Prieto, Raquel; Martinez-Madrid, Maria Jose; Reiter, Russel; Hardeland, Ruediger; Rol, Maria Angeles; Madrid, Juan Antonio

    2014-01-01

    Currently, in developed countries, nights are excessively illuminated (light at night), whereas daytime is mainly spent indoors, and thus people are exposed to much lower light intensities than under natural conditions. In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD), including perturbations in melatonin rhythm. Epidemiological studies show that CD is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer. Knowledge of retinal photoreceptors and the discovery of melanopsin in some ganglion cells demonstrate that light intensity, timing and spectrum must be considered to keep the biological clock properly entrained. Importantly, not all wavelengths of light are equally chronodisrupting. Blue light, which is particularly beneficial during the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition. Nocturnal blue light exposure is currently increasing, due to the proliferation of energy-efficient lighting (LEDs) and electronic devices. Thus, the development of lighting systems that preserve the melatonin rhythm could reduce the health risks induced by chronodisruption. This review addresses the state of the art regarding the crosstalk between light and the circadian system. PMID:25526564

  1. Adaptive potentiation in rod photoreceptors after light exposure

    OpenAIRE

    McKeown, Alex S; Kraft, Timothy W.

    2014-01-01

    Photoreceptors adapt to changes in illumination by altering transduction kinetics and sensitivity, thereby extending their working range. We describe a previously unknown form of rod photoreceptor adaptation in wild-type (WT) mice that manifests as a potentiation of the light response after periods of conditioning light exposure. We characterize the stimulus conditions that evoke this graded hypersensitivity and examine the molecular mechanisms of adaptation underlying the phenomenon. After e...

  2. Adaptive potentiation in rod photoreceptors after light exposure.

    Science.gov (United States)

    McKeown, Alex S; Kraft, Timothy W

    2014-06-01

    Photoreceptors adapt to changes in illumination by altering transduction kinetics and sensitivity, thereby extending their working range. We describe a previously unknown form of rod photoreceptor adaptation in wild-type (WT) mice that manifests as a potentiation of the light response after periods of conditioning light exposure. We characterize the stimulus conditions that evoke this graded hypersensitivity and examine the molecular mechanisms of adaptation underlying the phenomenon. After exposure to periods of saturating illumination, rods show a 10-35% increase in circulating dark current, an adaptive potentiation (AP) to light exposure. This potentiation grows as exposure to light is extended up to 3 min and decreases with longer exposures. Cells return to their initial dark-adapted sensitivity with a time constant of recovery of ∼7 s. Halving the extracellular Mg concentration prolongs the adaptation, increasing the time constant of recovery to 13.3 s, but does not affect the magnitude of potentiation. In rods lacking guanylate cyclase activating proteins 1 and 2 (GCAP(-/-)), AP is more than doubled compared with WT rods, and halving the extracellular Mg concentration does not affect the recovery time constant. Rods from a mouse expressing cyclic nucleotide-gated channels incapable of binding calmodulin also showed a marked increase in the amplitude of AP. Application of an insulin-like growth factor-1 receptor (IGF-1R) kinase inhibitor (Tyrphostin AG1024) blocked AP, whereas application of an insulin receptor kinase inhibitor (HNMPA(AM)3) failed to do so. A broad-acting tyrosine phosphatase inhibitor (orthovanadate) also blocked AP. Our findings identify a unique form of adaptation in photoreceptors, so that they show transient hypersensitivity to light, and are consistent with a model in which light history, acting via the IGF-1R, can increase the sensitivity of rod photoreceptors, whereas the photocurrent overshoot is regulated by Ca-calmodulin and Ca(2

  3. 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

  4. Shortest exposure time possible with LED curing lights

    NARCIS (Netherlands)

    Busemann, I.; Lipke, C.; Schattenberg, A.V.M.B.; Willershausen, B.; Ernst, C.P.

    2011-01-01

    PURPOSE: To investigate the shortest exposure time of different light emitting diode (LED)-curing devices for different resin composites in a clinically relevant laboratory model. METHODS: Nine LED curing devices (Bluephase, Bluephase 16i, Bluephase G2, Bluephase 20i/Ivoclar Vivadent, DEMI/sds Kerr,

  5. Shortest exposure time possible with LED curing lights

    NARCIS (Netherlands)

    Busemann, I.; Lipke, C.; Schattenberg, A.V.M.B.; Willershausen, B.; Ernst, C.P.

    2011-01-01

    PURPOSE: To investigate the shortest exposure time of different light emitting diode (LED)-curing devices for different resin composites in a clinically relevant laboratory model. METHODS: Nine LED curing devices (Bluephase, Bluephase 16i, Bluephase G2, Bluephase 20i/Ivoclar Vivadent, DEMI/sds Kerr,

  6. Sleep-Wake Actigraphy and Light Exposure During Spaceflight - Short

    Science.gov (United States)

    Czeisler, Charles A.; Wright, Kenneth P., Jr.; Ronda, Joseph

    2009-01-01

    Sleep-Wake Actigraphy and Light Exposure During Spaceflight - Short (Sleep-Short) will examine the effects of spaceflight on the sleep of the astronauts during space shuttle missions. Advancing state-of-the-art technology for monitoring, diagnosing and assessing treatment of sleep patterns is vital to treating insomnia on Earth and in space.

  7. Chandra Takes In The Bright Lights, Big City Of The Milky Way

    Science.gov (United States)

    2002-01-01

    NASA's Chandra X-ray Observatory has made a stunning, high-energy panorama of the central regions of our Milky Way galaxy. The findings are an important step toward understanding the most active area of the Milky Way as well as other galaxies throughout the universe. Like a sprawling megalopolis, the new Chandra images show hundreds of white dwarf stars, neutron stars and black holes bathed in an incandescent fog of multimillion-degree gas around a supermassive black hole. "The center of the galaxy is where the action is," said Q. Daniel Wang of the University of Massachusetts, Amherst. "With these images, we get a new perspective of the interplay between stars, gas and dust, as well as the magnetic fields and gravity in the region. We can see how such forces affect the immediate vicinity and may influence other aspects of the galaxy." Wang presented the montage of 30 separate Chandra images today at the American Astronomical Society meeting in Washington, and in a paper published in the Jan. 10, 2002, issue of the journal Nature. The images, made with the Advanced CCD Imaging Spectrometer (ACIS) July 16-21, 2001, covered a 400- by 900-light-year swath of the center of the galaxy. One immediate result was that the team could separate out the individual X-ray sources from the diffuse glow produced by hot gas. "We can now see that the sources are responsible for most of the X-rays from highly ionized iron previously attributed to the diffuse glow," said Eric Gotthelf, of Columbia University in New York, a co-author. "So we must now revise our notion of the hot gas, which appears to be about 10 times cooler than previously thought. It's only a relatively mild 10 million degrees!" The diffuse X-ray emission seems to be related to the turmoil and density of matter in the inner Milky Way. Stars are forming there at a much more rapid rate than in the galactic "suburbs." Many of the most massive stars in the galaxy are located in the galactic center and are furiously

  8. How Bright Is the Sun?

    Science.gov (United States)

    Berr, Stephen

    1991-01-01

    Presents a sequence of activities designed to allow eighth grade students to deal with one of the fundamental relationships that govern energy distribution. Activities guide students to measure light bulb brightness, discover the inverse square law, compare light bulb light to candle light, and measure sun brightness. (two references) (MCO)

  9. Very Bright and Efficient Microcavity Top-Emitting Quantum Dot Light-Emitting Diodes with Ag Electrodes.

    Science.gov (United States)

    Liu, Guohong; Zhou, Xiang; Chen, Shuming

    2016-07-01

    The microcavity effect in top-emitting quantum dot light-emitting diodes (TQLEDs) is theoretically and experimentally investigated. By carefully optimizing the cavity length, the thickness of the top Ag electrode and the thickness of the capping layer, very bright and efficient TQLEDs with external quantum efficiency (EQE) of 12.5% are demonstrated. Strong dependence of luminance and efficiency on cavity length is observed, in good agreement with theoretical calculation. By setting the normal-direction resonant wavelength around the peak wavelength of the intrinsic emission, highest luminance of 112 000 cd/m(2) (at a driving voltage of 7 V) and maximum current efficiency of 27.8 cd/A are achieved, representing a 12-fold and a 2.1-fold enhancement compared to 9000 cd/m(2) and 13.2 cd/A of the conventional bottom emitting devices, respectively, whereas the highest EQE of 12.5% is obtained by setting the resonant wavelength 30 nm longer than the peak wavelength of the intrinsic emission. Benefit from the very narrow spectrum of QDs and the low absorption of silver electrodes, the potential of microcavity effect can be fully exploited in TQLEDs.

  10. BRIGHT RAY-LIKE FEATURES IN THE AFTERMATH OF CORONAL MASS EJECTIONS: WHITE LIGHT VERSUS ULTRAVIOLET SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Ciaravella, A. [INAF-Osservatorio Astronomico di Palermo, P.za Parlamento 1, I-90134 Palermo (Italy); Webb, D. F. [Institute for Scientific Research, Boston College, Newton, MA 02459 (United States); Giordano, S. [INAF-Osservatorio Astrofisico di Torino, via Osservatorio 20, I-10025 Pino Torinese (Italy); Raymond, J. C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-03-20

    Current sheets (CSs) are important signatures of magnetic reconnection in the eruption of confined solar magnetic structures. Models of coronal mass ejections (CMEs) involve formation of a CS connecting the ejected flux rope with the post-eruption magnetic loops. CSs have been identified in white light (WL) images of CMEs as narrow rays trailing the outward moving CME core, and in ultraviolet spectra as narrow bright features emitting the [Fe XVIII] line. In this work, samples of rays detected in WL images or in ultraviolet spectra have been analyzed. Temperatures, widths, and line intensities of the rays have been measured, and their correlation to the CME properties has been studied. The samples show a wide range of temperatures with hot, coronal, and cool rays. In some cases, the UV spectra support the identification of rays as CSs, but they show that some WL rays are cool material from the CME core. In many cases, both hot and cool material are present, but offset from each other along the Ultraviolet Coronagraph Spectrometer slit. We find that about 18% of the WL rays show very hot gas consistent with the CS interpretation, while about 23% show cold gas that we attribute to cool prominence material draining back from the CME core. The remaining events have ordinary coronal temperatures, perhaps because they have relaxed back to a quiescent state.

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

    KAUST Repository

    Shen, Chao

    2013-05-01

    L > 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.

  12. GLOBE at Night: a Worldwide Citizen-Science Program to Increase Awareness of Light Pollution by Measuring Night Sky Brightness

    Science.gov (United States)

    Walker, C. E.; Pompea, S. M.

    2011-12-01

    The emphasis in the international citizen-science, star-hunting campaign, GLOBE at Night, is in bringing awareness to the public on issues of light pollution. Light pollution threatens not only observatory sites and our "right to starlight", but can affect energy consumption, wildlife and health. GLOBE at Night has successfully reached a few 100,000 citizen-scientists. What has contributed to its success? Foundational resources are available to facilitate the public's participation in promoting dark skies awareness. The GLOBE at Night website explains clearly the simple-to-participate-in 5 step program and offers background information and interactive games on key concepts. To promote the campaign via popular social media, GLOBE at Night created Facebook and Twitter pages. The program has been expanded to include trainings of the general public, but especially educators in schools, museums and science centers, in unique ways. Education kits for dark skies awareness have been distributed at the training workshops. The kit includes material for a light shielding demonstration, a digital Sky Quality Meter and "Dark Skies Rangers" activities. The activities are on how unshielded light wastes energy, how light pollution affects wildlife and how one can participate in a citizen-science star-hunt like GLOBE at Night. To increase participation in the 2011 campaign, children and adults submitted their sky brightness measurements in real time with smart phones or tablets using the web application at www.globeatnight.org/webapp/. With smart phones and tablets, the location, date and time register automatically. For those without smart mobile devices, user-friendly tools on the GLOBE at Night report page were reconfigured to determine latitude and longitude more easily and accurately. As a proto-type for taking multiple measurements, people in Tucson found it easy to adopt a street and take measurements every mile for the length of the street. The grid of measurements

  13. Carcinogenesis related to intense pulsed light and UV exposure

    DEFF Research Database (Denmark)

    Hedelund, L; Lerche, C; Wulf, H C;

    2006-01-01

    This study examines whether intense pulsed light (IPL) treatment has a carcinogenic potential itself or may influence ultraviolet (UV)-induced carcinogenesis. Secondly, it evaluates whether UV exposure may influence IPL-induced side effects. Hairless, lightly pigmented mice (n=144) received three...... observation period. Side effects were evaluated clinically. No tumors appeared in untreated control mice or in just IPL-treated mice. Skin tumors developed in UV-exposed mice independently of IPL treatments. The time it took for 50% of the mice to first develop skin tumor ranged from 47 to 49 weeks...

  14. Effects of light exposure on the TL dating of pottery

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Bleaching experiments on Chinese pottery fine grains were conducted under sunlight and laboratory light conditions. It is found that the thermoluminescence (TL) at high temperatures can be bleached significantly, but no effects were observed on TL signals used for the pre-dose dating technique. It is concluded that the pre-dose dating technique can be applied to samples even after light exposures. Pottery samples of Tang Dynasty and New Stone Age were studied. Modifications to routine pre-dose dating technique are proposed with adding preheat procedures and using saturation exponential fitting for the sensitivity change data. The modified technique can extend the dating range to New Stone Age.

  15. Relationship of chronotype to sleep, light exposure, and work-related fatigue in student workers.

    Science.gov (United States)

    Martin, Jeanne Sophie; Hébert, Marc; Ledoux, Elise; Gaudreault, Michaël; Laberge, Luc

    2012-04-01

    types. However, bright light exposure (≥ 1000 lux) did not differ between chronotypes. In conclusion, results suggest that student workers may constitute a high-risk population for sleep deprivation. Evening types seemed to cope less well with sleep deprivation, reporting poorer sleep quality and higher levels of work-related fatigue than intermediate types and morning types. The higher chronic work-related fatigue of evening types may be linked to their attenuated level of light exposure and weaker social zeitgebers. These results add credence to the hypothesis that eveningness entails a higher risk of health-impairing behaviors.

  16. 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.

  17. Amplitude reduction and phase shifts of melatonin, cortisol and other circadian rhythms after a gradual advance of sleep and light exposure in humans.

    Directory of Open Access Journals (Sweden)

    Derk-Jan Dijk

    Full Text Available BACKGROUND: The phase and amplitude of rhythms in physiology and behavior are generated by circadian oscillators and entrained to the 24-h day by exposure to the light-dark cycle and feedback from the sleep-wake cycle. The extent to which the phase and amplitude of multiple rhythms are similarly affected during altered timing of light exposure and the sleep-wake cycle has not been fully characterized. METHODOLOGY/PRINCIPAL FINDINGS: We assessed the phase and amplitude of the rhythms of melatonin, core body temperature, cortisol, alertness, performance and sleep after a perturbation of entrainment by a gradual advance of the sleep-wake schedule (10 h in 5 days and associated light-dark cycle in 14 healthy men. The light-dark cycle consisted either of moderate intensity 'room' light (∼90-150 lux or moderate light supplemented with bright light (∼10,000 lux for 5 to 8 hours following sleep. After the advance of the sleep-wake schedule in moderate light, no significant advance of the melatonin rhythm was observed whereas, after bright light supplementation the phase advance was 8.1 h (SEM 0.7 h. Individual differences in phase shifts correlated across variables. The amplitude of the melatonin rhythm assessed under constant conditions was reduced after moderate light by 54% (17-94% and after bright light by 52% (range 12-84%, as compared to the amplitude at baseline in the presence of a sleep-wake cycle. Individual differences in amplitude reduction of the melatonin rhythm correlated with the amplitude of body temperature, cortisol and alertness. CONCLUSIONS/SIGNIFICANCE: Alterations in the timing of the sleep-wake cycle and associated bright or moderate light exposure can lead to changes in phase and reduction of circadian amplitude which are consistent across multiple variables but differ between individuals. These data have implications for our understanding of circadian organization and the negative health outcomes associated with shift

  18. 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.

  19. Shortest exposure time possible with LED curing lights.

    Science.gov (United States)

    Busemann, Inga; Lipke, Claudia; Schattenberg, Anke; Willershausen, Brita; Ernst, Claus-Peter

    2011-02-01

    To investigate the shortest exposure time of different light emitting diode (LED)-curing devices for different resin composites in a clinically relevant laboratory model. Nine LED curing devices (Bluephase, Bluephase 16i, Bluephase G2, Bluephase 20i/Ivoclar Vivadent, DEMI/sds Kerr, Elipar FreeLight 2, Elipar S10/3M ESPE, Radii plus/SDI, mini LED Autofocus/Satelec) were investigated to polymerize Tetric EvoCeram (TEC) and Filtek Supreme XT B (FS) in the shades A1, A2, A3, A3.5, and A4. The Bluephase 20i was investigated in its high power and turbo modes. Stainless steel molds (Ø = 5 mm, h = 6 mm, six resin composite test samples per curing device, material, and shade) were filled in three increments of 2 mm thickness each and incrementally exposed with the light guide tip in a 7 mm distance from the bottom side to simulate a Class II curing situation. Surface hardness was measured 10 minutes post exposure at bottom surfaces of resin samples (n=3 per sample). A bottom/top-surface hardness ratio of 80% of a reference surface hardness cured at a zero-distance (40 seconds) was defined as clinically acceptable for safe curing. A statistical analysis (Excel) was carried out. To ensure a ratio in surface hardness of at least 80% the minimal exposure time(s) were: Elipar FreeLight 2, DEMI: TEC and FS: 10 seconds for all shades, except DEMI FS A4: 20 seconds. Elipar S10: 10 seconds for both, TEC and FS shades A2-A4 but 5 seconds for shades A1. Bluephase, Bluephase 16i and Bluephase G2: FS: 10 seconds for shades A1-A3.5; 20 seconds for shade A4. TEC: Bluephase: A1-A3.5: 10 seconds, A4: 20 seconds. Bluephase 16i: A1-A3: 10 seconds; A3.5 + A4: 30 seconds. Bluephase G2: A1-A3: 10 seconds; A3.5 + A4: 20 seconds. Bluephase 20i-HIP: 10 seconds for all shades of TEC and FS, Bluephase 20i-Turbo: 10 seconds for all shades of TEC but 5 seconds for all shades of FS: Radii plus: TEC A1-A3: 10 seconds; A3.5+A4: 20 seconds. FS A1, A2 and A4: 10 seconds; A3+A3.5: 20 seconds. Mini LED

  20. Blue Light and Ultraviolet Radiation Exposure from Infant Phototherapy Equipment.

    Science.gov (United States)

    Pinto, Iole; Bogi, Andrea; Picciolo, Francesco; Stacchini, Nicola; Buonocore, Giuseppe; Bellieni, Carlo V

    2015-01-01

    Phototherapy is the use of light for reducing the concentration of bilirubin in the body of infants. Although it has become a mainstay since its introduction in 1958, a better understanding of the efficacy and safety of phototherapy applications seems to be necessary for improved clinical practices and outcomes. This study was initiated to evaluate workers' exposure to Optical Radiation from different types of phototherapy devices in clinical use in Italy. During infant phototherapy the staff monitors babies periodically for around 10 min every hour, and fixation of the phototherapy beam light frequently occurs: almost all operators work within 30 cm of the phototherapy source during monitoring procedures, with most of them commonly working at ≤25 cm from the direct or reflected radiation beam. The results of this study suggest that there is a great variability in the spectral emission of equipments investigated, depending on the types of lamps used and some phototherapy equipment exposes operators to blue light photochemical retinal hazard. Some of the equipment investigated presents relevant spectral emission also in the UVA region. Taking into account that the exposure to UV in childhood has been established as an important contributing factor for melanoma risk in adults and considering the high susceptibility to UV-induced skin damage of the newborn, related to his pigmentary traits, the UV exposure of the infant during phototherapy should be "as low as reasonably achievable," considering that it is unnecessary to the therapy. It is recommended that special safety training be provided for the affected employees: in particular, protective eyewear can be necessary during newborn assistance activities carried out in proximity of some sources. The engineering design of phototherapy equipment can be optimized. Specific requirements for photobiological safety of lamps used in the phototherapy equipment should be defined in the safety product standard for such

  1. Ultraviolet light exposure, skin cancer risk and vitamin D production.

    Science.gov (United States)

    Rivas, Miguel; Rojas, Elisa; Araya, María C; Calaf, Gloria M

    2015-10-01

    The danger of overexposure to solar ultraviolet radiation has been widely reviewed since the 1980s due to the depletion of the ozone layer. However, the benefits of mild exposure of the skin to ultraviolet (UV) light have not been widely investigated. Numerous reports have demonstrated that an association exists between low light exposure to the sun, non-melanoma skin cancer and a lack of vitamin D synthesis. As vitamin D synthesis in the body depends on skin exposure to UVB radiation from the sun (wavelength, 290-320 nm), experimental measurements for this type of solar radiation are important. The present study analyzed data obtained from a laboratory investigating UV radiation from the sun at the University of Tarapacá (Arica, Chile), where systematic experimental UVB measurements had been performed using a calibrated biometer instrument since 2006. These data were compared with skin cancer data from the local population. The results demonstrated that the incidence of skin cancer systematically increased from 7.4 to 18.7 in men and from 10.0 to 21.7 in women between 2000 and 2006 in Arica, respectively; this increase may be due to multiple factors, including the lack of adequate levels of vitamin D in risk groups such as post-menopausal women and senior age. This marked increase may also be due to the high levels of UV radiation measured in this region throughout the year. However, it is not certain that the local population has adequate vitamin D levels, nor that their skin has been predominantly exposed to artificial light that does not allow adequate vitamin D synthesis. Thus, the current study presents the association between skin type IV, the time to induce solar erythema and the time required to produce 1,000 international units of vitamin D.

  2. HCN1 Channels Enhance Rod System Responsivity in the Retina under Conditions of Light Exposure.

    Directory of Open Access Journals (Sweden)

    Vithiyanjali Sothilingam

    Full Text Available Vision originates in rods and cones at the outer retina. Already at these early stages, diverse processing schemes shape and enhance image information to permit perception over a wide range of lighting conditions. In this work, we address the role of hyperpolarization-activated and cyclic nucleotide-gated channels 1 (HCN1 in rod photoreceptors for the enhancement of rod system responsivity under conditions of light exposure.To isolate HCN1 channel actions in rod system responses, we generated double mutant mice by crossbreeding Hcn1-/- mice with Cnga3-/- mice in which cones are non-functional. Retinal function in the resulting Hcn1-/- Cnga3-/- animals was followed by means of electroretinography (ERG up to the age of four month. Retinal imaging via scanning laser ophthalmoscopy (SLO and optical coherence tomography (OCT was also performed to exclude potential morphological alterations.This study on Hcn1-/- Cnga3-/- mutant mice complements our previous work on HCN1 channel function in the retina. We show here in a functional rod-only setting that rod responses following bright light exposure terminate without the counteraction of HCN channels much later than normal. The resulting sustained signal elevation does saturate the retinal network due to an intensity-dependent reduction in the dynamic range. In addition, the lack of rapid adaptational feedback modulation of rod photoreceptor output via HCN1 in this double mutant limits the ability to follow repetitive (flicker stimuli, particularly under mesopic conditions.This work corroborates the hypothesis that, in the absence of HCN1-mediated feedback, the amplitude of rod signals remains at high levels for a prolonged period of time, leading to saturation of the retinal pathways. Our results demonstrate the importance of HCN1 channels for regular vision.

  3. Bright light therapy in pregnant women with major depressive disorder: study protocol for a randomized, double-blind, controlled clinical trial.

    Science.gov (United States)

    Bais, Babette; Kamperman, Astrid M; van der Zwaag, Marjolein D; Dieleman, Gwen C; Harmsen van der Vliet-Torij, Hanneke W; Bijma, Hilmar H; Lieverse, Ritsaert; Hoogendijk, Witte J G; Lambregtse-van den Berg, Mijke P

    2016-11-08

    Depression during pregnancy is a common and high impact disease. Generally, 5-10 % of pregnant women suffer from depression. Children who have been exposed to maternal depression during pregnancy have a higher risk of adverse birth outcomes and more often show cognitive, emotional and behavioural problems. Therefore, early detection and treatment of antepartum depression is necessary. Both psychotherapy and antidepressant medication, first choice treatments in a non-pregnant population, have limitations in treating depression during pregnancy. Therefore, it is urgent and relevant to investigate alternative treatments for antepartum depression. Bright light therapy (BLT) is a promising treatment for pregnant women with depressive disorder, for it combines direct availability, sufficient efficacy, low costs and high safety, taking the safety for the unborn child into account as well. In this study, 150 pregnant women (12-18 weeks pregnant) with a DSM-V diagnosis of depressive disorder will be randomly allocated in a 1:1 ratio to one of the two treatment arms: treatment with BLT (9.000 lux) or treatment with dim red light therapy (100 lux). Both groups will be treated for 6 weeks at home on a daily basis for 30 min, within 30 min of habitual wake-up time. Follow-up will take place after 6 weeks of therapy, 3 and 10 weeks after end of therapy, at birth and 2, 6 and 18 months postpartum. Primary outcome will be the average change in depressive symptoms between the two groups, as measured by the Structured Interview Guide for the Hamilton Depression Scale - Seasonal Affective Disorder version and the Edinburg Postnatal Depression Scale. Changes in rating scale scores of these questionnaires over time will be analysed using generalized linear mixed models. Secondary outcomes will be the changes in maternal cortisol and melatonin levels, in maternal sleep quality and gestational age, birth weight, infant behaviour, infant cortisol exposure and infant cortisol stress

  4. A polymer based miniature loop heat pipe with silicon substrate and temperature sensors for high brightness light-emitting diodes

    NARCIS (Netherlands)

    Ye, H.; Sokolovskij, R.; Zeijl, H.W. van; Gielen, A.W.J.; Zhang, G.

    2014-01-01

    Solid State Lighting (SSL) systems, powered by light-emitting diodes (LEDs), are revolutionizing the lighting industry with energy saving and enhanced performance compared to traditional light sources. However, around 70%-80% of the electric power will still be transferred to heat. As the elevated t

  5. A polymer based miniature loop heat pipe with silicon substrate and temperature sensors for high brightness light-emitting diodes

    NARCIS (Netherlands)

    Ye, H.; Sokolovskij, R.; Zeijl, H.W. van; Gielen, A.W.J.; Zhang, G.

    2014-01-01

    Solid State Lighting (SSL) systems, powered by light-emitting diodes (LEDs), are revolutionizing the lighting industry with energy saving and enhanced performance compared to traditional light sources. However, around 70%-80% of the electric power will still be transferred to heat. As the elevated

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

    Energy Technology Data Exchange (ETDEWEB)

    Byeon, Kyeong-Jae [Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109 (United States); Cho, Joong-Yeon; Jo, Han-Byeol [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Lee, Heon, E-mail: heonlee@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of)

    2015-08-15

    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.

  7. Extragalactic background light: a measurement at 400 nm using dark cloud shadow*†- I. Low surface brightness spectrophotometry in the area of Lynds 1642

    Science.gov (United States)

    Mattila, K.; Lehtinen, K.; Väisänen, P.; von Appen-Schnur, G.; Leinert, Ch.

    2017-09-01

    We present the method and observations for the measurement of the Extragalactic Background Light (EBL) utilizing the shadowing effect of a dark cloud. We measure the surface brightness difference between the opaque cloud core and its unobscured surroundings. In the difference the large atmospheric and Zodiacal light components are eliminated and the only remaining foreground component is the scattered starlight from the cloud itself. Although much smaller, its separation is the key problem in the method. For its separation we use spectroscopy. While the scattered starlight has the characteristic Fraunhofer lines and 400 nm discontinuity, the EBL spectrum is smooth and without these features. Medium resolution spectrophotometry at λ = 380-580 nm was performed with VLT/FORS at ESO of the surface brightness in and around the high-galactic-latitude dark cloud Lynds 1642. Besides the spectrum for the core with AV ≳ 15 mag, further spectra were obtained for intermediate-opacity cloud positions. They are used as proxy for the spectrum of the impinging starlight spectrum and to facilitate the separation of the scattered starlight (cf. Paper II; Mattila et al.). Our spectra reach a precision of ≲ 0.5 × 10-9 erg cm-2 s-1 sr-1 Å-1 as required to measure an EBL intensity in range of ∼1 to a few times 10-9 erg cm-2 s-1 sr-1 Å-1. Because all surface brightness components are measured using the same equipment, the method does not require unusually high absolute calibration accuracy, a condition that has been a problem for some previous EBL projects.

  8. The formation and transformation of the spatial weak-light bright and dark solitons in a quantum dot molecule with the interdot tunneling coupling

    Science.gov (United States)

    Zeng, Kuanhong; Wang, Denglong; She, Yanchao; Luo, Xiaoqin

    2013-11-01

    We study analytically the properties of the optical absorption and the spatial weak-light solitons in a quantum dot molecule system with the interdot tunneling coupling (ITC). It is shown that, for the linear case, there exists tunneling induced transparency (TIT) in the context of a weak ITC, while the TIT can be replaced by Autler-Townes splitting in the presence of a strong ITC. For the nonlinear case, it is probable to realize the spatial optical solitons even under weak light intensity. Interestingly, we find that there appears transformation behavior between the bright and dark solitons by properly turning both the ITC strength and the detuning of the probe field. Meanwhile, the transformation condition of the bright and dark solitons is obtained. Additionally it is also found that the amplitude of the solitons first descends and then rises with the increasing of ITC strength. Our results may have potential applications for nonlinear optical experiments and optical telecommunication engineering in solid systems.

  9. Brain responses to violet, blue, and green monochromatic light exposures in humans: prominent role of blue light and the brainstem.

    Directory of Open Access Journals (Sweden)

    Gilles Vandewalle

    Full Text Available BACKGROUND: Relatively long duration retinal light exposure elicits nonvisual responses in humans, including modulation of alertness and cognition. These responses are thought to be mediated in part by melanopsin-expressing retinal ganglion cells which are more sensitive to blue light than violet or green light. The contribution of the melanopsin system and the brain mechanisms involved in the establishment of such responses to light remain to be established. METHODOLOGY/PRINCIPAL FINDINGS: We exposed 15 participants to short duration (50 s monochromatic violet (430 nm, blue (473 nm, and green (527 nm light exposures of equal photon flux (10(13ph/cm(2/s while they were performing a working memory task in fMRI. At light onset, blue light, as compared to green light, increased activity in the left hippocampus, left thalamus, and right amygdala. During the task, blue light, as compared to violet light, increased activity in the left middle frontal gyrus, left thalamus and a bilateral area of the brainstem consistent with activation of the locus coeruleus. CONCLUSION/SIGNIFICANCE: These results support a prominent contribution of melanopsin-expressing retinal ganglion cells to brain responses to light within the very first seconds of an exposure. The results also demonstrate the implication of the brainstem in mediating these responses in humans and speak for a broad involvement of light in the regulation of brain function.

  10. Brightness variation distributions among main belt asteroids from sparse light curve sampling with Pan-STARRS 1

    CERN Document Server

    McNeill, A; Jedicke, R; Wainscoat, R; Denneau, L; Veres, P; Magnier, E; Chambers, K C; Kaiser, N; Waters, C

    2016-01-01

    The rotational state of asteroids is controlled by various physical mechanisms including collisions, internal damping and the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. We have analysed the changes in magnitude between consecutive detections of approximately 60,000 asteroids measured by the PanSTARRS 1 survey during its first 18 months of operations. We have attempted to explain the derived brightness changes physically and through the application of a simple model. We have found a tendency toward smaller magnitude variations with decreasing diameter for objects of 1 < D < 8 km. Assuming the shape distribution of objects in this size range to be independent of size and composition our model suggests a population with average axial ratios 1 : 0.85 \\pm 0.13 : 0.71 \\pm 0.13, with larger objects more likely to have spin axes perpendicular to the orbital plane.

  11. The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder

    NARCIS (Netherlands)

    Meesters, Ybe; Winthorst, Wim H.; Duijzer, Wianne; Bos, Elisabeth; V, Hommes,

    2016-01-01

    Background The discovery of a novel photoreceptor in the retinal ganglion cells with a highest sensitivity of 470-490 nm blue light has led to research on the effects of short-wavelength light in humans. Several studies have explored the efficacy of monochromatic blue or blue-enriched light in the

  12. LIGHT EXPOSURE ASSESSMENT OF DANISH INDOOR, OUTDOOR AND NIGHT-SHIFT WORKERS

    DEFF Research Database (Denmark)

    Markvart, Jakob

    2016-01-01

    A research talk about: • The Lux@r project - The context of this talk • Light and light exposure - What When and Where • Light as a “one-dimensional unit” – things that matters: 1. Spectral sensitivity 2. Spatial sensitivity......A research talk about: • The Lux@r project - The context of this talk • Light and light exposure - What When and Where • Light as a “one-dimensional unit” – things that matters: 1. Spectral sensitivity 2. Spatial sensitivity...

  13. The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder

    OpenAIRE

    Meesters, Ybe; Winthorst, Wim H; Duijzer, Wianne B.; Hommes, Vanja

    2016-01-01

    Background The discovery of a novel photoreceptor in the retinal ganglion cells with a highest sensitivity of 470-490 nm blue light has led to research on the effects of short-wavelength light in humans. Several studies have explored the efficacy of monochromatic blue or blue-enriched light in the treatment of SAD. In this study, a comparison has been made between the effects of broad-wavelength light without ultraviolet (UV) wavelengths compared to narrow-band blue light in the treatment of ...

  14. The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder

    OpenAIRE

    Meesters, Ybe; Winthorst, Wim H; Duijzer, Wianne; Bos, Elisabeth; V, Hommes,

    2016-01-01

    Background The discovery of a novel photoreceptor in the retinal ganglion cells with a highest sensitivity of 470-490 nm blue light has led to research on the effects of short-wavelength light in humans. Several studies have explored the efficacy of monochromatic blue or blue-enriched light in the treatment of SAD. In this study, a comparison has been made between the effects of broad-wavelength light without ultraviolet (UV) wavelengths compared to narrow-band blue light in the treatment of ...

  15. Sleep-Wake Actigraphy and Light Exposure During Spaceflight-Long

    Science.gov (United States)

    Czeisler, Charles A.; Barger, Laura K.; Wright, Kenneth P., Jr.; Ronda, Joseph

    2009-01-01

    Sleep-Wake Actigraphy and Light Exposure During Spaceflight-Long (Sleep-Long) will examine the effects of spaceflight and ambient light exposure on the sleep-wake cycles of the crew members during long-duration stays on the space station.

  16. Exposure time to sunlight for ultra violet light therapy

    Directory of Open Access Journals (Sweden)

    Srinivas C

    1991-01-01

    Full Text Available Exposure time to sunlight for photo or photochemotherapy is arbitrarily determined. This could lead to inadequate or over exposure. As a sequence to our initial pilot study on exposure time for PUVASOL, we have now developed a bar chart which could be used as a guide to achieve a more logical and uniform exposure time during different months. We plan to extend the study to different zones in India.

  17. A multicenter randomized controlled trial for bright light therapy in adults with intellectual disabilities and depression: Study protocol and obstacle management.

    Science.gov (United States)

    Hamers, Pauline C M; Evenhuis, Heleen M; Hermans, Heidi

    2017-01-01

    Due to the limited cognitive and communicative abilities of adults with intellectual disabilities (ID), current treatment options for depression are often limited to lifestyle changes and pharmacological treatment. Bright light therapy (BLT) is an effective intervention for both seasonal and non-seasonal depression in the general population. BLT is an inexpensive, easy to carry out intervention with minimal side effects. However, knowledge on its anti-depressant effect in adults with ID is lacking. Obstacles in realizing a controlled intervention study in this particular study population may have contributed to this lack. To study the effect of BLT on depression in this population, it is necessary to successfully execute a multicenter randomized controlled trial (RCT). Therefore, the study protocol and the management of anticipated obstacles regarding this trial are presented.

  18. Si III OV Bright Line of Scattering Polarized Light That Has Been Observed in the CLASP and Its Center-to-Limb Variation

    Science.gov (United States)

    Katsukawa, Yukio; Ishikawa, Ryoko; Kano, Ryohei; Kubo, Masahito; Noriyuki, Narukage; Kisei, Bando; Hara, Hirohisa; Yoshiho, Suematsu; Goto, Motouji; Ishikawa, Shinnosuke; hide

    2017-01-01

    The CLASP (Chromospheric Lyman-Alpha Spectro- Polarimeter) rocket experiment, in addition to the ultraviolet region of the Ly alpha emission line (121.57 nm), emission lines of Si III (120.65 nm) and OV (121.83 nm) is can be observed. These are optically thin line compared to a Ly alpha line, if Rarere captured its polarization, there is a possibility that dripping even a new physical diagnosis chromosphere-transition layer. In particular, OV bright light is a release from the transition layer, further, three P one to one S(sub 0) is a forbidden line (cross-triplet transition between lines), it was not quite know whether to polarization.

  19. Bright Visible-Infrared Light Emitting Diodes Based on Hybrid Halide Perovskite with Spiro-OMeTAD as a Hole-Injecting Layer.

    Science.gov (United States)

    Jaramillo-Quintero, Oscar A; Sanchez, Rafael S; Rincon, Marina; Mora-Sero, Ivan

    2015-05-21

    Hybrid halide perovskites that are currently intensively studied for photovoltaic applications, also present outstanding properties for light emission. Here, we report on the preparation of bright solid state light emitting diodes (LEDs) based on a solution-processed hybrid lead halide perovskite (Pe). In particular, we have utilized the perovskite generally described with the formula CH3NH3PbI(3-x)Cl(x) and exploited a configuration without electron or hole blocking layer in addition to the injecting layers. Compact TiO2 and Spiro-OMeTAD were used as electron and hole injecting layers, respectively. We have demonstrated a bright combined visible-infrared radiance of 7.1 W·sr(-1)·m(-2) at a current density of 232 mA·cm(-2), and a maximum external quantum efficiency (EQE) of 0.48%. The devices prepared surpass the EQE values achieved in previous reports, considering devices with just an injecting layer without any additional blocking layer. Significantly, the maximum EQE value of our devices is obtained at applied voltages as low as 2 V, with a turn-on voltage as low as the Pe band gap (V(turn-on) = 1.45 ± 0.06 V). This outstanding performance, despite the simplicity of the approach, highlights the enormous potentiality of Pe-LEDs. In addition, we present a stability study of unsealed Pe-LEDs, which demonstrates a dramatic influence of the measurement atmosphere on the performance of the devices. The decrease of the electroluminescence (EL) under continuous operation can be attributed to an increase of the non-radiative recombination pathways, rather than a degradation of the perovskite material itself.

  20. The Young and Bright Type Ia Supernova ASASSN-14lp: Discovery, Early-Time Observations, First-Light Time, Distance to NGC 4666, and Progenitor Constraints

    CERN Document Server

    Shappee, B J; Holoien, T W -S; Prieto, J L; Contreras, C; Itagaki, K; Burns, C R; Kochanek, C S; Stanek, K Z; Alper, E; Basu, U; Beacom, J F; Bersier, D; Brimacombe, J; Conseil, E; Danilet, A B; Dong, Subo; Falco, E; Grupe, D; Hsiao, E Y; Kiyota, S; Morrell, N; Nicolas, J; Phillips, M M; Pojmanski, G; Simonian, G; Stritzinger, M; Szczygieł, D M; Thompson, T A; Thorstensen, J; Wagner, M; Woźniak, P R

    2015-01-01

    On 2014 Dec. 9.61, the All-Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin") discovered ASASSN-14lp just $\\sim2$ days after first light using a global array of 14-cm diameter telescopes. ASASSN-14lp went on to become a bright supernova ($V = 11.94$ mag), second only to SN 2014J for the year. We present prediscovery photometry (with a detection less than a day after first light) and ultraviolet through near-infrared photometric and spectroscopic data covering the rise and fall of ASASSN-14lp for more than 100 days. We find that ASASSN-14lp had a broad light curve ($\\Delta m_{15}(B) = 0.796 \\pm 0.001_{\\textrm{stat}}$), a $B$-band maximum at $2457015.823 \\pm 0.030_{\\textrm{stat}}$, a rise time of $16.94^{+ 0.11 }_{- 0.11 }$ days, and moderate host--galaxy extinction ($E(B-V)_{\\textrm{host}} = 0.329 \\pm 0.001_{\\textrm{stat}}$). Using ASASSN-14lp we derive a distance modulus for NGC 4666 of $\\mu = 30.834 \\pm 0.003_{\\textrm{stat}} \\pm 0.16_{\\textrm{syst}}$ corresponding to a distance of $14.68 \\pm 0.02_{\\...

  1. A double-blind randomized controlled trial to assess the effect of bright light therapy on depression in patients with Parkinson’s disease

    Directory of Open Access Journals (Sweden)

    Sonja Rutten

    2016-10-01

    Full Text Available Abstract Background A disturbed circadian rhythm seems to be a causal factor in the occurrence of depressive disorders in patients with Parkinson’s disease (PD. The circadian rhythm can be restored with light. Therefore, Bright Light Therapy (BLT might be a new treatment option for depression in PD patients. Methods/design In this double-blind controlled trial, 84 subjects with idiopathic PD are randomized to either BLT or a control light condition. The BLT condition emits white light with an intensity of 10,000 Lux, while the control device emits dim white light of 200 Lux, which is presumed to be too low to influence the circadian rhythm. Subjects receive 30 min of home treatment twice daily for three months. Timing of treatment is based on the individual chronotype. After finishing treatment, subjects enter a follow-up period of six months. The primary outcome of the study is the severity of depressive symptoms, as measured with the Hamilton Depression Rating Scale. Secondary outcomes are alternative depression measures, objective and subjective sleep measures, and salivary melatonin and cortisol concentrations. For exploratory purposes, we also assess the effects on motor symptoms, global cognitive function, comorbid psychiatric disorders, quality of life and caregiver burden. Data will be analyzed using a linear mixed models analysis. Discussion Performing a placebo-controlled trial on the effects of BLT in PD patients is challenging, as the appearance of the light may provide clues on the treatment condition. Moreover, fixed treatment times lead to an improved sleep-wake rhythm, which also influences the circadian system. With our study design, we do not compare BLT to placebo treatment, i.e. an ineffective control treatment. Rather, we compare structuring of the sleep-wake cycle in both conditions with additional BLT in the experimental condition, and additional dim light in the control condition. Participants are not informed about

  2. The first study of the light-travel time effect in bright eclipsing binaries in the Small Magellanic Cloud

    Science.gov (United States)

    Zasche, P.; Wolf, M.; Vraštil, J.

    2017-08-01

    The first 100 brightest eclipsing systems from the Small Magellanic Cloud were studied for their period changes. The photometric data from the surveys OGLE-II, OGLE-III, OGLE-IV and MACHO were combined with our new CCD observations obtained using the Danish 1.54-m telescope (La Silla, Chile). Besides the period changes the light curves were also analysed using the program phoebe, which provided the physical parameters of both eclipsing components. For 14 of these systems the additional bodies were found, having the orbital periods from 2 to 20 yr and the eccentricities were found to be up to 0.9. Amongst the sample of studied 100 brightest systems, we discussed the number of systems with particular period changes. About 10 per cent of these stars show eccentric orbit, about the same numbers have third bodies and about the same show the asymmetric light curves.

  3. 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.

  4. Retinal vascular calibre and response to light exposure and serial imaging

    DEFF Research Database (Denmark)

    von Hanno, T.; Sjølie, Anne K.; Mathiesen, E. B.

    2014-01-01

    and vein equivalents (CRAE and CRVE). Outcome measures were difference in calibres after prior light versus prior dark exposure and difference in calibre during each of the two imaging sequences. Results: CRVE was wider with prior light exposure (2.7%, p = 0.0001), comparing the first image in each image......Purpose: To investigate whether retinal vessel calibre measurements on optical retinal photography are affected by light and dark exposure prior to photography and whether the vessel calibre changes during an imaging sequence of several images. Methods: Digital optical retinal photographs were...... obtained from 32 healthy adults in two separate image sequences of six images during 1 min; one sequence with 10 min of dark exposure and one with 10 min of light exposure prior to imaging. Retinal arteriolar and venular calibres were measured computer-assisted and summarized as central retinal artery...

  5. 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......- 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...

  6. Novel high-brightness tunneling-regenerated multi-active-region AlGaInP light-emitting diode

    Institute of Scientific and Technical Information of China (English)

    郭霞; 沈光地; 王国宏; 王学忠; 杜金玉; 高国; 王康隆

    2003-01-01

    In order to resolve the prevailing problems in conventional light-emitting diodes (LEDs), novel high-efficiency tunneling-regenerated multi-active-region (TRMAR) LEDs are proposed, which have such advantages as low heat generation, carrier overflow level and non-radiation recombination rate and whose quantum efficiency and the output optical power can be scaled with the number of the active regions. Experiments show that the on-axis luminous intensity of TRMAR LEDs increases linearly with the number of active regions. The novel LEDs have high quantum efficiency under low current injection and their maximum on-axis luminous intensity exceeds 5 candelas at 20 mA current injection at the peak wavelength of 625 nm with a 15° angle cap.

  7. Solid-core and hollow-core photonic crystal fiber for generation of bright ultraviolet light (Conference Presentation)

    Science.gov (United States)

    Joly, Nicolas Y.; Jiang, Xin; Travers, John C.; Ermolov, Alexey; Russell, Philip S.

    2016-09-01

    Over the last two decades the interest in photonic crystal fiber (PCF) has grown considerably, particularly in nonlinear optics where it allows enhanced control over the dispersion landscape. Although silica is the material most commonly used to fabricate PCF, its limited window of transmission and its susceptibility to optical damage at wavelengths below 350nm is driving the development of fibers made from glasses with transmission windows extending into the deep ultraviolet and the mid-infrared. An alternative is offered by gas-filled hollow-core fiber, in which the light propagates predominantly in the gas. In kagomé-style hollow-core PCF filled with noble gas, the weak anomalous dispersion of the empty fiber is balanced by the normal dispersion of the filling gas, resulting in a versatile system whose dispersion landscape can be adjusted in real time [Travers et al., JOSAB 28, A11 (2011)]. Under appropriate conditions the launched pulse undergoes soliton self-compression followed by emission of a band of dispersive radiation in the UV. UV light tunable down to 113 nm has been generated with this technique [Russell et al., Nat. Photon. 8, 278 (2014)]. Solid-core ZBLAN (fluorozirconate) glass PCF is transparent from 0.2 to 7.8µm. Launching 1nJ 140fs pulses at 1µm wavelength into a 1µm diameter core resulted, after 4cm of propagation, in generation of a supercontinuum spectrum extending from 210nm to beyond 2µm. In strong contrast to silica PCF, the ZBLAN PCF showed no signs of any solarization-related damage, even when operating over many hours [Jiang et al., Nat. Photon. 9, 133 (2015)].

  8. Bright light therapy for seasonal affective disorder in Israel (latitude 32.6 degrees N): a single case placebo-controlled study.

    Science.gov (United States)

    Moscovici, L

    2006-09-01

    We describe a patient diagnosed as having seasonal affective disorder (SAD, winter depression), an unlikely condition in Israel (latitude 32.6 degrees N), a country with relatively minor daylight photoperiodic changes between seasons. Case report. A 46-year-old woman with a clinical picture of depression (Diagnostic and Statistical Manual of Mental Disorders diagnostic criteria for 'major depression with seasonal pattern') reacted positively to 3 weeks of daily bright light therapy of 10,000 lux/wide spectrum. She was asked to wear dark sunglasses during placebo sessions to accommodate an A-B-C single-case-design. The intervention resulted in an improvement of 74-80% in the Hamilton anxiety and depression scales (clinician-rated) and the Beck depression inventory, similar to results obtained in high latitude regions. The depression and anxiety levels returned close to baseline levels following 1 week of the placebo intervention. Seasonal affective disorder is apparently not limited to certain latitudes. The effect of light therapy was short-lived after discontinuation of the treatment, with rapid relapse occurring in the placebo phase.

  9. Caenorhabditis elegans as a model to study the impact of exposure to light emitting diode (LED) domestic lighting.

    Science.gov (United States)

    Abdel-Rahman, Fawzia; Okeremgbo, Bethel; Alhamadah, Fatimah; Jamadar, Sakha; Anthony, Kevin; Saleh, Mahmoud A

    2017-04-16

    This study aimed to investigate the biological impact of exposure on domestic light emitting diodes (LED) lighting using the free-living nematode Caenorhabditis elegans as a model. Nematodes were separately exposed to white LED light covering the range of 380-750 nm, blue light at 450 nm and black light at 380-420 nm for one life cycle (egg to adult) with dark exposure as the control. Each light range induced stress to the nematode C. elegans such as reducing the number of the hatched eggs and/or delayed the maturation of the hatched eggs to the adult stage. In addition, it lowered or prevented the ability of adults to lay eggs and impaired the locomotion in the exposed worms. The observed type of biological stress was also associated with the production of reactive oxygen species (ROS) as compared to nematodes grown in the dark. It is concluded that the blue light component of white LED light may cause health problems, and further investigation is required to test commercial brands of white LEDs that emit different amounts of blue light.

  10. Do wild great tits avoid exposure to light at night?

    NARCIS (Netherlands)

    De Jong, M.; Ouyang, Jenny; van Grunsven, Roy H. A.; Visser, M.E.; Spoelstra, K.

    2016-01-01

    Studies of wild populations have provided important insights into the effects of artificial light at night on organisms, populations and ecosystems. However, in most studies the exact amount of light at night individuals are exposed to remains unknown. Individuals can potentially control their

  11. Do wild great tits avoid exposure to light at night?

    NARCIS (Netherlands)

    De Jong, M.; Ouyang, Jenny; van Grunsven, Roy H. A.; Visser, M.E.; Spoelstra, K.

    2016-01-01

    Studies of wild populations have provided important insights into the effects of artificial light at night on organisms, populations and ecosystems. However, in most studies the exact amount of light at night individuals are exposed to remains unknown. Individuals can potentially control their night

  12. Do Wild Great Tits Avoid Exposure to Light at Night?

    NARCIS (Netherlands)

    de Jong, Maaike; Ouyang, Jenny Q; van Grunsven, Roy H A; Visser, Marcel E; Spoelstra, Kamiel

    2016-01-01

    Studies of wild populations have provided important insights into the effects of artificial light at night on organisms, populations and ecosystems. However, in most studies the exact amount of light at night individuals are exposed to remains unknown. Individuals can potentially control their night

  13. Do wild great tits avoid exposure to light at night?

    NARCIS (Netherlands)

    Jong, De Maaike; Ouyang, Jenny Q.; Grunsven, van Roy H.A.; Visser, Marcel E.; Spoelstra, Kamiel

    2016-01-01

    Studies of wild populations have provided important insights into the effects of artificial light at night on organisms, populations and ecosystems. However, in most studies the exact amount of light at night individuals are exposed to remains unknown. Individuals can potentially control their ni

  14. Blue light-induced immunosuppression in Bactrocera dorsalis adults, as a carryover effect of larval exposure.

    Science.gov (United States)

    Tariq, K; Noor, M; Hori, M; Ali, A; Hussain, A; Peng, W; Chang, C-J; Zhang, H

    2017-05-09

    Detrimental effects of ultraviolet (UV) light on living organisms are well understood, little is known about the effects of blue light irradiation. Although a recent study revealed that blue light caused more harmful effects on insects than UV light and blue light irradiation killed insect pests of various orders including Diptera, the effects of blue light on physiology of insects are still largely unknown. Here we studied the effects of blue light irradiation on cuticular melanin in larval and the immune response in adult stage of Bactrocera dorsalis. We also evaluated the effects of blue light exposure in larval stage on various age and mass at metamorphosis and the mediatory role of cuticular melanin in carryover effects of larval stressors across metamorphosis. We found that larvae exposed to blue light decreased melanin contents in their exoskeleton with smaller mass and delayed metamorphosis than insects reared without blue light exposure. Across metamorphosis, lower melanotic encapsulation response and higher susceptibility to Beauveria bassiana was detected in adults that had been exposed to blue light at their larval stage, thereby constituting the first evidence that blue light impaired adult immune function in B. dorsalis as a carryover effect of larval exposure.

  15. Influence of light exposure at nighttime on sleep development and body growth of preterm infants.

    Science.gov (United States)

    Kaneshi, Yosuke; Ohta, Hidenobu; Morioka, Keita; Hayasaka, Itaru; Uzuki, Yutaka; Akimoto, Takuma; Moriichi, Akinori; Nakagawa, Machiko; Oishi, Yoshihisa; Wakamatsu, Hisanori; Honma, Naoki; Suma, Hiroki; Sakashita, Ryuichi; Tsujimura, Sei-ichi; Higuchi, Shigekazu; Shimokawara, Miyuki; Cho, Kazutoshi; Minakami, Hisanori

    2016-02-15

    Previous studies have demonstrated that a light-dark cycle has promoted better sleep development and weight gain in preterm infants than constant light or constant darkness. However, it was unknown whether brief light exposure at night for medical treatment and nursing care would compromise the benefits brought about by such a light-dark cycle. To examine such possibility, we developed a special red LED light with a wavelength of >675 nm which preterm infants cannot perceive. Preterm infants born at growth as long as the infants are exposed to regular light-dark cycles.

  16. Evaluating metabolic response to light exposure in Lactobacillus species via targeted metabolic profiling.

    Science.gov (United States)

    Xu, Mengyang; Zhong, Fanyi; Zhu, Jiangjiang

    2017-02-01

    This study reported metabolic profiles of three representative strains from Lactobacillus species, and explored their metabolic response to visible light exposure. We utilized strains from three Lactobacillus species, Lactobacillus acidophilus, Lactobacillus fermentum and Lactobacillus delbrueckii as our model bacteria and applied mass spectrometry base targeted metabolomics to specifically investigate 221 metabolites within multiple metabolic pathways. Similar and diverse metabolome from three tested strains were discovered. Furthermore, all three Lactobacillus strains demonstrated different metabolic profiles in comparison between light expose verse control. In all three strains, 12 metabolites were detected to have significant differences (p-value<0.01) in light exposure culture compared to the control samples (culture grown without light exposure). Principal components analysis using these significantly changed metabolites clearly separated the exposure and control groups in all three studied Lactobacillus strains. Additionally, metabolic pathway impact analysis indicated that several commonly impacted pathways can be observed.

  17. Acute light exposure suppresses circadian rhythms in clock gene expression.

    Science.gov (United States)

    Grone, Brian P; Chang, Doris; Bourgin, Patrice; Cao, Vinh; Fernald, Russell D; Heller, H Craig; Ruby, Norman F

    2011-02-01

    Light can induce arrhythmia in circadian systems by several weeks of constant light or by a brief light stimulus given at the transition point of the phase response curve. In the present study, a novel light treatment consisting of phase advance and phase delay photic stimuli given on 2 successive nights was used to induce circadian arrhythmia in the Siberian hamster ( Phodopus sungorus). We therefore investigated whether loss of rhythms in behavior was due to arrhythmia within the suprachiasmatic nucleus (SCN). SCN tissue samples were obtained at 6 time points across 24 h in constant darkness from entrained and arrhythmic hamsters, and per1, per2 , bmal1, and cry1 mRNA were measured by quantitative RT-PCR. The light treatment eliminated circadian expression of clock genes within the SCN, and the overall expression of these genes was reduced by 18% to 40% of entrained values. Arrhythmia in per1, per2, and bmal1 was due to reductions in the amplitudes of their oscillations. We suggest that these data are compatible with an amplitude suppression model in which light induces singularity in the molecular circadian pacemaker.

  18. The Differential Effect of Ultraviolet Light Exposure on Cataract Rate across Regions of the Lens

    OpenAIRE

    Abraham, Alison G.; Cox, Christopher; West, Sheila

    2010-01-01

    This study was an investigation of the effect of ultraviolet B light exposure on the risk of cortical cataract as a function of the region of the lens. The degree to which the lower nasal predominance of cortical cataract is a result of UVB exposure was assessed.

  19. Does pupil constriction under blue and green monochromatic light exposure change with age?

    Science.gov (United States)

    Daneault, Véronique; Vandewalle, Gilles; Hébert, Marc; Teikari, Petteri; Mure, Ludovic S; Doyon, Julien; Gronfier, Claude; Cooper, Howard M; Dumont, Marie; Carrier, Julie

    2012-06-01

    Many nonvisual functions are regulated by light through a photoreceptive system involving melanopsin-expressing retinal ganglion cells that are maximally sensitive to blue light. Several studies have suggested that the ability of light to modulate circadian entrainment and to induce acute effects on melatonin secretion, subjective alertness, and gene expression decreases during aging, particularly for blue light. This could contribute to the documented changes in sleep and circadian regulatory processes with aging. However, age-related modification in the impact of light on steady-state pupil constriction, which regulates the amount of light reaching the retina, is not demonstrated. We measured pupil size in 16 young (22.8±4 years) and 14 older (61±4.4 years) healthy subjects during 45-second exposures to blue (480 nm) and green (550 nm) monochromatic lights at low (7×10(12) photons/cm2/s), medium (3×10(13) photons/cm2/s), and high (10(14) photons/cm2/s) irradiance levels. Results showed that young subjects had consistently larger pupils than older subjects for dark adaptation and during all light exposures. Steady-state pupil constriction was greater under blue than green light exposure in both age groups and increased with increasing irradiance. Surprisingly, when expressed in relation to baseline pupil size, no significant age-related differences were observed in pupil constriction. The observed reduction in pupil size in older individuals, both in darkness and during light exposure, may reduce retinal illumination and consequently affect nonvisual responses to light. The absence of a significant difference between age groups for relative steady-state pupil constriction suggests that other factors such as tonic, sympathetic control of pupil dilation, rather than light sensitivity per se, account for the observed age difference in pupil size regulation. Compared to other nonvisual functions, the light sensitivity of steady-state pupil constriction appears to

  20. Does pupil constriction under blue and green monochromatic light exposure change with age?

    Science.gov (United States)

    Daneault, Véronique; Vandewalle, Gilles; Hébert, Marc; Teikari, Petteri; Mure, Ludovic S.; Doyon, Julien; Gronfier, Claude; Cooper, Howard M.; Dumont, Marie; Carrier, Julie

    2017-01-01

    Many non-visual functions are regulated by light through a photoreceptive system involving melanopsin-expressing retinal ganglion cells that are maximally sensitive to blue light. Several studies have suggested that the ability of light to modulate circadian entrainment and to induce acute effects on melatonin secretion, subjective alertness and gene expression, decreases during aging, particularly for blue light. This could contribute to the documented changes in sleep and circadian regulatory processes with aging. However, age-related modification in the impact of light on steady-state pupil constriction, which regulates the amount of light reaching the retina, is not demonstrated. We measured pupil size in 16 young (22.8±4y) and 14 older (61±4.4y) healthy subjects during 45s exposures to blue (480nm) and green (550nm) monochromatic lights at low (7×1012 photons/cm2/s), medium (3×1013 photons/cm2/s), and high (1014 photons/cm2/s) irradiance levels. Results showed that young subjects had consistently larger pupils than older subjects, for dark adaptation and during all light exposures. Steady-state pupil constriction was greater under blue than green light exposure in both age groups and increased with increasing irradiance. Surprisingly, when expressed in relation to baseline pupil size, no significant age-related differences were observed in pupil constriction. The observed reduction in pupil size in older individuals, both in darkness and during light exposure, may reduce retinal illumination and consequently affect non-visual responses to light. The absence of a significant difference between age groups for relative steady-state pupil constriction suggests that other factors such as tonic, sympathetic control of pupil dilation, rather than light sensitivity per se, account for the observed age difference in pupil size regulation. Compared to other nonvisual functions, the light sensitivity of steady-state pupil constriction appears to remain relatively

  1. 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.

  2. Noise effects and filtering in controlled light exposure microscopy

    NARCIS (Netherlands)

    R.A. Hoebe; C.J.F. van Noorden; E.M.M. Manders

    2010-01-01

    Phototoxicity and photobleaching are major limitations of fluorescence live-cell microscopy. A straightforward way to limit phototoxicity and photobleaching is reduction of the excitation light dose, but this causes loss of image quality. In confocal fluorescence microscopy, the field of view is ill

  3. Fluctuations of MS births and UV-light exposure

    NARCIS (Netherlands)

    Verheul, F.; Smolders, J.; Trojano, M.; Lepore, V.; Zwanikken, C.; Amato, M. P.; Grand'Maison, F.; Butzkueven, H.; Marrosu, M.; Duquette, P.; Comi, G.; Izquierdo, G.; Grammond, P.; Lus, G.; Petersen, T.; Bergamaschi, R.; Giuliani, G.; Boz, C.; Coniglio, G.; Van Pesch, V.; Lechner-Scott, J.; Cavalla, P.; Granella, F.; Avolio, C.; Fiol, M.; Poehlau, D.; Saladino, M. L.; Gallo, P.; Deri, N.; Oleschko Arruda, W.; Paine, M.; Ferro, M.; Barnett, M.; Cabrera-Gomez, J. A.; Slee, M.; Moore, F.; Shaw, C.; Petkovska-Boskova, T.; Rutherford, M.; Engelsen, O.; Damoiseaux, J.; Hupperts, R.

    2013-01-01

    Background Patients with multiple sclerosis (MS) are more frequently born in spring when compared to autumn. Fluctuation of UV-light has been hypothesized to drive this phenomenon. Aim To assess the correlation between fluctuation of sunlight and birth season in persons with MS. Methods For this rec

  4. The Influence of the Environment and Clothing on Human Exposure to Ultraviolet Light

    OpenAIRE

    Jin Liu; Wei Zhang

    2015-01-01

    Objection The aim of this study is to determine the effect of clothing and the environment on human exposure to ultraviolet light. Methods The ultraviolet (ultraviolet A and ultraviolet B) light intensity was measured, and air quality parameters were recorded in 2014 in Beijing, China. Three types of clothing (white polyester cloth, pure cotton white T-shirt, and pure cotton black T-shirt) were individually placed on a mannequin. The ultraviolet (ultraviolet A and ultraviolet B) light intensi...

  5. Research on the Inactivation Effect of Pulsed Bright Light to Bacillus subtilis in water%脉冲强光对水中枯草杆菌灭活效果的研究

    Institute of Scientific and Technical Information of China (English)

    赵伟; 马玉坤

    2014-01-01

    Pulsed bright light sterilization technology developed in recent years is a new type of cold steriliza-tion technique with strong white light flashes for sterilization. This paper compares inactivation effect of pulsed bright light and UV with Bacillus subtilis as target microorganism. By changing input voltage and frequency of light flashes, effect factors of pulsed bright light sterilization is studied.%脉冲强光杀菌技术是近年来开发的一种新型冷杀菌技术,利用强烈的白光闪照进行杀菌。以枯草杆菌为目标微生物,对比研究脉冲强光与紫外线对微生物的灭活效果。并通过改变脉冲强光装置的输入电压和闪照次数,研究了影响脉冲强光杀菌的影响因素。

  6. Association of Light Exposure on Physical Activity and Sedentary Time in Young People

    Directory of Open Access Journals (Sweden)

    Daniel Aggio

    2015-03-01

    Full Text Available Background: To investigate whether light exposure was associated with objectively measured physical activity (PA and sedentary behaviour in young people. Methods: Participants (n = 229, 46.7% female were young people (mean 8.8 years [SD ± 2.2] from the borough of Camden, UK. Daily sedentary time, moderate and vigorous PA (MVPA and light exposure were measured using a tri-axial accelerometer with an ambient light sensor during the summer. Multiple linear regression models examined associations between average daily light exposure, sedentary time and time in MVPA. Models were repeated investigating weekdays and weekend days separately. Analyses were adjusted for pre-specified covariables, including age, sex, device wear time, ethnic group, school and body fat. Results: There were significant associations between average daily light exposure and time sedentary (β coefficient = −11.2, 95% CI, −19.0 to −3.4 and in MVPA (β coefficient = 3.5, 95% CI, 1.2 to 5.9. Light exposure was significantly associated with weekend sedentary time (β coefficient = −10.0, 95% CI, −17.6, −2.4, weekend MVPA (β coefficient = 3.7, 95% CI, 1.7, 5.7, weekday sedentary time (β coefficient = −15.0, 95% CI, −22.7 to −7.2, but not weekday MVPA (β coefficient = 2.0, 95% CI, −0.5 to 4.5. Conclusion: Average daily light exposure is positively associated with time in MVPA and negatively associated with sedentary time. Increasing daylight exposure may be a useful intervention strategy for promoting physical activity.

  7. The effect of blue light exposure in an ocular melanoma animal model

    Directory of Open Access Journals (Sweden)

    Odashiro Alexandre N

    2009-04-01

    Full Text Available Abstract Background Uveal melanoma (UM cell lines, when exposed to blue light in vitro, show a significant increase in proliferation. In order to determine if similar effects could be seen in vivo, we investigated the effect of blue light exposure in a xenograft animal model of UM. Methods Twenty New Zealand albino rabbits were injected with 1.0 × 106 human UM cells (92.1 in the suprachoroidal space of the right eye. Animals were equally divided into two groups; the experimental group was exposed to blue light, while the control group was protected from blue light exposure. The eyes were enucleated after sacrifice and the proliferation rates of the re-cultured tumor cells were assessed using a Sulforhodamine-B assay. Cells were re-cultured for 1 passage only in order to maintain any in vivo cellular changes. Furthermore, Proliferating Cell Nuclear Antigen (PCNA protein expression was used to ascertain differences in cellular proliferation between both groups in formalin-fixed, paraffin-embedded eyes (FFPE. Results Blue light exposure led to a statistically significant increase in proliferation for cell lines derived from intraocular tumors (p Conclusion There is an increasing amount of data suggesting that blue light exposure may influence the progression of UM. Our results support this notion and warrant further studies to evaluate the ability of blue light filtering lenses to slow disease progression in UM patients.

  8. Ultraviolet light exposure influences skin cancer in association with latitude.

    Science.gov (United States)

    Rivas, Miguel; Araya, María C; Caba, Fresia; Rojas, Elisa; Calaf, Gloria M

    2011-04-01

    The increase in the amount of solar ultraviolet (UV) light that reaches the earth is considered to be responsible for the worldwide increase in skin cancer. It has been reported that excessive levels of UVA and UVB light have multiple effects, which can be harmful to humans. Experimental measurements were obtained using wide-band solar light YES biometers from 2006 to 2009 in Arica, Chile and from 2003 to 2006 in Valdivia, Chile, both instruments having been calibrated according to the World Health Organization (WHO) criteria and integrated into the Chilean Meteorological Organization network. To explain the possible effect of radiation on skin cancer, revised pathological reports in Arica and Valdivia were analyzed. In Arica, data on men and women were collected between 1997 and 1998-2002, and in Valdivia, between 1997-2000 and 2001-2007. In this study, comparative values of ultraviolet index (UVI) from the above datasets, were analyzed. Arica is a city located in the subtropical zone of northern Chile, 25 meters above sea level, with a latitude of 18˚49'S and a longitude of 70˚19'W. It has a microclimate characterized by stable meteorological conditions throughout the year, including low precipitation (<5 mm per decade), predictable winds, a high percentage of clear sky days and high ground reflectivity due to the presence of light sand. Due to its location near sea level, the population performs a great number of outdoor activities. Valdivia is a city located in the southern part of Chile, 19 meters above sea level with a latitude of 39˚38'S and a longitude of 73˚5'W. The aim of the present study was to determine the relationship between latitude and the risk of skin cancer in two cities with different latitudes. The incidence of skin cancer per 100,000 persons significantly (P<0.05) increased in both genders between the periods 1997-2000 and 2001-2007 in Arica. However, it decreased in men between the periods 1993-1997 and 1998-2002 in Valdivia. The results

  9. Astrophotography on the go using short exposures with light mounts

    CERN Document Server

    Ashley, Joseph

    2015-01-01

    No longer are heavy, sturdy, expensive mounts and tripods required to photograph deep space. With today's advances in technology, all that is required is an entry-DSLR and an entry level GoTo telescope. Here is all of the information needed to start photographing the night sky without buying expensive tracking mounts. By using multiple short exposures and combining them with mostly ‘freeware’ computer programs, the effect of image rotation can be minimized to a point where it is undetectable in normal astrophotography, even for a deep-sky object such as a galaxy or nebula. All the processes, techniques, and equipment needed to use inexpensive, lightweight altazimuth and equatorial mounts and very short exposures photography to image deep space objects are explained, step-by-step, in full detail, supported by clear, easy to understand graphics and photographs.   Currently available lightweight mounts and tripods are identified and examined from an economic versus capability perspective to help users deter...

  10. The brightness of colour.

    Directory of Open Access Journals (Sweden)

    David Corney

    Full Text Available BACKGROUND: 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. RESULTS: 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. CONCLUSIONS: The data suggest that perceptions

  11. Fluorescence-guided surgery of retroperitoneal-implanted human fibrosarcoma in nude mice delays or eliminates tumor recurrence and increases survival compared to bright-light surgery.

    Directory of Open Access Journals (Sweden)

    Fuminari Uehara

    Full Text Available The aim of this study is to determine if fluorescence-guided surgery (FGS can eradicate human fibrosarcoma growing in the retroperitoneum of nude mice. One week after retroperitoneal implantation of human HT1080 fibrosarcoma cells, expressing green fluorescent protein (GFP (HT-1080-GFP, in nude mice, bright-light surgery (BLS was performed on all tumor-bearing mice (n = 22. After BLS, mice were randomized into 2 treatment groups; BLS-only (n = 11 or the combination of BLS + FGS (n = 11. The residual tumors remaining after BLS were resected with FGS using a hand-held portable imaging system under fluorescence navigation. The average residual tumor area after BLS + FGS was significantly smaller than after BLS-only (0.4 ± 0.4 mm(2 and 10.5 ± 2.4 mm(2, respectively; p = 0.006. Five weeks after surgery, the fluorescent-tumor areas of BLS- and BLS + FGS-treated mice were 379 ± 147 mm(2 and 11.7 ± 6.9 mm(2, respectively, indicating that FGS greatly inhibited tumor recurrence compared to BLS. The combination of BLS + FGS significantly decreased fibrosarcoma recurrence compared to BLS-only treated mice (p < 0.001. Mice treated with BLS+FGS had a significantly higher disease-free survival rate than mice treated with BLS-only at five weeks after surgery. These results suggest that combination of BLS + FGS significantly reduced the residual fibrosarcoma volume after BLS and improved disease-free survival.

  12. Untargeted Metabolomics Reveals Predominant Alterations in Lipid Metabolism Following Light Exposure in Broccoli Sprouts

    Directory of Open Access Journals (Sweden)

    Mariateresa Maldini

    2015-06-01

    Full Text Available The consumption of vegetables belonging to the family Brassicaceae (e.g., broccoli and cauliflower is linked to a reduced incidence of cancer and cardiovascular diseases. The molecular composition of such plants is strongly affected by growing conditions. Here we developed an unbiased metabolomics approach to investigate the effect of light and dark exposure on the metabolome of broccoli sprouts and we applied such an approach to provide a bird’s-eye view of the overall metabolic response after light exposure. Broccoli seeds were germinated and grown hydroponically for five days in total darkness or with a light/dark photoperiod (16 h light/8 h dark cycle. We used an ultra-performance liquid-chromatography system coupled to an ion-mobility, time-of-flight mass spectrometer to profile the large array of metabolites present in the sprouts. Differences at the metabolite level between groups were analyzed using multivariate statistical analyses, including principal component analysis and correlation analysis. Altered metabolites were identified by searching publicly available and in-house databases. Metabolite pathway analyses were used to support the identification of subtle but significant changes among groups of related metabolites that may have gone unnoticed with conventional approaches. Besides the chlorophyll pathway, light exposure activated the biosynthesis and metabolism of sterol lipids, prenol lipids, and polyunsaturated lipids, which are essential for the photosynthetic machinery. Our results also revealed that light exposure increased the levels of polyketides, including flavonoids, and oxylipins, which play essential roles in the plant’s developmental processes and defense mechanism against herbivores. This study highlights the significant contribution of light exposure to the ultimate metabolic phenotype, which might affect the cellular physiology and nutritional value of broccoli sprouts. Furthermore, this study highlights the

  13. [Inactivation of EV71 by Exposure to Heat and Ultraviolet Light].

    Science.gov (United States)

    Xie, Jing; Li, Dandi; Xie, Guangcheng; Hu, Yaqian; Zhang, Qing; Kong, Xiangyu; Guo, Nijun; Li, Yuning; Duan, Zhaojun

    2015-09-01

    Enterovirus 71 (EV71) is a major agent of hand, foot and mouth disease that can cause a severe burden of disease to children. To identify an effective method for the control and prevention of EV71, we studied the effect of exposure to heat and ultraviolet (UV) light upon EV71 inactivation. We found that exposure to 50 degrees C could not inactivate the infectivity of EV71. However, exposure to 60 degrees C and 70 degrees C could inactivate EV71 effectively. EV71 could be inactivated after exposure to UV light at a distance between the sample and a lamp of 30 cm for 30 min or 60 min because viral genomic RNA was destroyed. However, fetal bovine serum (FBS) could attenuate the inactivation proffered by heat and UV light. Attenuation effects of FBS were correlated positively with FBS concentration. Hence, EV71 can be inactivated by exposure to heat and UV light, and our results could provide guidance on prevention of the spread of EV71.

  14. Exposure of fluid milk to LED light negatively affects consumer perception and alters underlying sensory properties.

    Science.gov (United States)

    Martin, Nicole; Carey, Nancy; Murphy, Steven; Kent, David; Bang, Jae; Stubbs, Tim; Wiedmann, Martin; Dando, Robin

    2016-06-01

    Fluid milk consumption per capita in the United States has been steadily declining since the 1940s. Many factors have contributed to this decline, including the increasing consumption of carbonated beverages and bottled water. To meet the challenge of stemming the decline in consumption of fluid milk, the dairy industry must take a systematic approach to identifying and correcting for factors that negatively affect consumers' perception of fluid milk quality. To that end, samples of fluid milk were evaluated to identify factors, with a particular focus on light-emitting diode (LED) light exposure, which negatively affect the perceived sensory quality of milk, and to quantify their relative effect on the consumer's experience. Fluid milk samples were sourced from 3 processing facilities with varying microbial postprocessing contamination patterns based on historical testing. The effect of fat content, light exposure, age, and microbiological content were assayed across 23 samples of fluid milk, via consumer, descriptive sensory, and instrumental analyses. Most notably, light exposure resulted in a broad negative reaction from consumers, more so than samples with microbiological contamination exceeding 20,000 cfu/mL on days approaching code. The predominant implication of the study is that a component of paramount importance in ensuring the success of the dairy industry would be to protect fluid milk from all sources of light exposure, from processing plant to consumer.

  15. Special Features of Photodegradation of Organic Compounds upon Exposure to Excilamp Light

    Science.gov (United States)

    Sokolova, I. V.; Vershinin, O. N.; Nevolina, K. A.

    2016-08-01

    The use of gas discharge sources of modern spontaneous radiation - excilamps - for photodegradation of organic compounds is discussed. The process of photodegradation upon exposure to excilamp light is considered on an example of degradation of a widespread herbicide - 2,4-dichlorophenoxyacetic acid (2,4-D) - in a continuous-flow photoreactor upon exposure to light of Xe2 (λ rad ~ 172 nm), KrCl (λ rad ~ 222 nm), and XeBr (λ rad ~ 283 nm) excilamps. It is found that the degradation of 2,4-D after exposure to Xe2 excilamp light occurs much more effective than upon exposure to other radiation sources. However, the dechlorination process accompanying the photodegradation of 2,4-D in an aqueous solution upon exposure to the KrCl excilamp is more intensive than that upon exposure to Xe2 lamp. The dynamics of changing the toxicant concentration in the solution during UV irradiation is established. The toxicity of 2,4-D aqueous solutions and photolysis products after irradiation are estimated. It is found that the initial bioluminescence index increases upon exposure to XeBr excilamp light, thereby reducing the toxicity in comparison with the Xe2 and KrCl excilamps. The solutions become most toxic under excitation by the Xe2 excilamp. We have succeeded in reducing the toxicity and increasing the efficiency of the photoreactor with the KrCl excilamp by addition of hydrogen peroxide. In this case, the complete 2,4-D decay has been achieved.

  16. Changes in manganese superoxide dismutase expression after exposure of the retina to intense light.

    Science.gov (United States)

    Yamamoto, M; Lidia, K; Gong, H; Onitsuka, S; Kotani, T; Ohira, A

    1999-02-01

    Manganese superoxide dismutase (Mn-SOD) is a naturally-occurring scavenger of superoxide, one of several reactive oxygen intermediates. To determine if Mn-SOD expression is enhanced as a defensive mechanism against oxidative challenges, such as intense light exposure, rats were exposed to cyclic light (80 lux) for 2 weeks, intense light (1,800 lux) for 24 h, and then again to cyclic light. Experimental and control (exposed to cyclic light only) eyes were enucleated 3 h, 1, 3, 7, and 14 days after light challenge. Protein expression was examined immunohistochemically using rabbit antisera against rat Mn-SOD. There was no significant difference between the light-exposed and the control groups in the thickness of the outer nuclear layers. Both retinal pigment epithelial cells and photoreceptor inner segments in the normal retina were labeled for Mn-SOD. Mn-SOD labeling was lost 3 h and day 1 after light challenge. It was re-expressed in the retinal pigment epithelial cells 3, 7, and 14 days after the light challenge, and in the photoreceptor inner segments after day 14. These results suggest that the retina might have a protective potential against light damage, in which Mn-SOD may play an important role.

  17. LIGHT / DARK PREFERENCE IN Danio rerio: EFFECTS OF LIGHT EXPOSURE DURATION AND DAY PERIOD

    Directory of Open Access Journals (Sweden)

    Claudio Alberto Gellis de Mattos Dias

    2014-10-01

    Full Text Available The animals have anatomical and physiological structures influenced by luminosity. In fish, the pineal gland cells contain photoreceptors and the suprachiasmatic nucleus seems to be involved in biological rhythm just like in other vertebrates. This work aims to describe the role of luminosity and day periods in Danio rerio's Light/Dark preference. For this purpose 160 naive adult undetermined sex Zebrafish were divided into 5 groups of 32 subjects and kept in isolated aquaria with light control. Afterwards, each fish was tested in the Light/Dark aquaria, with water column of 5 centimeters. There was an habituation period of 5 minutes (300 seconds followed by removal of the sliding doors, allowing the subjects to explore the apparatus for 15 minutes (900 seconds. Tests were performed in different day periods, as follows: Morning (06:00 – 12:00 h; Afternoon (12:00 – 18:00 h; Night (18:00 – 24:00 h; Late Night (24:00 – 06:00 h. Our results show that the time of permanence is sensitive to day period. The number of crossings and latency were not influenced by the period of the day. Further studies regarding biological basis of Light/Dark Preference should be carried out in order to understand the role of circadian function in Danio rerio's behavior. Keywords: Danio rerio, zebrafish, behavior, light-dark preference, anxiety. DOI: http://dx.doi.org/10.18561/2179-5746/biotaamazonia.v4n3p106-111

  18. Exposure-based Algorithm for Removing Systematics out of the CoRoT Light Curves

    CERN Document Server

    Guterman, P; Faigler, S

    2015-01-01

    The CoRoT space mission was operating for almost 6 years, producing thousands of continuous photometric light curves. The temporal series of exposures are processed by the production pipeline, correcting the data for known instrumental effects. But even after these model-based corrections, some collective trends are still visible in the light curves. We propose here a simple exposure-based algorithm to remove instrumental effects. The effect of each exposure is a function of only two instrumental stellar parameters, position on the CCD and photometric aperture. The effect is not a function of the stellar flux, and therefore much more robust. As an example, we show that the $\\sim2\\%$ long-term variation of the early run LRc01 is nicely detrended on average. This systematics removal process is part of the CoRoT legacy data pipeline.

  19. Optical-Fiber-Matrix Exposure Using Light-Emitting-Diode Sources

    Science.gov (United States)

    Horiuchi, Toshiyuki; Mirumachi, Naofumi; Ooshima, Yuki

    2007-09-01

    A new projection exposure method without using reticles was proposed, and the feasibility of printing arbitrary patterns was investigated. The preparation of expensive reticles is not favorable for the small-volume production of micro-electro-mechanical systems (MEMS), optomechanical systems, and their components. On the other hand, long turnaround time (TAT) becomes a fatal bottleneck preventing the rapid follow-up of various design changes. As a countermeasure, we previously proposed a new exposure method named optical-fiber-matrix exposure. In this method, patterns are delineated by superimposing light spots from an optical-fiber matrix, and expensive reticles are not necessary. Therefore, patterns are easily changeable by controlling the pattern delineation program. However, in the previous method, light rays from one intensive lamp were divided and switched using small mechanical shutters placed at each fiber entrance, and the shutters were not sufficiently reliable. For this reason, violet light-emitting diodes (LEDs) were used in this research in place of the lamp source and mechanical shutters, and the light or dark state at each optical fiber end was controlled using a microcomputer that switched each LED attached to each fiber entrance one by one. Since the illuminance of each LED was different, LEDs with approximately the same illuminance were selectively used, and each illuminance was adjusted to be uniform by inserting an individual color filter. Thus, the widths of patterns printed by scanning different fiber elements were homogenized. Since line-and-space patterns and various alphabet patterns were successfully printed, the feasibility of fabricating a large-scale optical-fiber matrix was also investigated. An optical-fiber line matrix composed of more than 330 fibers was fabricated without including any gaps between neighbor fibers. There will probably be no fatal problems to enlarge the matrix scale. Although the exposure speed should be improved

  20. Evaluation of blue light exposure to beta brainwaves on simulated night driving

    Science.gov (United States)

    Purawijaya, Dandri Aly; Fitri, Lulu Lusianti; Suprijanto

    2015-09-01

    Numbers of night driving accident in Indonesia since 2010 are exponentially rising each year with total of loss more than 50 billion rupiah. One of the causes that contribute to night driving accident is drowsiness. Drowsiness is affected by circadian rhythm resulted from the difference of blue light quality and quantity between night and day. Blue light may effect on human physiology through non-visual pathway by suppressing melatonin hormone suppression that influence drowsiness. Meanwhile, the production of hormones and other activities in brain generate bioelectrical activity such as brainwaves and can be recorded using Electroencephalograph (EEG). Therefore, this research objective is to evaluate the effect of blue light exposure to beta brainwave emergence during night driving simulation to a driver. This research was conducted to 4 male subjects who are able to drive and have a legitimate car driving license. The driving simulator was done using SCANIA Truck Driving Simulator on freeform driving mode in dark environment. Subjects drove for total 32 minutes. The data collections were taken in 2 days with 16 minutes for each day. The 16 minutes were divided again into 8 minutes adaptation in dark and 8 minutes for driving either in blue light exposure or in total darkness. While driving the simulation, subjects' brainwaves were recorded using EEG EMOTIV 14 Channels, exposed by LED monochromatic blue light with 160 Lux from source and angle 45o and sat 1 m in front of the screen. Channels used on this research were for visual (O1; O2), cognition (F3; F4; P7; P8), and motor (FC5; FC6). EEG brainwave result was filtered with EEGLab to obtain beta waves at 13 - 30 Hz frequencies. Results showed that beta waves response to blue light varied for each subject. Blue light exposure either increased or decreased beta waves in 2 minutes pattern and maintaining beta waves on cognition and motor area in 3 out of 4 subjects. Meanwhile, blue light exposure did not maintain

  1. Hydroxyl radicals cause fluctuation in intracellular ferrous ion levels upon light exposure during photoreceptor cell death.

    Science.gov (United States)

    Imamura, Tomoyo; Hirayama, Tasuku; Tsuruma, Kazuhiro; Shimazawa, Masamitsu; Nagasawa, Hideko; Hara, Hideaki

    2014-12-01

    Iron accumulation is a potential pathogenic event often seen in age-related macular degeneration (AMD) patients. In this study, we focused on the relationship between AMD pathology and concentrations of ferrous ion, which is a highly reactive oxygen generator in biological systems. Murine cone-cells-derived 661 W cells were exposed to white fluorescence light at 2500 lx for 1, 3, 6, or 12 h. Levels of ferrous ions, reactive oxygen species (ROS), and hydroxyl radicals were detected by RhoNox-1, a novel fluorescent probe for the selective detection of ferrous ion, 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate, acetyl ester (CM-H2DCFDA), and 3'-p-(aminophenyl) fluorescein, respectively. Reduced glutathione, total iron levels and photoreceptor cell death were also measured. Two genes related to iron metabolism, transferrin receptor 1 (TfR1) and H ferritin (HFt), were quantified by RT-PCR. The effects of ferrous ion on cell death and hydroxyl radical production were determined by treatment with a ferrous ion chelating agent, 2,2'-bipyridyl. We found that the ferrous ion level decreased with light exposure in the short time frame, whereas it was upregulated during a 6-h light exposure. Total iron, ROS, cell death rate, and expression of TfR and HFt genes were significantly increased in a time-dependent manner in 661 W cells exposed to light. Chelation with 2,2'-bipyridyl reduced the level of hydroxyl radicals and protected against light-induced cell death. These results suggest that light exposure decreases ferrous ion levels and enhances iron uptake in photoreceptor cells. Ferrous ion may be involved in light-induced photoreceptor cell death through production of hydroxyl radicals. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Exposure of Metarhizium acridum mycelium to light induces tolerance to UV-B radiation.

    Science.gov (United States)

    Brancini, Guilherme T P; Rangel, Drauzio E N; Braga, Gilberto Ú L

    2016-03-01

    Metarhizium acridum is an entomopathogenic fungus commonly used as a bioinsecticide. The conidium is the fungal stage normally employed as field inoculum in biological control programs and must survive under field conditions such as high ultraviolet-B (UV-B) exposure. Light, which is an important stimulus for many fungi, has been shown to induce the production of M. robertsii conidia with increased stress tolerance. Here we show that a two-hour exposure to white or blue/UV-A light of fast-growing mycelium induces tolerance to subsequent UV-B irradiation. Red light, however, does not have the same effect. In addition, we established that this induction can take place with as little as 1 min of white-light exposure. This brief illumination scheme could be relevant in future studies of M. acridum photobiology and for the production of UV-B resistant mycelium used in mycelium-based formulations for biological control. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Exposure to dim artificial light at night increases REM sleep and awakenings in humans.

    Science.gov (United States)

    Cho, Chul-Hyun; Lee, Heon-Jeong; Yoon, Ho-Kyoung; Kang, Seung-Gul; Bok, Ki-Nam; Jung, Ki-Young; Kim, Leen; Lee, Eun-Il

    2016-01-01

    Exposure to artificial light at night (ALAN) has become increasing common, especially in developed countries. We investigated the effect of dALAN exposure during sleep in healthy young male subjects. A total of 30 healthy young male volunteers from 21 to 29 years old were recruited for the study. They were randomly divided into two groups depending on light intensity (Group A: 5 lux and Group B: 10 lux). After a quality control process, 23 healthy subjects were included in the study (Group A: 11 subjects, Group B: 12 subjects). Subjects underwent an NPSG session with no light (Night 1) followed by an NPSG session randomly assigned to two different dim light conditions (5 or 10 lux, dom λ: 501.4 nm) for a whole night (Night 2). We found significant sleep structural differences between Nights 1 and 2, but no difference between Groups A and B. Exposure to dALAN during sleep was significantly associated with increased wake time after sleep onset (WASO; F = 7.273, p = 0.014), increased Stage N1 (F = 4.524, p = 0.045), decreased Stage N2 (F = 9.49, p = 0.006), increased Stage R (F = 6.698, p = 0.017) and non-significantly decreased REM density (F = 4.102, p = 0.056). We found that dALAN during sleep affects sleep structure. Exposure to dALAN during sleep increases the frequency of arousals, amount of shallow sleep and amount of REM sleep. This suggests adverse effects of dALAN during sleep on sleep quality and suggests the need to avoid exposure to dALAN during sleep.

  4. Parental Exposure to Dim Light at Night Prior to Mating Alters Offspring Adaptive Immunity

    Science.gov (United States)

    Cissé, Yasmine M.; Russart, Kathryn L.G.; Nelson, Randy J.

    2017-01-01

    Exposure to dim light at night (dLAN) disrupts natural light/dark cycles and impairs endogenous circadian rhythms necessary to maintain optimal biological function, including the endocrine and immune systems. We have previously demonstrated that white dLAN compromises innate and cell mediated immune responses in adult Siberian hamsters (Phodopus sungorus). We hypothesized that dLAN has transgenerational influences on immune function. Adult male and female Siberian hamsters were exposed to either dark nights (DARK) or dLAN (~5 lux) for 9 weeks, then paired in full factorial design, mated, and thereafter housed under dark nights. Offspring were gestated and reared in dark nights, then tested as adults for cell-mediated and humoral immunity. Maternal exposure to dLAN dampened delayed type hypersensitivity (DTH) responses in male offspring. Maternal and paternal exposure to dLAN reduced DTH responses in female offspring. IgG antibodies to a novel antigen were elevated in offspring of dams exposed to dLAN. Paternal exposure to dLAN decreased splenic endocrine receptor expression and global methylation in a parental sex-specific manner. Together, these data suggest that exposure to dLAN has transgenerational effects on endocrine-immune function that may be mediated by global alterations in the epigenetic landscape of immune tissues. PMID:28361901

  5. Exposure of WO3 Photoanodes to Ultraviolet Light Enhances Photoelectrochemical Water Oxidation.

    Science.gov (United States)

    Li, Tengfei; He, Jingfu; Peña, Bruno; Berlinguette, Curtis P

    2016-09-28

    Exposure of WO3 photoanodes to sustained irradiation by ultraviolet (UV) light induces a morphology change that enhances the photoelectrochemical (PEC) activity towards the oxygen evolution reaction (OER). A 30% enhancement in photocurrent density at 1.23 V vs RHE was measured despite a nominal change in onset potential. A structural and electrochemical analysis of the films before and after exposure to UV irradiation indicates that a higher film porosity and correspondingly higher specific surface area is responsible for the enhancement in PEC activity. The effect of prolonged UV irradiation on the WO3 films is fundamentally different to that which was previously observed for BiVO4 films.

  6. Light Emission Requires Exposure to the Atmosphere in Ex Vivo Bioluminescence Imaging

    Directory of Open Access Journals (Sweden)

    Yusuke Inoue

    2006-04-01

    Full Text Available The identification of organs bearing luciferase activity by in vivo bioluminescence imaging (BLI is often difficult, and ex vivo imaging of excised organs plays a complementary role. This study investigated the importance of exposure to the atmosphere in ex vivo BLI. Mice were inoculated with murine pro-B cell line Ba/F3 transduced with firefly luciferase and p190 BCR-ABL. They were killed following in vivo BLI, and whole-body imaging was done after death and then after intraperitoneal air injection. In addition, the right knee was exposed and imaged before and after the adjacent bones were cut. Extensive light signals were seen on in vivo imaging. The luminescence disappeared after the animal was killed, and air injection restored the light emission from the abdomen only, suggesting a critical role of atmospheric oxygen in luminescence after death. Although no substantial light signal at the right knee was seen before bone cutting, light emission was evident after cutting. In conclusion, in ex vivo BLI, light emission requires exposure to the atmosphere. Bone destruction is required to demonstrate luciferase activity in the bone marrow after death.

  7. Comparison and correction of the light sensor output from 48 wearable light exposure devices by using a side-by-side field calibration method

    DEFF Research Database (Denmark)

    Markvart, Jakob; Hansen, Åse Marie; Christoffersen, Jens

    2015-01-01

    . We tested 48 Actiwatch devices side by side under various light sources and present the red, green, blue, and white light response variability among the Actiwatches. The influence of different spatial and spectral light environments on the white light response when compared with the output from...... by the equipment variability. To compensate for inter-equipment variability we stress the need for a field calibration procedure. When light exposure devices of lower grade quality are used in spectrally and spatially changing light environments, daylight from a diffused overcast sky is suggested to be used...

  8. Effects of exposure to ultraviolet light on the development of Rana pipiens, the northern leopard frog

    Energy Technology Data Exchange (ETDEWEB)

    Williams, J.J.; Wofford, H.W. [Union Univ., Jackson, TN (United States)

    1996-10-01

    The increase in ultraviolet light intensity levels due to ozone depletion recently has been linked to the decline in amphibian population. In this experiment, eggs and larvae of Rana pipiens were subjected to differing amounts of ultraviolet radiation to determine the effects of ultraviolet light on the development of amphibian tadpoles. The total length, length of body without tail, and maximum width of each specimen was recorded for a month of the tadpoles` development, including several measurements after the ultraviolet exposures were concluded. It was found that ultraviolet exposure significantly reduced the size of the organisms in comparison with the control group in all three measured areas. Ultraviolet radiation altered the health and appearance of the exposed organisms and was lethal at large amounts. This experiment showed that ultraviolet radiation could cause many problems in developing amphibians. By slowing their development and physically weakening predation, thus contributing to a decline in overall population levels.

  9. Space Brightness Evaluation for a Daylit Room

    Directory of Open Access Journals (Sweden)

    Takashi Maruyama

    2011-05-01

    Full Text Available One of the most important problems for lighting design is how to reduce an electric energy. One way to solve this problem is use of daylight, but little is known how to perceive a brightness of a room illuminated by daylight come in through a window and artificial light. Although the horizontal illuminance increases because of daylight, we would not perceive the room as bright as brightness estimated by the illuminance. The purpose of this study is to measure the space brightness for daylit room and to propose a evaluation method. The experiment was conducted with a couple of miniature office rooms, standard room and test room. Test room has several types of windows and standard room has no window. Subject was asked to evaluate the brightness of the test room relative to the standard room with method of magnitude estimation. It was found that brightness of daylit room did not increase simply with horizontal illuminance. Subject perceived a daylit room darker than a room illuminated only by the artificial light even if horizontal illuminance of these room was same. The effect of daylight on space brightness would vary with the window size and intensity of daylight or artificial light.

  10. A single night light exposure acutely alters hormonal and metabolic responses in healthy participants

    Directory of Open Access Journals (Sweden)

    Mohammed S Albreiki

    2017-01-01

    Full Text Available Many animal studies have reported an association between melatonin suppression and the disturbance of metabolic responses; yet, few human studies have investigated bright light effects on metabolic and hormonal responses at night. This study investigated the impact of light on plasma hormones and metabolites prior to, and after, an evening meal in healthy participants. Seventeen healthy participants, 8 females (22.2 ± 2.59 years, mean ± s.d. and 9 males (22.8 ± 3.5 years were randomised to a two-way cross-over design protocol; dim light (DL (500 lux sessions, separated by at least seven days. Saliva and plasma samples were collected prior to and after a standard evening meal at specific intervals. Plasma non-esterified fatty acid (NEFA levels were significantly higher pre-meal in DL compared to BL (P < 0.01. Plasma glucose and insulin levels were significantly greater post-meal in the BL compared to DL session (P = 0.02, P = 0.001, respectively. Salivary melatonin levels were significantly higher in the DL compared to those in BL session (P = 0.005. BL at night was associated with significant increases in plasma glucose and insulin suggestive of glucose intolerance and insulin insensitivity. Raised pre-prandial NEFA levels may be due to changes in insulin sensitivity or the presence of melatonin and/or light at night. Plasma triglyceride (TAG levels were the same in both sessions. These results may explain some of the health issues reported in shift workers; however, further studies are needed to elucidate the cause of these metabolic changes.

  11. Short communication: artificial ultraviolet B light exposure increases vitamin D levels in cow plasma and milk.

    Science.gov (United States)

    Jakobsen, Jette; Jensen, Søren Krogh; Hymøller, Lone; Andersen, Elisabeth Wreford; Kaas, Poul; Burild, Anders; Jäpelt, Rie Bak

    2015-09-01

    The number of dairy cows without access to pasture or sunlight is increasing; therefore, the content of vitamin D in dairy products is decreasing. Ultimately, declining vitamin D levels in dairy products will mean that dairy products are a negligible source of natural vitamin D for humans. We tested the ability of a specially designed UVB lamp to enhance the vitamin D3 content in milk from dairy cows housed indoors. This study included 16 cows divided into 4 groups. Each group was exposed daily to artificial UVB light simulating 1, 2, 3, or 4 h of summer sun at 56°N for 24 d, and the group with simulated exposure to 2 h of summer sun daily continued to be monitored for 73 d. We found a significant increase in 25-hydroxyvitamin D3 (25OHD3) levels in plasma as well as vitamin D3 and 25OHD3 levels in milk after daily exposure for 24 d in all treatment groups. Extending daily exposure to artificial UVB light to 73 d did not lead to an increase of vitamin D3 or 25OHD3 level in the milk. In conclusion, the change in production facilities for dairy cows providing cows with no access to pasture and sunlight causes a decrease of vitamin D levels in dairy products. This decrease may be prevented by exposing cows to artificial UVB light in the stable.

  12. In-car nocturnal blue light exposure improves motorway driving: a randomized controlled trial.

    Directory of Open Access Journals (Sweden)

    Jacques Taillard

    Full Text Available Prolonged wakefulness greatly decreases nocturnal driving performance. The development of in-car countermeasures is a future challenge to prevent sleep-related accidents. The aim of this study is to determine whether continuous exposure to monochromatic light in the short wavelengths (blue light, placed on the dashboard, improves night-time driving performance. In this randomized, double-blind, placebo-controlled, cross-over study, 48 healthy male participants (aged 20-50 years drove 400 km (250 miles on motorway during night-time. They randomly and consecutively received either continuous blue light exposure (GOLite, Philips, 468 nm during driving or 2*200 mg of caffeine or placebo of caffeine before and during the break. Treatments were separated by at least 1 week. The outcomes were number of inappropriate line crossings (ILC and mean standard deviation of the lateral position (SDLP. Eight participants (17% complained about dazzle during blue light exposure and were removed from the analysis. Results from the 40 remaining participants (mean age ± SD: 32.9±11.1 showed that countermeasures reduced the number of inappropriate line crossings (ILC (F(2,91.11 = 6.64; p<0.05. Indeed, ILC were lower with coffee (12.51 [95% CI, 5.86 to 19.66], p = 0.001 and blue light (14.58 [CI, 8.75 to 22.58], p = 0.003 than with placebo (26.42 [CI, 19.90 to 33.71]. Similar results were found for SDLP. Treatments did not modify the quality, quantity and timing of 3 subsequent nocturnal sleep episodes. Despite a lesser tolerance, a non-inferior efficacy of continuous nocturnal blue light exposure compared with caffeine suggests that this in-car countermeasure, used occasionally, could be used to fight nocturnal sleepiness at the wheel in blue light-tolerant drivers, whatever their age. More studies are needed to determine the reproducibility of data and to verify if it can be generalized to women.ClinicalTrials.gov NCT01070004.

  13. Chronic exposure to light reverses the effect of maternal separation on proteins in the prefrontal cortex.

    Science.gov (United States)

    Dimatelis, J J; Stein, D J; Russell, V A

    2013-11-01

    Animals subjected to maternal separation display behavioural and endocrine disturbances, as well as structural and functional changes in the prefrontal cortex and limbic areas. The aim of the present study was to determine the effect of maternal separation and treatment with either chronic constant light exposure or anti-depressant (escitalopram) on proteins in the prefrontal cortex. Four experimental groups of male Sprague-Dawley rats were subjected to (1) normal rearing, (2) maternal separation (3 h per day from postnatal day 2 (P2) to P14), (3) maternal separation followed by chronic light exposure (P42-P63) or (4) maternal separation followed by treatment with the anti-depressant drug, escitalopram (P68-P100). Groups 1-3 were treated with saline as vehicle control for the escitalopram-treated group. At P101, all rats were decapitated, and the prefrontal cortex was collected and stored at -80 °C. Tissue from three rats per group was pooled and proteins determined by isobaric tagging for relative and absolute quantification using matrix-assisted laser desorption/ionisation tandem mass spectrometry. Maternal separation led to disruptions in the prefrontal cortex that included hypometabolism by decreasing energy-related proteins (creatine kinase B, aconitate hydratase), decreased cell signalling (synapsin I, calmodulin, 14-3-3 protein epsilon) and impaired plasticity (spectrin, microtubule-associated protein). Maternal separation also increased dihydropyrimidinase-related protein/collapsin response mediator protein (CRMP) and myelin proteolipid protein. Exposure of maternally separated animals to constant light during adolescence reversed the hypometabolic state by increasing energy-related proteins in the prefrontal cortex and increasing cell signalling and cytoskeletal proteins and decreasing the expression of CRMP. Escitalopram had similar effects to light by increasing ATP synthase in maternally separated rats and dissimilar effects by increasing 2',3'-cyclic

  14. Response of the diatom Phaeodactylum tricornutum to photooxidative stress resulting from high light exposure.

    Directory of Open Access Journals (Sweden)

    Nuno Domingues

    Full Text Available The response of microalgae to photooxidative stress resulting from high light exposure is a well-studied phenomenon. However, direct analyses of photosystem II (PSII D1 protein (the main target of photoinhibition in diatoms are scarce. In this study, the response of the diatom model species Phaeodactylum tricornutum to short-term exposure to high light was examined and the levels of D1 protein determined immunochemically. Low light (LL acclimated cells (40 µmol photons m(-2 s(-1 subjected to high light (HL, 1,250 µmol photons m(-2 s(-1 showed rapid induction of non-photochemical quenching (NPQ and ca. 20-fold increase in diatoxanthin (DT concentration. This resulted from the conversion of diadinoxanthin (DD to DT through the activation of the DD-cycle. D1 protein levels under LL decreased about 30% after 1 h of the addition of lincomycin (LINC, a chloroplast protein synthesis inhibitor, showing significant D1 degradation and repair under low irradiance. Exposure to HL lead to a 3.2-fold increase in D1 degradation rate, whereas average D1 repair rate was 1.3-x higher under HL than LL, leading to decreased levels of D1 protein under HL. There were significant effects of both HL and LINC on P. tricornutum maximum quantum yield of PSII (F(v/F(m, showing a reduction of active PSII reaction centres. Partial recovery of F(v/F(m in the dark demonstrates the photosynthetic resilience of this diatom to changes in the light regime. P. tricornutum showed high allocation of total protein to D1 and an active D1-repair cycle to limit photoinhibition.

  15. A newly proposed disease condition produced by light exposure during night: asynchronization.

    Science.gov (United States)

    Kohyama, Jun

    2009-04-01

    The bedtime of preschoolers/pupils/students in Japan has become progressively later with the result sleep duration has become progressively shorter. With these changes, more than half of the preschoolers/pupils/students in Japan recently have complained of daytime sleepiness, while approximately one quarter of junior and senior high school students in Japan reportedly suffer from insomnia. These preschoolers/pupils/students may be suffering from behaviorally induced insufficient sleep syndrome due to inadequate sleep hygiene. If this diagnosis is correct, they should be free from these complaints after obtaining sufficient sleep by avoiding inadequate sleep hygiene. However, such a therapeutic approach often fails. Although social factors are often involved in these sleep disturbances, a novel clinical notion--asynchronization--can further a deeper understanding of the pathophysiology of these disturbances. The essence of asynchronization is a disturbance in various aspects (e.g., cycle, amplitude, phase and interrelationship) of the biological rhythms that normally exhibit circadian oscillation, presumably involving decreased activity of the serotonergic system. The major trigger of asynchronization is hypothesized to be a combination of light exposure during the night and a lack of light exposure in the morning. In addition to basic principles of morning light and an avoidance of nocturnal light exposure, presumable potential therapeutic approaches for asynchronization involve both conventional ones (light therapy, medications (hypnotics, antidepressants, melatonin, vitamin B12), physical activation, chronotherapy) and alternative ones (kampo, pulse therapy, direct contact, control of the autonomic nervous system, respiration (qigong, tanden breathing), chewing, crawling). A morning-type behavioral preference is described in several of the traditional textbooks for good health. The author recommends a morning-type behavioral lifestyle as a way to reduce

  16. Impact of light exposure on thyroid-stimulating hormone results using the Siemens Advia Centaur TSH-3Ultra assay.

    Science.gov (United States)

    Armer, Jane; Giles, Diane; Lancaster, Ian; Brownbill, Kathryn

    2017-09-01

    Background Thyroid-stimulating hormone (TSH) is used as the first-line test of thyroid function. Siemens Healthcare Diagnostics recommend that Siemens Centaur reagents must be protected from light in the assay information and on reagent packaging. We have compared the effect of light exposure on results using Siemens TSH-3Ultra and follicle-stimulating hormone reagents. The thyroid-stimulating hormone reagent includes fluoroscein thiocyanate whereas the follicle-stimulating hormone reagent does not. Methods Three levels of quality controls were analysed using SiemensTSH-3Ultra and follicle-stimulating hormone reagent packs that had been kept protected from light or exposed to light at 6-h intervals for 48 h and then at 96 h. Results Thyroid-stimulating hormone results were significantly lower after exposure of TSH-3Ultra reagent packs to light. Results were >15% lower at all three levels of quality control following 18 h of light exposure and continued to decrease until 96 h. There was no significant difference in follicle-stimulating hormone results whether reagents had been exposed to or protected from light. Conclusions Thyroid-stimulating hormone results but not follicle-stimulating hormone results are lowered after exposure of reagent packs to light. Laboratories must ensure that TSH-3Ultra reagents are not exposed to light and analyse quality control samples on every reagent pack to check that there has not been light exposure prior to delivery. The labelling on TSH-3Ultra reagent packs should reflect the significant effect of light exposure compared with the follicle-stimulating hormone reagent. We propose that the effect of light exposure on binding of fluoroscein thiocyanate to the solid phase antibody causes the falsely low results.

  17. Effects of white light-emitting diode (LED) exposure on retinal pigment epithelium in vivo.

    Science.gov (United States)

    Jaadane, Imene; Villalpando Rodriguez, Gloria Elisa; Boulenguez, Pierre; Chahory, Sabine; Carré, Samuel; Savoldelli, Michèle; Jonet, Laurent; Behar-Cohen, Francine; Martinsons, Christophe; Torriglia, Alicia

    2017-06-29

    Ageing and alteration of the functions of the retinal pigment epithelium (RPE) are at the origin of lost of vision seen in age-related macular degeneration (AMD). The RPE is known to be vulnerable to high-energy blue light. The white light-emitting diodes (LED) commercially available have relatively high content of blue light, a feature that suggest that they could be deleterious for this retinal cell layer. The aim of our study was to investigate the effects of "white LED" exposure on RPE. For this, commercially available white LEDs were used for exposure experiments on Wistar rats. Immunohistochemical stain on RPE flat mount, transmission electron microscopy and Western blot were used to exam the RPE. LED-induced RPE damage was evaluated by studying oxidative stress, stress response pathways and cell death pathways as well as the integrity of the outer blood-retinal barrier (BRB). We show that white LED light caused structural alterations leading to the disruption of the outer blood-retinal barrier. We observed an increase in oxidized molecules, disturbance of basal autophagy and cell death by necrosis. We conclude that white LEDs induced strong damages in rat RPE characterized by the breakdown of the BRB and the induction of necrotic cell death. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  18. Brightness-equalized quantum dots

    Science.gov (United States)

    Lim, Sung Jun; Zahid, Mohammad U.; Le, Phuong; Ma, Liang; Entenberg, David; Harney, Allison S.; Condeelis, John; Smith, Andrew M.

    2015-10-01

    As molecular labels for cells and tissues, fluorescent probes have shaped our understanding of biological structures and processes. However, their capacity for quantitative analysis is limited because photon emission rates from multicolour fluorophores are dissimilar, unstable and often unpredictable, which obscures correlations between measured fluorescence and molecular concentration. Here we introduce a new class of light-emitting quantum dots with tunable and equalized fluorescence brightness across a broad range of colours. The key feature is independent tunability of emission wavelength, extinction coefficient and quantum yield through distinct structural domains in the nanocrystal. Precise tuning eliminates a 100-fold red-to-green brightness mismatch of size-tuned quantum dots at the ensemble and single-particle levels, which substantially improves quantitative imaging accuracy in biological tissue. We anticipate that these materials engineering principles will vastly expand the optical engineering landscape of fluorescent probes, facilitate quantitative multicolour imaging in living tissue and improve colour tuning in light-emitting devices.

  19. Night work, light exposure and melatonin on work days and days off

    DEFF Research Database (Denmark)

    Daugaard, Stine; Garde, Anne Helene; Bonde, Jens Peter Ellekilde

    2017-01-01

    We aimed to examine the effects of night work on salivary melatonin concentration during and subsequent to night work and the mediating role of light. We included 254 day workers and 87 night workers who were followed during 322 work days and 301 days off work. Each day was defined as the 24 hour...... period starting from the beginning of a night shift or from waking in the mornings with day work and days off. Light levels were recorded and synchronized with diary information (start and end of sleep and work). On average, participants provided four saliva samples per day, and these were analyzed....... For light exposure, we estimated the total, direct and indirect effects of night work on melatonin concentrations obtaining 95% confidence intervals through bootstrapping. On work days, night workers showed 15% lower salivary melatonin concentrations compared with day workers (-15.0%; 95% CI: -31.4%; 5...

  20. Manifestation of Hyperandrogenism in the Continuous Light Exposure-Induced PCOS Rat Model

    Directory of Open Access Journals (Sweden)

    Xuezhi Kang

    2015-01-01

    Full Text Available Polycystic ovary syndrome (PCOS is a complex endocrine and metabolic disorder, and its pathogenesis has yet to be completely clarified. A fully convincing animal model has not been established for PCOS. In earlier studies, researchers have shown that the exposure of rats to continuous light can induce PCOS; nevertheless, hyperandrogenism, a key characteristic observed in human PCOS, has not been reported previously. In the present study, we found that (1 body weights decreased in female rats in a continuous light environment with both ovarian and uterine augmentation; (2 the estrous cycle in rats under continuous light environment was disordered, and polycystic ovary-like changes occurred, accompanied with fur loss and lethargy; and (3 serum testosterone levels in rats in a continuous light environment significantly increased. Our data suggest that continuous light can lead to the occurrence of PCOS in female rats without the need for drugs; this is a reasonable PCOS animal model that is more consistent with the natural disease state in humans; and poor sleep habits or negligence of sleep hygiene may be an important lifestyle factor in pathogenesis of PCOS.

  1. Modeling filamentous cyanobacteria reveals the advantages of long and fast trichomes for optimizing light exposure.

    Science.gov (United States)

    Tamulonis, Carlos; Postma, Marten; Kaandorp, Jaap

    2011-01-01

    Cyanobacteria form a very large and diverse phylum of prokaryotes that perform oxygenic photosynthesis. Many species of cyanobacteria live colonially in long trichomes of hundreds to thousands of cells. Of the filamentous species, many are also motile, gliding along their long axis, and display photomovement, by which a trichome modulates its gliding according to the incident light. The latter has been found to play an important role in guiding the trichomes to optimal lighting conditions, which can either inhibit the cells if the incident light is too weak, or damage the cells if too strong. We have developed a computational model for gliding filamentous photophobic cyanobacteria that allows us to perform simulations on the scale of a Petri dish using over 10(5) individual trichomes. Using the model, we quantify the effectiveness of one commonly observed photomovement strategy--photophobic responses--in distributing large populations of trichomes optimally over a light field. The model predicts that the typical observed length and gliding speeds of filamentous cyanobacteria are optimal for the photophobic strategy. Therefore, our results suggest that not just photomovement but also the trichome shape itself improves the ability of the cyanobacteria to optimize their light exposure.

  2. Modeling filamentous cyanobacteria reveals the advantages of long and fast trichomes for optimizing light exposure.

    Directory of Open Access Journals (Sweden)

    Carlos Tamulonis

    Full Text Available Cyanobacteria form a very large and diverse phylum of prokaryotes that perform oxygenic photosynthesis. Many species of cyanobacteria live colonially in long trichomes of hundreds to thousands of cells. Of the filamentous species, many are also motile, gliding along their long axis, and display photomovement, by which a trichome modulates its gliding according to the incident light. The latter has been found to play an important role in guiding the trichomes to optimal lighting conditions, which can either inhibit the cells if the incident light is too weak, or damage the cells if too strong. We have developed a computational model for gliding filamentous photophobic cyanobacteria that allows us to perform simulations on the scale of a Petri dish using over 10(5 individual trichomes. Using the model, we quantify the effectiveness of one commonly observed photomovement strategy--photophobic responses--in distributing large populations of trichomes optimally over a light field. The model predicts that the typical observed length and gliding speeds of filamentous cyanobacteria are optimal for the photophobic strategy. Therefore, our results suggest that not just photomovement but also the trichome shape itself improves the ability of the cyanobacteria to optimize their light exposure.

  3. Repeated exposures to blue light-activated eosin Y enhance inactivation of E. faecalis biofilms, in vitro.

    Science.gov (United States)

    Marinic, Karlo; Manoil, Daniel; Filieri, Anna; Wataha, John C; Schrenzel, Jacques; Lange, Norbert; Bouillaguet, Serge

    2015-09-01

    In dentistry, antibacterial photodynamic therapy (a-PDT) has shown promising results for inactivating bacterial biofilms causing carious, endodontic and periodontal diseases. In the current study, we assessed the ability of eosin Y exposed to 3 irradiation protocols at inactivating Enterococcus faecalis biofilms, in vitro. E. faecalis biofilms formed on hydroxyapatite disks were incubated with eosin Y (10-80μM), then activated with blue light using different irradiation protocols. Biofilms exposed to continuous exposure were incubated for 40min before being light-activated for 960 s. For the intermittent exposure, biofilms were exposed 4 times to the light/photosensitizer combination (960 s total) without renewing the photosensitizer. For repeated a-PDT, the same light dose was delivered in a series of 4 irradiation periods separated by dark periods; fresh photosensitizer was added between each light irradiation. After treatment, bacteria were immediately labeled with LIVE/DEAD BacLight Bacterial Viability kit and viability was assessed by flow cytometry (FCM). Results were statistically analyzed using one-way ANOVA and Tukey multiple comparison intervals (α=0.05). The viability of E. faecalis biofilms exposed to 10μM eosin Y, was significantly reduced compared to controls (light only-eosin Y only). After a second exposure to blue light-activated eosin Y, viability significantly decreased from 58% to 12% whereas 6.5% of the bacterial biofilm remained live after a third exposure (p<0.05). Only 3.5% of the bacterial population survived after the fourth exposure. The results of this study indicate that blue light-activated eosin Y can photoinactivate E. faecalis biofilms grown on hydroxyapatite disks. Also, repeated exposures to blue light-activated eosin Y were shown to significantly improve efficacy. Further studies seem warranted to optimize the antibacterial activity of blue light-activated eosin Y on major oral pathogens. Copyright © 2015 Elsevier B.V. All

  4. Lung inflammation and genotoxicity in mice lungs after pulmonary exposure to candle light combustion particles.

    Science.gov (United States)

    Skovmand, Astrid; Damiao Gouveia, Ana Cecilia; Koponen, Ismo Kalevi; Møller, Peter; Loft, Steffen; Roursgaard, Martin

    2017-07-05

    Candle burning produces a large amount of particles that contribute substantially to the exposure to indoor particulate matter. The exposures to various types of combustion particles, such as diesel exhaust particles, have been associated with increased risk of lung cancer by mechanisms that involve oxidative stress, inflammation and genotoxicity. The aim of this study was to compare pulmonary effects of candle light combustion particles (CP) with two benchmark diesel exhaust particles (A-DEP and SRM2975). Intratracheal (i.t.) instillation of CP (5mg/kg bodyweight) in C57BL/6n mice produced a significant influx of alveolar macrophages and polymorphonuclear leukocytes and increased concentrations of proteins and lactate dehydrogenase activity in bronchoalveolar fluid. Lower levels of these markers of inflammation and cytotoxicity were observed after i.t. instillation of the same dose of A-DEP or SRM2975. The i.t. instillation of CP did not generate oxidative damage to DNA in lung tissue, measured as DNA strand breaks and human 8-oxoguanine glycosylase-sensitive sites by the comet assay. The lack of genotoxic response was confirmed in lung epithelial (A549) cells, although the exposure to CP increased intracellular levels of reactive oxygen species. In conclusion, pulmonary exposure to particles from burning candles is associated with inflammation and cytotoxicity in the lungs. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Burkina Faso - BRIGHT II

    Data.gov (United States)

    Millennium Challenge Corporation — Millennium Challenge Corporation hired Mathematica Policy Research to conduct an independent evaluation of the BRIGHT II program. The three main research questions...

  6. Effect of light exposure on in vitro germination and germ tube growth of eight species of rust fungi.

    Science.gov (United States)

    Buck, James W; Dong, Weibo; Mueller, Daren S

    2010-01-01

    The effects of light on urediniospore germination and germ tube elongation was studied with eight species of rust fungi that infect ornamental plants or row crops. Exposure of six species of fungi to cool white fluorescent light at 400 or 600 micromol s(-1) m(-2) for 24 h significantly reduced germination with largest decreases typically observed at 600 micromol s(-1) m(-2). Germination and germ tube elongation did not recover during 24 h dark incubation after 18 h exposure to fluorescent light at 600 micromol s(-1) m(-2), indicating the effects were not reversible. Germ tube elongation of all fungi was negatively affected by increased length of exposure to fluorescent light. Increased exposure to fluorescent light differentially affected germination of the fungi with Puccinia hemerocallidis, Phakopsora pachyrhizi, Pucciniastrum vaccinii and Puccinia menthae negatively affected and Puccinia sorghi, Puccinia triticina, Puccinia pelargonii-zonalis and Puccinia iridis relatively unaffected in 10 h incubation. Exposure of Ph. pachyrhizi and P. triticina urediniospores to sunlight rapidly reduced germination and germ tube elongation with no germination observed for Ph. pachyrhizi after 2.5 h. Germ tube elongation but not germination of hydrated urediniospores of Ph. pachyrhizi and P. triticina was significantly reduced compared to dry urediniospores exposed to 10 h fluorescent light followed by 24 h dark incubation. Exposure to fluorescent light (all fungi) or sunlight (two fungi) negatively affected urediniospore germ tube elongation. Differences observed in urediniospore germination between fungi suggest some species have co-evolved with their host for differing light conditions. Our data suggests exposure of urediniospores to strong light could inactivate rust fungi on plant surfaces or in the atmosphere.

  7. Controlled Energy Transfer from a Ligand to an Eu(III) Ion: A Unique Strategy To Obtain Bright-White-Light Emission and Its Versatile Applications.

    Science.gov (United States)

    Boddula, Rajamouli; Singh, Kasturi; Giri, Santanab; Vaidyanathan, Sivakumar

    2017-09-05

    A new diphenylamine-functionalized ancillary-ligand-coordinated europium(III) β-diketonate complex showed incomplete photoexcitation energy transfer from a ligand to a Eu(III) ion. A solvatochromism study led to a balancing of the primary colors to obtain single-molecule white-light emission. Thermal-sensing analysis of the europium complex was executed. The europium complex, conjugated with a near-UV-light-emitting diode (395 nm), showed appropriate white-light-emission CIE color coordinates (x = 0.34 and y = 0.33) with a 5152 K correlated color temperature.

  8. The Transcriptional Responses and Metabolic Consequences of Acclimation to Elevated Light Exposure in Grapevine Berries

    Directory of Open Access Journals (Sweden)

    Kari du Plessis

    2017-07-01

    Full Text Available An increasing number of field studies that focus on grapevine berry development and ripening implement systems biology approaches; the results are highlighting not only the intricacies of the developmental programming/reprogramming that occurs, but also the complexity of how profoundly the microclimate influences the metabolism of the berry throughout the different stages of development. In a previous study we confirmed that a leaf removal treatment to Sauvignon Blanc grapes, grown in a highly characterized vineyard, primarily affected the level of light exposure to the berries throughout their development. A full transcriptomic analysis of berries from this model vineyard details the underlying molecular responses of the berries in reaction to the exposure and show how the berries acclimated to the imposing light stress. Gene expression involved in the protection of the photosynthetic machinery through rapid protein-turnover and the expression of photoprotective flavonoid compounds were most significantly affected in green berries. Overall, the transcriptome analysis showed that the berries implemented multiple stress-mitigation strategies in parallel and metabolite analysis was used to support the main findings. Combining the transcriptome data and amino acid profiling provided evidence that amino acid catabolism probably contributed to the mitigation of a likely energetic deficit created by the upregulation of (energetically costly stress defense mechanisms. Furthermore, the rapid turnover of essential proteins involved in the maintenance of primary metabolism and growth in the photosynthetically active grapes appeared to provide precursors for the production of protective secondary metabolites such as apocarotenoids and flavonols in the ripening stages of the berries. Taken together, these results confirmed that the green grape berries responded to light stress much like other vegetative organs and were able to acclimate to the increased

  9. Using the Larval Zebrafish Locomotor Asssay in Functional Neurotoxicity Screening: Light Brightness and the Order of Stimulus Presentation Affect the Outcome

    Science.gov (United States)

    We are evaluating methods to screen/prioritize large numbers of chemicals using 6 day old zebrafish (Danio rerio) as an alternative model for detecting neurotoxic effects. Our behavioral testing paradigm simultaneously tests individual larval zebrafish under sequential light and...

  10. Does oral exposure to cadmium and lead mediate susceptibility to colitis? The dark-and-bright sides of heavy metals in gut ecology

    Science.gov (United States)

    Breton, Jérôme; Daniel, Catherine; Vignal, Cécile; Body-Malapel, Mathilde; Garat, Anne; Plé, Coline; Foligné, Benoît

    2016-01-01

    Although the heavy metals cadmium (Cd) and lead (Pb) are known environmental health concerns, their long-term impacts on gut ecology and susceptibility to gastrointestinal autoimmune diseases have not been extensively investigated. We sought to determine whether subchronic oral exposure to Cd or Pb is a risk factor for the development and progression of inflammatory bowel disease (IBD). Mice were exposed to various doses of CdCl2 or PbCl2 in drinking water for 1, 4 or 6 weeks prior to infection with Salmonella, the induction of colitis with dextran sodium sulfate (DSS) or trinitrobenzene sulfonic acid (TNBS). In human cell-based models, exposure to Cd and Pb is associated with reduced transepithelial electric resistance and changes in bacteria-induced cytokine responses. Although 1- and 6-week exposures did not have clear effects on the response to Salmonella infectious challenges, 1-week short-term treatments with CdCl2 tended to enhance intestinal inflammation in mice. Unexpectedly, subchronic exposure to Cd and (to a lesser extent) Pb significantly mitigated some of the symptoms of DSS-induced colitis and reduced the severity of TNBS colitis in a dose-dependent manner. The possible adaptive and immunosuppressive mechanisms by which heavy metals might reduce intestinal inflammation are explored and discussed.

  11. Observations and diagnostics in high brightness beams

    Energy Technology Data Exchange (ETDEWEB)

    Cianchi, A., E-mail: alessandro.cianchi@roma2.infn.it [University of Rome Tor Vergata and INFN-Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome (Italy); Anania, M.P.; Bisesto, F.; Castellano, M.; Chiadroni, E.; Pompili, R.; Shpakov, V. [INFN-LNF, Via Enrico Fermi 40, 00044 Frascati (Italy)

    2016-09-01

    The brightness is a figure of merit largely used in the light sources, like FEL (Free Electron Lasers), but it is also fundamental in several other applications, as for instance Compton backscattering sources, beam driven plasma accelerators and THz sources. Advanced diagnostics are essential tools in the development of high brightness beams. 6D electron beam diagnostics will be reviewed with emphasis on emittance measurement.

  12. 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...

  13. Gender features and estrous cycle variations of nocturnal behavior of mice after a single exposure to light at night.

    Science.gov (United States)

    Datta, Siddhartha; Samanta, Diptaman; Sinha, Priyobrata; Chakrabarti, Nilkanta

    2016-10-01

    Light at night alters behavior and cognitive performances in rodents, the variations of which in gender and stages of reproductive cycle in females are elusive. Young mice habituated in light:dark (12:12h) cycle were given a single exposure of light (100lx) at early night for one hour duration followed by experimentations in open field (closed wall with circular big arena), elevated plus maze and square habituated field for memory performance using novel object recognition task. Light effects were compared with results found during without light conditions. Proestrous females appeared to have greater locomotor activity, less anxiety and better memory performance compared to the diestrous females at night without light exposure. The status of locomotor activity, anxiety and memory performance of male mice at night without light exposure appeared to be comparable to females where the stage of estrous cycle is important to characterize the nocturnal behavior of male mice. Light maximally affected proestrous females with decrease in locomotor activity, increase in anxiety and failure of memory performance. Male and diestrous female mice performed memory performance without alteration of locomotor activity and anxiety after exposure to light where males performed better memory performance with greater locomotor activity and more anxiety compared to that of diestrous females. The present study characterizes the mice nocturnal behavior with and without a single exposure to light stimuli with its gender features and estrous cycle variation. In addition, the study indicates an association of memory performance with locomotor activity and anxiety in mice nocturnal behavior. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Wine bottle colour and oxidative spoilage: whole bottle light exposure experiments under controlled and uncontrolled temperature conditions.

    Science.gov (United States)

    Dias, Daniel A; Clark, Andrew C; Smith, Trevor A; Ghiggino, Kenneth P; Scollary, Geoffrey R

    2013-06-15

    Exposure of a Chardonnay wine to light from a mercury vapour lamp under controlled temperature conditions showed that colour enhancement was dependent on bottle colour. The increase in colouration was Antique Greenlight exposure. Without temperature control, wine colour development was highest in Antique Green and lowest in Flint. This alternate order reflects the ability of the darker bottles to retain heat longer than lighter coloured ones as confirmed by surface temperature decay rates. Specific pigments contributing to the wine colour enhancement in uncontrolled temperature/light exposure experiments could not be identified, although tentative evidence was obtained for the presence of flavan-3-ol based compounds. The different bottle glass surfaces did not influence the rate of loss of dissolved oxygen or oxidation of ascorbic acid. The potential to develop the results obtained in this study to identify markers for light and/or temperature exposure of white wines is discussed.

  15. Smokers' responses to advertisements for regular and light cigarettes and potential reduced-exposure tobacco products.

    Science.gov (United States)

    Hamilton, William L; Norton, Giulia diStefano; Ouellette, Tammy K; Rhodes, Wiliam M; Kling, Ryan; Connolly, Gregory N

    2004-12-01

    This study examines smokers' responses to advertisements for potentially reduced exposure tobacco products (PREP), light cigarettes, and regular cigarettes. A convenience sample of 600 adult smokers reviewed one actual advertisement for each type of product. Smokers ranked the products on health risk, amount of tar, and carcinogenicity, and identified the messages they perceived the advertisements to convey. Smokers perceived PREP products as having lower health risks (mean = 5.4 on a scale of 1-10) and carcinogens (6.6) than light cigarettes (5.8 and 6.9, respectively, p carcinogen levels than regular cigarettes (8.2 and 8.8, respectively, p tobacco products that are contrary to the scientific evidence. Explicit and implicit advertising messages may be strengthened by the perceived government endorsement. This supports the Institute of Medicine's recommendation to regulate the promotion, advertising, and labeling of PREP tobacco products and light cigarettes. Effective regulation may need to focus on consumer perceptions resulting from advertisements rather than the explicit content of advertising text.

  16. Sunspot Bright Points

    CERN Document Server

    Choudhary, Debi Prasad

    2010-01-01

    We used the flux calibrated images through the Broad Band Filter Imager and Stokes Polarimeter data obtained with the Solar Optical Telescope onboard the Hinode spacecraft to study the properties of bright points in and around the sunspots. The well isolated bright points were selected and classified as umbral dot, peripheral umbral dot, penumbral grains and G-band bright point depending on their location. Most of the bright points are smaller than about 150 km. The larger points are mostly associated with the penumbral features. The bright points are not uniformly distributed over the umbra but preferentially located around the penumbral boundary and in the fast decaying parts of umbra. The color temperature of the bright points, derived using the continuum irradiance, are in the range of 4600 K to 6600 K with cooler ones located in the umbra. The temperature increases as a function of distance from the center to outside. The G-band, CN-band and CaII H flux of the bright points as a function of their blue ba...

  17. Investigation of Mg doping profile in the p-cladding layer for high-brightness AlGaInP-based light emitting diodes.

    Science.gov (United States)

    Oh, Hwa Sub; Ryu, Ho Soung; Park, Joon Mo; Lee, Hyung Joo; Kim, Young Jin; Jang, In Kyu; Park, Ji Hoon; Kwak, Joon Seop; Baek, Jong Hyeob

    2014-08-01

    We investigated 590 nm light-emitting diodes appropriate for full-color display applications in terms of their electrical and optical behaviors during operation according to their Mg doping profile in the p-cladding layer. As the hole concentration in the "b" zone of the p-cladding layer is increased from 3.4 x 10(17) to 6.7 x 10(17), the light output power increases by 41% due to the enhancement of the hole injection into the active region and also due to the minimization of the carrier overflow problem. However, at an oversaturation of Mg doping with excess [Cp2Mg]/[III] in the "b" zone, the internal quantum efficiency degrades because of the decrease in hole concentration because of the oversaturated material problem.

  18. Effect of Interior Chromaticness on Space Brightness

    Directory of Open Access Journals (Sweden)

    Hidenari Takada

    2011-05-01

    Full Text Available To design a lighting environment, horizontal illuminance is generally used as the brightness of a room. But it is reported that a subjective brightness does not always match the horizontal illuminance. For example, the room furnished with high saturated colored objects is perceived brighter than the room furnished with achromatic objects, even though the horizontal illuminance is the same. To investigate a effect of interior chromaticness on space brightness, we conducted the experiment in four miniature rooms that were different in terms of chromaticness of interior decorating surfaces, but kept lightness of surfaces constant. Subjects were asked to set the illuminance of reference room, that is furnished with achromatic objects, to equate the brightness of the test room, that is with chromatic objects. Four of seven subjects needed less illuminance to get the equality of space brightness if the test room had a saturated objects. The illuminance ratio of test to reference room was about 1.4. Other three subjects set the illuminance of reference room almost equal to test room. Thus, there are differences between individuals so further work would be needed to estimate the quantitative effect of interior chromaticness on space brightness.

  19. Independent associations of exposure to evening light and nocturnal urinary melatonin excretion with diabetes in the elderly.

    Science.gov (United States)

    Obayashi, Kenji; Saeki, Keigo; Iwamoto, Junko; Ikada, Yoshito; Kurumatani, Norio

    2014-04-01

    Circadian misalignment between internal and environmental rhythms dysregulates glucose homeostasis because of disruption of the biological clock, and increases risk of diabetes. Although exposure to evening light and decreased melatonin secretion are both associated with the circadian misalignment, it remains unclear whether they are associated with diabetes. In this cross-sectional study on 513 elderly individuals (mean age, 72.7 years), we measured ambulatory light intensity during the 4 h prior to bedtime at 1-min intervals during two consecutive days and overnight urinary 6-sulfatoxymelatonin excretion (UME) along with glucose metabolism. The median average intensity of evening light exposure and UME were 25.4 lux (interquartile range 17.5-37.6) and 6.6 μg (interquartile range 3.9-9.7), respectively. Both log-transformed average intensity of evening light exposure and log-transformed UME were significantly associated with diabetes in a multivariate logistic regression model adjusted for covariates, including gender, body mass index, duration in bed, and night-time light exposure [adjusted odds ratio (OR), 1.72; 95% confidence interval (CI), 1.12-2.64; p = 0.01; and adjusted OR, 0.66; 95% CI, 0.44-0.97; p = 0.04; respectively]. An increase in evening light exposure from 17.5 to 37.6 lux (25-75th percentiles) was associated with a 51.2% (95% CI, 8.2-111.4%) increase in prevalent diabetes, and an increase in UME from 3.9 to 9.7 μg (25-75th percentiles) was associated with a 32.0% (95% CI, 1.9-52.8%) decrease in prevalent diabetes. In conclusion, this study in elderly individuals demonstrated that evening light exposure in home settings and UME were significantly and independently associated with diabetes.

  20. Analysis of temperature increase in swine gingiva after exposure to a Polywave(®) LED light curing unit.

    Science.gov (United States)

    Maucoski, Cristiane; Zarpellon, Driellen Christine; Dos Santos, Fabio Andre; Lipinski, Leandro Cavalcante; Campagnoli, Eduardo Bauml; Rueggeberg, Frederick Allen; Arrais, Cesar Augusto Galvão

    2017-08-18

    This study evaluated the temperature increase in swine gingival temperature after exposure to light emitted by a Polywave(®) LED light curing unit (LCU, Bluephase 20i, Ivoclar Vivadent). After local Ethics Committee approval (protocol 711/2015), 40 pigs were subjected to general anesthesia and the LCU tip was placed 5mm from the buccal gingival tissue (GT) close to lower lateral incisors. A thermocouple probe (Thermes WFI, Physitemp) was inserted into the gingival sulcus before and immediately after exposure to light. Real-time temperature (°C) was measured after the following exposure modes were applied: High Power (20s-H, 40s-H, and 60s-H) or Turbo mode (5s-T), either with or without the presence of rubber dam (RD) interposed between the LCU tip and GT (n=10). The presence of gingival lesions after the exposures was also evaluated. Peak temperature (°C) and the temperature increase during exposure over that of the pre-exposure baseline value (ΔT) data were analyzed using 2-way ANOVA followed by Bonferroni's post-hoc test (α=5%). A binary logistic regression analysis determined the risk of gingival lesion development. Without RD, no significant difference in ΔT was observed among 20s-H, 40s-H, and 60s-H groups, which showed the highest temperature values, while the 5s-T exposure showed the lowest ΔT, regardless of RD. RD reduced ΔT only for the 20s-H group (p=0.004). Gingival lesions were predominantly observed using 40s-H, with RD, and 60s-H, with and without RD. Exposure to a LCU light might be harmful to swine gingiva only when high radiant exposure values are delivered, regardless of the use of RD. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  1. Giant Surface Conductivity Enhancement in a Carbon Nanotube Composite by Ultraviolet Light Exposure.

    Science.gov (United States)

    Long, Christian J; Orloff, Nathan D; Twedt, Kevin A; Lam, Thomas; Vargas-Lara, Fernando; Zhao, Minhua; Natarajan, Bharath; Scott, Keana C; Marksz, Eric; Nguyen, Tinh; Douglas, Jack F; McClelland, Jabez; Garboczi, Edward; Obrzut, Jan; Liddle, J Alexander

    2016-09-07

    Carbon nanotube composites are lightweight, multifunctional materials with readily adjustable mechanical and electrical properties-relevant to the aerospace, automotive, and sporting goods industries as high-performance structural materials. Here, we combine well-established and newly developed characterization techniques to demonstrate that ultraviolet (UV) light exposure provides a controllable means to enhance the electrical conductivity of the surface of a commercial carbon nanotube-epoxy composite by over 5 orders of magnitude. Our observations, combined with theory and simulations, reveal that the increase in conductivity is due to the formation of a concentrated layer of nanotubes on the composite surface. Our model implies that contacts between nanotube-rich microdomains dominate the conductivity of this layer at low UV dose, while tube-tube transport dominates at high UV dose. Further, we use this model to predictably pattern conductive traces with a UV laser, providing a facile approach for direct integration of lightweight conductors on nanocomposite surfaces.

  2. 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'.

  3. Beech leaf colonization by the endophyte Apiognomonia errabunda dramatically depends on light exposure and climatic conditions.

    Science.gov (United States)

    Bahnweg, G; Heller, W; Stich, S; Knappe, C; Betz, G; Heerdt, C; Kehr, R D; Ernst, D; Langebartels, C; Nunn, A J; Rothenburger, J; Schubert, R; Wallis, P; Müller-Starck, G; Werner, H; Matyssek, R; Sandermann Jr, H

    2005-11-01

    Ozone and light effects on endophytic colonization by Apiognomonia errabunda of adult beech trees (Fagus sylvatica) and their putative mediation by internal defence compounds were studied at the Kranzberg Forest free-air ozone fumigation site. A. errabunda colonization was quantified by "real-time PCR" (QPCR). A. errabunda-specific primers allowed detection without interference by DNA from European beech and several species of common genera of plant pathogenic fungi, such as Mycosphaerella, Alternaria, Botrytis, and Fusarium. Colonization levels of sun and shade leaves of European beech trees exposed either to ambient or twice ambient ozone regimes were determined. Colonization was significantly higher in shade compared to sun leaves. Ozone exhibited a marginally inhibitory effect on fungal colonization only in young leaves in 2002. The hot and dry summer of 2003 reduced fungal colonization dramatically, being more pronounced than ozone treatment or sun exposure. Levels of soluble and cell wall-bound phenolic compounds were approximately twice as high in sun than in shade leaves. Acylated flavonol 3- O-glycosides with putatively high UV-B shielding effect were very low in shade canopy leaves. Ozone had only a minor influence on secondary metabolites in sun leaves. It slightly increased kaempferol 3- O-glucoside levels exclusively in shade leaves. The frequently prominent hydroxycinnamic acid derivative, chlorogenic acid, was tested for its growth inhibiting activity against Apiognomonia and showed an IC50 of approximately 8 mM. Appearance of Apiognomonia-related necroses strongly correlated with the occurrence of the stress metabolite, 3,3',4,4'-tetramethoxybiphenyl. Infection success of Apiognomonia was highly dependent on light exposure, presumably affected by the endogenous levels of constitutive phenolic compounds. Ozone exerted only minor modulating effects, whereas climatic factors, such as pronounced heat periods and drought, were dramatically overriding.

  4. YAG:Ce/(Gd,Y)AG:Ce dual-layered composite structure ceramic phosphors designed for bright white light-emitting diodes with various CCT.

    Science.gov (United States)

    Hu, Chen; Shi, Yun; Feng, Xiqi; Pan, Yubai

    2015-07-13

    Y3Al5O12:Ce and (Gd,Y)3Al5O12:Ce ceramic phosphors were fabricated by solid-state reaction method under vacuum sintering. Pure garnet phase of these (Gd,Y)AG:Ce ceramics was confirmed by X-ray diffraction (XRD) with Gd content of 0, 25%, 50% and 75%, respectively. The electroluminescent properties of the unpacked and packed LED devices based on YAG:Ce and (Gd,Y)AG:Ce ceramics were measured. The highest luminous efficacy of 130.5 lm/W was achieved by YAG:Ce ceramic phosphor with thickness of 0.4 mm. However, the correlated color temperature (CCT) of the LED device based on it was high due to a lack of red component in the emission light. Therefore, Y3Al5O12:Ce/(Gdx,Y1-x)3Al5O12:Ce dual-layered composite structure ceramics phosphor were designed and fabricated according to the color space chromaticity diagram. In one demonstration, various CCT could be tuned from 3100 K to 3600 K by these dual-layered structure, while the luminous efficacy can reach 109.9 lm/W. The high luminous efficacy and safe warm white light emitted by these dual-layered phosphors made them promising candidate for white LED devices.

  5. A Correlation between the Intrinsic Brightness and Average Decay Rate of Gamma-Ray Burst X-Ray Afterglow Light Curves

    Science.gov (United States)

    Racusin, J. L.; Oates, S. R.; de Pasquale, M.; Kocevski, D.

    2016-07-01

    We present a correlation between the average temporal decay ({α }{{X},{avg},\\gt 200{{s}}}) and early-time luminosity ({L}{{X},200{{s}}}) of X-ray afterglows of gamma-ray bursts as observed by the Swift X-ray Telescope. Both quantities are measured relative to a rest-frame time of 200 s after the γ-ray trigger. The luminosity-average decay correlation does not depend on specific temporal behavior and contains one scale-independent quantity minimizing the role of selection effects. This is a complementary correlation to that discovered by Oates et al. in the optical light curves observed by the Swift Ultraviolet Optical Telescope. The correlation indicates that, on average, more luminous X-ray afterglows decay faster than less luminous ones, indicating some relative mechanism for energy dissipation. The X-ray and optical correlations are entirely consistent once corrections are applied and contamination is removed. We explore the possible biases introduced by different light-curve morphologies and observational selection effects, and how either geometrical effects or intrinsic properties of the central engine and jet could explain the observed correlation.

  6. Effects of white light-emitting diode (LED) light exposure with different correlated color temperatures (CCTs) on human lens epithelial cells in culture.

    Science.gov (United States)

    Xie, Chen; Li, Xiuyi; Tong, Jianping; Gu, Yangshun; Shen, Ye

    2014-01-01

    Cataract is the major cause for legal blindness in the world. Oxidative stress on the lens epithelial cells (hLECs) is the most important factor in cataract formation. Cumulative light-exposure from widely used light-emitting diodes (LEDs) may pose a potential oxidative threat to the lens epithelium, due to the high-energy blue light component in the white-light emission from diodes. In the interest of perfecting biosafety standards for LED domestic lighting, this study analyzed the photobiological effect of white LED light with different correlated color temperatures (CCTs) on cultured hLECs. The hLECs were cultured and cumulatively exposed to multichromatic white LED light with CCTs of 2954, 5624, and 7378 K. Cell viability of hLECs was measured by Cell Counting Kit-8 (CCK-8) assay. DNA damage was determined by alkaline comet assay. Intracellular reactive oxygen species (ROS) generation, cell cycle, and apoptosis were quantified by flow cytometry. Compared with 2954 and 5624 K LED light, LED light having a CCT of 7378 K caused overproduction of intracellular ROS and severe DNA damage, which triggered G2 /M arrest and apoptosis. These results indicate that white LEDs with a high CCT could cause significant photobiological damage to hLECs. © 2014 The American Society of Photobiology.

  7. Effect of exposure to continuous light and melatonin on ovarian follicular kinetics in the skipper frog, Rana cyanophlyctis.

    Science.gov (United States)

    Udaykumar, K; Joshi, B N

    1997-01-01

    Ovarian follicular kinetics and gravimetric changes in the ovary and oviducts were studied in the skipper frog, Rana cyanophlyctis, following exposure to continuous light and melatonin treatment during the breeding season. Daily late-afternoon injections of melatonin (15 micrograms subcutaneous) for 30 days decreased the gonadosomatic index (GSI), whereas continuously available melatonin from subcutaneous implants did not influence the GSI compared to those of controls. Exposure to continuous light for 30 days stimulated the GSI, and melatonin given as daily injections prevented the continuous-light induced increase in GSI. Oviductal weights decreased only in the melatonin-injected groups. Data on follicular kinetics revealed a decrease in first-growth-phase (FGP) oocytes and an increase in medium-sized second-growth-phase (MSGP) and large-sized second-growth-phase (LSGP) oocytes following continuous-light exposure. Melatonin administered to continuous-light-exposed frogs did not change the FGP oocyte number; however, it reduced both the MSGP and LSGP oocytes. Melatonin administration to frogs held in a light and dark cycle increased FGP oocytes and decreased MSGP and LSGP oocytes. Atretic follicles increased in all melatonin-treated groups. The results suggest that continuous light stimulates and melatonin inhibits reproductive function in this species.

  8. Pilot study of a novel classroom designed to prevent myopia by increasing children’s exposure to outdoor light

    Science.gov (United States)

    Wang, Mengrui; Jin, Ling; Zhao, Yongyi; Chen, Shangji; Wang, Congyao; Zhang, Guoshan; Wang, Qilin; Deng, Qiaoming; Liu, Yubo; Morgan, Ian G.; He, Mingguang; Liu, Yizhi

    2017-01-01

    We sought to assess light characteristics and user acceptability of a prototype Bright Classroom (BC), designed to prevent children’s myopia by exposing them to light conditions resembling the outdoors. Conditions were measured throughout the school year in the glass-constructed BC, a traditional classroom (TC) and outdoors. Teachers and children completed user questionnaires, and children rated reading comfort at different light intensities. A total of 230 children (mean age 10.2 years, 57.4% boys) and 13 teachers (36.8 years, 15.4% men) completed questionnaires. The median (Inter Quartile Range) light intensity in the BC (2,540 [1,330–4,060] lux) was greater than the TC (477 [245–738] lux, P 5,000 lux) was at the upper limit of children’s comfort for reading. In summary, light intensity in the BC exceeds TC, and is at the practical upper limit for routine use. Children and teachers prefer the BC. PMID:28759614

  9. A Bright Fluorescent Probe for H2S Enables Analyte-Responsive, 3D Imaging in Live Zebrafish Using Light Sheet Fluorescence Microscopy.

    Science.gov (United States)

    Hammers, Matthew D; Taormina, Michael J; Cerda, Matthew M; Montoya, Leticia A; Seidenkranz, Daniel T; Parthasarathy, Raghuveer; Pluth, Michael D

    2015-08-19

    Hydrogen sulfide (H2S) is a critical gaseous signaling molecule emerging at the center of a rich field of chemical and biological research. As our understanding of the complexity of physiological H2S in signaling pathways evolves, advanced chemical and technological investigative tools are required to make sense of this interconnectivity. Toward this goal, we have developed an azide-functionalized O-methylrhodol fluorophore, MeRho-Az, which exhibits a rapid >1000-fold fluorescence response when treated with H2S, is selective for H2S over other biological analytes, and has a detection limit of 86 nM. Additionally, the MeRho-Az scaffold is less susceptible to photoactivation than other commonly used azide-based systems, increasing its potential application in imaging experiments. To demonstrate the efficacy of this probe for H2S detection, we demonstrate the ability of MeRho-Az to detect differences in H2S levels in C6 cells and those treated with AOAA, a common inhibitor of enzymatic H2S synthesis. Expanding the use of MeRho-Az to complex and heterogeneous biological settings, we used MeRho-Az in combination with light sheet fluorescence microscopy (LSFM) to visualize H2S in the intestinal tract of live zebrafish. This application provides the first demonstration of analyte-responsive 3D imaging with LSFM, highlighting the utility of combining new probes and live imaging methods for investigating chemical signaling in complex multicellular systems.

  10. EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2014. Scientific Opinion on the substantiation of a health claim related to a combination of lutein and zeaxanthin and improved vision under bright light conditions pursuant to Article 13(5) of Regulation (EC) No 1924/2006

    DEFF Research Database (Denmark)

    Tetens, Inge

    EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2014. Scientific Opinion on the substantiation of a health claim related to a combination of lutein and zeaxanthin and improved vision under bright light conditions pursuant to Article 13(5) of Regulation (EC) No 1924/2006....

  11. Influence of exposure in ovo to different light wavelengths on the lateralization of social response in zebrafish larvae.

    Science.gov (United States)

    Sovrano, Valeria Anna; Bertolucci, Cristiano; Frigato, Elena; Foà, Augusto; Rogers, Lesley J

    2016-04-01

    Exposure of the chick embryo to different wavelengths of light of the same intensity has shown that only certain wavelengths may be important in generating visual asymmetries. This study aimed to detect the possible influence of different wavelengths of light on development of asymmetry of social recognition in zebrafish larvae, tested using the fish's mirror image as the stimulus. From fertilization until day 10 post-hatching zebrafish were kept in five different lighting conditions: natural light/dark (LD) cycle, complete darkness (DD), and artificial LD cycles with 14 h of monochromatic light (red, green, or violet light) and 10 h of darkness (rLD 14:10, gLD 14:10, vLD 14:10, respectively). On day 10 after hatching, the zebrafish larvae were subjected to a mirror test. A preference for using the left eye to scrutinize their mirror image was apparent only in zebrafish larvae exposed to and reared under a natural LD cycle, and not following exposure to any of other lighting conditions. These results are discussed with reference to other evidence of brain lateralization.

  12. Supramolecular Organization of Thylakoid Membranes in De-etioplasts Upon Exposure to Light

    Institute of Scientific and Technical Information of China (English)

    Yangyang Wang; Weitong Cui; Shihua Shen; Hui Chen

    2012-01-01

    Chloroplast is the most prominent form of plastid occurring in all green plant tissues and contains a thylakoid membrane system that carries the photosynthetic electron transport chain converting light energy into chemical energy in the forms of ATP and NADPH.Thylakoids are the dominating structure inside fully mature chloroplasts.The formation and alteration of the thylakoid membrane structure and composition are closely connected to the development of the chloroplasts from simple,undifferentiated proplastids.Despite the importance of thylakoid membranes for photosynthesis and the energy metabolism of plants,the molecular processes connected to the origin,synthesis,maintenance and adaptation of thylakoid membranes remain poorly understood.In this study,the proteome difference in developing thylakoid membranes,including integral and peripheral proteins,in the process of de-etiolated rice seedlings were analyzed by 2-DE,and the structural changes and effects of such difference on photosynthetic ability were also examined.The ultrastructure of etioplasts changed notably upon exposure to light for 1 h,5 h and 9 h.After 5 h of illumination,paracrystalline PLB transformation was completed with transverse short tubules dispersed in stroma.The first stacked thylakoid membranes were observed at time point 9 h of illumination.In the continuous illumination,the formation of intergranal thylakoid was directly from PLB material without an intervening vesicular stage.In order to investigate the function and organization of the photosynthetic membrane proteins,the low-temperature (77 K) fluorescence emission spectra of membrane factions isolated from etioplasts,de-etioplasts and mature chloroplasts were investigated.The fluorescence emission spectra from de-etioplasts and mature chloroplasts exhibited a clear red maximum centered at 681 nm and a shoulder in the far-red region near 735 nm.The 681 nm band was slightly red-shifted with the increase of illumination duration

  13. Lighting

    Data.gov (United States)

    Federal Laboratory Consortium — Lighting Systems Test Facilities aid research that improves the energy efficiency of lighting systems. • Gonio-Photometer: Measures illuminance from each portion of...

  14. Brightness discrimination in budgerigars (Melopsittacus undulatus.

    Directory of Open Access Journals (Sweden)

    Olle Lind

    Full Text Available Birds have excellent spatial acuity and colour vision compared to other vertebrates while spatial contrast sensitivity is relatively poor for unknown reasons. Contrast sensitivity describes the detection of gratings of varying spatial frequency. It is unclear whether bird brightness discrimination between large uniform fields is poor as well. Here we show that budgerigars (Melopsittacus undulatus need a Michelson contrast of 0.09 to discriminate between large spatially separated achromatic fields in bright light conditions. This is similar to the peak contrast sensitivity of 10.2 (0.098 Michelson contrast for achromatic grating stimuli established in earlier studies. The brightness discrimination threshold described in Weber fractions is 0.18, which is modest compared to other vertebrates.

  15. Meeting contribution: Bright lights on giant planets

    Science.gov (United States)

    Miller, S.

    2007-04-01

    Prof Miller explained that his scientific background was in chemistry rather than astronomy, but that he had become involved with planetary science, and especially aurorae, through an interest in the chemical composition of planetary atmospheres. The various colours seen in aurorae were powerful probes of the chemical constituents of atmospheres, and the speaker illustrated this with an image of the aurora borealis of our own planet. The deep red emission seen at the highest celestial altitudes could be attributed to atomic oxygen, and likewise the brighter green emission below it. Towards the lower edge of the aurora, closest to the horizon, reddish-pink emission stemmed from molecular nitrogen.

  16. Bright Lights and Questions: Using Mutual Interrogation

    Science.gov (United States)

    Adam, Aishikin; Alangui, Willy; Barton, Bill

    2010-01-01

    Mutual Interrogation is a research methodology for ethnomathematics proposed by Alangui in 2006 in an attempt to avoid the potential inequality set up when a restricted cultural practice is viewed through the lens of the near-universal and highly developed research domain of mathematics. Using three significant examples of mutual interrogation in…

  17. CA BrightStor

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    CA推出的BrightStor系列存储管理解决方案已经成为企业电子商务体系架构管理战略中举足轻重的组成部分。BrightStor是一整套企业级的智能化存储管理解决方案,定位在存储硬件设备和上层应用之间,通过各种集成化的产品和工具为驻留在企业任何位置的数据提供全方位的、有效的存储管理和保护。

  18. Macronutrients, Phytochemicals, and Antioxidant Activity of Soybean Sprout Germinated with or without Light Exposure.

    Science.gov (United States)

    Chen, Yeming; Chang, Sam K C

    2015-06-01

    This study examined the macronutrients, phytochemicals, and antioxidant activities of yellow soybean sprout (YSS) and green soybean sprout (GSS) with different germination days. YSS and GSS were obtained by sprouting soybean in darkness or with light exposure at 21 °C. Lipid, protein, carbohydrate, and ash contents were analyzed before and after soybean germination. Phytochemicals (total phenolic compounds, saponin, and isoflavone) were also determined. DPPH, ferric reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC) were determined to examine the antioxidant activities of soybean sprout. Results showed YSS had a higher yield than GSS. Based on dry mass composition, 7-d germination of GSS decreased 14% protein, 37% lipid, 22% carbohydrate, and 16% ash, whereas 7-d germination of YSS decreased 6% protein and 47% lipid. Carbohydrate did not change and ash significantly increased for the 7-d germinated YSS. Lipid was greatly metabolized in germination, which explained why the protein relative percentage in dried soybean sprout was higher than that in the corresponding soybean. Total phenolic compounds and saponin (mg/g soybean sprout, dry basis) had the same accumulation trend in soybean sprout with the increases in germination days. Aglycone isoflavones (genistein, glycitein, and daidzein) and daidzin showed an increased trend, whereas malonylgenistin and malonylglycitin showed a decreased trend with germination days for both GSS and YSS. The change in other isoflavones did not show definite trends. GSS had 20% more antioxidant activities than YSS (7-d germinated soybean sprout). The increases in ORAC antioxidant activity suggest eating GSS may be more beneficial than GSS for promoting human health.

  19. Bright Economic Prospects

    Institute of Scientific and Technical Information of China (English)

    Zhang Minqiu

    2004-01-01

    @@ India is expected to register an 8.2% growth rate for the 2003-04 fiscal year. The overall economic situation this year has been satisfactory despite the scaled down 6-6.5% growth rate for the new fiscal year due to oil price hikes, reduced monsoon volume and some 7% inflation. Judging from the following factors, bright prospects are in store for the country down the road.

  20. Ontogeny and adolescent alcohol exposure in Wistar rats: open field conflict, light/dark box and forced swim test.

    Science.gov (United States)

    Desikan, Anita; Wills, Derek N; Ehlers, Cindy L

    2014-07-01

    Epidemiological studies have demonstrated that heavy drinking and alcohol abuse and dependence peak during the transition between late adolescence and early adulthood. Studies in animal models have demonstrated that alcohol exposure during adolescence can cause a modification in some aspects of behavioral development, causing the "adolescent phenotype" to be retained into adulthood. However, the "adolescent phenotype" has not been studied for a number of behavioral tests. The objective of the present study was to investigate the ontogeny of behaviors over adolescence/young adulthood in the light/dark box, open field conflict and forced swim test in male Wistar rats. These data were compared to previously published data from rats that received intermittent alcohol vapor exposure during adolescence (AIE) to test whether they retained the "adolescent phenotype" in these behavioral tests. Three age groups of rats were tested (post-natal day (PD) 34-42; PD55-63; PD69-77). In the light/dark box test, younger rats escaped the light box faster than older adults, whereas AIE rats returned to the light box faster and exhibited more rears in the light than controls. In the open field conflict test, both younger and AIE rats had shorter times to first enter the center, spent more time in the center of the field, were closer to the food, and consumed more food than controls. In the forced swim test no clear developmental pattern emerged. The results of the light/dark box and the forced swim test do not support the hypothesis that adolescent ethanol vapor exposure can "lock-in" all adolescent phenotypes. However, data from the open field conflict test suggest that the adolescent and the AIE rats both engaged in more "disinhibited" and food motivated behaviors. These data suggest that, in some behavioral tests, AIE may result in a similar form of behavioral disinhibition to what is seen in adolescence.

  1. Light

    DEFF Research Database (Denmark)

    Prescott, N.B.; Kristensen, Helle Halkjær; Wathes, C.M.

    2004-01-01

    This chapter presents the effect of artificial light environments (light levels, colour, photoperiod and flicker) on the welfare of broilers in terms of vision, behaviour, lameness and mortality......This chapter presents the effect of artificial light environments (light levels, colour, photoperiod and flicker) on the welfare of broilers in terms of vision, behaviour, lameness and mortality...

  2. Stability of the Stevia-Derived Sweetener Rebaudioside A in Solution as Affected by Ultraviolet Light Exposure.

    Science.gov (United States)

    Zhang, Jiewen; Bell, Leonard N

    2017-02-20

    Rebaudioside A is a natural noncaloric high-potency sweetener extracted from the leaves of Stevia rebaudiana. With rebaudioside A use increasing in foods, understanding the factors affecting its stability is necessary. This project evaluated the degradation rate constants of rebaudioside A in water, 0.1 M phosphate buffer, and 0.1 M citrate buffer at pH 3 and 7 as a function of ultraviolet (UV) light intensity (365 nm, 0 μW/cm(2) for dark conditions, 27 μW/cm(2) for low intensity, and 190 μW/cm(2) for high intensity) at 32.5 °C. Rebaudioside A stability was adversely affected by light exposure. The pseudo-1st-order degradation rate constants increased significantly (P exposure to UV light resulted in rebaudioside A degradation occurring approximately 10 times faster in citrate than in phosphate buffers at both pH levels. The sensitivity of rebaudioside A to UV light was greater in citrate buffers than in water or phosphate buffers. The use of light-protective packaging for beverages containing rebaudioside A will improve its stability.

  3. In vivo temperature rise in anesthetized human pulp during exposure to a polywave LED light curing unit.

    Science.gov (United States)

    Runnacles, Patrício; Arrais, Cesar Augusto Galvão; Pochapski, Marcia Thais; Dos Santos, Fábio André; Coelho, Ulisses; Gomes, João Carlos; De Goes, Mário Fernando; Gomes, Osnara Maria Mongruel; Rueggeberg, Frederick Allen

    2015-05-01

    This in vivo study evaluated pulp temperature (PT) rise in human premolars during exposure to a light curing unit (LCU) using selected exposure modes (EMs). After local Ethics Committee approval, intact first upper premolars, requiring extraction for orthodontic reasons, from 8 volunteers, received infiltrative and intraligamental anesthesia. The teeth (n=15) were isolated using rubber dam and a minute pulp exposure was attained. A sterile probe from a wireless, NIST-traceable, temperature acquisition system was inserted directly into the coronal pulp chamber, and real time PT (°C) was continuously monitored while the buccal surface was exposed to polywave light from a LED LCU (Bluephase 20i, Ivoclar Vivadent) using selected EMs allowing a 7-min span between each exposure: 10-s either in low (10-s/L) or high (10-s/H); 5-s-turbo (5-s/T); and 60-s-high (60-s/H) intensities. Peak PT values and PT increases from baseline (ΔT) after exposure were subjected to one-way, repeated measures ANOVAs, and Bonferroni's post hoc tests (α=0.05). Linear regression analysis was performed to establish the relationship between applied radiant exposure and ΔT. All EMs produced higher peak PT than the baseline temperature (p<0.001). The 60-s/H mode generated the highest peak PT and ΔT (p<0.001), with some teeth exhibiting ΔT higher than 5.5°C. A significant, positive relationship between applied radiant exposure and ΔT (r(2)=0.916; p<0.001) was noted. Exposing intact, in vivo anesthetized human upper premolars to a polywave LED LCU increases PT, and depending on EM and the tooth, PT increase can be higher than the critical ΔT, thought to be associated with pulpal necrosis. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  4. Enriching lighting design.

    Science.gov (United States)

    Brawley, Elizabeth C

    2009-01-01

    Good lighting is perhaps the most important and least understood element in designing healthcare environments. Both physically and mentally challenged individuals become more vulnerable and dependent on their environment to compensate for sensory impairments, including dimming eyesight, which interferes to some degree with daily activities as well as social and leisure activities - the things that provide emotional and social well-being. Too few building designs today result in lighting that meets the needs of these individuals, regardless of age. Typical lighting in most care environments is inadequate to meet lighting needs affecting both vision and the photobiological (non-visual) needs of synchronization of circadian rhythm, which impacts sleep and depression. Well-designed lighting is one of the most important design elements that will support an individual's ability to perform normal daily activities and decrease the level of disability associated with these impairments. Daylight contains the spectrum to which the circadian clock is most sensitive and provides higher light levels during the day. Easily accessible outdoor gardens encourage individuals outside, providing the necessary regular exposure to direct bright light that sunlight provides. The combination good interior lighting and regular daylight exposure contributes to regaining and maintaining an active and fulfilling lifestyle - greatly improving quality of life.

  5. The influence of red light exposure at night on circadian metabolism and physiology in Sprague-Dawley rats.

    Science.gov (United States)

    Dauchy, Robert T; Wren, Melissa A; Dauchy, Erin M; Hoffman, Aaron E; Hanifin, John P; Warfield, Benjamin; Jablonski, Michael R; Brainard, George C; Hill, Steven M; Mao, Lulu; Dobek, Georgina L; Dupepe, Lynell M; Blask, David E

    2015-01-01

    Early studies on rodents showed that short-term exposure to high-intensity light (> 70 lx) above 600 nm (red-appearing) influences circadian neuroendocrine and metabolic physiology. Here we addressed the hypothesis that long-term, low-intensity red light exposure at night (rLEN) from a 'safelight' emitting no light below approximately 620 nm disrupts the nocturnal circadian melatonin signal as well as circadian rhythms in circulating metabolites, related regulatory hormones, and physi- ologic parameters. Male Sprague-Dawley rats (n = 12 per group) were maintained on control 12:12-h light:dark (300 lx; lights on, 0600) or experimental 12:12 rLEN (8.1 lx) lighting regimens. After 1 wk, rats underwent 6 low-volume blood draws via cardiocentesis (0400, 0800, 1200, 1600, 2000, and 2400) over a 4-wk period to assess arterial plasma melatonin, total fatty acid, glucose, lactic acid, pO2, pCO2, insulin, leptin and corticosterone concentrations. Results revealed plasma melatonin levels (mean ± 1 SD) were high in the dark phase (197.5 ± 4.6 pg/mL) and low in the light phase (2.6 ± 1.2 pg/mL) of control condi- tions and significantly lower than controls under experimental conditions throughout the 24-h period (P < 0.001). Prominent circadian rhythms of plasma levels of total fatty acid, glucose, lactic acid, pO2, pCO2, insulin, leptin, and corticosterone were significantly (P < 0.05) disrupted under experimental conditions as compared with the corresponding entrained rhythms under control conditions. Therefore, chronic use of low-intensity rLEN from a common safelight disrupts the circadian organization of neuroendocrine, metabolic, and physiologic parameters indicative of animal health and wellbeing.

  6. The darkening of zinc yellow: XANES speciation of chromium in artist;s paints after light and chemical exposures

    Energy Technology Data Exchange (ETDEWEB)

    Zanella, Luciana; Casadio, Francesca; Gray, Kimberly A.; Warta, Richard; Ma, Qing; Gaillard, Jean-François

    2012-03-14

    The color darkening of selected brushstrokes of the masterpiece A Sunday on La Grande Jatte - 1884 (by Georges Seurat) has been attributed to the alteration of the chromate pigment zinc yellow. The pigment originally displays a bright greenish-yellow color but may undergo, after aging, darkening to a dull, ocher tone. We used XANES to probe the oxidation state of Cr on paint reconstructions, and show that color changes are associated with the reduction of Cr(VI) to Cr(III). Paint mixtures containing the pigment and linseed oil to mimic mixtures used in La Grande Jatte were subjected to artificial aging in the presence of light, SO{sub 2}, and variable air humidity - 50 and 90% relative humidity. High relative humidity led to the largest degree of Cr(VI) reduction whereas low relative humidity promoted light-induced alterations. These results are corroborated by visible reflectance measurements on the same laboratory samples and contribute to a better understanding of the chemical reactivity of chromate pigments, which are present in many historical works of art.

  7. Improvement in Brightness Uniformity by Compensating for the Threshold Voltages of Both the Driving Thin-Film Transistor and the Organic Light-Emitting Diode for Active-Matrix Organic Light-Emitting Diode Displays

    Science.gov (United States)

    Fan, Ching-Lin; Lai, Hui-Lung; Chang, Jyu-Yu

    2010-05-01

    In this paper, we propose a novel pixel design and driving method for active-matrix organic light-emitting diode (AM-OLED) displays using low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs). The proposed threshold voltage compensation circuit, which comprised five transistors and two capacitors, has been verified to supply uniform output current by simulation work using the automatic integrated circuit modeling simulation program with integrated circuit emphasis (AIM-SPICE) simulator. The driving scheme of this voltage programming method includes four periods: precharging, compensation, data input, and emission. The simulated results demonstrate excellent properties such as low error rate of OLED anode voltage variation (<1%) and high output current. The proposed pixel circuit shows high immunity to the threshold voltage deviation characteristics of both the driving poly-Si TFT and the OLED.

  8. Food quality and the risk of light exposure affect patch-choice decisions in the slime mold Physarum polycephalum.

    Science.gov (United States)

    Latty, Tanya; Beekman, Madeleine

    2010-01-01

    How individuals deal with multiple conflicting demands is an important aspect of foraging ecology, yet work on foraging behavior has typically neglected neurologically simple organisms. Here we examine the impact of an abiotic risk (light) and energetic status on the foraging decisions of a protist, the slime mold Physarum polycephalum. We examined patch choice in a "non-risky" environment by presenting starved and non-starved P. polycephalum amoebas with a choice between two shaded food patches (one high quality, one low quality). We next examined patch choice in the presence of a conflict between foraging risk (light exposure) and food quality by presenting amoebas with a choice between a shaded, low-quality patch, and a light-exposed, high-quality patch. When both patches were shaded, 100% of amoebas selected the higher quality food patch, irrespective of food-quality differences or the individual's energetic status. When light exposure and food quality conflicted, amoebas selected the patch with the higher food quality when the quality difference between the patches was high. When the quality difference between patches was small, amoebas selected the shaded, lower quality patch.

  9. Measurement of illumination exposure in postpartum women

    Directory of Open Access Journals (Sweden)

    Stein Martin T

    2003-05-01

    Full Text Available Abstract Background Low levels of light exposure at critical times are thought to cause seasonal affective disorder. Investigators, in studies demonstrating the usefulness of bright light therapy, also have implicated light's role in non-seasonal depression. The precise cause of postpartum depression has not been delineated, but it seemed possible that new mothers would spend reduced time in daylight. The goal of this study was to examine the levels of illumination experienced by postpartum mothers and to discover any relationship between light exposure and mood levels experienced during the postpartum period. Methods Fifteen postpartum women, who did not have any baseline indication of depression, wore a wrist device (Actillume for 72 hours to measure their exposure to light. At the end of the recording period, they completed a self-reported measure of mood. The mean light exposure of these postpartum women (expressed as the 24-hour average logarithm of illumination in lux was compared with that of a representative sample of women of comparable age, residence, and seasonal months of recording. Mood levels were then rank-ordered and tested for correlation with light exposure levels. Results There was no significant difference between the amount of light [log10lux] experienced by postpartum (1.01 SD 0.236 and control women (1.06 SD 0.285. Mood was not correlated with illumination in the postpartum sample. Conclusions Postpartum women in San Diego did not receive reduced light, nor was low mood related to low illumination.

  10. Exposure to light enhances pre-adult fitness in two dark-dwelling sympatric species of ants

    Directory of Open Access Journals (Sweden)

    Sharma Vijay

    2008-12-01

    Full Text Available Abstract Background In insects, circadian clocks play a key role in enhancing fitness by regulating life history traits such as developmental time and adult lifespan. These clocks use environmental light/dark (LD cycles to fine-tune a wide range of behavioral and physiological processes. To study the effect of environmental LD conditions on pre-adult fitness components, we used two dark-dwelling sympatric species of ants (the night active Camponotus compressus and the day active Camponotus paria, which normally develop underground and have fairly long pre-adult developmental time. Results Our results suggest that ants develop fastest as pre-adults when maintained under constant light (LL, followed closely by 12:12 hr light/dark (LD, and then constant darkness (DD. While light exposure alters developmental rates of almost all stages of development, the overall pre-adult development in LL is speeded-up (relative to DD by ~37% (34 days in C. compressus and by ~35% (31 days in C. paria. In LD too, development is faster (relative to DD by ~29% (26 days in C. compressus and by ~28% (25 days in C. paria. Pre-adult viability of both species is also higher under LL and LD compared to DD. While pre-adult development time and viability is enhanced in LL and LD, clutch-size undergoes reduction, at least in C. compressus. Conclusion Exposure to light enhances pre-adult fitness in two dark-dwelling species of Camponotus by speeding-up development and by enhancing viability. This suggests that social ants use environmental light/dark cycles to modulate key life history traits such as pre-adult development time and viability.

  11. Improvement in Brightness Uniformity by Compensating for the Threshold Voltages of Both the Driving Thin-Film Transistor and the Organic Light-Emitting Diode for Active-Matrix Organic Light-Emitting Diode Displays

    Directory of Open Access Journals (Sweden)

    Ching-Lin Fan

    2014-01-01

    Full Text Available This paper proposes a novel pixel circuit design and driving method for active-matrix organic light-emitting diode (AM-OLED displays that use low-temperature polycrystalline-silicon thin-film transistors (LTPS-TFTs as driving element. The automatic integrated circuit modeling simulation program with integrated circuit emphasis (AIM-SPICE simulator was used to verify that the proposed pixel circuit, which comprises five transistors and one capacitor, can supply uniform output current. The voltage programming method of the proposed pixel circuit comprises three periods: reset, compensation with data input, and emission periods. The simulated results reflected excellent performance. For instance, when ΔVTH=±0.33 V, the average error rate of the OLED current variation was low (<0.8%, and when ΔVTH_OLED=+0.33 V, the error rate of the OLED current variation was 4.7%. Moreover, when the I×R (current × resistance drop voltage of a power line was 0.3 V, the error rate of the OLED current variation was 5.8%. The simulated results indicated that the proposed pixel circuit exhibits high immunity to the threshold voltage deviation of both the driving poly-Si TFTs and OLEDs, and simultaneously compensates for the I×R drop voltage of a power line.

  12. 405 nm light exposure of osteoblasts and inactivation of bacterial isolates from arthroplasty patients: potential for new disinfection applications?

    Directory of Open Access Journals (Sweden)

    RS McDonald

    2013-01-01

    Full Text Available Infection rates after arthroplasty surgery are between 1-4 %, rising significantly after revision procedures. To reduce the associated costs of treating these infections, and the patients’ post-operative discomfort and trauma, a new preventative method is required. High intensity narrow spectrum (HINS 405 nm light has bactericidal effects on a wide range of medically important bacteria, and it reduced bacterial bioburden when used as an environmental disinfection method in a Medical Burns Unit. To prove its safety for use for environmental disinfection in orthopaedic theatres during surgery, cultured osteoblasts were exposed to HINS-light of intensities up to 15 mW/cm2 for 1 h (54 J/cm2. Intensities of up to 5 mW/cm2 for 1 h had no effect on cell morphology, activity of alkaline phosphatase, synthesis of collagen or osteocalcin expression, demonstrating that under these conditions this dose is the maximum safe exposure for osteoblasts; after exposure to 15 mW/cm2 all parameters of osteoblast function were significantly decreased. Viability (measured by protein content and Crystal Violet staining of the osteoblasts was not influenced by exposure to 5 mW/cm2 for at least 2 h. At 5 mW/cm2 HINS-light is an effective bactericide. It killed 98.1 % of Staphylococcus aureus and 83.2 % Staphylococcus epidermis populations seeded on agar surfaces, and is active against both laboratory strains and clinical isolates from infected hip and knee arthroplasties. HINS-light could have potential for development as a method of disinfection to reduce transmission of bacteria during arthroplasty, with wider applications in diverse surgical procedures involving implantation of a medical device.

  13. Contrasted sensitivity of DMSP production to high light exposure in two Arctic under-ice blooms

    NARCIS (Netherlands)

    Galindo, Virginie; Levasseur, Maurice; Mundy, Christopher John; Gosselin, Michel; Scarratt, Michael; Papakyriakou, Tim; Stefels, Jacqueline; Gale, Matthew A.; Tremblay, Jean-Eric; Lizotte, Martine

    In polar regions, low-light acclimated phytoplankton thriving under sea ice may be suddenly exposed to high irradiance when ice pack breaks or surface currents carry them into adjacent ice-free areas. Here we experimentally determined how rapid shifts in light regime affect the phytoplankton and the

  14. Contrasted sensitivity of DMSP production to high light exposure in two Arctic under-ice blooms

    NARCIS (Netherlands)

    Galindo, Virginie; Levasseur, Maurice; Mundy, Christopher John; Gosselin, Michel; Scarratt, Michael; Papakyriakou, Tim; Stefels, Jacqueline; Gale, Matthew A.; Tremblay, Jean-Eric; Lizotte, Martine

    2016-01-01

    In polar regions, low-light acclimated phytoplankton thriving under sea ice may be suddenly exposed to high irradiance when ice pack breaks or surface currents carry them into adjacent ice-free areas. Here we experimentally determined how rapid shifts in light regime affect the phytoplankton and the

  15. 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...

  16. Lung inflammation and genotoxicity in mice lungs after pulmonary exposure to candle light combustion particles

    DEFF Research Database (Denmark)

    Skovmand, Astrid; Damiao Gouveia, Ana Cecilia; Koponen, Ismo Kalevi

    2017-01-01

    Candle burning produces a large amount of particles that contribute substantially to the exposure to indoor particulate matter. The exposures to various types of combustion particles, such as diesel exhaust particles, have been associated with increased risk of lung cancer by mechanisms that invo......Candle burning produces a large amount of particles that contribute substantially to the exposure to indoor particulate matter. The exposures to various types of combustion particles, such as diesel exhaust particles, have been associated with increased risk of lung cancer by mechanisms...... a significant influx of alveolar macrophages and polymorphonuclear leukocytes and increased concentrations of proteins and lactate dehydrogenase activity in bronchoalveolar fluid. Lower levels of these markers of inflammation and cytotoxicity were observed after i.t. instillation of the same dose of A...

  17. Test-retest repeatability of the pupil light response to blue and red light stimuli in normal human eyes using a novel pupillometer

    DEFF Research Database (Denmark)

    Herbst, Kristina; Sander, Birgit; Milea, Dan

    2011-01-01

    In this study, we evaluated the repeatability of pupil responses to colored light stimuli in healthy subjects using a prototype chromatic pupillometer. One eye of 10 healthy subjects was tested twice in the same day using monochromatic light exposure at two selected wavelengths (660 and 470¿nm......, we have developed a novel prototype of color pupillometer which demonstrates good repeatability in evoking and recording the pupillary response to a bright blue and red light stimulus....

  18. Cytotoxic responses to 405nm light exposure in mammalian and bacterial cells: Involvement of reactive oxygen species.

    Science.gov (United States)

    Ramakrishnan, Praveen; Maclean, Michelle; MacGregor, Scott J; Anderson, John G; Grant, M Helen

    2016-06-01

    Light at wavelength 405 nm is an effective bactericide. Previous studies showed that exposing mammalian cells to 405 nm light at 36 J/cm(2) (a bactericidal dose) had no significant effect on normal cell function, although at higher doses (54 J/cm(2)), mammalian cell death became evident. This research demonstrates that mammalian and bacterial cell toxicity induced by 405 nm light exposure is accompanied by reactive oxygen species production, as detected by generation of fluorescence from 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate. As indicators of the resulting oxidative stress in mammalian cells, a decrease in intracellular reduced glutathione content and a corresponding increase in the efflux of oxidised glutathione were observed from 405 nm light treated cells. The mammalian cells were significantly protected from dying at 54 J/cm(2) in the presence of catalase, which detoxifies H2O2. Bacterial cells were significantly protected by sodium pyruvate (H2O2 scavenger) and by a combination of free radical scavengers (sodium pyruvate, dimethyl thiourea (OH scavenger) and catalase) at 162 and 324 J/cm(2). Results therefore suggested that the cytotoxic mechanism of 405 nm light in mammalian cells and bacteria could be oxidative stress involving predominantly H2O2 generation, with other ROS contributing to the damage.

  19. Light exposure of chick embryo influences lateralized recall of imprinting memory.

    Science.gov (United States)

    Johnston, A N; Rogers, L J

    1999-12-01

    Environmental cues, such as light during the later part of incubation, are known to establish lateralization of some forms of visually guided behaviors in birds. The authors investigated the effect of light on lateralized recall of imprinting memory in chicks. On Day E19 of incubation, one eye was occluded for 24 hr. The other eye received stimulation by light. Chicks were imprinted and then tested for their imprinting preferences after administration of a low dose (500 ng) of glutamate into either hemisphere. Chicks that had the right eye exposed to light during incubation showed recall of the imprinting stimulus after injection of the left hemisphere but not after injection into the right hemisphere. The reverse was found for chicks that had the left eye exposed to light. Hence, the hemisphere ipsilateral to the eye exposed to light before hatching became essential for recall of imprinting memory. The hemisphere used in recall of imprinting memory received indirect visual inputs and was determined by environmental stimulation (asymmetrical light input).

  20. Effects of radiant exposure and wavelength spectrum of light-curing units on chemical and physical properties of resin cements

    Directory of Open Access Journals (Sweden)

    Adriano Fonseca Lima

    2016-11-01

    Full Text Available Objectives In this study, we evaluated the influence of different radiant exposures provided by single-peak and polywave light-curing units (LCUs on the degree of conversion (DC and the mechanical properties of resin cements. Materials and Methods Six experimental groups were established for each cement (RelyX ARC, 3M ESPE; LuxaCore Dual, Ivoclar Vivadent; Variolink, DMG, according to the different radiant exposures (5, 10, and 20 J/cm2 and two LCUs (single-peak and polywave. The specimens were made (7 mm in length × 2 mm in width × 1 mm in height using silicone molds. After 24 hours of preparation, DC measurement was performed using Fourier transform infrared spectrometry. The same specimens were used for the evaluation of mechanical properties (flexural strength, FS; elastic modulus, E by a three-point bending test. Data were assessed for normality, after which two-way analysis of variance (ANOVA and post hoc Tukey's test were performed. Results No properties of the Variolink cement were influenced by any of the considered experimental conditions. In the case of the RelyX ARC cement, DC was higher when polywave LCU was used; FS and E were not influenced by the conditions evaluated. The LuxaCore cement showed greater sensitivity to the different protocols. Conclusions On the basis of these results, both the spectrum of light emitted and the radiant exposure used could affect the properties of resin cements. However, the influence was material-dependent.

  1. How Bright Can Supernovae Get?

    Science.gov (United States)

    Kohler, Susanna

    2016-04-01

    Supernovae enormous explosions associated with the end of a stars life come in a variety of types with different origins. A new study has examined how the brightest supernovae in the Universe are produced, and what limits might be set on their brightness.Ultra-Luminous ObservationsRecent observations have revealed many ultra-luminous supernovae, which haveenergies that challenge our abilities to explain them usingcurrent supernova models. An especially extreme example is the 2015 discovery of the supernova ASASSN-15lh, which shone with a peak luminosity of ~2*1045 erg/s, nearly a trillion times brighter than the Sun. ASASSN-15lh radiated a whopping ~2*1052 erg in the first four months after its detection.How could a supernova that bright be produced? To explore the answer to that question, Tuguldur Sukhbold and Stan Woosley at University of California, Santa Cruz, have examined the different sources that could produce supernovae and calculated upper limits on the potential luminosities ofeach of these supernova varieties.Explosive ModelsSukhbold and Woosley explore multiple different models for core-collapse supernova explosions, including:Prompt explosionA stars core collapses and immediately explodes.Pair instabilityElectron/positron pair production at a massive stars center leads to core collapse. For high masses, radioactivity can contribute to delayed energy output.Colliding shellsPreviously expelled shells of material around a star collide after the initial explosion, providing additional energy release.MagnetarThe collapsing star forms a magnetar a rapidly rotating neutron star with an incredibly strong magnetic field at its core, which then dumps energy into the supernova ejecta, further brightening the explosion.They then apply these models to different types of stars.Setting the LimitThe authors show that the light curve of ASASSN-15lh (plotted in orange) can be described by a model (black curve) in which a magnetar with an initial spin period of 0.7 ms

  2. The relationship between obesity and exposure to light at night: cross-sectional analyses of over 100,000 women in the Breakthrough Generations Study

    National Research Council Canada - National Science Library

    McFadden, Emily; Jones, Michael E; Schoemaker, Minouk J; Ashworth, Alan; Swerdlow, Anthony J

    2014-01-01

    There has been a worldwide epidemic of obesity in recent decades. In animal studies, there is convincing evidence that light exposure causes weight gain, even when calorie intake and physical activity are held constant...

  3. Bright Star Astrometry with URAT

    CERN Document Server

    Zacharias, Norbert

    2015-01-01

    The U.S. Naval Observatory Robotic Astrometric Telescope (URAT) is observing the northern sky since April 2012 for an astrometric survey. Multiple overlaps per year are performed in a single bandpass (680$-$750 nm) using the "redlens" 20 cm aperture astrograph and a mosaic of large CCDs. Besides the regular, deep survey to magnitude 18.5, short exposures with an objective grating are taken to access stars as bright as 3rd magnitude. A brief overview of the program, observing and reductions is given. Positions on the 8 to 20 mas level are obtained of 66,202 Hipparcos stars at current epochs. These are compared to the Hipparcos Catalog to investigate its accuracy. About 20\\% of the observed Hipparcos stars are found to have inconsitent positions with the Hipparcos Catalog prediction on the 3 sigma level or over (about 75 mas or more discrepant position offsets). Some stars are now seen at an arcsec (or 25 sigma) off their Hipparcos Catalog predicted position.

  4. Association between light exposure at night and insomnia in the general elderly population: the HEIJO-KYO cohort.

    Science.gov (United States)

    Obayashi, Kenji; Saeki, Keigo; Kurumatani, Norio

    2014-11-01

    Chronic circadian misalignment between the internal and environmental rhythms, which is typically related to night-shift work and clock-gene variants, is associated with disruption of suprachiasmatic nucleus function and increased risk of insomnia. Under controlled laboratory conditions, light at night (LAN) suppresses melatonin secretion, delays the internal biological rhythm, and reduces sleepiness. Therefore, LAN exposure may cause circadian misalignment and insomnia, though it remains unclear in real-life situations whether LAN exposure is associated with insomnia. To evaluate an association between LAN exposure and sleep quality in home settings, we conducted a cross-sectional community-based study in 857 elderly individuals (mean age, 72.2 years). We evaluated bedroom light intensity using a light meter and subjectively and objectively measured sleep quality using the Pittsburgh Sleep Quality Index and an actigraph, respectively, along with urinary 6-sulfatoxymelatonin excretion. Compared with the lowest quartile group of LAN intensity, the highest quartile group revealed a significantly higher odds ratio (OR) for subjective insomnia in a multivariate model adjusted for age, gender, body mass index, daytime physical activity, urinary 6-sulfatoxymelatonin excretion, bedtime, rising time, and day length (adjusted OR, 1.61, 95% confidence interval, 1.05-2.45, p=0.029). In addition, higher OR for subjective insomnia was significantly associated with the increase in quartiles of LAN intensity (ptrend=0.043). Consistently, we observed significant association trends between the increase in quartiles of LAN intensity and poorer actigraphic sleep quality, including decreased sleep efficiency, prolonged sleep-onset latency, increased wake-after-sleep onset, shortened total sleep time, and delayed sleep-mid time in multivariate models adjusted for the covariates mentioned above (all ptrendassociated with both subjectively and objectively measured sleep quality in a

  5. Non-linear increase of vitamin D content in eggs from chicks treated with increasing exposure times of ultraviolet light.

    Science.gov (United States)

    Kühn, Julia; Schutkowski, Alexandra; Hirche, Frank; Baur, Anja C; Mielenz, Norbert; Stangl, Gabriele I

    2015-04-01

    Vitamin D fortified food can help to reduce the prevalence for vitamin D deficiency. Previous data provided evidence that eggs from hens exposed to ultraviolet (UV) light contain large quantities of vitamin D. In the current study, we assessed the efficacy of vitamin D enrichment in eggs upon increasing daily UVB exposure times. We further addressed the question whether extended UVB irradiation affects the skin content of 7-dehydrocholesterol. To this end, 35 hens were assigned to 7 groups of 5 animals each and were exposed to UVB light (76μW/cm(2)) for 0, 15, 30, 60, 120, 180 and 300min per day, respectively. Eggs from the treatment groups were collected at baseline and after 2, 3 and 4 weeks of treatment, respectively. Skin samples were gained at the end of 4 weeks. Vitamin D metabolites were quantified by liquid chromatography-tandem mass spectrometry. The contents of vitamin D3 and 25(OH)D3 in egg yolk raised non-linear in response to increasing daily UVB exposure times. The vitamin D3 content did not reach a clear-cut plateau within the chosen UVB treatment times. A daily UVB exposure time of 300min resulted in vitamin D3 contents of 28.6μg/100g egg yolk dry matter. In contrast to vitamin D3, the 25(OH)D3 content in the egg yolk achieved a maximum upon an UVB irradiation time of 60min/d. The cutaneous 7-dehydrocholesterol contents were not altered in response to the chosen UVB irradiation times. In conclusion, the data show a distinct non-linear dose-response relationship of UVB exposure times on the total vitamin D content in eggs. This article is part of a special issue entitled '17th Vitamin D Workshop'.

  6. Inactivation of mycobacterium smegmatis following exposure to 405-nanometer light from a supraluminous diode array.

    Science.gov (United States)

    Guffey, J Stephen; Payne, William; James, Leslie

    2013-05-01

    To determine the potential for blue light (405 nm) to produce a bactericidal effect on Mycobacterium smegmatis. Additionally, the study sought to evaluate a series of doses in terms of their respective bactericidal capabilities. The effect of blue light on Staphylococcus aureus has been studied and it was found that a bactericidal outcome can be obtained with low doses of blue light. M. smegmatis was tested because of the recent appearance of the Mycobacterium family of organisms as a public health threat among persons receiving tattoos. The organism was treated in vitro with 405 nm light emitted from a supraluminous diode (SLD) array. Doses of 60 Jcm-2, 90 Jcm-2, 120 Jcm-2, 150 Jcm-2, 180 Jcm-2, 215 Jcm-2, and 250 Jcm-2 were used. Colony counts were performed and compared to untreated controls using Student t tests and one-way ANOVA with Tukey post hoc analysis. The results revealed statistically significant bactericidal effects of the blue light on M. smegmatis (F6, 28 = 50.518, P = 0.000). The treatment reduced the number of bacterial colonies at all doses, but 60 Jcm-2 did not produce a statistically significant kill rate. All other doses produced a significant kill rate with 120 Jcm-2, 150 Jcm-2, and 215 Jcm-2, demonstrating the most effective kill rates of 98.3%, 96.7%, and 100%, respectively. Appropriate doses of 405 nm light from an SLD array can kill M. smegmatis in vitro. A dose of at least 100 Jcm-2 dose is needed for the most effective inactivation of the organism. The dose response for this organism to blue light is not linear. Some degree of effectiveness is lost at 180 Jcm-2 and 250 Jcm-2. .

  7. Inactivation and potential reactivation of pathogenic Escherichia coli O157:H7 in apple juice following ultraviolet light exposure at three monochromatic wavelengths.

    Science.gov (United States)

    Yin, Fugui; Zhu, Yan; Koutchma, Tatiana; Gong, Joshua

    2015-04-01

    Ultraviolet (UV) light irradiation at 254 nm is considered as a novel non-thermal method for decontamination of foodborne pathogenic bacteria. However, lower penetration depth of UV light at 254 nm in apple juice resulted in higher UV dose consumption during apple juice decontamination. In addition, no studies are available on the reactivation of pathogens following exposure to UV light in drinks and beverages. Two novel monochromatic UV light sources (λ = 222 and 282 nm) have been developed for bacterial disinfection. However, the inactivation of pathogenic Escherichia coli O157:H7 following exposure to these UV wavelengths is still unclear. Therefore, the present study was conducted to determine the inactivation and reactivation potential of pathogenic E. coli O157:H7 in apple juice following exposure to UV light at three monochromatic wavelengths: Far UV (λ = 222 nm), Far UV+ (λ = 282 nm) and UVC light (λ = 254 nm). The results showed that E. coli O157:H7 is acid-resistant, and up to 99.50% of cells survived in apple juice when incubated at 20 °C for 24 h. Inactivation of E. coli O157:H7 following exposure to Far UV light (2.81 Log reduction) was higher (P exposure to UV light as determined by the regular plating method. In addition, the exposure to Far UV light at 222 nm followed by incubating at 37 °C significantly decreased (P < 0.05) the survival of E. coli O157:H7 during dark incubation phase compared to that of UVC and Far UV+ light.

  8. Light

    CERN Document Server

    Robertson, William C

    2003-01-01

    Why is left right and right left in the mirror? Baffled by the basics of reflection and refraction? Wondering just how the eye works? If you have trouble teaching concepts about light that you don t fully grasp yourself, get help from a book that s both scientifically accurate and entertaining with Light. By combining clear explanations, clever drawings, and activities that use easy-to-find materials, this book covers what science teachers and parents need to know to teach about light with confidence. It uses ray, wave, and particle models of light to explain the basics of reflection and refraction, optical instruments, polarization of light, and interference and diffraction. There s also an entire chapter on how the eye works. Each chapter ends with a Summary and Applications section that reinforces concepts with everyday examples. Whether you need a deeper understanding of how light bends or a good explanation of why the sky is blue, you ll find Light more illuminating and accessible than a college textbook...

  9. Exposure of bovine dermal tissue to ultraviolet light under the Antarctic ozone hole

    Science.gov (United States)

    Takahashi, Tetsuya; Ogura, Takayuki; Tanaka, Keisuke; Hattori, Shunji; Kudoh, Sakae; Imura, Satoshi

    2016-12-01

    Bovine dermis was exposed outdoors in the Antarctic in 2013 to study the skin damage caused by short-wavelength ultraviolet light under the ozone hole. Collagen was extracted from the exposed dermis with pepsin. The amount of solubilized collagen in the exposed dermis was only 20%-40% of that in dermis shielded from ultraviolet light. The dermis was most difficult to extract when exposed in summer, and then when exposed in spring. Differential scanning calorimetry was used to determine the melting endothermic behavior of the dermal tissue. The peak temperature was highest for the dermis exposed in summer. The exposed dermis was degraded with cyanogen bromide to determine whether cross-linking had occurred. Cross-linked peptides were detected in the dermis exposed in summer or spring, but the dermis exposed in autumn did not differ markedly from the light-shielded dermis. These data show that cross-linkages were readily formed in the collagen molecule chains in dermis exposed to ultraviolet light in summer, when solar elevation is highest and the period of sunshine is longest. A comparison of the dermis exposed in spring and that exposed in autumn showed that cross-linkages were formed more readily by ultraviolet light in spring, when the ozone hole occurred.

  10. Spatial Model of Sky Brightness Magnitude in Langkawi Island, Malaysia

    Science.gov (United States)

    Redzuan Tahar, Mohammad; Kamarudin, Farahana; Umar, Roslan; Khairul Amri Kamarudin, Mohd; Hazmin Sabri, Nor; Ahmad, Karzaman; Rahim, Sobri Abdul; Sharul Aikal Baharim, Mohd

    2017-03-01

    Sky brightness is an essential topic in the field of astronomy, especially for optical astronomical observations that need very clear and dark sky conditions. This study presents the spatial model of sky brightness magnitude in Langkawi Island, Malaysia. Two types of Sky Quality Meter (SQM) manufactured by Unihedron are used to measure the sky brightness on a moonless night (or when the Moon is below the horizon), when the sky is cloudless and the locations are at least 100 m from the nearest light source. The selected locations are marked by their GPS coordinates. The sky brightness data obtained in this study were interpolated and analyzed using a Geographic Information System (GIS), thus producing a spatial model of sky brightness that clearly shows the dark and bright sky areas in Langkawi Island. Surprisingly, our results show the existence of a few dark sites nearby areas of high human activity. The sky brightness of 21.45 mag arcsec{}-2 in the Johnson-Cousins V-band, as the average of sky brightness equivalent to 2.8 × {10}-4{cd} {{{m}}}-2 over the entire island, is an indication that the island is, overall, still relatively dark. However, the amount of development taking place might reduce the number in the near future as the island is famous as a holiday destination.

  11. Spatial Model of Sky Brightness Magnitude in Langkawi Island, Malaysia

    Science.gov (United States)

    Redzuan Tahar, Mohammad; Kamarudin, Farahana; Umar, Roslan; Khairul Amri Kamarudin, Mohd; Sabri, Nor Hazmin; Ahmad, Karzaman; Rahim, Sobri Abdul; Sharul Aikal Baharim, Mohd

    2017-03-01

    Sky brightness is an essential topic in the field of astronomy, especially for optical astronomical observations that need very clear and dark sky conditions. This study presents the spatial model of sky brightness magnitude in Langkawi Island, Malaysia. Two types of Sky Quality Meter (SQM) manufactured by Unihedron are used to measure the sky brightness on a moonless night (or when the Moon is below the horizon), when the sky is cloudless and the locations are at least 100 m from the nearest light source. The selected locations are marked by their GPS coordinates. The sky brightness data obtained in this study were interpolated and analyzed using a Geographic Information System (GIS), thus producing a spatial model of sky brightness that clearly shows the dark and bright sky areas in Langkawi Island. Surprisingly, our results show the existence of a few dark sites nearby areas of high human activity. The sky brightness of 21.45 mag arcsec{}-2 in the Johnson-Cousins V-band, as the average of sky brightness equivalent to 2.8 × {10}-4{cd} {{{m}}}-2 over the entire island, is an indication that the island is, overall, still relatively dark. However, the amount of development taking place might reduce the number in the near future as the island is famous as a holiday destination.

  12. Flow cytometric assessment of Streptococcus mutans viability after exposure to blue light-activated curcumin.

    Science.gov (United States)

    Manoil, Daniel; Filieri, Anna; Gameiro, Cécile; Lange, Norbert; Schrenzel, Jacques; Wataha, John C; Bouillaguet, Serge

    2014-09-01

    Streptococcus mutans biofilms are considered as primary causative agents of dental caries. Photodynamic antimicrobial chemotherapy (PACT) has been recently proposed as a strategy for inactivating dental biofilms. This study aimed to investigate the effect of blue light-activated curcumin on S. mutans viability and to explore its potential as a new anti-caries therapeutic agent. The effect of different concentrations and incubation times of photo-activated curcumin on the survival of S. mutans in planktonic and biofilm models of growth was assessed by flow cytometry. Streptococcus mutans in planktonic suspensions or biofilms formed on hydroxyapatite disks were incubated for 5 or 10min with curcumin prior to blue light activation. Bacteria were labeled with SYTO 9 and propidium iodide before viability was assessed by flow cytometry. Results were statistically analyzed using one-way ANOVA and Tukey multiple comparison intervals (α=0.05). For planktonic cultures, 0.2μM of light-activated curcumin significantly reduced S. mutans viability (p<0.05). For biofilm cultures, light-activated curcumin at concentration of 40-60μM only suppressed viability by 50% (p<0.05). Independently of the mode of growth, incubation time has no significant effect on PACT efficiency. This study indicates that blue light-activated curcumin can efficiently inactivate planktonic cultures of S. mutans whereas biofilms were more resistant to treatment. Flow cytometry allowed the detection of bacteria with damaged membranes that were unable to replicate and grow after cell sorting. Further studies seem warranted to optimize the efficacy of light-activated curcumin against S. mutans biofilms. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Patterning and Conductivity Modulation of Conductive Polymers by UV Light Exposure

    DEFF Research Database (Denmark)

    Edberg, Jesper; Iandolo, Donata; Brooke, Robert;

    2016-01-01

    A novel patterning technique of conductive polymers produced by vapor phase polymerization is demonstrated. The method involves exposing an oxidant film to UV light which changes the local chemical environment of the oxidant and subsequently the polymerization kinetics. This procedure is used...... to control the conductivity in the conjugated polymer poly(3,4-ethylenedioxythiophene):tosylate by more than six orders of magnitude in addition to producing high-resolution patterns and optical gradients. The mechanism behind the modulation in the polymerization kinetics by UV light irradiation as well...... as the properties of the resulting polymer are investigated....

  14. Out of the Lab and into the Bathroom: Evening Short-Term Exposure to Conventional Light Suppresses Melatonin and Increases Alertness Perception

    Directory of Open Access Journals (Sweden)

    Heinz Schoepp

    2013-01-01

    Full Text Available Life in 24-h society relies on the use of artificial light at night that might disrupt synchronization of the endogenous circadian timing system to the solar day. This could have a negative impact on sleep–wake patterns and psychiatric symptoms. The aim of the study was to investigate the influence of evening light emitted by domestic and work place lamps in a naturalistic setting on melatonin levels and alertness in humans. Healthy subjects (6 male, 3 female, 22–33 years were exposed to constant dim light (<10 lx for six evenings from 7:00 p.m. to midnight. On evenings 2 through 6, 1 h before habitual bedtime, they were also exposed to light emitted by 5 different conventional lamps for 30 min. Exposure to yellow light did not alter the increase of melatonin in saliva compared to dim light baseline during (38 ± 27 pg/mL vs. 39 ± 23 pg/mL and after light exposure (39 ± 22 pg/mL vs. 44 ± 26 pg/mL. In contrast, lighting conditions including blue components reduced melatonin increase significantly both during (office daylight white: 25 ± 16 pg/mL, bathroom daylight white: 24 ± 10 pg/mL, Planon warm white: 26 ± 14 pg/mL, hall daylight white: 22 ± 14 pg/mL and after light exposure (office daylight white: 25 ± 15 pg/mL, bathroom daylight white: 23 ± 9 pg/mL, Planon warm white: 24 ± 13 pg/mL, hall daylight white: 22 ± 26 pg/mL. Subjective alertness was significantly increased after exposure to three of the lighting conditions which included blue spectral components in their spectra. Evening exposure to conventional lamps in an everyday setting influences melatonin excretion and alertness perception within 30 min.

  15. Estimating photoreceptor excitations from spectral outputs of a personal light exposure measurement device.

    Science.gov (United States)

    Cao, Dingcai; Barrionuevo, Pablo A

    2015-03-01

    The intrinsic circadian clock requires photoentrainment to synchronize the 24-hour solar day. Therefore, light stimulation is an important component of chronobiological research. Currently, the chronobiological research field overwhelmingly uses photopic illuminance that is based on the luminous efficiency function, V(λ), to quantify light levels. However, recent discovery of intrinsically photosensitive retinal ganglion cells (ipRGCs), which are activated by self-contained melanopsin photopigment and also by inputs from rods and cones, makes light specification using a one-dimensional unit inadequate. Since the current understanding of how different photoreceptor inputs contribute to the circadian system through ipRGCs is limited, it is recommended to specify light in terms of the excitations of five photoreceptors (S-, M-, L-cones, rods and ipRGCs; Lucas et al., 2014). In the current study, we assessed whether the spectral outputs from a commercially available spectral watch (i.e. Actiwatch Spectrum) could be used to estimate photoreceptor excitations. Based on the color sensor spectral sensitivity functions from a previously published work, as well as from our measurements, we computed spectral outputs in the long-wavelength range (R), middle-wavelength range (G), short-wavelength range (B) and broadband range (W) under 52 CIE illuminants (25 daylight illuminants, 27 fluorescent lights). We also computed the photoreceptor excitations for each illuminant using human photoreceptor spectral sensitivity functions. Linear regression analyses indicated that the Actiwatch spectral outputs could predict photoreceptor excitations reliably, under the assumption of linear responses of the Actiwatch color sensors. In addition, R, G, B outputs could classify illuminant types (fluorescent versus daylight illuminants) satisfactorily. However, the assessment of actual Actiwatch recording under several testing light sources showed that the spectral outputs were subject to

  16. Endogenous Retinoic Acid Required to Maintain the Epidermis Following Ultraviolet Light Exposure in SKH-1 Hairless Mice.

    Science.gov (United States)

    Gressel, Katherine L; Duncan, F Jason; Oberyszyn, Tatiana M; La Perle, Krista M; Everts, Helen B

    2015-01-01

    Ultraviolet light B (UVB) exposure induces cutaneous squamous cell carcinoma (cSCC), one of the most prevalent human cancers. Reoccurrence of cSCC in high-risk patients is prevented by oral retinoids. But oral retinoid treatment causes significant side effects; and patients develop retinoid resistance. Exactly how retinoids prevent UVB-induced cSCC is currently not well understood. Retinoid resistance blocks mechanistic studies in the leading mouse model of cSCC, the UVB-exposed SKH-1 hairless mouse. To begin to understand the role of retinoids in UVB-induced cSCC we first examined the localization pattern of key retinoid metabolism proteins by immunohistochemistry 48 h after UVB treatment of female SKH-1 mice. We next inhibited retinoic acid (RA) synthesis immediately after UVB exposure. Acute UVB increased RA synthesis, signaling and degradation proteins in the stratum granulosum. Some of these proteins changed their localization; while other proteins just increased in intensity. In contrast, acute UVB reduced the retinoid storage protein lectin:retinol acyltransferase (LRAT) in the epidermis. Inhibiting RA synthesis disrupted the epidermis and impaired differentiation. These data suggest that repair of the epidermis after acute UVB exposure requires endogenous RA synthesis.

  17. Light

    CERN Document Server

    Ditchburn, R W

    2011-01-01

    This classic study, available for the first time in paperback, clearly demonstrates how quantum theory is a natural development of wave theory, and how these two theories, once thought to be irreconcilable, together comprise a single valid theory of light. Aimed at students with an intermediate-level knowledge of physics, the book first offers a historical introduction to the subject, then covers topics such as wave theory, interference, diffraction, Huygens' Principle, Fermat's Principle, and the accuracy of optical measurements. Additional topics include the velocity of light, relativistic o

  18. Cetacean noise criteria revisited in the light of proposed exposure limits for harbour porpoises

    DEFF Research Database (Denmark)

    Tougaard, Jakob; Wright, Andrew John; Madsen, Professor Peter Teglberg

    2015-01-01

    that harbour and finless porpoises are more sensitive to sound than expected from extrapolations based on results from bottlenose dolphins. Furthermore, the results from TTS experiments and field studies of behavioural reactions to noise, suggest that response thresholds and TTS critically depend on stimulus...... frequency. Sound exposure levels for pure tones that induce TTS are reasonably consistent at about 100 dB above the hearing threshold for pure tones and sound pressure thresholds for avoidance reactions are in the range of 40–50 dB above the hearing threshold. We propose that frequency weighting...

  19. High brightness microwave lamp

    Science.gov (United States)

    Kirkpatrick, Douglas A.; Dolan, James T.; MacLennan, Donald A.; Turner, Brian P.; Simpson, James E.

    2003-09-09

    An electrodeless microwave discharge lamp includes a source of microwave energy, a microwave cavity, a structure configured to transmit the microwave energy from the source to the microwave cavity, a bulb disposed within the microwave cavity, the bulb including a discharge forming fill which emits light when excited by the microwave energy, and a reflector disposed within the microwave cavity, wherein the reflector defines a reflective cavity which encompasses the bulb within its volume and has an inside surface area which is sufficiently less than an inside surface area of the microwave cavity. A portion of the reflector may define a light emitting aperture which extends from a position closely spaced to the bulb to a light transmissive end of the microwave cavity. Preferably, at least a portion of the reflector is spaced from a wall of the microwave cavity. The lamp may be substantially sealed from environmental contamination. The cavity may include a dielectric material is a sufficient amount to require a reduction in the size of the cavity to support the desired resonant mode.

  20. The interaction between humic acid and naphthalene after exposure to visible and UV light

    Science.gov (United States)

    Nechaev, L. V.; Tchaikovskaya, O. N.

    2015-12-01

    Dissolved organic matter plays an important role in pollution migration from human waste to aquatic environments. In this study, the effect of humic acid (HA) on the photo-chemical transformation of naphthalene by irradiation model solar and UV light was reported using fluorescence quenching titrations. It was calculated the interactions between naphthalene and humic acids. It is found that the molecular complex of humic acid and naphthalene is more stable to UV irradiation, compared with the model solar radiation. The application of molecular fluorescence spectrometry is a useful sensitive tool evaluate intermolecular HA and naphthalene interactions.

  1. Chronotype, Light Exposure, Sleep, and Daytime Functioning in High School Students Attending Morning or Afternoon School Shifts: An Actigraphic Study.

    Science.gov (United States)

    Martin, Jeanne Sophie; Gaudreault, Michael M; Perron, Michel; Laberge, Luc

    2016-04-01

    Adolescent maturation is associated with delays of the endogenous circadian phase. Consequently, early school schedules may lead to a mismatch between internal and external time, which can be detrimental to adolescent sleep and health. In parallel, chronotype is known to play a role in adolescent health; evening chronotype adolescents are at higher risk for sleep problems and lower academic achievement. In the summer of 2008, Kénogami High School (Saguenay, Canada) was destroyed by fire. Kénogami students were subsequently relocated to Arvida High School (situated 5.3 km away) for the 2008-2009 academic year. A dual school schedule was implemented, with Arvida students attending a morning schedule (0740-1305 h) and Kénogami students an afternoon schedule (1325-1845 h). This study aimed to investigate the effects of such school schedules and chronotype on sleep, light exposure, and daytime functioning. Twenty-four morning and 33 afternoon schedule students wore an actigraph during 7 days to measure sleep and light exposure. Academic achievement was obtained from school. Subjects completed validated questionnaires on daytime sleepiness, psychological distress, social rhythms, school satisfaction, alcohol, and chronotype. Overall, afternoon schedule students had longer sleep duration, lower sleepiness, and lower light exposure than morning schedule students. Evening chronotypes (E-types) reported higher levels of sleepiness than morning chronotypes (M-types) in both morning and afternoon schedules. Furthermore, M-types attending the morning schedule reported higher sleepiness than M-types attending the afternoon schedule. No difference was found between morning and afternoon schedule students with regard to academic achievement, psychological distress, social rhythms, school satisfaction, and alcohol consumption. However, in both schedules, M-type had more regular social rhythms and lower alcohol consumption. In summary, this study emphasizes that an early school

  2. Black light visualized solar lentigines on the shoulders and upper back are associated with objectively measured UVR exposure and cutaneous malignant melanoma

    DEFF Research Database (Denmark)

    Idorn, Luise Winkel; Datta, Pameli; Heydenreich, Jakob;

    2015-01-01

    Previous studies on the association of solar lentigines with ultraviolet radiation (UVR) exposure have been based on retrospective questionnaires about UVR exposure. We aimed to investigate the association between solar lentigines and UVR exposure in healthy individuals using objective measurements...... and graded into 3 categories using black light photographs to show sun damage. Current UVR exposure in healthy controls was assessed by personal electronic UVR dosimeters that measured time-related UVR and by corresponding exposure diaries during a summer season. Sunburn history was assessed by interviews......, as well as time spent outdoors around noon on holidays and beach trips during a summer season, most likely reflecting past UVR exposure, and that solar lentigines are a risk factor for CMM....

  3. Aftereffect of Adaptation to Illusory Brightness

    OpenAIRE

    Xinguang Cao; Hiroyuki Ito

    2011-01-01

    Several figures are known to induce illusory brightness. We tested whether adaptation to illusory brightness produced an aftereffect in brightness. After viewing a gray square area having illusory brightness (e.g., due to brightness contrast or illusory contours) for ten seconds, the illusion-inducing surround vanished. After three seconds, subjects reported whether the square area was seen as brighter than, darker than, or the same brightness as a control gray square area. The luminance of t...

  4. Occupational exposure of welders to ultraviolet and "blue light" radiation emitted during TIG and MMA welding based on field measuremants

    Directory of Open Access Journals (Sweden)

    Agnieszka Wolska

    2013-02-01

    Full Text Available Background: The aim of the study was to present the results of welders' occupational exposure to "blue light" and UV radiation carried out at industrial workstations during TIG and MMA welding. Materials and methods: Measurements were performed at 13 workstations (TIG welding: 6; MMA welding: 7, at which different welding parameters and materials were used. The radiation level was measured using a wide-range radiometer and a set of detectors, whose spectral responses were adequately fit to particular hazard under study. The measurement points corresponded with the location of eye and hand. Results: The highest values of eye irradiance were found for aluminum TIG welding. Effective irradiance of actinic UV was within the range Es = 7.79-37.6 W/m2; UVA total irradiance, EUVA = 18-53.1 W/m2 and effective blue-light irradiance EB = 35-67 W/m2. The maximum allowance time ranged from 1.7 to 75 s, which means that in some cases even unintentional very short eye exposure can exceed MPE. Conclusions: The influence of welded material and the type of electrode coating on the measured radiation level were evidenced. The exceeded value of MPE for photochemical hazard arising for the eyes and skin was found at all measured workstations. Welders should use appropriately the eye and face protective equipment and avoid direct staring at welding arc when starting an arcwelding operation. Besides, the lack of head and neck skin protection can induce acute and chronic harmful health effects. Therefore, an appropriate wear of personal protective equipment is essential for welders' health. Med Pr 2013;64(1:69–82

  5. Transient anhedonia phenotype and altered circadian timing of behaviour during night-time dim light exposure in Per3−/− mice, but not wildtype mice

    Science.gov (United States)

    Martynhak, Bruno Jacson; Hogben, Alexandra L.; Zanos, Panos; Georgiou, Polymnia; Andreatini, Roberto; Kitchen, Ian; Archer, Simon N.; von Schantz, Malcolm; Bailey, Alexis; van der Veen, Daan R.

    2017-01-01

    Industrialisation greatly increased human night-time exposure to artificial light, which in animal models is a known cause of depressive phenotypes. Whilst many of these phenotypes are ‘direct’ effects of light on affect, an ‘indirect’ pathway via altered sleep-wake timing has been suggested. We have previously shown that the Period3 gene, which forms part of the biological clock, is associated with altered sleep-wake patterns in response to light. Here, we show that both wild-type and Per3−/− mice showed elevated levels of circulating corticosterone and increased hippocampal Bdnf expression after 3 weeks of exposure to dim light at night, but only mice deficient for the PERIOD3 protein (Per3−/−) exhibited a transient anhedonia-like phenotype, observed as reduced sucrose preference, in weeks 2–3 of dim light at night, whereas WT mice did not. Per3−/− mice also exhibited a significantly smaller delay in behavioural timing than WT mice during weeks 1, 2 and 4 of dim light at night exposure. When treated with imipramine, neither Per3−/− nor WT mice exhibited an anhedonia-like phenotype, and neither genotypes exhibited a delay in behavioural timing in responses to dLAN. While the association between both Per3−/− phenotypes remains unclear, both are alleviated by imipramine treatment during dim night-time light. PMID:28071711

  6. Goethe's Exposure of Newton's theory a polemic on Newton's theory of light and colour

    CERN Document Server

    Goethe, Johann Wolfgang von

    2016-01-01

    Johann Wolfgang von Goethe, although best known for his literary work, was also a keen and outspoken natural scientist. In the second polemic part of Zur Farbenlehre (Theory of Colours), for example, Goethe attacked Isaac Newton's ground-breaking revelation that light is heterogeneous and not immutable, as was previously thought.This polemic was unanimously rejected by the physicists of the day, and has often been omitted from compendia of Goethe's works. Indeed, although Goethe repeated all of Newton's key experiments, he was never able to achieve the same results. Many reasons have been proposed for this, ranging from the psychological — such as a blind hatred of Newtonism, self-deceit and paranoid psychosis — to accusations of incapability — Goethe simply did not understand the experiments. Yet Goethe was never to be dissuaded from this passionate conviction.This translation of Goethe's second polemic, published for the first time in English, makes it clear that Goethe did understand the thrust of Ne...

  7. Methylene blue toxicity in zebrafish cell line is dependent on light exposure.

    Science.gov (United States)

    Costa, Simone Rutz da; Monteiro, Mauricio da Costa; da Silva Júnior, Flavio Manoel Rodrigues; Sandrini, Juliana Zomer

    2016-08-01

    Methylene blue (MB) has been widely applied in the clinical area and is currently being used in aquaculture as biocide. Some recent studies have emphasized the importance of understanding the action mechanism and the MB cellular targets. In this sense, zebrafish is considered a relevant model to study the intrinsic pathway of apoptosis as well as the cellular responses involving DNA damage and repair. So, the aim of the present study was to compare MB action mechanisms in a zebrafish cell line, both in the absence (MB alone; dark toxicity) and in the presence of photosynthetically active radiation (MB+PAR; phototoxicity). There was a significant increase of the levels of reactive oxygen and nitrogen species 3 h after MB treatment, whereas this increase was only observed 12 h after treatment with MB+PAR. All treatments with MB resulted in an increase in DNA damage after 3 and 6 h. However, cell death by apoptosis was observed from 6 h after treatment with MB+PAR and 12 h after treatment with MB alone. The expression of genes related to apoptosis was altered after MB and MB+PAR treatment. Therefore, this zebrafish cell line is sensitive to the photodynamic action of MB; MB is able to generate DNA damage and induce apoptosis in this cell line both alone and in the presence of PAR. However, the pathways leading to apoptosis in this model appear to be dependent on the type of MB exposure (in the presence or absence of PAR).

  8. Bactericidal Effects of 405 nm Light Exposure Demonstrated by Inactivation of Escherichia, Salmonella, Shigella, Listeria, and Mycobacterium Species in Liquid Suspensions and on Exposed Surfaces

    Directory of Open Access Journals (Sweden)

    Lynne E. Murdoch

    2012-01-01

    Full Text Available The bactericidal effect of 405 nm light was investigated on taxonomically diverse bacterial pathogens from the genera Salmonella, Shigella, Escherichia, Listeria, and Mycobacterium. High-intensity 405 nm light, generated from an array of 405-nm light-emitting diodes (LEDs, was used to inactivate bacteria in liquid suspension and on exposed surfaces. L. monocytogenes was most readily inactivated in suspension, whereas S. enterica was most resistant. In surface exposure tests, L. monocytogenes was more susceptible than Gram-negative enteric bacteria to 405 nm light when exposed on an agar surface but interestingly less susceptible than S. enterica after drying onto PVC and acrylic surfaces. The study findings, that 405 nm light inactivates diverse types of bacteria in liquids and on surfaces, in addition to the safety advantages of this visible (non-UV wavelength light, indicate the potential of this technology for a range of decontamination applications.

  9. Exposure machine lfy eye type UV-LED surface light source of collimated light system%复眼式UV-LED面光源的曝光机平行光系统

    Institute of Scientific and Technical Information of China (English)

    闵秀红

    2014-01-01

    印制电路板生产设备紫外线曝光机的光源系统,其能耗大、使用维护成本高、含汞等缺陷,在倡导节能环保的当今,业界一直致力于改进。UV-LED面光源作为新一代绿色环保紫外线光源,为印制电路板曝光领域带来革命性的变化。文章通过分析传统平行光紫外曝光机光学系统特点,设计了一种平行光紫外线曝光机适用的UV-LED面光源系统,UV-LED灯珠光功率利用率大幅提高,光照均匀性优良,并且不改变曝光机结构的情况下,可直接安装使用。实验表明,采用了复眼式阵列光学透镜结构设计的UV-LED面光源系统,完全可替代传统平行光紫外曝光机光源。%The light source system of ultraviolet exposure machine which is the PCB production equipment, has high energy consumption, high using and maintenance costs, mercury and other defects. To promote energy-saving environmental protection industry today, the industry has been working to improve. UV-LED surface light source as a new generation of green ultraviolet light source, brings the revolutionary change for the PCB exposure ifeld. In this paper, through the analysis of features of the traditional collimated light ultraviolet exposure machine, it designed a kind of UV-LED surface light source system for the collimated light ultraviolet exposure machine, a substantial increase in UV-LED light pearl power efifciency, illumination uniformity is good, and does not change the exposure machine structure, can be directly installed. Experiments show that, the UV-LED surface light source system using the optical lens structure of lfy's eye array can completely replace the traditional collimated l light ultraviolet exposure machine light source.

  10. 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

  11. 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...

  12. 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

  13. Effect of Caffeic Acid and Low-Power Laser Light Co-Exposure on Viability of Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Gheibi

    2015-08-01

    Full Text Available Background The resistance of Pseudomonas aeruginosa to antibiotics is a big problem, especially in burns and wound infections. Laser irradiation affects microorganisms by denaturing their proteins, which involves changes in the chemical or physical properties of the protein. Objectives The aim of this study was to investigate the effect of caffeic acid and low-power laser light co-exposure on Pseudomonas aeruginosa isolated from burn wounds. Materials and Methods Ten bacterial samples were collected from patients with burn wound infections at Shahid Motahhari medical center of Tehran. The He-Ne laser was used in this study with output power of 2 mW. Results The data significantly indicated that both the caffeic acid and laser treatment alone reduced the number of colony-forming units compared to control cultures. Co-exposure of bacterial suspensions to caffeic acid and laser at three time points showed the following number of colony-forming units 240.23 ± 60.15, 148.13 ± 52.66 and 84.57 ± 35, respectively. The best concentrations of caffeic acid to achieve countable colonies were 1.5 and 1.75 mM. At the concentration of 1.5 mM of caffeic acid, the number of colonies significantly reduced to 280.78 ± 59 (P = 0.008 while at 1.75 mM the number of colonies reduced to 234.07 ± 72.28 (P = 0.0001. Conclusions Caffeic acid treatment reduced bacterial growth and resulted in a decreased number of colony formation. The simultaneous effect of caffeic acid and laser at three time courses showed a synergic effect in reducing colony formation compared to the control and caffeic acid, and laser alone.

  14. The influence of exposure to UVβ of fluorescent light on the bone remodeling of hypoestrogenic Macaca fascicularis

    Directory of Open Access Journals (Sweden)

    I. A. Rachman

    2001-06-01

    Full Text Available The prevention of osteoporosis is a spesific problem that should be dealt with by increasing the women's lift expectation. The decrease of calcitriol and estrogen levels, which have a receptor in the osteoblast, will result in bone mineralization (due to calcitriol and the information of type 1 collagen (due to estrogen. The formation of calcitriol with the main basic materials from vitamin D3 is achieved with the aid of sunray UVβ, The changes in the lifestyle of women, which make them now accustomed to performing indoor activities and prevent them from being exposed to UVβ all day, have resulted in the decrease of vitamin D3 in calcitriol in women. In addition, when entering the menopausal age they will be threatened with early osteoporosis. The exposure to the UVβ of fluorescent light with the wave length identical to sun of 290-320 nm has long been known as a modality for treating skin diseases in the hope that the production of vitamin D3  will be increased. We exposed Macaca fascicularis, whose estrogen levels were set at normal, beginning low, beginning very low levels, to UVβ of fluorescent light. It showed that the Macaca fascicularis that were exposed to UVβ experienced an increase in osteocalcin with unchanged DPD which means that bone remodeling remains unchanged. By contrast, Macaca fascicularis with normal, beginning low, and beginning very low estrogen levels which were not exposed to UVβ were found to experience a decrease in osteocalcin and unchanged DPD levels. This means that a change has occurred in the bone remodeling toward bone resorption. (Med J Indones 2001; 10: 63-8Keywords: UVβ, osteoporosis, estrogen, vitamin D3, calcitriol, osteocalcin, DPD

  15. Effects of chronic elevated ozone exposure on gas exchange responses of adult beech trees (Fagus sylvatica) as related to the within-canopy light gradient.

    Science.gov (United States)

    Kitao, Mitsutoshi; Löw, Markus; Heerdt, Christian; Grams, Thorsten E E; Häberle, Karl-Heinz; Matyssek, Rainer

    2009-02-01

    The effects of elevated O3 on photosynthetic properties in adult beech trees (Fagus sylvatica) were investigated in relation to leaf mass per area as a measure of the gradually changing, within-canopy light availability. Leaves under elevated O3 showed decreased stomatal conductance at unchanged carboxylation capacity of Rubisco, which was consistent with enhanced delta 13C of leaf organic matter, regardless of the light environment during growth. In parallel, increased energy demand for O3 detoxification and repair was suggested under elevated O3 owing to enhanced dark respiration. Only in shade-grown leaves,light-limited photosynthesis was reduced under elevated O3, this effect being accompanied by lowered F(v)/F(m). These results suggest that chronic O3 exposure primarily caused stomatal closure to adult beech trees in the field regardless of the within-canopy light gradient. However, light limitation apparently raised the O3 sensitivity of photosynthesis and accelerated senescence in shade leaves.

  16. Selective-area growth of periodic nanopyramid light-emitting diode arrays on GaN/sapphire templates patterned by multiple-exposure colloidal lithography.

    Science.gov (United States)

    Xiong, Zhuo; Wei, Tongbo; Zhang, Yonghui; Zhang, Xiang; Yang, Chao; Liu, Zhiqiang; Yuan, Guodong; Li, Jinmin; Wang, Junxi

    2017-03-17

    Gallium nitride-based nanopyramid light-emitting diodes are a promising technology to achieve highly efficient solid-state lighting and beyond. Here, periodic nanopyramid light-emitting diode arrays on gallium nitride/sapphire templates were fabricated by selective-area metalorganic chemical vapor deposition and multiple-exposure colloidal lithography. The electric field intensity distribution of incident light going through polystyrene microspheres and photoresist are simulated using finite-different time-domain method. Nitrogen as the carrier gas and a low V/III ratio (ratio of molar flow rate of group-V to group-III sources) are found to be important in order to form gallium nitride nanopyramid. In addition, a broad yellow emission in photoluminescence and cathodoluminescence spectra were observed. This phenomena showed the potential of nanopyramid light-emitting diodes to realize long wavelength visible emissions.

  17. Selective-area growth of periodic nanopyramid light-emitting diode arrays on GaN/sapphire templates patterned by multiple-exposure colloidal lithography

    Science.gov (United States)

    Xiong, Zhuo; Wei, Tongbo; Zhang, Yonghui; Zhang, Xiang; Yang, Chao; Liu, Zhiqiang; Yuan, Guodong; Li, Jinmin; Wang, Junxi

    2017-03-01

    Gallium nitride-based nanopyramid light-emitting diodes are a promising technology to achieve highly efficient solid-state lighting and beyond. Here, periodic nanopyramid light-emitting diode arrays on gallium nitride/sapphire templates were fabricated by selective-area metalorganic chemical vapor deposition and multiple-exposure colloidal lithography. The electric field intensity distribution of incident light going through polystyrene microspheres and photoresist are simulated using finite-different time-domain method. Nitrogen as the carrier gas and a low V/III ratio (ratio of molar flow rate of group-V to group-III sources) are found to be important in order to form gallium nitride nanopyramid. In addition, a broad yellow emission in photoluminescence and cathodoluminescence spectra were observed. This phenomena showed the potential of nanopyramid light-emitting diodes to realize long wavelength visible emissions.

  18. Pengaruh ketebalan bahan dan lamanya waktu penyinaran terhadap kekerasan permukaan resin komposit sinar (Effects of materials thickness and length of light exposure on the surface hardness light-cured composite resins

    Directory of Open Access Journals (Sweden)

    Annette Alexandra Susanto

    2006-03-01

    Full Text Available Light-cured resin composite is one of the most commonly used molding materials due to its easy-to-mold characteristic. Nevertheless, care must be taken while treating this material, especially with respect to material thickness and how long it is exposed to light. Failure to treat the material with these optimal parameters will result in undesired hardness. To determine the most favorable value of these two parameters, an experiment was done with 3 different material thicknesses, and 3 different exposure times. After the sample of the resin composite was removed from its molding, it was stored under humid condition for 24 hours. Afterwards hardness test was done on the sample using Micro Vickers Hardness tester from this experiment, the significant difference in hardness was obtained and the maximum hardness was evaluated from the resin composite sample with 2 mm thickness and 60 seconds light exposure.

  19. High light exposure on seed coat increases lipid accumulation in seeds of castor bean (Ricinus communis L.), a nongreen oilseed crop.

    Science.gov (United States)

    Zhang, Yang; Mulpuri, Sujatha; Liu, Aizhong

    2016-05-01

    Little was known on how sunlight affects the seed metabolism in nongreen seeds. Castor bean (Ricinus communis L.) is a typical nongreen oilseed crop and its seed oil is an important feedstock in industry. In this study, photosynthetic activity of seed coat tissues of castor bean in natural conditions was evaluated in comparison to shaded conditions. Our results indicate that exposure to high light enhances photosynthetic activity in seed coats and consequently increases oil accumulation. Consistent results were also reached using cultured seeds. High-throughput RNA-Seq analyses further revealed that genes involved in photosynthesis and carbon conversion in both the Calvin-Benson cycle and malate transport were differentially expressed between seeds cultured under light and dark conditions, implying several venues potentially contributing to light-enhanced lipid accumulation such as increased reducing power and CO2 refixation which underlie the overall lipid biosynthesis. This study demonstrated the effects of light exposure on oil accumulation in nongreen oilseeds and greatly expands our understanding of the physiological roles that light may play during seed development in nongreen oilseeds. Essentially, our studies suggest that potential exists to enhance castor oil yield through increasing exposure of the inflorescences to sunlight either by genetically changing the plant architecture (smart canopy) or its growing environment.

  20. Photometric indicators of visual night sky quality derived from all-sky brightness maps

    Science.gov (United States)

    Duriscoe, Dan M.

    2016-09-01

    Wide angle or fisheye cameras provide a high resolution record of artificial sky glow, which results from the scattering of escaped anthropogenic light by the atmosphere, over the sky vault in the moonless nocturnal environment. Analysis of this record yields important indicators of the extent and severity of light pollution. The following indicators were derived through numerical analysis of all-sky brightness maps: zenithal, average all-sky, median, brightest, and darkest sky brightness. In addition, horizontal and vertical illuminance, resulting from sky brightness were computed. A natural reference condition to which the anthropogenic component may be compared is proposed for each indicator, based upon an iterative analysis of a high resolution natural sky model. All-sky brightness data, calibrated in the V band by photometry of standard stars and converted to luminance, from 406 separate data sets were included in an exploratory analysis. Of these, six locations representing a wide range of severity of impact from artificial sky brightness were selected as examples and examined in detail. All-sky average brightness is the most unbiased indicator of impact to the environment, and is more sensitive and accurate in areas of slight to moderate light pollution impact than zenith brightness. Maximum vertical illuminance provides an excellent indicator of impacts to wilderness character, as does measures of the brightest portions of the sky. Zenith brightness, the workhorse of field campaigns, is compared to the other indicators and found to correlate well with horizontal illuminance, especially at relatively bright sites. The median sky brightness describes a brightness threshold for the upper half of the sky, of importance to telescopic optical astronomy. Numeric indicators, in concert with all-sky brightness maps, provide a complete assessment of visual sky quality at a site.

  1. New Low Surface Brightness Dwarf Galaxies Detected Around Nearby Spirals

    CERN Document Server

    Karachentsev, I D; Zilch, T; Blauensteiner, M; Elvov, M; Hochleitner, P; Hubl, B; Kerschhuber, G; Küppers, S; Neyer, F; Pölzl, R; Remmel, P; Schneider, O; Sparenberg, R; Trulson, U; Willems, G; Ziegler, H

    2015-01-01

    We conduct a survey of low surface brightness (LSB) satellite galaxies around the Local Volume massive spirals using long exposures with small amateur telescopes. We identified 27 low and very low surface brightness objects around the galaxies NGC,672, 891, 1156, 2683, 3344, 4258, 4618, 4631, and 5457 situated within 10 Mpc from us, and found nothing new around NGC,2903, 3239, 4214, and 5585. Assuming that the dwarf candidates are the satellites of the neighboring luminous galaxies, their absolute magnitudes are in the range of -8.6 > M_B > -13.3, their effective diameters are 0.4-4.7 kpc, and the average surface brightness is 26.1 mag/sq arcsec. The mean linear projected separation of the satellite candidates from the host galaxies is 73 kpc. Our spectroscopic observations of two LSB dwarfs with the Russian 6-meter telescope confirm their physical connection to the host galaxies NGC,891 and NGC,2683.

  2. Consecutive Bright Pulses in the Vela Pulsar

    CERN Document Server

    Palfreyman, Jim L; Dickey, John M; Young, Timothy G; Hotan, Claire E; 10.1088/2041-8205/735/1/L17

    2011-01-01

    We report on the discovery of consecutive bright radio pulses from the Vela pulsar, a new phenomenon that may lead to a greater understanding of the pulsar emission mechanism. This results from a total of 345 hr worth of observations of the Vela pulsar using the University of Tasmania's 26 m radio telescope to study the frequency and statistics of abnormally bright pulses and sub-pulses. The bright pulses show a tendency to appear consecutively. The observations found two groups of six consecutive bright pulses and many groups of two to five bright pulses in a row. The strong radio emission process that produces the six bright pulses lasts between 0.4 and 0.6 s. The numbers of bright pulses in sequence far exceed what would be expected if individual bright pulses were independent random events. Consecutive bright pulses must be generated by an emission process that is long lived relative to the rotation period of the neutron star.

  3. Application of UV-LED surface light source in PCB solder mask exposure%UV-LED面光源在PCB阻焊曝光中的应用

    Institute of Scientific and Technical Information of China (English)

    闵秀红

    2013-01-01

    In recent years, the development of the UV-LED, bring revolutionary changes in the field of PCB exposure. It is energy efficient and has constant light intensity, good temperature control, and almost zero maintenance cost. It promotes UV-LED surface light source replacing the traditional exposure lamp and becomes a trend.In accordance with the characteristics of the ultraviolet light source for PCB solder mask exposure process, this paper discusses not only the related technologies to overcome the difficulties in the promotion and application, but also provided solutions through experimental data, analysis of the factors of impact on the uniformity, the time and the resolution of UV-LED surface light source exposure. Using scanning mixed-wavelength UV-LED surface light source exposure mode, the practice shows that it is energy efficient, and the light intensity distribution is uniform and stable, is able to fully meet the requirements of the indicators of the anti-welds exposure process, and the maneuverability is strong, and it will play a catalytic role in the PCB exposure process for quality improvement and energy conservation.%  近年来随着UV-LED的问世,为印制电路板曝光领域带来革命性的变化。其高效节能、恒定的光照强度、优秀的温度控制、几乎为零的维护成本。促使UV-LED面光源替代传统曝光灯成为发展趋势。文章针对印制电路板阻焊曝光工艺紫外光源的特点,论述了推广应用中需要克服的相关技术及解决方法;并通过实验数据,分析出影响UV-LED面光源曝光均匀性、时间、解析度的因素。实践表明,采用扫描式、混合波长的UV-LED面光源曝光方式,高效节能、光强分布均匀稳定、能够完全满足阻焊曝光过程对光源的指标要求,可操作性强,对印制电路板曝光工艺的品质提升与节能降耗将起到推动作用。

  4. Fast algal eco-toxicity assessment: Influence of light intensity and exposure time on Chlorella vulgaris inhibition by atrazine and DCMU.

    Science.gov (United States)

    Camuel, Alexandre; Guieysse, Benoit; Alcántara, Cynthia; Béchet, Quentin

    2017-06-01

    In order to develop a rapid assay suitable for algal eco-toxicity assessments under conditions representative of natural ecosystems, this study evaluated the short-term (atrazine and DCMU using oxygen productivity measurements. When Chlorella vulgaris was exposed to these herbicides under 'standard' low light intensity (as prescribed by OECD201 guideline), the 20min-EC50 values recorded via oxygen productivity (atrazine: 1.32±0.07μM; DCMU: 0.31±0.005μM) were similar the 96-h EC50 recorded via algal growth (atrazine: 0.56μM; DCMU: 0.41μM), and within the range of values reported in the literature. 20min-EC50 values increased by factors of 3.0 and 2.1 for atrazine and DCMU, respectively, when light intensity increased from 60 to 1400μmolm(-2)s(-1) of photosynthetically active radiation, or PAR. Further investigation showed that exposure time significantly also impacted the sensitivity of C. vulgaris under high light intensity (>840μmolm(-2)s(-1) as PAR) as the EC50 for atrazine and DCMU decreased by up to 6.2 and 2.1 folds, respectively, after 50min of exposure at a light irradiance of 1400μmolm(-2)s(-1) as PAR. This decrease was particularly marked at high light intensities and low algae concentrations and is explained by the herbicide disruption of the electron transfer chain triggering photo-inhibition at high light intensities. Eco-toxicity assessments aiming to understand the potential impact of toxic compounds on natural ecosystems should therefore be performed over sufficient exposure times (>20min for C. vulgaris) and under light intensities relevant to these ecosystems. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. 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

  6. Automated Detection and Tracking of Solar Magnetic Bright Points

    CERN Document Server

    Crockett, P J; Mathioudakis, M; Keenan, F P

    2009-01-01

    Magnetic Bright Points (MBPs) in the internetwork are among the smallest objects in the solar photosphere and appear bright against the ambient environment. An algorithm is presented that can be used for the automated detection of the MBPs in the spatial and temporal domains. The algorithm works by mapping the lanes through intensity thresholding. A compass search, combined with a study of the intensity gradient across the detected objects, allows the disentanglement of MBPs from bright pixels within the granules. Object growing is implemented to account for any pixels that might have been removed when mapping the lanes. The images are stabilized by locating long-lived objects that may have been missed due to variable light levels and seeing quality. Tests of the algorithm employing data taken with the Swedish Solar Telescope (SST), reveal that ~90% of MBPs within a 75"x 75" field of view are detected.

  7. Lattice and emittance optimization techniques and the ALS brightness upgrade

    Science.gov (United States)

    Steier, C.; Madur, A.; Nishimura, H.; Robin, D.; Sannibale, F.; Sun, C.; Wan, W.; Yang, L.

    2011-09-01

    An upgrade project is under way to further improve the brightness of the Advanced Light Source at Berkeley Lab by reducing its horizontal emittance from 6.3 to 2.2 nm (effective emittance in the straights from 6.4 to 2.5 nm). This will result in a brightness increase by a factor of three for bend magnet beamlines and at least a factor of two for insertion device beamlines and will keep the ALS competitive with newer sources. This paper presents an overview of the upgrade project with emphasis on the nonlinear beam dynamics simulations. It also discusses in a more general way the techniques used at LBNL for finding optimum lattices (e.g. the ones with maximum brightness) and optimizing the particle dynamics, thereby increasing beam lifetime and stability.

  8. Perceiving the Intensity of Light

    Science.gov (United States)

    Purves, Dale; Williams, S. Mark; Nundy, Surajit; Lotto, R. Beau

    2004-01-01

    The relationship between luminance (i.e., the photometric intensity of light) and its perception (i.e., sensations of lightness or brightness) has long been a puzzle. In addition to the mystery of why these perceptual qualities do not scale with luminance in any simple way, "illusions" such as simultaneous brightness contrast, Mach bands,…

  9. Early life exposure to artificial light at night affects the physiological condition: An experimental study on the ecophysiology of free-living nestling songbirds.

    Science.gov (United States)

    Raap, Thomas; Casasole, Giulia; Pinxten, Rianne; Eens, Marcel

    2016-11-01

    Light pollution or artificial light at night (ALAN) is increasingly recognised to be an important anthropogenic environmental pressure on wildlife, affecting animal behaviour and physiology. Early life experiences are extremely important for the development, physiological status and health of organisms, and as such, early exposure to artificial light may have detrimental consequences for organism fitness. We experimentally manipulated the light environment of free-living great tit nestlings (Parus major), an important model species in evolutionary and environmental research. Haptoglobin (Hp) and nitric oxide (NOx), as important indicators of immunity, health, and physiological condition, were quantified in nestlings at baseline (13 days after hatching) and after a two night exposure to ALAN. We found that ALAN increased Hp and decreased NOx. ALAN may increase stress and oxidative stress and reduce melatonin which could subsequently lead to increased Hp and decreased NOx. Haptoglobin is part of the immune response and mounting an immune response is costly in energy and resources and, trade-offs are likely to occur with other energetically demanding tasks, such as survival or reproduction. Acute inhibition of NOx may have a cascading effect as it also affects other physiological aspects and may negatively affect immunocompetence. The consequences of the observed effects on Hp and NOx remain to be examined. Our study provides experimental field evidence that ALAN affects nestlings' physiology during development and early life exposure to ALAN could therefore have long lasting effects throughout adulthood.

  10. [KINETICS OF PHOTO-INDUCED FREE RADICALS IN THE HUMAN HAIR CHESTNUT COLOR AFTER SHORT PERIODS OF RED, GREEN, BLUE AND WHITE LIGHT EXPOSURE].

    Science.gov (United States)

    Tskhvediani, N; Chikvaidze, E; Tsibadze, A; Kvachadze, I; Gogoladze, T; Katsitadze, A

    2016-04-01

    The aim of the study was to investigate the kinetics of photo-induced free radicals in the human hair chestnut color with short-term exposure to visible light in different frequency ranges. Studies carried out on human volunteers aged 17-21 years (n=37). Hairs of volunteers of the study were not treated with dyes and other active cosmetic preparations. Hairs bundled in a bun had a length - 1.5 cm, weight - 40 mg. At the beginning background EPR-spectrum of a sample was measured and then hairs were irradiated with visible light (blue, green, red and white) of different wavelength subsequently; exposure duration - 60 minutes; after the exposure the kinetics of photo-induced free radicals was measured within 60 minutes. The radiation source was selected LED array of the four crystals that provides a nearly monochromatic radiation spectrum having no parasitic infrared and ultraviolet radiations. The studies give a reason to assume that the impact on hairs by visible electromagnetic rays a leading factor is their frequency characteristics: on the one hand - the proximity of the blue light to ultraviolet radiation, and on the other - the red light to the infrared range.

  11. GOMOS bright limb ozone data set

    Directory of Open Access Journals (Sweden)

    S. Tukiainen

    2015-01-01

    Full Text Available We have created a daytime ozone profile data set from the measurements of the Global Ozone Monitoring by Occultation of Stars (GOMOS instrument on board the Envisat satellite. This so-called GOMOS bright limb (GBL data set contains ~ 358 000 stratospheric daytime ozone profiles measured by GOMOS in 2002–2012. The GBL data set complements the widely used GOMOS night-time data based on stellar occultation measurements. The GBL data set is based on the GOMOS daytime occultations but instead of the transmitted star light, we use limb scattered solar light. The ozone profiles retrieved from these radiance spectra cover 18–60 km tangent height range and have approximately 2–3 km vertical resolution. We show that these profiles are generally in better than 10% agreement with the NDACC (Network for the Detection of Atmospheric Composition Change ozone sounding profiles and with the GOMOS night-time, MLS (Microwave Limb Sounder, and OSIRIS (Optical Spectrograph, and InfraRed Imaging System satellite measurements. However, there is a 10–13% negative bias at 40 km tangent height and a 10–50% positive bias at 50 km when the solar zenith angle > 75°. These biases are most likely caused by stray light which is difficult to characterize and remove entirely from the measured spectra. Nevertheless, the GBL data set approximately doubles the amount of useful GOMOS ozone profiles and improves coverage of the summer pole.

  12. Artificial light and nocturnal activity in gammarids

    Directory of Open Access Journals (Sweden)

    Elizabeth K. Perkin

    2014-03-01

    Full Text Available Artificial light is gaining attention as a potential stressor to aquatic ecosystems. Artificial lights located near streams increase light levels experienced by stream invertebrates and we hypothesized light would depress night drift rates. We also hypothesized that the effect of light on drift rates would decrease over time as the invertebrates acclimated to the new light level over the course of one month’s exposure. These hypotheses were tested by placing Gammarus spp. in eight, 75 m × 1 m artificial flumes. One flume was exposed to strong (416 lx artificial light at night. This strong light created a gradient between 4.19 and 0.04 lx over the neighboring six artificial flumes, while a control flume was completely covered with black plastic at night. Night-time light measurements taken in the Berlin area confirm that half the flumes were at light levels experienced by urban aquatic invertebrates. Surprisingly, no light treatment affected gammarid drift rates. In contrast, physical activity measurements of in situ individually caged G. roeseli showed they increased short-term activity levels in nights of complete darkness and decreased activity levels in brightly lit flumes. Both nocturnal and diurnal drift increased, and day drift rates were unexpectadly higher than nocturnal drift.

  13. Timed maternal melatonin treatment reverses circadian disruption of the fetal adrenal clock imposed by exposure to constant light.

    Directory of Open Access Journals (Sweden)

    Natalia Mendez

    Full Text Available Surprisingly, in our modern 24/7 society, there is scant information on the impact of developmental chronodisruption like the one experienced by shift worker pregnant women on fetal and postnatal physiology. There are important differences between the maternal and fetal circadian systems; for instance, the suprachiasmatic nucleus is the master clock in the mother but not in the fetus. Despite this, several tissues/organs display circadian oscillations in the fetus. Our hypothesis is that the maternal plasma melatonin rhythm drives the fetal circadian system, which in turn relies this information to other fetal tissues through corticosterone rhythmic signaling. The present data show that suppression of the maternal plasma melatonin circadian rhythm, secondary to exposure of pregnant rats to constant light along the second half of gestation, had several effects on fetal development. First, it induced intrauterine growth retardation. Second, in the fetal adrenal in vivo it markedly affected the mRNA expression level of clock genes and clock-controlled genes as well as it lowered the content and precluded the rhythm of corticosterone. Third, an altered in vitro fetal adrenal response to ACTH of both, corticosterone production and relative expression of clock genes and steroidogenic genes was observed. All these changes were reversed when the mother received a daily dose of melatonin during the subjective night; supporting a role of melatonin on overall fetal development and pointing to it as a 'time giver' for the fetal adrenal gland. Thus, the present results collectively support that the maternal circadian rhythm of melatonin is a key signal for the generation and/or synchronization of the circadian rhythms in the fetal adrenal gland. In turn, low levels and lack of a circadian rhythm of fetal corticosterone may be responsible of fetal growth restriction; potentially inducing long term effects in the offspring, possibility that warrants further

  14. Night Sky Brightness at San Pedro Martir Observatory

    Science.gov (United States)

    Plauchu-Frayn, I.; Richer, M. G.; Colorado, E.; Herrera, J.; Córdova, A.; Ceseña, U.; Ávila, F.

    2017-03-01

    We present optical UBVRI zenith night sky brightness measurements collected on 18 nights during 2013 to 2016 and SQM measurements obtained daily over 20 months during 2014 to 2016 at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir (OAN-SPM) in México. The UBVRI data is based upon CCD images obtained with the 0.84 m and 2.12 m telescopes, while the SQM data is obtained with a high-sensitivity, low-cost photometer. The typical moonless night sky brightness at zenith averaged over the whole period is U = 22.68, B = 23.10, V = 21.84, R = 21.04, I = 19.36, and SQM = 21.88 {mag} {{arcsec}}-2, once corrected for zodiacal light. We find no seasonal variation of the night sky brightness measured with the SQM. The typical night sky brightness values found at OAN-SPM are similar to those reported for other astronomical dark sites at a similar phase of the solar cycle. We find a trend of decreasing night sky brightness with decreasing solar activity during period of the observations. This trend implies that the sky has become darker by Δ U = 0.7, Δ B = 0.5, Δ V = 0.3, Δ R=0.5 mag arcsec‑2 since early 2014 due to the present solar cycle.

  15. Sky brightness and twilight measurements at Jogyakarta city, Indonesia

    Science.gov (United States)

    Herdiwijaya, Dhani

    2016-11-01

    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.

  16. Night sky brightness at San Pedro Martir Observatory

    CERN Document Server

    Plauchu-Frayn, I; Colorado, E; Herrera, J; Cordova, A; Cesena, U; Avila, F

    2016-01-01

    We present optical UBVRI zenith night sky brightness measurements collected on eighteen nights during 2013--2016 and SQM measurements obtained daily over twenty months during 2014--2016 at the Observatorio Astronomico Nacional on the Sierra San Pedro Martir (OAN-SPM) in Mexico. The UBVRI data is based upon CCD images obtained with the 0.84m and 2.12m telescopes, while the SQM data is obtained with a high-sensitivity, low-cost photometer. The typical moonless night sky brightness at zenith averaged over the whole period is U = 22.68, B = 23.10, V = 21.84, R = 21.04, I = 19.36, and SQM = 21.88 mag/square arcsec, once corrected for zodiacal light. We find no seasonal variation of the night sky brightness measured with the SQM. The typical night sky brightness values found at OAN-SPM are similar to those reported for other astronomical dark sites at a similar phase of the solar cycle. We find a trend of decreasing night sky brightness with decreasing solar activity during period of the observations. This trend im...

  17. 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...

  18. Detrimental effects of constant light exposure and high-fat diet on circadian energy metabolism and insulin sensitivity

    NARCIS (Netherlands)

    Coomans, C.P.; Berg, S.A.A. van den; Houben, T.; Klinken, J.B. van; Berg, R. van den; Pronk, A.C.M.; Havekes, L.M.; Romijn, J.A.; Dijk, K.W. van; Biermasz, N.R.; Meijer, J.H.

    2013-01-01

    Circadian rhythm disturbances are observed in, e.g., aging and neurodegenerative diseases and are associated with an increased incidence of obesity and diabetes. We subjected male C57Bl/6J mice to constant light [12-h light-light (LL) cycle] to examine the effects of a disturbed circadian rhythm on

  19. Impact on Vitamin D2, Vitamin D4 and Agaritine in Agaricus bisporus Mushrooms after Artificial and Natural Solar UV Light Exposure

    DEFF Research Database (Denmark)

    Urbain, Paul; Valverde, Juan; Jakobsen, Jette

    2016-01-01

    Commercial mushroom production can expose mushrooms post-harvest to UV light for purposes of vitamin D2 enrichment by converting the naturally occurring provitamin D2 (ergosterol). The objectives of the present study were to artificially simulate solar UV-B doses occurring naturally in Central...... between UV light exposure and agaritine content. The artificial UV-B dose of 0.53 J/cm(2) raised the vitamin D2 content to significantly (P dry weight (DW) than sun exposure (3.9 ± 0.8 μg/g dry DW). We observed a positive correlation between vitamin D4 and vitamin...... with all UV-B doses both artificial and natural solar, probably due to its known instability. The biological action of vitamin D from UV-exposed mushrooms reflects the activity of these two major vitamin D analogues (D2, D4). Vitamin D4 should be analysed and agaritine disregarded in future studies of UV...

  20. High-brightness rf linear accelerators

    Energy Technology Data Exchange (ETDEWEB)

    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. (LEW)

  1. High-brightness rf linear accelerators

    Energy Technology Data Exchange (ETDEWEB)

    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. (LEW)

  2. Effects of caffeine on sister chromatid exchange (SCE) after exposure to uv light or triaziquone studied with a fluorescence plus giemsa (FPG) technique

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, W.; Bauknecht, T.

    1978-01-19

    Studies are reported that are designed to analyze the mechanism by which caffeine reduces the induction of SCE by uv light or alkylating agents. The substantial points are (1) caffeine does not inhibit SCE formatin, and (2) the caffeine-mediated apparent decrease of SCE induction after uv or triaziquone, exposure is due to a selective destruction of those metaphases otherwise exhibiting a high number of SCE. These findings and their relevance to the ascertainment of the SCE-forming process are discussed.

  3. Adaptive Lighting

    DEFF Research Database (Denmark)

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

    2015-01-01

    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...... offered by adaptive lighting control are created by the ways that the system components, the network and data flow can be coordinated through software so that the dynamic variations are controlled in ways that meaningfully adapt according to people’s situations and design intentions. This book discusses...... 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...

  4. Influence of light-exposure methods and depths of cavity on the microhardness of dual-cured core build-up resin composites

    Directory of Open Access Journals (Sweden)

    Keiichi YOSHIDA

    2014-01-01

    Full Text Available Objective: The purpose of this study was to evaluate the Knoop hardness number (KHN of dual-cured core build-up resin composites (DCBRCs at 6 depths of cavity after 3 post-irradiation times by 4 light-exposure methods. Material and Methods: Five specimens each of DCBRCs (Clearfil DC Core Plus [DCP] and Unifil Core EM [UCE] were filled in acrylic resin blocks with a semi-cylindrical cavity and light-cured using an LED light unit (power density: 1,000 mW/cm2at the top surface by irradiation for 20 seconds (20 s, 40 seconds (40 s, bonding agent plus 20 seconds (B+20 s, or 40 seconds plus light irradiation of both sides of each acrylic resin block for 40 seconds each (120 s. KHN was measured at depths of 0.5, 2.0, 4.0, 6.0, 8.0, and 10.0 mm at 0.5 hours, 24 hours, and 7 days post-irradiation. Statistical analysis was performed using repeated measures ANOVA and Tukey's compromise post-hoc test with a significance level of p0.05. In DCP, and not UCE, at 24 hours and 7 days post-irradiation, the B+20 s method showed significantly higher KHN at all depths of cavity, except the depth of 0.5 mm (p<0.05. Conclusion: KHN depends on the light-exposure method, use of bonding agent, depth of cavity, post-irradiation time, and material brand. Based on the microhardness behavior, DCBRCs are preferably prepared by the effective exposure method, when used for a greater depth of cavity.

  5. Estimation of safe exposure time from an ophthalmic operating microscope with regard to ultraviolet radiation and blue-light hazards to the eye

    Science.gov (United States)

    Michael, Ralph; Wegener, Alfred

    2004-08-01

    Hazards from the optical radiation of an operating microscope that cause damage at the corneal, lenticular, and retinal levels were investigated; we considered, in particular, ultraviolet radiation (UVR) and blue light. The spectral irradiance from a Zeiss operation microscope OPMI VISU 200 was measured in the corneal plane between 300 and 1100 nm. Effective irradiance and radiance were calculated with relative spectral effectiveness data from the American Conference for Governmental and Industrial Hygienists. Safe exposure time to avoid UVR injury to the lens and cornea was found to be 2 h without a filter, 4 h with a UVR filter, 200 h with a yellow filter, and 400 h with a filter combination. Safe exposure time to avoid retinal photochemical injury was found to be 3 min without a filter and with a UVR filter, 10 min with a yellow filter, and 49 min with a filter combination. The effective radiance limit for retinal thermal injury was not exceeded. The hazard due to the UVR component from the operating microscope is not critical, and operation time can be safely prolonged with the use of appropriate filters. The retinal photochemical hazard appears critical without appropriate filters, permitting only some minutes of safe exposure time. The calculated safe exposure times are for worst-case conditions and maximal light output and include a safety factor.

  6. Dopamine and light: effects on facial emotion recognition.

    Science.gov (United States)

    Cawley, Elizabeth; Tippler, Maria; Coupland, Nicholas J; Benkelfat, Chawki; Boivin, Diane B; Aan Het Rot, Marije; Leyton, Marco

    2017-06-01

    Bright light can affect mood states and social behaviours. Here, we tested potential interacting effects of light and dopamine on facial emotion recognition. Participants were 32 women with subsyndromal seasonal affective disorder tested in either a bright (3000 lux) or dim light (10 lux) environment. Each participant completed two test days, one following the ingestion of a phenylalanine/tyrosine-deficient mixture and one with a nutritionally balanced control mixture, both administered double blind in a randomised order. Approximately four hours post-ingestion participants completed a self-report measure of mood followed by a facial emotion recognition task. All testing took place between November and March when seasonal symptoms would be present. Following acute phenylalanine/tyrosine depletion (APTD), compared to the nutritionally balanced control mixture, participants in the dim light condition were more accurate at recognising sad faces, less likely to misclassify them, and faster at responding to them, effects that were independent of changes in mood. Effects of APTD on responses to sad faces in the bright light group were less consistent. There were no APTD effects on responses to other emotions, with one exception: a significant light × mixture interaction was seen for the reaction time to fear, but the pattern of effect was not predicted a priori or seen on other measures. Together, the results suggest that the processing of sad emotional stimuli might be greater when dopamine transmission is low. Bright light exposure, used for the treatment of both seasonal and non-seasonal mood disorders, might produce some of its benefits by preventing this effect.

  7. Signal transduction and HIV transcriptional activation after exposure to ultraviolet light and other DNA-damaging agents

    Energy Technology Data Exchange (ETDEWEB)

    Valerie, K.; Laster, W.S.; Luhua Cheng; Kirkham, J.C.; Reavey, Peter; Kuemmerle, N.B. [Virginia Commonwealth Univ., Richmond, VA (United States). Dept. of Radiation Oncology

    1996-08-01

    Short wavelength (254 nm) ultraviolet light (UVC) radiation was much more potent in activating transcription of human immunodeficiency virus 1 (HIV) reporter genes stably integrated into the genomes of human and monkey cells than ionizing radiation (IR) from a {sup 137}Cs source at similarly cytotoxic doses. A similar differential was also observed when c-jun transcription levels were examined. However, these transcription levels do not correlate with activation of nuclear factor (NF)-kB and AP-1 measured by band-shift assays, i.e. both types of radiation produce similar increases in NF-kB and AP-1 activity, suggesting existence of additional levels of regulation during these responses. Because of the well-established involvement of cytoplasmic signaling pathways in the cellular response to tumor necrosis factor-{alpha} (TNF-{alpha}), UVC, and IR using other types of assays, the role of TNF-{alpha} in the UVC response of HIV and c-jun was investigated in our cell system. We demonstrate that UVC and TNF-{alpha} activate HIV gene expression in a synergistic fashion, suggesting that it is unlikely that TNF-{alpha} is involved in UVC activation of HIV transcription in stably transfected HeLa cells. Moreover, maximum TNF-{alpha} stimulation resulted in one order of magnitude lower levels of HIV expression than that observed after UVC exposure. We also observed an additive effect of UVC and TNF-{alpha} on c-jun steady-state mRNA levels, suggestive of a partial overlap in activation mechanism of c-jun by UVC and TNF-{alpha}; yet these responses are distinct to some extent. Our results indicate that the HIV, and to some extent also the c-jun, transcriptional responses to UVC are not the result of TNF-{alpha} stimulation and subsequent downstream cytoplasmic signaling events in HeLa cells. In addition to the new data, this report also summarizes our current views regarding UVC-induced activations of HIV gene expression in stably transfected cells. (Author).

  8. Differential response of planktonic primary, bacterial, and dimethylsulfide production rates to static vs. dynamic light exposure in upper mixed-layer summer sea waters

    Science.gov (United States)

    Galí, M.; Simó, R.; Pérez, G. L.; Ruiz-González, C.; Sarmento, H.; Royer, S.-J.; Fuentes-Lema, A.; Gasol, J. M.

    2013-12-01

    Microbial plankton experience short-term fluctuations in total solar irradiance and in its spectral composition as they are vertically moved by turbulence in the oceanic upper mixed layer (UML). The fact that the light exposure is not static but dynamic may have important consequences for biogeochemical processes and ocean-atmosphere fluxes. However, most biogeochemical processes other than primary production, like bacterial production or dimethylsulfide (DMS) production, are seldom measured in sunlight and even less often in dynamic light fields. We conducted four experiments in oligotrophic summer stratified Mediterranean waters, where a sample from the UML was incubated in ultraviolet (UV)-transparent bottles at three fixed depths within the UML and on a vertically moving basket across the same depth range. We assessed the response of the phyto- and bacterioplankton community with physiological indicators based on flow cytometry singe-cell measurements, fast repetition rate fluorometry (FRRf), phytoplankton pigment concentrations and particulate light absorption. Dynamic light exposure caused a subtle disruption of the photoinhibition and photoacclimation processes associated with ultraviolet radiation (UVR), which slightly alleviated bacterial photoinhibition but did not favor primary production. Gross DMS production (GPDMS) decreased sharply with depth in parallel to shortwave UVR, and displayed a dose-dependent response that mixing did not significantly disrupt. To our knowledge, we provide the first measurements of GPDMS under in situ UV-inclusive optical conditions.

  9. Short-term sleep deprivation with nocturnal light exposure alters time-dependent glucagon-like peptide-1 and insulin secretion in male volunteers.

    Science.gov (United States)

    Gil-Lozano, Manuel; Hunter, Paola M; Behan, Lucy-Ann; Gladanac, Bojana; Casper, Robert F; Brubaker, Patricia L

    2016-01-01

    The intestinal L cell is the principal source of glucagon-like peptide-1 (GLP-1), a major determinant of insulin release. Because GLP-1 secretion is regulated in a circadian manner in rodents, we investigated whether the activity of the human L cell is also time sensitive. Rhythmic fluctuations in the mRNA levels of canonical clock genes were found in the human NCI-H716 L cell model, which also showed a time-dependent pattern in their response to well-established secretagogues. A diurnal variation in GLP-1 responses to identical meals (850 kcal), served 12 h apart in the normal dark (2300) and light (1100) periods, was also observed in male volunteers maintained under standard sleep and light conditions. These findings suggest the existence of a daily pattern of activity in the human L cell. Moreover, we separately tested the short-term effects of sleep deprivation and nocturnal light exposure on basal and postprandial GLP-1, insulin, and glucose levels in the same volunteers. Sleep deprivation with nocturnal light exposure disrupted the melatonin and cortisol profiles and increased insulin resistance. Moreover, it also induced profound derangements in GLP-1 and insulin responses such that postprandial GLP-1 and insulin levels were markedly elevated and the normal variation in GLP-1 responses was abrogated. These alterations were not observed in sleep-deprived participants maintained under dark conditions, indicating a direct effect of light on the mechanisms that regulate glucose homeostasis. Accordingly, the metabolic abnormalities known to occur in shift workers may be related to the effects of irregular light-dark cycles on these glucoregulatory pathways.

  10. Combined effects of exposure to dim light at night and fine particulate matter on C3H/HeNHsd mice.

    Science.gov (United States)

    Hogan, Matthew K; Kovalycsik, Taylor; Sun, Qinghua; Rajagopalan, Sanjay; Nelson, Randy J

    2015-11-01

    Air and light pollution contribute to fetal abnormalities, increase prevalence of cancer, metabolic and cardiorespiratory diseases, and central nervous system (CNS) disorders. A component of air pollution, particulate matter, and the phenomenon of dim light at night (dLAN) both result in neuroinflammation, which has been implicated in several CNS disorders. The combinatorial role of these pollutants on health outcomes has not been assessed. Male C3H/HeNHsd mice, with intact melatonin production, were used to model humans exposed to circadian disruption by dLAN and contaminated environmental air. We hypothesized exposure to 2.5 μm of particulate matter (PM2.5) and dLAN (5lx) combines to upregulate neuroinflammatory cytokine expression and alter hippocampal morphology compared to mice exposed to filtered air (FA) and housed under dark nights (LD). We also hypothesized that exposure to PM2.5 and dLAN provokes anxiety-like and depressive-like responses. For four weeks, four groups of mice were simultaneously exposed to ambient concentrated PM2.5 or FA and/or dLAN or LD. Following exposure, mice underwent several behavioral assays and hippocampi were collected for qPCR and morphological analyses. Our results are generally comparable to previous PM2.5 and dLAN reports conducted on mice and implicate PM2.5 and dLAN as potential factors contributing to depression and anxiety. Short-term exposure to PM2.5 and dLAN upregulated neuroinflammatory cytokines and altered CA1 hippocampal structural changes, as well as provoked depressive-like responses (anhedonia). However, combined, PM2.5 and dLAN exposure did not have additive effects, as hypothesized, suggesting a ceiling effect of neuroinflammation may exist in response to multiple pollutants.

  11. 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) 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...

  12. Light treatment of mood disorders

    OpenAIRE

    Parry, Barbara L.; Maurer, Eva L.

    2003-01-01

    In 1981, seven patients with nonseasonal depression were treated with bright white light in 1982, bright artificial light was used to treat a manic-depressive patient with a seasonal mood cycle. In the last 20 years, a plethora of studies have further defined the depressive populations, who are responsive to light treatment; the optimal timing, intensity, spectral frequency, and duration of treatment; its comparison with other pharmacological interventions; predictors of response; side-effect...

  13. Effects of chronic elevated ozone exposure on gas exchange responses of adult beech trees (Fagus sylvatica) as related to the within-canopy light gradient

    Energy Technology Data Exchange (ETDEWEB)

    Kitao, Mitsutoshi [Hokkaido Research Center, Forestry and Forest Products Research Institute, Sapporo 062-8516 (Japan)], E-mail: kitao@ffpri.affrc.go.jp; Loew, Markus [Ecophysiology of Plants, Technische Universitaet Muenchen, Am Hochanger 13, 85354 Freising (Germany); Heerdt, Christian [Bioclimatology and Air Pollution Research, Technische Universitaet Muenchen, Am Hochanger 13, 85354 Freising (Germany); Grams, Thorsten E.E.; Haeberle, Karl-Heinz; Matyssek, Rainer [Ecophysiology of Plants, Technische Universitaet Muenchen, Am Hochanger 13, 85354 Freising (Germany)

    2009-02-15

    The effects of elevated O{sub 3} on photosynthetic properties in adult beech trees (Fagus sylvatica) were investigated in relation to leaf mass per area as a measure of the gradually changing, within-canopy light availability. Leaves under elevated O{sub 3} showed decreased stomatal conductance at unchanged carboxylation capacity of Rubisco, which was consistent with enhanced {delta}{sup 13}C of leaf organic matter, regardless of the light environment during growth. In parallel, increased energy demand for O{sub 3} detoxification and repair was suggested under elevated O{sub 3} owing to enhanced dark respiration. Only in shade-grown leaves, light-limited photosynthesis was reduced under elevated O{sub 3}, this effect being accompanied by lowered F{sub v}/F{sub m}. These results suggest that chronic O{sub 3} exposure primarily caused stomatal closure to adult beech trees in the field regardless of the within-canopy light gradient. However, light limitation apparently raised the O{sub 3} sensitivity of photosynthesis and accelerated senescence in shade leaves. - Across leaf differentiation in adult beech crowns, elevated ozone acted through stomatal closure on gas exchange although enhancing photosynthetic sensitivity of shaded leaves.

  14. Morphometric comparison of the acute rabbit corneal response to 1540-nm laser light following in-vitro exposure to millisecond or nanosecond pulse widths

    Science.gov (United States)

    Eurell, Thomas E.; Johnson, Thomas E.; Roach, William P.

    2002-06-01

    Significant damage to rabbit corneal tissue was produced by a single pulse, in vitro exposure of 1540 m infrared laser light operating in either millisecond or nanosecond pulse widths. Millisecond pulse widths of infrared laser light produced a marked coagulative necrosis of both the corneal epithelium and stroma. We also noted histologic alterations in the stromal matrix within the beam path that we interpreted as matrix remodeling. To test this interpretation, we used an indirect immunohistochemical procedure to detect Matrix Metalloproteinase-2 (MMP-2) activity. Immunohistochemistry revealed that the MMP-2 reaction was mostly limited to the margins of the beam path. In addition, the MMP-2 reaction was less intense than expected given the significant tissue changes observed in the histologic sections. Exposure of rabbit corneal tissue to the nanosecond pulse widths produced a less severe coagulative necrosis of the tissue when compared to the millisecond exposures. However, a markedly stronger immunohistochemical pattern than would have been predicted from the histologic sections was observed, with approximately half of the beam path filled with MMP-2 reaction product. These data suggest an association between infrared laser pulse width and the degree of extracellular matrix remodeling in rabbit corneal tissue.

  15. VERITAS Observations under Bright Moonlight

    CERN Document Server

    ,

    2015-01-01

    The presence of moonlight is usually a limiting factor for imaging atmospheric Cherenkov telescopes due to the high sensitivity of the camera photomultiplier tubes (PMTs). In their standard configuration, the extra noise limits the sensitivity of the experiment to gamma-ray signals and the higher PMT currents also accelerates PMT aging. Since fall 2012, observations have been carried out with VERITAS under bright moonlight (Moon illumination $> 35\\%$), in two observing modes, by reducing the voltage applied to the PMTs and with UV bandpass filters, which allow observations up to $\\sim80\\%$ Moon illumination resulting in $29\\%$ more observing time over the course of the year. In this presentation, we provide details of these new observing modes and their performance relative to the standard VERITAS observations.

  16. Black light visualized solar lentigines on the shoulders and upper back are associated with objectively measured UVR exposure and cutaneous malignant melanoma.

    Science.gov (United States)

    Idorn, Luise Winkel; Datta, Pameli; Heydenreich, Jakob; Philipsen, Peter Alshede; Wulf, Hans Christian

    2015-02-01

    Previous studies on the association of solar lentigines with ultraviolet radiation (UVR) exposure have been based on retrospective questionnaires about UVR exposure. We aimed to investigate the association between solar lentigines and UVR exposure in healthy individuals using objective measurements, and to investigate the association between solar lentigines and cutaneous malignant melanoma (CMM). Forty-eight patients with CMM and 48 controls that matched the patients individually by age, sex, constitutive skin type and occupation participated. Solar lentigines on the shoulders and upper back were counted and graded into 3 categories using black light photographs to show sun damage. Current UVR exposure in healthy controls was assessed by personal electronic UVR dosimeters that measured time-related UVR and by corresponding exposure diaries during a summer season. Sunburn history was assessed by interviews. Among controls, the number of solar lentigines was positively associated with daily hours spent outdoors between noon and 3 pm on holidays (P = 0.027), days at the beach (P = 0.048) and reported number of life sunburns (P < 0.001). Compared with matched controls CMM patients had a higher number of solar lentigines (P = 0.044). There was a positive association between CMM and higher solar lentigines grade; Category III versus Category I (P = 0.002) and Category II versus Category I (P = 0.014). Our findings indicate that solar lentigines in healthy individuals are associated with number of life sunburns, as well as time spent outdoors around noon on holidays and beach trips during a summer season, most likely reflecting past UVR exposure, and that solar lentigines are a risk factor for CMM.

  17. Impact of light-exposure on the metabolite balance of transgenic potato tubers with modified glycoalkaloid biosynthesis.

    Science.gov (United States)

    Shepherd, Louise Vida Traill; Hackett, Christine Anne; Alexander, Colin James; McNicol, James William; Sungurtas, Julia Anne; McRae, Diane; McCue, Kent Frank; Belknap, William Richardson; Davies, Howard Vivian

    2016-06-01

    Metabolite profiling (liquid chromatography-mass spectrometry (LC-MS) and gas chromatography (GC-MS)) was used to assess the impact of light on the composition of transgenic potato (Solanum tuberosum L. cv. Desirée) with reduced glycoalkaloid content via the down-regulation of the SGT1 gene. Transgenic tubers exhibited an almost complete knock-out of α-solanine production and light had little impact on its accumulation. Levels of α-chaconine increased significantly in the peel of both the control and transgenic lines when exposed to light, particularly in the transgenic line. Major differences in metabolite profiles existed between outer and inner tuber tissues, and between light and dark-treated tubers. Many of the light-induced changes are explicable in terms of pathways known to be affected by stress responses. The impact of transgenesis on profiles was much less than that of tissue type or light and most differences were explicable in terms of the modification to the glycoalkaloid pathway.

  18. Antigen exposure in the late light period induces severe symptoms of food allergy in an OVA-allergic mouse model.

    Science.gov (United States)

    Tanabe, Kana; Kitagawa, Eri; Wada, Misaki; Haraguchi, Atsushi; Orihara, Kanami; Tahara, Yu; Nakao, Atsuhito; Shibata, Shigenobu

    2015-09-30

    The mammalian circadian clock controls many physiological processes that include immune responses and allergic reactions. Several studies have investigated the circadian regulation of intestinal permeability and tight junctions known to be affected by cytokines. However, the contribution of circadian clock to food allergy symptoms remains unclear. Therefore, we investigated the role of the circadian clock in determining the severity of food allergies. We prepared an ovalbumin food allergy mouse model, and orally administered ovalbumin either late in the light or late in the dark period under light-dark cycle. The light period group showed higher allergic diarrhea and weight loss than the dark period group. The production of type 2 cytokines, IL-13 and IL-5, from the mesenteric lymph nodes and ovalbumin absorption was higher in the light period group than in the dark period group. Compared to the dark period group, the mRNA expression levels of the tight junction proteins were lower in the light period group. We have demonstrated that increased production of type 2 cytokines and intestinal permeability in the light period induced severe food allergy symptoms. Our results suggest that the time of food antigen intake might affect the determination of the severity of food allergy symptoms.

  19. Aftereffect of Adaptation to Illusory Brightness

    Directory of Open Access Journals (Sweden)

    Xinguang Cao

    2011-05-01

    Full Text Available Several figures are known to induce illusory brightness. We tested whether adaptation to illusory brightness produced an aftereffect in brightness. After viewing a gray square area having illusory brightness (e.g., due to brightness contrast or illusory contours for ten seconds, the illusion-inducing surround vanished. After three seconds, subjects reported whether the square area was seen as brighter than, darker than, or the same brightness as a control gray square area. The luminance of the tested square area was physically unchanged. The results show that when the black surround inducing brightness contrast suddenly became gray (i.e., vanished, the center gray square tended to look darker than a control gray square. Similarly, after viewing a subjective square consisting of black-line terminations, the square area tended to look darker than the control even though the afterimage of the lines could not be seen. These results indicate that induced or illusory brightness causes an aftereffect in brightness regardless of the appearance of negative afterimages of the illusion-inducing components.

  20. Organ specific analysis of the anaerobic primary metabolism in rice and wheat seedlings II: light exposure reduces needs for fermentation and extends survival during anaerobiosis.

    Science.gov (United States)

    Mustroph, Angelika; Boamfa, Elena I; Laarhoven, Lucas J J; Harren, Frans J M; Pörs, Yvonne; Grimm, Bernhard

    2006-12-01

    Low oxygen stress in plants can occur during flooding and compromise the availability and utilization of carbohydrates in root and shoot tissues. Low-oxygen-tolerant rice and -sensitive wheat plants were analyzed under anaerobiosis in light to evaluate main factors of the primary metabolism that affect sensitivity against oxygen deprivation: activity of glycolysis and the rate of photosynthesis. Relatively stable ATP contents (93 and 58% of aerated control levels after 24 h anaerobiosis) in illuminated shoot tissues account for enhanced tolerance of rice and wheat seedlings to anaerobiosis upon light exposure in comparison to anoxia in darkness. Although the photosynthetic process was inhibited during low oxygen stress, which was partly due to CO(2) deficiency, more light-exposed than dark-incubated seedlings survived. Illuminated plants could tolerate a 70% lower anaerobic ethanol production in shoots in comparison to darkness, although still an 18-times higher ethanol production rate was determined in rice than in wheat leaves. In conclusion, light-exposed plants grown under anaerobiosis may recycle low amounts of generated oxygen between photosynthesis and dissimilation and generate additional energy not only from substrate phosphorylation during glycolysis but also from other sources like cyclic electron transport.

  1. Enhanced optical power of GaN-based light-emitting diode with compound photonic crystals by multiple-exposure nanosphere-lens lithography

    Science.gov (United States)

    Zhang, Yonghui; Wei, Tongbo; Xiong, Zhuo; Shang, Liang; Tian, Yingdong; Zhao, Yun; Zhou, Pengyu; Wang, Junxi; Li, Jinmin

    2014-07-01

    The light-emitting diodes (LEDs) with single, twin, triple, and quadruple photonic crystals (PCs) on p-GaN are fabricated by multiple-exposure nanosphere-lens lithography (MENLL) process utilizing the focusing behavior of polystyrene spheres. Such a technique is easy and economical for use in fabricating compound nano-patterns. The optimized tilted angle is decided to be 26.6° through mathematic calculation to try to avoid the overlay of patterns. The results of scanning electron microscopy and simulations reveal that the pattern produced by MENLL is a combination of multiple ovals. Compared to planar-LED, the light output power of LEDs with single, twin, triple, and quadruple PCs is increased by 14.78%, 36.03%, 53.68%, and 44.85% under a drive current 350 mA, respectively. Furthermore, all PC-structures result in no degradation of the electrical properties. The stimulated results indicate that the highest light extraction efficiency of LED with the clover-shape triple PC is due to the largest scattering effect on propagation of light from GaN into air.

  2. Genetic control of prophage induction in Haemophilus influenzae after exposure to psoralen plus near-uv light

    Energy Technology Data Exchange (ETDEWEB)

    George, M.; Notani, N.K.

    1980-09-01

    Prophage S2 could be induced by psoralen plus near-uv light (PNUV) from a wild-type strain of Haemophilus influenzae, from uv light-sensitive strains uvr-1 and uvr-2, and PNUV-sensitive strains PSO1 and PSO7, but not from a recombination-deficient strain, rec-1. The levels of prophage induction were comparable in the wild type and an ATP-dependent DNase-deficient strain, KW31, even though the PNUV-induced degradation in the latter strain was considerably lower. Prophage induction could be observed even with chloramphenicol present before, during, and 30 min after PNUV treatment.

  3. Extremely High Current, High-Brightness Energy Recovery Linac

    CERN Document Server

    Ben-Zvi, Ilan; Beavis, Dana; Blaskiewicz, Michael; Bluem, Hans; Brennan, Joseph M; Burger, Al; Burrill, Andrew; Calaga, Rama; Cameron, Peter; Chang, Xiangyun; Cole, Michael; Connolly, Roger; Delayen, Jean R; Favale, Anthony; Gassner, David M; Grimes, Jacob T; Hahn, Harald; Hershcovitch, Ady; Holmes, Douglas; Hseuh Hsiao Chaun; Johnson, Peter; Kayran, Dmitry; Kewisch, Jorg; Kneisel, Peter; Lambiase, Robert; Litvinenko, Vladimir N; McIntyre, Gary; Meng, Wuzheng; Nehring, Thomas; Nicoletti, Tony; Oerter, Brian; Pate, David; Phillips, Larry; Preble, Joseph P; Rank, Jim; Rao, Triveni; Rathke, John; Roser, Thomas; Russo, Thomas; Scaduto, Joseph; Schultheiss, Tom; Segalov, Zvi; Smith, Kevin T; Todd, Alan M M; Warren-Funk, L; Williams, Neville; Wu, Kuo-Chen; Yakimenko, Vitaly; Yip, Kin; Zaltsman, Alex; Zhao, Yongxiang

    2005-01-01

    Next generation ERL light-sources, high-energy electron coolers, high-power Free-Electron Lasers, powerful Compton X-ray sources and many other accelerators were made possible by the emerging technology of high-power, high-brightness electron beams. In order to get the anticipated performance level of ampere-class currents, many technological barriers are yet to be broken. BNL's Collider-Accelerator Department is pursuing some of these technologies for its electron cooling of RHIC application, as well as a possible future electron-hadron collider. We will describe work on CW, high-current and high-brightness electron beams. This will include a description of a superconducting, laser-photocathode RF gun and an accelerator cavity capable of producing low emittance (about 1 micron rms normalized) one nano-Coulomb bunches at currents of the order of one ampere average.

  4. Microwave Brightness Temperature and Lunar Son Dielectric Property Retrieve

    Institute of Scientific and Technical Information of China (English)

    J. Wu; D.H. Li; A.T. Altyntsev; B.I. Lubyshev

    2005-01-01

    Among many scientific objectives of lunar exploration, investigations on lunar soil become more and more attractive to the scientists duo to the existence of abundant 3He and ilmenite in the lunar soil and their possible utilization. Although the soil composition determination on the lunar surface is available by visible light spectrometer, γ/X-ray spectrometer etc, the evaluations on the total reserves of 3He and ilmenite in the lunar deep and on the thickness of the lunar soil are still impossible so far. In this paper, the authors first give a rough analysis of the microwave brightness temperature images of the lunar disc observed using the NRAO 12 Meter Telescope and Siberian Solar Radio Telescope; then introduce our researches on the microwave dielectric properties of lunar soil simulators; finally, discuss some basic relations between the microwave brightness temperature and lunar soil properties.

  5. Brightness and darkness as perceptual dimensions

    NARCIS (Netherlands)

    Vladusich, T.; Lucassen, M.P.; Cornelissen, F.W.

    2007-01-01

    A common-sense assumption concerning visual perception states that brightness and darkness cannot coexist at a given spatial location. One corollary of this assumption is that achromatic colors, or perceived grey shades, are contained in a one-dimensional (1-D) space varying from bright to dark. The

  6. Brightness Alteration with Interweaving Contours

    Directory of Open Access Journals (Sweden)

    Sergio Roncato

    2012-12-01

    Full Text Available Chromatic induction is observed whenever the perceived colour of a target surface shifts towards the hue of a neighbouring surface. Some vivid manifestations may be seen in a white background where thin coloured lines have been drawn (assimilation or when lines of different colours are collinear (neon effect or adjacent (watercolour to each other. This study examines a particular colour induction that manifests in concomitance with an opposite effect of colour saturation (or anti-spread. The two phenomena can be observed when a repetitive pattern is drawn in which outline thin contours intercept wider contours or surfaces, colour spreading appear to fill the surface occupied by surfaces or thick lines whereas the background traversed by thin lines is seen as brighter or filled of a saturated white. These phenomena were first observed by Bozzi (1975 and Kanizsa (1979 in figural conditions that did not allow them to document their conjunction. Here we illustrate various manifestations of this twofold phenomenon and compare its effects with the known effects of brightness and colour induction. Some conjectures on the nature of these effects are discussed.

  7. 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

  8. Antioxidant properties of green tea extract protect reduced fat soft cheese against oxidation induced by light exposure

    DEFF Research Database (Denmark)

    Huvaere, Kevin; Nielsen, Jacob Holm; Bakman, Mette

    2011-01-01

    The effect of two different antioxidants, EDTA and green tea extract (GTE), used individually or in combination, on the light-induced oxidation of reduced fat soft cheeses (0.2 and 6% fat) was investigated. In samples with 0.2% fat, lipid hydroperoxides as primary lipid oxidation products were...

  9. EFFECTS OF ULTRAVIOLET-B LIGHT AND POLYAROMATIC HYDROCARBON EXPOSURE ON SEA URCHIN DEVELOPMENT AND BACTERIAL BIOLUMINESCENCE

    Science.gov (United States)

    Polycyclic aromatic hydrocarbons (PAHs) are relatively common contaminants of the Gulf of Mexico and may be activated to more toxic metabolites by ultraviolet-B (UV-B) light. A marine bacterial bioassay system (Vibrio fischeri) which focused on the reduction of luciferase-mediate...

  10. Brief light exposure at night disrupts the circadian rhythms in eye growth and choroidal thickness in chicks.

    Science.gov (United States)

    Nickla, Debora L; Totonelly, Kristen

    2016-05-01

    Changes in ocular growth that lead to myopia or hyperopia are associated with alterations in the circadian rhythms in eye growth, choroidal thickness and intraocular pressure in animal models of emmetropization. Recent studies have shown that light at night has deleterious effects on human health, acting via "circadian disruptions" of various diurnal rhythms, including changes in phase or amplitude. The purpose of this study was to determine the effects of brief, 2-h episodes of light in the middle of the night on the rhythms in axial length and choroidal thickness, and whether these alter eye growth and refractive error in the chick model of myopia. Starting at 2 weeks of age, birds received 2 h of light between 12:00 am and 2:00 am for 7 days (n = 12; total hours of light: 14 h). Age-matched controls had a continuous dark night (n = 14; 14L/10D). Ocular dimensions were measured using high-frequency A-scan ultrasonography on the first day of the experiment, and again on day 7, at 6-h intervals, starting at noon (12 pm, 6 pm, 12 am, 6 am, 12 pm). Measurements during the night were done under a photographic safe-light. These data were used to determine rhythm parameters of phase and amplitude. 2 groups of birds, both experimental (light at night) and control, were measured with ultrasound at various intervals over the course of 4 weeks to determine growth rates. Refractive errors were measured in 6 experimental and 6 control birds at the end of 2 weeks. Eyes of birds in a normal L/D cycle showed sinusoidal 24-h period diurnal rhythms in axial length and choroid thickness. Light in the middle of the night caused changes in both the rhythms in axial length and choroidal thickness, such that neither could be fit to a sine function having a period of 24 h. Light caused an acute, transient stimulation in ocular growth rate in the subsequent 6-h period (12 am-6 am), that may be responsible for the increased growth rate seen 4 weeks later, and the more

  11. Galaxy selection and the surface brightness distribution

    CERN Document Server

    McGaugh, S S; Schombert, J M

    1995-01-01

    Optical surveys for galaxies are biased against the inclusion of low surface brightness (LSB) galaxies. Disney (1976) suggested that the constancy of disk central surface brightness noticed by Freeman (1970) was not a physical result, but instead was an artifact of sample selection. Since LSB galaxies do exist, the pertinent and still controversial issue is if these newly discovered galaxies constitute a significant percentage of the general galaxy population. In this paper, we address this issue by determining the space density of galaxies as a function of disk central surface brightness. Using the physically reasonable assumption (which is motivated by the data) that central surface brightness is independent of disk scale length, we arrive at a distribution which is roughly flat (\\ie approximately equal numbers of galaxies at each surface brightness) faintwards of the Freeman (1970) value. Brightwards of this, we find a sharp decline in the distribution which is analogous to the turn down in the luminosity ...

  12. Nutritional value of cold-pressed rapeseed oil during long term storage as influenced by the type of packaging material, exposure to light & oxygen and storage temperature.

    Science.gov (United States)

    Wroniak, Małgorzata; Rękas, Agnieszka

    2016-02-01

    The effect of various conditions (storage temperature, exposure to light, access of oxygen) and different packaging material (amber glass, amber polyethylene terephthalate) on the nutritional value of cold-pressed rapeseed oil during 12 months of storage was investigated. Quantified quality parameters included: acidity, peroxide value, spectrophotometric indices (K 232 , K 268 ), fatty acid composition, tocopherols and sterols. Storage of oil at 4 °C was found to be most appropriate for maintaining the quality of cold-pressed rapeseed oil. Exposure of oil samples stored at room temperature to light in combination with the access of oxygen caused the most pronounced losses in the total tocopherols (ca. 90-91 % of α-T, and ca. 80-81 % of γ-T), total phytosterols (ca. 15-16 %) and substantial deterioration in oil qualitative properties. Although storage at room temperature is common for use in households, storage of at low temperatures (4 °C) significantly increases the possibility of prolonged shelf life of cold-pressed rapeseed oil.

  13. Exposure to welding fumes increases lung cancer risk among light smokers but not among heavy smokers: evidence from two case-control studies in Montreal.

    Science.gov (United States)

    Vallières, Eric; Pintos, Javier; Lavoué, Jérôme; Parent, Marie-Élise; Rachet, Bernard; Siemiatycki, Jack

    2012-08-01

    We investigated relationships between occupational exposure to gas and arc welding fumes and the risk of lung cancer among workers exposed to these agents throughout the spectrum of industries. Two population-based case-control studies were conducted in Montreal. Study I (1979-1986) included 857 cases and 1066 controls, and Study II (1996-2001) comprised 736 cases and 894 controls. Detailed job histories were obtained by interview and evaluated by an expert team of chemist-hygienists to estimate degree of exposure to approximately 300 substances for each job. Gas and arc welding fumes were among the agents evaluated. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) of lung cancer using logistic regression, adjusting for smoking history and other covariates. The two studies provided similar results, so a pooled analysis was conducted. Among all subjects, no significant association was found between lung cancer and gas welding fumes (OR = 1.1; 95% CI = 0.9-1.4) or arc welding fumes (OR = 1.0; 95% CI = 0.8-1.2). However, when restricting attention to light smokers, there was an increased risk of lung cancer in relation to gas welding fumes (OR = 2.9; 95% CI = 1.7-4.8) and arc welding fumes (OR = 2.3; 95% CI = 1.3-3.8), with even higher OR estimates among workers with the highest cumulative exposures. In conclusion, there was no detectable excess risk of lung cancer due to welding fumes among moderate to heavy smokers; but among light smokers we found an excess risk related to both types of welding fumes.

  14. Why does the Northern Light shine so brightly?

    DEFF Research Database (Denmark)

    Bjørnskov, Christian; Svendsen, Gert Tinggaard

    2002-01-01

    Based on institutional economics, the paper develops a new model pointing at two main reasons why Scandinavia is doing so well in economic terms, namely the level of decentralisation and social capital in its broad sense. The idea in the model is that a political system, which decentralises power......, means less lobbyism because access to economically harmful rent seeking is more costly. Consequently, social capital and the trust in other people and the political leadership will increase. This model, suggesting one single social capital measure, is applied to countries in both Western and Eastern...

  15. Bright Sparks of Our Future!

    Science.gov (United States)

    Riordan, Naoimh

    2016-04-01

    My name is Naoimh Riordan and I am the Vice Principal of Rockboro Primary School in Cork City, South of Ireland. I am a full time class primary teacher and I teach 4th class, my students are aged between 9-10 years. My passion for education has developed over the years and grown towards STEM (Science, Technology, Engineering and Mathematics) subjects. I believe these subjects are the way forward for our future. My passion and beliefs are driven by the unique after school programme that I have developed. It is titled "Sparks" coming from the term Bright Sparks. "Sparks" is an after school programme with a difference where the STEM subjects are concentrated on through lessons such as Science, Veterinary Science Computer Animation /Coding, Eco engineering, Robotics, Magical Maths, Chess and Creative Writing. All these subjects are taught through activity based learning and are one-hour long each week for a ten-week term. "Sparks" is fully inclusive and non-selective which gives all students of any level of ability an opportunity to engage into these subjects. "Sparks" is open to all primary students in County Cork. The "Sparks" after school programme is taught by tutors from the different Universities and Colleges in Cork City. It works very well because the tutor brings their knowledge, skills and specialised equipment from their respective universities and in turn the tutor gains invaluable teaching practise, can trial a pilot programme in a chosen STEM subject and gain an insight into what works in the physical classroom.

  16. Bright Streaks and Dark Fans

    Science.gov (United States)

    2007-01-01

    The south polar region of Mars is covered every year by a layer of carbon dioxide ice. In a region called the 'cryptic terrain,' the ice is translucent and sunlight can penetrate through the ice to warm the surface below. The ice layer sublimates (evaporates) from the bottom. The dark fans of dust seen in this image come from the surface below the layer of ice, carried to the top by gas venting from below. The translucent ice is 'visible' by virtue of the effect it has on the tone of the surface below, which would otherwise have the same color and reflectivity as the fans. Bright streaks in this image are fresh frost. The CRISM team has identified the composition of these streaks to be carbon dioxide. Observation Geometry Image PSP_003113_0940 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 26-Mar-2007. The complete image is centered at -85.8 degrees latitude, 106.0 degrees East longitude. The range to the target site was 244.9 km (153.0 miles). At this distance the image scale is 49.0 cm/pixel (with 2 x 2 binning) so objects 147 cm across are resolved. The image shown here has been map-projected to 50 cm/pixel . The image was taken at a local Mars time of 06:20 PM and the scene is illuminated from the west with a solar incidence angle of 79 degrees, thus the sun was about 11 degrees above the horizon. At a solar longitude of 207.6 degrees, the season on Mars is Northern Autumn.

  17. UV-Light Exposure of Insulin: Pharmaceutical Implications upon Covalent Insulin Dityrosine Dimerization and Disulphide Bond Photolysis

    OpenAIRE

    Manuel Correia; Maria Teresa Neves-Petersen; Per Bendix Jeppesen; Søren Gregersen; Steffen B Petersen

    2012-01-01

    In this work we report the effects of continuous UV-light (276 nm, ~2.20 W.m(-2)) excitation of human insulin on its absorption and fluorescence properties, structure and functionality. Continuous UV-excitation of the peptide hormone in solution leads to the progressive formation of tyrosine photo-product dityrosine, formed upon tyrosine radical cross-linkage. Absorbance, fluorescence emission and excitation data confirm dityrosine formation, leading to covalent insulin dimerization. Furtherm...

  18. But for the bad, there would not be good: Grounding valence in brightness through shared relational structures

    OpenAIRE

    Semin, Gün Refik; Lakens, Daniel; Foroni Francesco

    2011-01-01

    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 might play an important role in the valence– brightness association. In 6 experiments, we show that while black ideographs are consistently judged ...

  19. Effect of long- and short-term exposure to laser light at 1070 nm on growth of Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Aabo, Thomas; Perch-Nielsen, Ivan R.; Dam, Jeppe Seidelin

    2010-01-01

    The effect of a 1070-nm continuous and pulsed wave ytterbium fiber laser on the growth of Saccharomyces cerevisiae single cells is investigated over a time span of 4 to 5 h. The cells are subjected to optical traps consisting of two counterpropagating plane wave beams with a uniform flux along......, but instead a continuous response to the increased accumulated dose is found in the regime investigated from 0.7 to 2.6 mW. Furthermore, by keeping the delivered dose constant and varying the exposure time and power—i.e. pulsing—we find that the growth of S. cerevisiae cells is increasingly inhibited...

  20. Bright boys the making of information technology

    CERN Document Server

    Green, Tom

    2010-01-01

    Everything has a beginning. None was more profound-and quite as unexpected-than Information Technology. Here for the first time is the untold story of how our new age came to be and the bright boys who made it happen. What began on the bare floor of an old laundry building eventually grew to rival in size the Manhattan Project. The unexpected consequence of that journey was huge---what we now know as Information Technology. For sixty years the bright boys have been totally anonymous while their achievements have become a way of life for all of us. "Bright Boys" brings them home. By 1950 they'd

  1. South African night sky brightness during high aerosol epochs

    CERN Document Server

    Winkler, Hartmut; Marang, Fred

    2014-01-01

    Sky conditions in the remote, dry north-western interior of South Africa are now the subject of considerable interest in view of the imminent construction of numerous solar power plants in this area. Furthermore, the part of this region in which the core of the SKA is to be located (which includes SALT) has been declared an Astronomical Advantage Zone, for which sky brightness monitoring will now be mandatory. In this project we seek to characterise the sky brightness profile under a variety of atmospheric conditions. Key factors are of course the lunar phase and altitude, but in addition the sky brightness is also significantly affected by the atmospheric aerosol loading, as that influences light beam scattering. In this paper we chose to investigate the sky characteristics soon after the Mount Pinatubo volcanic eruption in 1991, which resulted in huge ash masses reaching the stratosphere (where they affected solar irradiance for several years). We re-reduced photometric sky measurements from the South Afric...

  2. Removing lateral chromatic aberration in bright field optical microscopy.

    Science.gov (United States)

    Guzmán-Altamirano, Miguel; Gutiérrez-Medina, Braulio

    2015-06-01

    We present an efficient alternative to remove lateral chromatic aberration (LCA) in bright field light microscopy images. Our procedure is based on error calibration using time-sequential acquisition at different wavelengths, and error correction through digital image warping. Measurement of the displacements of fiducial marks in the red and green images relative to blue provide calibration factors that are subsequently used in test images to realign color channels digitally. We demonstrate quantitative improvement in the position and boundaries of objects in target slides and in the color content and morphology of specimens in stained biological samples. Our results show a reduction of LCA content below the 0.1% level.

  3. Completion of the Brightness Upgrade of the ALS

    Science.gov (United States)

    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.; Schlueter, R.; Sun, C.; Tarawneh, H.; Wan, W.; Williams, E.; Yin, L.; Zhou, Q.; Jin, J.; Zhang, J.; Chen, C.; Wen, Y.; Wu, J.

    2014-03-01

    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.

  4. Brightness of synchrotron radiation from wigglers

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2014-01-01

    According to literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so called `depth-of-field' effects. In fact, the particle beam cross section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. I...

  5. The Visual Brightness Behavior of p/ Halley during 1981-1987

    Science.gov (United States)

    Green, D. W. E.; Morris, C. S.

    1987-11-01

    The overall behavior of the total visual coma brightness of P/Halley during 1981-1987 is discussed. Observations used in this study include ˜75 published "V" magnitudes obtained with large telescopes (usually with CCDs) prior to July 1985 and ˜3500 total magnitudes (published in the International Comet Quarterly) estimated visually with smaller telescopes during the period July 1985-February 1987. We discuss the observed macroscopic light curve and provide preliminary least- square fits to the traditional power4aw formula. While the heliocentric brightness (H) variation with respect to heliocentric distance (r) did not follow expectations closely, P/Halley's maximum brightness during 1986 Feb.-Apr. fell somewhere between the most pessimistic and the most optimistic forecasts. We also review brightness variations on smaller timescales (hours, days), noting that several definite outbursts in total visual magnitude occurred during Oct. 1985-May 1986 which can be correlated with outbursts observed at other wavelengths.

  6. The analogy between stereo depth and brightness.

    Science.gov (United States)

    Brookes, A; Stevens, K A

    1989-01-01

    Apparent depth in stereograms exhibits various simultaneous-contrast and induction effects analogous to those reported in the luminance domain. This behavior suggests that stereo depth, like brightness, is reconstructed, ie recovered from higher-order spatial derivatives or differences of the original signal. The extent to which depth is analogous to brightness is examined. There are similarities in terms of contrast effects but dissimilarities in terms of the lateral inhibition effects traditionally attributed to underlying spatial-differentiation operators.

  7. Stability of individual carotenoids, retinol and tocopherols in human plasma during exposure to light and after extraction.

    Science.gov (United States)

    Su, Q; Rowley, K G; O'Dea, K

    1999-06-11

    We have modified gradient HPLC procedures for simultaneous quantification of retinol, gamma-tocopherol, alpha-tocopherol, lutein/zeaxanthin, beta-cryptoxanthin, trans-lycopene, cis-lycopene, alpha-carotene and beta-carotene in 200-microl aliquots of human plasma. The photosensitivity of these analytes in plasma exposed to fluorescent lighting for up to 72 h was investigated and most were stable under these conditions. The stability of these analytes held in darkness at -20 degrees C, 4 degrees C or room temperature for up to 48 h after extraction from plasma was also investigated. Variability in measurement of most analytes was greater at room temperature than at 4 degrees C or -20 degrees C. There were statistically significant variations in the measured concentrations of some analytes in samples kept cold. However, the magnitude of these variations was small and of little biological significance, particularly over the first 24 h.

  8. Impact on Vitamin D2, Vitamin D4 and Agaritine in Agaricus bisporus Mushrooms after Artificial and Natural Solar UV Light Exposure.

    Science.gov (United States)

    Urbain, Paul; Valverde, Juan; Jakobsen, Jette

    2016-09-01

    Commercial mushroom production can expose mushrooms post-harvest to UV light for purposes of vitamin D2 enrichment by converting the naturally occurring provitamin D2 (ergosterol). The objectives of the present study were to artificially simulate solar UV-B doses occurring naturally in Central Europe and to investigate vitamin D2 and vitamin D4 production in sliced Agaricus bisporus (button mushrooms) and to analyse and compare the agaritine content of naturally and artificially UV-irradiated mushrooms. Agaritine was measured for safety aspects even though there is no rationale for a link between UV light exposure and agaritine content. The artificial UV-B dose of 0.53 J/cm(2) raised the vitamin D2 content to significantly (P < 0.001) higher levels of 67.1 ± 9.9 μg/g dry weight (DW) than sun exposure (3.9 ± 0.8 μg/g dry DW). We observed a positive correlation between vitamin D4 and vitamin D2 production (r(2) = 0.96, P < 0.001) after artificial UV irradiation, with vitamin D4 levels ranging from 0 to 20.9 μg/g DW. The agaritine content varied widely but remained within normal ranges in all samples. Irrespective of the irradiation source, agaritine dropped dramatically in conjunction with all UV-B doses both artificial and natural solar, probably due to its known instability. The biological action of vitamin D from UV-exposed mushrooms reflects the activity of these two major vitamin D analogues (D2, D4). Vitamin D4 should be analysed and agaritine disregarded in future studies of UV-exposed mushrooms.

  9. The new world atlas of artificial night sky brightness

    CERN Document Server

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

    2016-01-01

    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{\\deg}N and 60{\\deg}S, 88% of Europe, and almost half of the United States experience light-polluted nights.

  10. 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.

  11. Development of immunity against viral and bacterial antigens after repeated exposures to suberythemal doses of ultraviolet light

    Directory of Open Access Journals (Sweden)

    S. A. Snopov

    2012-01-01

    Full Text Available The effects of ultraviolet (UV radiation on human infectious immunity are not well studied. On the one hand, solar and artificial UU sources have been shown to change cytokine levels in human skin, lymphocyte subpopulation counts in parepheral blood, lymphocyte DNA synthesis and prolifarative response to mitogens. On the other hand, there are just only one or two observations suggesting an influence of UV radiation on human infection course. For instance, UV irradiations have been reported to induce a reccurence of orofacial vesicular lesions caused by herpes siplex virus. Moreover, there is a lack of data concerning immune effects of suberythtemal doses of UV in spite of a long history of using them by Russian prophylactic medicine. In this work we questioned whether such suberythemal UV exposures can affect the immune responses of children to infectious conjunctivitis, to simultaneous measles and polio vaccinations and to simultaneous polio and diphtheria-tetanus vaccinations. In peripheral blood of vaccinated children we examined leukocyte counts (monocytes, neutrophils, eosinophils, lymphocytes, percentages of lymphocyte subpopulations (CD3+, CD20+, CD4+, CD8+, CD25+, HLADR+, concentrations of cytokines (IL-1 beta, TNF-alpha, IFN- amma и IL-10, DNA-synthetic activity of lymphocytes and titres of antibodies against measles and diphtheria toxin. We observed no local or systemic reactions to the vaccines in the UV-group while a moderate rise in body temperature occured in several children from unexposed group. In the blood of childeren from UV-group we found increases in CD25+ и HLADR+ cell percentages, IL- 1 beta and IL-10 concentrations, PWMinduced DNA synthesis in mononuclears, and no decreases in formation of antibodies against measles and diphreria. We concluded that suberythemal UV exposures of children modulated their further responses to imminisations perhaps through the activation of a T helper 2-like

  12. Light induces translocation of NF-κB p65 to the mitochondria and suppresses expression of cytochrome c oxidase subunit III (COX III) in the rat retina

    Energy Technology Data Exchange (ETDEWEB)

    Tomita, Hiroshi, E-mail: htomita@iwate-u.ac.jp [Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University Division of Science and Engineering, 4-3-5 Ueda, Morioka, Iwate 020-8551 (Japan); Soft-Path Engineering Research Center (SPERC), Faculty of Science and Engineering, Iwate University, Morioka 020-8551 (Japan); Clinical Research, Innovation and Education Center, Tohoku University Hospital, 1-1 Seiryo, Aoba, Sendai, Miyagi 980-8574 (Japan); Tabata, Kitako, E-mail: ktabata@iwate-u.ac.jp [Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University Division of Science and Engineering, 4-3-5 Ueda, Morioka, Iwate 020-8551 (Japan); Takahashi, Maki, E-mail: mqdelta@iwate-u.ac.jp [Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University Division of Science and Engineering, 4-3-5 Ueda, Morioka, Iwate 020-8551 (Japan); Nishiyama, Fumiaki, E-mail: t2114018@iwate-u.ac.jp [Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University Division of Science and Engineering, 4-3-5 Ueda, Morioka, Iwate 020-8551 (Japan); Sugano, Eriko, E-mail: sseriko@iwate-u.ac.jp [Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University Division of Science and Engineering, 4-3-5 Ueda, Morioka, Iwate 020-8551 (Japan); Soft-Path Engineering Research Center (SPERC), Faculty of Science and Engineering, Iwate University, Morioka 020-8551 (Japan)

    2016-05-13

    The transcription factor nuclear factor kappaB (NF-κB) plays various roles in cell survival, apoptosis, and inflammation. In the rat retina, NF-κB activity increases after exposure to damaging light, resulting in degeneration of photoreceptors. Here, we report that in dark-adapted rats exposed for 6 h to bright white light, the p65 subunit of retinal NF-κB translocates to the mitochondria, an event associated with a decrease in expression of cytochrome c oxidase subunit III (COX III). However, sustained exposure for 12 h depleted p65 from the mitochondria, and enhanced COX III expression. Treatment with the protective antioxidant PBN prior to light exposure prevents p65 depletion in the mitochondria and COX III upregulation during prolonged exposure, and apoptosis in photoreceptor cells. These results indicate that COX III expression is sensitive to the abundance of NF-κB p65 in the mitochondria, which, in turn, is affected by exposure to damaging light. - Highlights: • Damaging light exposure of the retina induces NF-κB p65 mitochondrial translocation. • NF-κB p65 mitochondrial translocation is associated with the decrease of COX III expression. • Prolonged light exposure depletes mitochondrial p65 resulting in the increase in COX III expression. • NF-κB p65 and COX III expression play an important role in the light-induced photoreceptor degeneration.

  13. Exposure of Microcystis aeruginosa to Hydrogen Peroxide under Light: Kinetic Modeling of Cell Rupture and Simultaneous Microcystin Degradation.

    Science.gov (United States)

    Huo, Xiangchen; Chang, De-Wei; Tseng, Jing-Hua; Burch, Michael D; Lin, Tsair-Fuh

    2015-05-01

    The effect of hydrogen peroxide on the cell integrity of a cyanobacterium, Microcystis aeruginosa, and on the release and degradation of microcystins (MCs) under simulated sunlight was investigated. The cyanobacterium was exposed to H2O2 in the range of 0-60 mg·L(-1) for 3.5 h. Production of OH radical in the solution was estimated by a chemical probe method. More than 99% (2 log) of the M. aeruginosa cells were ruptured or damaged by 3 h for all the treatments. Loss of cell integrity over time revealed two distinct phases. Cells retained their integrity during the initial lag phase and rapidly ruptured following first-order reaction afterward. A linear relationship was found between the duration of the lag phase and the steady-state concentration of OH radical. Release of MCs was closely correlated with the loss of cell integrity. Sequential reaction models were developed to simulate the release and degradation of MCs. These models were able to quantitatively describe the kinetics of all reactions under different H2O2 doses and extended exposure time. In particular, the models successfully predicted the concentration change of MCs using independently measured parameters. These models provide a simple and quantitative means to estimate the interaction of oxidants and cells and the consequent release of metabolites during oxidation treatment of cyanobacterium-laden waters.

  14. Lightning detection and exposure algorithms for smartphones

    Science.gov (United States)

    Wang, Haixin; Shao, Xiaopeng; Wang, Lin; Su, Laili; Huang, Yining

    2015-05-01

    This study focuses on the key theory of lightning detection, exposure and the experiments. Firstly, the algorithm based on differential operation between two adjacent frames is selected to remove the lightning background information and extract lighting signal, and the threshold detection algorithm is applied to achieve the purpose of precise detection of lightning. Secondly, an algorithm is proposed to obtain scene exposure value, which can automatically detect external illumination status. Subsequently, a look-up table could be built on the basis of the relationships between the exposure value and average image brightness to achieve rapid automatic exposure. Finally, based on a USB 3.0 industrial camera including a CMOS imaging sensor, a set of hardware test platform is established and experiments are carried out on this platform to verify the performances of the proposed algorithms. The algorithms can effectively and fast capture clear lightning pictures such as special nighttime scenes, which will provide beneficial supporting to the smartphone industry, since the current exposure methods in smartphones often lost capture or induce overexposed or underexposed pictures.

  15. Response of some antioxidant parameters in post juveniles of Clarias gariepinus after exposure to Nigerian crude oil (Forcados, Bonny Light and Qua-Iboe).

    Science.gov (United States)

    Kayode, Saliu Joseph; Chidimma, Ugorji Ijeoma; Alwell, Ekpendu Emeka

    2014-12-01

    The adverse effect of crude oil on aquatic ecosystem is a modern day peril. This study investigated the acute toxicities of some Nigerian crude oil (Forcados, Bonnylight and Qua-Iboe) against Clarias gariepinus and the antioxidant enzyme response of the fish to the pollutants. The toxicity assessment was based on LC50 at 96 h. Static renewal bioassays were used to determine the toxicological effects of the 3 crude oils on the antioxidant enzymes of post juveniles Clarias gariepinus using the liver. The 96 h LC50 value for Qua Iboe was 18.966 mL L(-1), Forcados, 2.776 mL L(-1) and Bonny light, 3.948 mL L(-1), indicating that Forcados is the most toxic of the crude oils. Induction of the Glutathione-S-transferase (GST), Glutathione (GSH), Superoxide dismutase (SOD) and Catalase (CAT) in the liver of Clarias gariepinus exposed to Forcados and Bonny light for a period of 28 days was inhibited while it was enhanced in Qua-Iboe crude oil. Malondialdehyde (MDA) levels increased with increasing toxicity and exposure time. SOD, CAT, GSH, GST and MDA are reliable environmental biomarkers for crude oil induced oxidative stress in Clarias gariepinus and therefore useful biological indicators of environmental contamination in the aquatic ecosystem.

  16. The influence of pulsed light exposure mode on quality and bioactive compounds of fresh-cut mangoes.

    Science.gov (United States)

    de Almeida Lopes, Mônica Maria; Silva, Ebenezer Oliveira; Laurent, Sandrine; Charles, Florence; Urban, Laurent; de Miranda, Maria Raquel Alcântara

    2017-07-01

    This study investigated the effect of pulsed light (PL) on the respiratory rate, quality (firmness, color and soluble solid content), bioactive compounds (ascorbate and carotenoid) and total antioxidant activity of fresh-cut "Tommy Atkins" mangoes. Fresh-cut mangoes were subjected to PL treatments: control (0P), 1 pulse (1P; 0.7 J cm(-2)), 4 successive pulses (4P; 2.80 J cm(-2)) and 1 pulse per day for 4 days (1P4D; 2.80 J cm(-2)) before storage for 7 days at 6 °C. The 1P and the 4P treatments reduced fresh mass loss during storage, while 4P-treated samples also showed a slower decline of yellow color, as shown by parameter b and overall better visual appearance. After 7 days of storage, total ascorbate content was 40% higher in the 1P4D treatment than in control, whereas total carotenoid content (0.894 mg g(-1) FM) and total antioxidant activity (144 μmol trolox 100 g(-1) FM) were the highest in the 4P-treated samples. Results suggest that PL mode of application is more important than the fluence or final dose received by fresh-cut mangoes; moreover, 4P is an effective method to preserve, or even improve quality of fresh-cut mangoes.

  17. The new World Atlas of Artificial Sky Brightness

    Science.gov (United States)

    Falchi, Fabio; Cinzano, Pierantonio; Kyba, Christopher C. M.; Portnov, Boris A.

    2015-08-01

    I present the main steps toward the completion of the new World Atlas of Artificial Sky Brightness (WA II) and some results. The computational technique has been updated, in comparison to the first World Atlas, to take into account both sources and sites elevation. The elevation data are from USGS GTOPO30 global digital elevation model, with the same pixel size as the WA II maps. The upward emission function used to compute the Atlas is a three parameters function. The parameters can be constrained to the database of Earth based night sky brightness measurements. In this way we can use the better fitting upward function for the final map’s calibration. We maintained constant atmosphere parameters over the entire Earth, identical to those used for the first Atlas (Garstang atmospheric clarity coefficient k=1, equivalent to a vertical extinction at sea level of 0.33 magnitude in the V band). This was done in order to avoid introducing a local bias due to different conditions that may confound the light pollution propagation effects. The radiance data used are those from Visible Infrared Imaging Radiometer Suite (VIIRS) Day-Night Band (DNB) on board the Suomi NPP satellite. The use of this newly available radiance data allows for an increased real resolution, even while maintaining the same 30"x30" lat-lon pixel size. Anyway, a higher resolution is really appreciable only in the immediate proximity of sources of light pollution (e.g. inside a big city). The VIIRS DNB data used for the input data were chosen from the months ranging from May to September in order to avoid introducing bias from the variable snow coverage in mid to high northern latitudes. In the southern hemisphere this problem is far less pronounced. The WA II takes advantage of the now enormous database of Earth based sky brightness measurements obtained mainly with Sky Quality Meters, but also with CCD measurements.

  18. Exposure to light and darkness and its influence on physiological measures of intensive care unit patients-a systematic literature review.

    Science.gov (United States)

    Weiss, B; Spies, C; Piazena, H; Penzel, T; Fietze, I; Luetz, A

    2016-09-01

    Sleep-wake patterns are often significantly disturbed in critically ill patients. This disturbance is closely linked to secondary brain dysfunctions in these patients. Sedation not only impairs sleep quality in ICU patients but also has detrimental effects on short- and long-term outcome. In other contexts, light therapy has been proven to be effective in maintaining and resynchronizing circadian rhythmicity in humans. The objective of this systematic review was to analyse studies that investigated the effect of exposure to light or darkness on physiological measures and clinical outcomes of adult ICU patients. Studies were systematically identified by searching electronic bibliographic databases (The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, 2002) and MEDLINE via PubMed). The search algorithm identified a total of 156 articles, 10 of which were taken into final review. These 10 selected articles included 3 were monocentric RCTs, five prospective cohort studies, one retrospective cohort study, and one manuscript that included a partial systematic review of the literature. Included trials were published between 2007 and 2015. Five of these studies used multiple intervention approaches while four trials used a single intervention approach. Among all studies, 1,278 patients were analysed (489 prospectively). There was a high heterogeneity among the studies in terms of applied intervention and outcome measures. The most frequent methodological limitations were a lack of precise definitions regarding the illuminance and the light spectrum utilised. The analyses indicate that further studies including clearly defined interventions with objective outcome measures, as these are currently lacking, would add significant knowledge to this new field of research.

  19. 光照对绿芦笋汁色泽稳定性的影响%Effect of Light Exposure on Color Stability of Green Asparagus Juice

    Institute of Scientific and Technical Information of China (English)

    陈学红; 秦卫东; 马利华; 郑永华; 郁步青

    2015-01-01

    To explore the effect of light exposure on color stability of green asparagus juice during storage time ,the pasteurized juice were exposed to natural light and dark at ambient temperature .The changes of color ,chlorophyll ,carotenoids ,vitamin C ,total phenolics ,reducing sugar and amino acids con‐tents we re studied in green asparagus juice during storage time .The results showed that light exposure sig‐nificantly affected the color stability of green asparagus juice .The decrease of chlorophyll and the increase of carotenoids contents were inhibited by dark storage .At the same time ,the greenness of asparagus juice was kept .Vitamin C ,total phenolics and reducing sugar contents were closely correlated with the color of green asparagus juice .There was no significant correlation between amino acids and color of green aspara‐gus juice .The decrease of vitamin C ,total phenolics and reducing sugar contents were prevented by dark storage and the color stability of green asparagus juice was effectively kept .%为了探讨光对绿芦笋汁色泽稳定性的影响,将杀菌处理后的绿芦笋汁于自然光及黑暗(避光)条件下常温贮藏,研究绿芦笋汁在贮藏期间的色泽、叶绿素、类胡萝卜素、维生素C、总酚、还原糖和氨基酸质量浓度的变化。结果表明:光照对绿芦笋汁的色泽稳定性影响显著;避光贮藏可有效延缓绿芦笋汁叶绿素的降解,抑制类胡萝卜素质量浓度的上升,保持绿芦笋汁的绿色;维生素C、总酚和还原糖与绿芦笋汁的色泽密切相关,氨基酸与其色泽无显著相关性,避光贮藏可有效抑制维生素C、总酚和还原糖质量浓度的降低,从而有效地维持了绿芦笋汁的色泽稳定性。

  20. X-ray bright groups and their galaxies

    CERN Document Server

    Helsdon, S F; Helsdon, Stephen F.; Ponman, Trevor J.

    2002-01-01

    Combining X-ray data from the ROSAT PSPC and optical data drawn from the literature, we examine in detail the relationship between the X-ray and optical properties of X-ray bright galaxy groups. We find a relationship between optical luminosity and X-ray temperature consistent with that expected from self-similar scaling of galaxy systems, L_B \\propto T^{1.6 +/- 0.2}. The self-similar form and continuity of the L_B : T relation from clusters to groups and the limited scatter seen in this relation, implies that the star formation efficiency is rather similar in all these systems. We find that the bright extended X-ray components associated with many central galaxies in groups appear to be more closely related to the group than the galaxy itself, and we suggest that these are group cooling flows rather than galaxy halos. In addition we find that the optical light in these groups appears to be more centrally concentrated than the light in clusters. We also use the optical and X-ray data to investigate whether ea...

  1. Ultra Low Surface Brightness Imaging with the Dragonfly Telephoto Array

    CERN Document Server

    Abraham, Roberto G

    2014-01-01

    We describe the Dragonfly Telephoto Array, a robotic imaging system optimized for the detection of extended ultra low surface brightness structures. The array consists of eight Canon 400mm f/2.8 telephoto lenses coupled to eight science-grade commercial CCD cameras. The lenses are mounted on a common framework and are co-aligned to image simultaneously the same position on the sky. The system provides an imaging capability equivalent to a 0.4m aperture f/1.0 refractor with a 2.6 deg X 1.9 deg field of view. The system has no obstructions in the light path, optimized baffling, and internal optical surfaces coated with a new generation of anti-reflection coatings based on sub-wavelength nanostructures. As a result, the array's point spread function has a factor of ~10 less scattered light at large radii than well-baffled reflecting telescopes. The Dragonfly Telephoto Array is capable of imaging extended structures to surface brightness levels below 30 mag/arcsec^2 in 10h integrations (without binning or foregro...

  2. A Bright Single Photon Source Based on a Diamond Nanowire

    CERN Document Server

    Babinec, T; Khan, M; Zhang, Y; Maze, J; Hemmer, P R; Loncar, M

    2009-01-01

    The development of a robust light source that emits one photon at a time is an outstanding challenge in quantum science and technology. Here, at the transition from many to single photon optical communication systems, fully quantum mechanical effects may be utilized to achieve new capabilities, most notably perfectly secure communication via quantum cryptography. Practical implementations place stringent requirements on the device properties, including fast and stable photon generation, efficient collection of photons, and room temperature operation. Single photon light emitting devices based on fluorescent dye molecules, quantum dots, nanowires, and carbon nanotube material systems have all been explored, but none have simultaneously demonstrated all criteria. Here, we describe the design, fabrication, and characterization of a bright source of single photons consisting of an individual Nitrogen-vacancy color center (NV center) in a diamond nanowire operating in ambient conditions. The nanowire plays a posit...

  3. TIGER Burned Brightly in JAMIC

    Science.gov (United States)

    Olson, Sandra L.; Kashiwagi, Takashi

    2001-01-01

    The Transition From Ignition to Flame Growth Under External Radiation in 3D (TIGER- 3D) experiment, which is slated to fly aboard the International Space Station, conducted a series of highly successful tests in collaboration with the University of Hokkaido using Japan's 10-sec JAMIC drop tower. The tests were conducted to test engineering versions of advanced flight diagnostics such as an infrared camera for detailed surface temperature measurements and an infrared spectroscopic array for gas-phase species concentrations and temperatures based on detailed spectral emissions in the near infrared. Shown in the top figure is a visible light image and in the bottom figure is an infrared image at 3.8 mm obtained during the microgravity tests. The images show flames burning across cellulose samples against a slow wind of a few centimeters per second (wind is from right to left). These flow velocities are typical of spacecraft ventilation systems that provide fresh air for the astronauts. The samples are ignited across the center with a hot wire, and the flame is allowed to spread upwind and/or downwind. As these images show, the flames prefer to spread upwind, into the fresh air, which is the exact opposite of flames on Earth, which spread much faster downwind, or with the airflow, as in forest fires.

  4. Refinement of a limit cycle oscillator model of the effects of light on the human circadian pacemaker

    Science.gov (United States)

    Jewett, M. E.; Kronauer, R. E.; Brown, E. N. (Principal Investigator)

    1998-01-01

    In 1990, Kronauer proposed a mathematical model of the effects of light on the human circadian pacemaker. Although this model predicted many general features of the response of the human circadian pacemaker to light exposure, additional data now available enable us to refine the original model. We first refined the original model by incorporating the results of a dose response curve to light into the model's predicted relationship between light intensity and the strength of the drive onto the pacemaker. Data from three bright light phase resetting experiments were then used to refine the amplitude recovery characteristics of the model. Finally, the model was tested and further refined using data from an extensive phase resetting experiment in which a 3-cycle bright light stimulus was presented against a background of dim light. In order to describe the results of the four resetting experiments, the following major refinements to the original model were necessary: (i) the relationship between light intensity (I) and drive onto the pacemaker was reduced from I1/3 to I0.23 for light levels between 150 and 10,000 lux; (ii) the van der Pol oscillator from the original model was replaced with a higher-order limit cycle oscillator so that amplitude recovery is slower near the singularity and faster near the limit cycle; (iii) a direct effect of light on circadian period (tau x) was incorporated into the model such that as I increases, tau x decreases, which is in accordance with "Aschoff's rule". This refined model generates the following testable predictions: it should be difficult to enhance normal circadian amplitude via bright light; near the critical point of a type 0 phase response curve (PRC) the slope should be steeper than it is in a type 1 PRC; and circadian period measured during forced desynchrony should be directly affected by ambient light intensity.

  5. 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 cont

  6. 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

  7. The outer disks of early-type galaxies. I. Surface-brightness profiles of barred galaxies

    NARCIS (Netherlands)

    Erwin, Peter; Pohlen, Michael; Beckman, John E.

    2008-01-01

    We present a study of 66 barred, early-type (S0-Sb) disk galaxies, focused on the disk surface brightness profile outside the bar region, with the aim of throwing light on the nature of Freeman type I and II profiles, their origins, and their possible relation to disk truncations. This paper discuss

  8. Mesopic models : from brightness matching to visual performance in night-time driving: a review

    NARCIS (Netherlands)

    Eloholma, M.; Liesiö, M.; Halonen, L.; Walkey, H.; Goodman, T.; Alferdinck, J.W.A.M.; Frieding, A.; Schanda, J.; Bodrogi, P.; Várady, G.

    2005-01-01

    At present, suitable methods to evaluate the visual effectiveness of lighting products in the mesopic region are not available. The majority of spectral luminous efficiency functions obtained to date in the mesopic range have been acquired by heterochromatic brightness matching. However, the most re

  9. THE TULLY-FISHER RELATION FOR LOW SURFACE BRIGHTNESS GALAXIES - IMPLICATIONS FOR GALAXY EVOLUTION

    NARCIS (Netherlands)

    Zwaan, M.A.; VAN DER HULST, JM; DE BLOK, WJG; MCGAUGH, SS

    1995-01-01

    We present the B-band Tully-Fisher relation for low surface brightness (LSB) galaxies. These LSB galaxies follow the same Tully-Fisher relation as normal spiral galaxies. This implies that the mass-to-light ratio (M/L) of LSB galaxies is typically a factor of 2 larger than that of normal galaxies of

  10. The outer disks of early-type galaxies. I. Surface-brightness profiles of barred galaxies

    NARCIS (Netherlands)

    Erwin, Peter; Pohlen, Michael; Beckman, John E.

    We present a study of 66 barred, early-type (S0-Sb) disk galaxies, focused on the disk surface brightness profile outside the bar region, with the aim of throwing light on the nature of Freeman type I and II profiles, their origins, and their possible relation to disk truncations. This paper

  11. Bright stars observed by FIMS/SPEAR

    CERN Document Server

    Jo, Young-Soo; Min, Kyoung-Wook; Choi, Yeon-Ju; Lim, Tae-Ho; Lim, Yeo-Myeong; Edelstein, Jerry; Han, Wonyong

    2015-01-01

    In this paper, we present a catalogue of the spectra of bright stars observed during the sky survey using the Far-Ultraviolet Imaging Spectrograph (FIMS), which was designed primarily to observe diffuse emissions. By carefully eliminating the contamination from the diffuse background, we obtain the spectra of 70 bright stars observed for the first time with a spectral resolution of 2--3 {\\AA} over the wavelength of 1370--1710 {\\AA}. The far-ultraviolet spectra of an additional 139 stars are also extracted with a better spectral resolution and/or higher reliability than those of the previous observations. The stellar spectral type of the stars presented in the catalogue spans from O9 to A3. The method of spectral extraction of the bright stars is validated by comparing the spectra of 323 stars with those of the International Ultraviolet Explorer (IUE) observations.

  12. A brightness exceeding simulated Langmuir limit

    Energy Technology Data Exchange (ETDEWEB)

    Nakasuji, Mamoru [2-15-11, Serigaya-chou, Kounan-ku, Yokohama-shi, Kanagawa-ken (Japan)

    2013-08-15

    When an excitation of the first lens determines a beam is parallel beam, a brightness that is 100 times higher than Langmuir limit is measured experimentally, where Langmuir limits are estimated using a simulated axial cathode current density which is simulated based on a measured emission current. The measured brightness is comparable to Langmuir limit, when the lens excitation is such that an image position is slightly shorter than a lens position. Previously measured values of brightness for cathode apical radii of curvature 20, 60, 120, 240, and 480 μm were 8.7, 5.3, 3.3, 2.4, and 3.9 times higher than their corresponding Langmuir limits, respectively, in this experiment, the lens excitation was such that the lens and the image positions were 180 mm and 400 mm, respectively. From these measured brightness for three different lens excitation conditions, it is concluded that the brightness depends on the first lens excitation. For the electron gun operated in a space charge limited condition, some of the electrons emitted from the cathode are returned to the cathode without having crossed a virtual cathode. Therefore, method that assumes a Langmuir limit defining method using a Maxwellian distribution of electron velocities may need to be revised. For the condition in which the values of the exceeding the Langmuir limit are measured, the simulated trajectories of electrons that are emitted from the cathode do not cross the optical axis at the crossover, thus the law of sines may not be valid for high brightness electron beam systems.

  13. Dark Dunes Over-riding Bright Dunes

    Science.gov (United States)

    2000-01-01

    Some martian sand dunes may be more active than others. In this picture, wind has caused the dark and somewhat crescent-shaped dunes to advance toward the lower left. While their movement cannot actually be seen in this April 1998snapshot, the location of their steepest slopes--their slip faces--on their southwestern sides indicates the direction of movement. Oddly, these dark dunes have moved across and partly cover sets of smaller, bright ridges that also formed by wind action.This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image illustrates an intriguing martian 'find.' Strangely, the two dune types have different shapes and a different relative brightness. There are two explanations for the relationship seen here, and neither can be distinguished as 'the answer'--(1) it is possible that the brighter dunes are old and cemented, and represent some ancient wind activity, whereas the dark dunes are modern and are marching across the older, 'fossilized' dune forms, or (2) the bright dunes are composed of grains that are much larger or more dense than those that compose the dark dunes. In the latter scenario, the bright dunes move more slowly and are over-taken by the dark dunes because their grains are harder to transport. An interpretation involving larger or denser grains is consistent with the small size and even-spacing of the bright dunes, as well, but usually on Earth such features occur on the surfaces of larger, finer-grained dunes, not under them. The actual composition of either the bright or dark materials are unknown. This example is located on the floor of an impact crater in western Arabia Terra at 10.7oN, 351.0oW. The picture is illuminated from the right.

  14. Burnout and Light Treatment

    NARCIS (Netherlands)

    Meesters, Y.; Waslander, M.

    The core symptom of the burnout syndrome is emotional exhaustion, which leads to impaired functioning on the job. Studies of sufferers of seasonal affective disorders and of healthy people show that energy levels can be improved by exposing them to bright light. It is hypothesized that energy levels

  15. Burnout and Light Treatment

    NARCIS (Netherlands)

    Meesters, Y.; Waslander, M.

    2010-01-01

    The core symptom of the burnout syndrome is emotional exhaustion, which leads to impaired functioning on the job. Studies of sufferers of seasonal affective disorders and of healthy people show that energy levels can be improved by exposing them to bright light. It is hypothesized that energy levels

  16. Blue Laser Imaging-Bright Improves Endoscopic Recognition of Superficial Esophageal Squamous Cell Carcinoma

    Directory of Open Access Journals (Sweden)

    Akira Tomie

    2016-01-01

    Full Text Available Background/Aims. The aim of this study was to evaluate the endoscopic recognition of esophageal squamous cell carcinoma (ESCC using four different methods (Olympus white light imaging (O-WLI, Fujifilm white light imaging (F-WLI, narrow band imaging (NBI, and blue laser imaging- (BLI- bright. Methods. We retrospectively analyzed 25 superficial ESCCs that had been examined using the four different methods. Subjective evaluation was provided by three endoscopists as a ranking score (RS of each image based on the ease of detection of the cancerous area. For the objective evaluation we calculated the color difference scores (CDS between the cancerous and noncancerous areas with each of the four methods. Results. There was no difference between the mean RS of O-WLI and F-WLI. The mean RS of NBI was significantly higher than that of O-WLI and that of BLI-bright was significantly higher than that of F-WLI. Moreover, the mean RS of BLI-bright was significantly higher than that of NBI. Furthermore, in the objective evaluation, the mean CDS of BLI-bright was significantly higher than that of O-WLI, F-WLI, and NBI. Conclusion. The recognition of superficial ESCC using BLI-bright was more efficacious than the other methods tested both subjectively and objectively.

  17. Blue Laser Imaging-Bright Improves Endoscopic Recognition of Superficial Esophageal Squamous Cell Carcinoma

    Science.gov (United States)

    Tomie, Akira; Yagi, Nobuaki; Kitae, Hiroaki; Majima, Atsushi; Horii, Yusuke; Kitaichi, Tomoko; Onozawa, Yuriko; Suzuki, Kentaro; Kimura-Tsuchiya, Reiko; Okayama, Tetsuya; Kamada, Kazuhiro; Katada, Kazuhiro; Uchiyama, Kazuhiko; Ishikawa, Takeshi; Takagi, Tomohisa; Naito, Yuji; Itoh, Yoshito

    2016-01-01

    Background/Aims. The aim of this study was to evaluate the endoscopic recognition of esophageal squamous cell carcinoma (ESCC) using four different methods (Olympus white light imaging (O-WLI), Fujifilm white light imaging (F-WLI), narrow band imaging (NBI), and blue laser imaging- (BLI-) bright). Methods. We retrospectively analyzed 25 superficial ESCCs that had been examined using the four different methods. Subjective evaluation was provided by three endoscopists as a ranking score (RS) of each image based on the ease of detection of the cancerous area. For the objective evaluation we calculated the color difference scores (CDS) between the cancerous and noncancerous areas with each of the four methods. Results. There was no difference between the mean RS of O-WLI and F-WLI. The mean RS of NBI was significantly higher than that of O-WLI and that of BLI-bright was significantly higher than that of F-WLI. Moreover, the mean RS of BLI-bright was significantly higher than that of NBI. Furthermore, in the objective evaluation, the mean CDS of BLI-bright was significantly higher than that of O-WLI, F-WLI, and NBI. Conclusion. The recognition of superficial ESCC using BLI-bright was more efficacious than the other methods tested both subjectively and objectively. PMID:27738428

  18. The historical investigation of cometary brightness

    Science.gov (United States)

    Hughes, David W.

    1998-12-01

    The interpretation of the way in which the brightness of a comet varied as a function of both its heliocentric and geocentric distance was essentially started by Isaac Newton in his book Philosophiae Naturalis Principia Mathematica, published in 1687. Astronomers have argued about the form of this variability ever since, and for many years it was regarded as an important clue as to the physical nature of the cometary nucleus and its decay process. This paper reviews our understanding of the causes of cometary brightness variability between about 1680 and the 1950s.

  19. Light therapy: Methodological issues from an engineering perspective.

    NARCIS (Netherlands)

    Hoof, J van; Westerlaken,; Aries,; Schoutens,; Aarts,; Sinoo,; Wouters, EJM; Van Someren,

    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

  20. Light pollution: Assessment of sky glow on two dark sky regions of Portugal.

    Science.gov (United States)

    Lima, Raul Cerveira; Pinto da Cunha, José; Peixinho, Nuno

    2016-01-01

    Artificial light at night (ALAN), producing light pollution (LP), is not a matter restricted to astronomy anymore. Light is part of modern societies and, as a consequence, the natural cycle day-night (bright-dark) has been interrupted in a large segment of the global population. There is increasing evidence that exposure to certain types of light at night and beyond threshold levels may produce hazardous effects to humans and the environment. The concept of "dark skies reserves" is a step forward in order to preserve the night sky and a means of enhancing public awareness of the problem of spread of light pollution worldwide. The aim of this study was to assess the skyglow at two sites in Portugal, the Peneda-Gerês National Park (PNPG) and the region now known as Dark Sky Alqueva Reserve. The latter site was classified as a "Starlight Tourism Destination" by the Starlight Foundation (the first in the world to achieve this classification) following a series of night sky measurements in situ described herein. The measurements at PNPG also contributed to the new set of regulations concerning light pollution at this national park. This study presents the first in situ systematic measurements of night sky brightness, showing that at the two sites the skies are mostly in levels 3 to 4 of the Bortle 9-level scale (with level 1 being the best achievable). The results indicate that the sources of light pollution and skyglow can be attributed predominantly to contamination from nearby urban regions.

  1. Inactivation of uptake hydrogenase leads to enhanced and sustained hydrogen production with high nitrogenase activity under high light exposure in the cyanobacterium Anabaena siamensis TISTR 8012

    Directory of Open Access Journals (Sweden)

    Khetkorn Wanthanee

    2012-10-01

    Full Text Available Abstract Background Biohydrogen from cyanobacteria has attracted public interest due to its potential as a renewable energy carrier produced from solar energy and water. Anabaena siamensis TISTR 8012, a novel strain isolated from rice paddy field in Thailand, has been identified as a promising cyanobacterial strain for use as a high-yield hydrogen producer attributed to the activities of two enzymes, nitrogenase and bidirectional hydrogenase. One main obstacle for high hydrogen production by A. siamensis is a light-driven hydrogen consumption catalyzed by the uptake hydrogenase. To overcome this and in order to enhance the potential for nitrogenase based hydrogen production, we engineered a hydrogen uptake deficient strain by interrupting hupS encoding the small subunit of the uptake hydrogenase. Results An engineered strain lacking a functional uptake hydrogenase (∆hupS produced about 4-folds more hydrogen than the wild type strain. Moreover, the ∆hupS strain showed long term, sustained hydrogen production under light exposure with 2–3 folds higher nitrogenase activity compared to the wild type. In addition, HupS inactivation had no major effects on cell growth and heterocyst differentiation. Gene expression analysis using RT-PCR indicates that electrons and ATP molecules required for hydrogen production in the ∆hupS strain may be obtained from the electron transport chain associated with the photosynthetic oxidation of water in the vegetative cells. The ∆hupS strain was found to compete well with the wild type up to 50 h in a mixed culture, thereafter the wild type started to grow on the relative expense of the ∆hupS strain. Conclusions Inactivation of hupS is an effective strategy for improving biohydrogen production, in rates and specifically in total yield, in nitrogen-fixing cultures of the cyanobacterium Anabaena siamensis TISTR 8012.

  2. Effect of Exposure to Various Durations of Light on Serum Insulin-Like Growth Factor-I in Prepubertal Holstein Heifers

    Directory of Open Access Journals (Sweden)

    L. J. Spicer

    2007-01-01

    Full Text Available Our objective was to determine if prolonged exposure to various durations of light (i.e., photoperiod would affect serum IGF-I concentrations in heifers. Thus, 16 Holstein heifers, 2 to 4 mo of age, were exposed during a 5-wk pretreatment period to 12 h of cool-white fluorescent light (L at an intensity of 1200 lux and 12 h of dark (D. At 5 wk, photoperiods were adjusted to 24 L: 0 D (24 L, 20 L: 4 d (20 L, 16 L: 8 D (16 L or 8 L: 16 D (8 L per 24 h (n=4 heifers per photoperiod treatment. Blood was sampled at 5 wk and monthly for 4 mo. During each sampling period, blood was collected at 16-h intervals for 48 h and serum IGF-I was determined by RIA. Photoperiod treatment, month of experiment and their interactions affected serum IGF-I concentrations. Averaged over months, concentrations of serum IGF-I was greatest in heifers on 16 L; heifers on 20 L had IGF-I concentrations similar to 8 L, 16 L and 24 L and heifers on 24 L had concentrations similar to that of heifers on 8 L. Heifers in all treatment groups exhibited an increase in serum IGF-I concentration during the 4 mo of treatment. Heifers on 16 L and 20 L exhibited the greatest difference in serum IGF-I concentrations compared with 8L heifers after 3 mo of treatment. In conclusion, 16 L increases concentrations of serum IGF-I above that seen for heifers treated with

  3. Theodolite Ring Lights

    Science.gov (United States)

    Clark, David

    2006-01-01

    Theodolite ring lights have been invented to ease a difficulty encountered in the well-established optical-metrology practice of using highly reflective spherical tooling balls as position references. A theodolite ring light produces a more easily visible reflection and eliminates the need for an autocollimating device. A theodolite ring light is a very bright light source that is well centered on the optical axis of the instrument. It can be fabricated, easily and inexpensively, for use on a theodolite or telescope of any diameter.

  4. 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.

  5. A photometric investigation of a bright Geminid

    NARCIS (Netherlands)

    Degewij, J.; Diggelen, Johannes van

    1968-01-01

    Photographic observations of meteors in the Netherlands started with a bright Geminid of photographic magnitude −8 observed on December 11, 1955, 21h39m55s by M. Alberts. From the assumed radiant and velocity we have constructed the trajectory of the bolide. The luminosity of the trail has been dete

  6. Probable Bright Supernova discovered by PSST

    Science.gov (United States)

    Smith, K. W.; Wright, D.; Smartt, S. J.; Young, D. R.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.

    2016-09-01

    A bright transient, which is a probable supernova, has been discovered as part of the Pan-STARRS Survey for Transients (PSST). Information on all objects discovered by the Pan-STARRS Survey for Transients is available at http://star.pst.qub.ac.uk/ps1threepi/ (see Huber et al. ATel #7153).

  7. Brightness of synchrotron radiation from wigglers

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca, E-mail: gianluca.geloni@xfel.eu [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2016-01-21

    According to the literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so-called ‘depth-of-field’ effects. In fact, the particle beam cross-section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. We exemplify this formalism in simple limiting cases. We consider the problem of the calculation of the wiggler source size by means of numerical simulations alone, which play the same role of an experiment. We report a significant numerical disagreement between exact calculations and approximations currently used in the literature.

  8. Dark matter in low surface brightness galaxies

    NARCIS (Netherlands)

    de Blok, WJG; McGaugh, SS; Persic, M; Salucci, P

    1997-01-01

    Low Surface Brightness (LSB) galaxies form a large population of disc galaxies that extend the Hubble sequence towards extreme late-types. They are only slowly evolving, and still in an early evolutionary state. The Tully-Fisher relation and rotation curves of LSB galaxies both show that LSB

  9. Brightness and darkness as perceptual dimensions.

    Directory of Open Access Journals (Sweden)

    Tony Vladusich

    2007-10-01

    Full Text Available A common-sense assumption concerning visual perception states that brightness and darkness cannot coexist at a given spatial location. One corollary of this assumption is that achromatic colors, or perceived grey shades, are contained in a one-dimensional (1-D space varying from bright to dark. The results of many previous psychophysical studies suggest, by contrast, that achromatic colors are represented as points in a color space composed of two or more perceptual dimensions. The nature of these perceptual dimensions, however, presently remains unclear. Here we provide direct evidence that brightness and darkness form the dimensions of a two-dimensional (2-D achromatic color space. This color space may play a role in the representation of object surfaces viewed against natural backgrounds, which simultaneously induce both brightness and darkness signals. Our 2-D model generalizes to the chromatic dimensions of color perception, indicating that redness and greenness (blueness and yellowness also form perceptual dimensions. Collectively, these findings suggest that human color space is composed of six dimensions, rather than the conventional three.

  10. Alberta Associations for Bright Children Members' Handbook.

    Science.gov (United States)

    Alberta Association for Bright Children, Edmonton.

    This handbook is designed to provide information to parents of gifted children in Alberta, Canada. The handbook outlines the mission and objectives of the Alberta Associations for Bright Children and describes the structure of the non-profit organization. The booklet then addresses: (1) the characteristics of gifted children; (2) the rights of…

  11. Brightness of synchrotron radiation from wigglers

    Science.gov (United States)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2016-01-01

    According to the literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so-called 'depth-of-field' effects. In fact, the particle beam cross-section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. We exemplify this formalism in simple limiting cases. We consider the problem of the calculation of the wiggler source size by means of numerical simulations alone, which play the same role of an experiment. We report a significant numerical disagreement between exact calculations and approximations currently used in the literature.

  12. Robust fitting of diurnal brightness temperature cycle

    CSIR Research Space (South Africa)

    Udahemuka, G

    2007-11-01

    Full Text Available for a pixel concerned. Robust fitting of observed Diurnal Temperature Cycle (DTC) taken over a day of a given pixel without cloud cover and other abnormally conditions such as fire can give a data based brightness temperature model for a given pixel...

  13. Bright Future for Petroleum Development Cooperation

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhenqing

    1996-01-01

    @@ China's oil prospects look bright, since reform and opening speed up. The oil production of 1995 is 148 million tons and the confirmed reserves of oil and gas only occupy one-fifth of those possible to be verified, the petroleum exploration will be deepened to locate and confirm the remaining reserves.

  14. Simultaneous brightness contrast of foraging Papilio butterflies.

    Science.gov (United States)

    Kinoshita, Michiyo; Takahashi, Yuki; Arikawa, Kentaro

    2012-05-22

    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.

  15. Toxicity assessment of anatase and rutile titanium dioxide nanoparticles: The role of degradation in different pH conditions and light exposure.

    Science.gov (United States)

    De Matteis, Valeria; Cascione, Mariafrancesca; Brunetti, Virgilio; Toma, Chiara Cristina; Rinaldi, Rosaria

    2016-12-01

    Titanium dioxide nanoparticles (TiO2NPs), in the two crystalline forms, rutile and anatase, have been widely used in many industrial fields, especially in cosmetics. Therefore, a lot of details about their safety issues have been discussed by the scientific community. Many studies have led to a general agreement about TiO2NPs toxicity, in particular for anatase form, but no mechanism details have been proved yet. In this study, data confirm the different toxic potential of rutile and anatase TiO2NPs in two cell lines up to 5nM nanoparticles concentration. Moreover, we evaluated the role of titanium ions released by TiO2NPs in different conditions, at pH=4.5 (the typical lysosomal compartment pH) and at pH=5.5 (the skin physiological pH) in conditions of darkness and light, to mimic the dermal exposure of cosmetics. Anatase nanoparticles were proner to degradation both in the acidic conditions and at skin pH. Our study demonstrates that pH and sunlight are dominant factors to induce oxidative stress, TiO2NPs degradation and toxicity effects.

  16. Dynamics of annular bright field imaging in scanning transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Findlay, S.D., E-mail: scott@sigma.t.u-tokyo.ac.jp [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); Shibata, N. [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); PRESTO, Japan Science and Technology Agency, Saitama 332-0012 (Japan); Sawada, H.; Okunishi, E.; Kondo, Y. [JEOL Ltd., Tokyo 196-8558 (Japan); Ikuhara, Y. [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587 (Japan); WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2010-06-15

    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.

  17. The nature of solar brightness variations

    Science.gov (United States)

    Shapiro, A. I.; Solanki, S. K.; Krivova, N. A.; Cameron, R. H.; Yeo, K. L.; Schmutz, W. K.

    2017-09-01

    Determining the sources of solar brightness variations1,2, often referred to as solar noise3, is important because solar noise limits the detection of solar oscillations3, is one of the drivers of the Earth's climate system4,5 and is a prototype of stellar variability6,7—an important limiting factor for the detection of extrasolar planets. Here, we model the magnetic contribution to solar brightness variability using high-cadence8,9 observations from the Solar Dynamics Observatory (SDO) and the Spectral And Total Irradiance REconstruction (SATIRE)10,11 model. The brightness variations caused by the constantly evolving cellular granulation pattern on the solar surface were computed with the Max Planck Institute for Solar System Research (MPS)/University of Chicago Radiative Magnetohydrodynamics (MURaM)12 code. We found that the surface magnetic field and granulation can together precisely explain solar noise (that is, solar variability excluding oscillations) on timescales from minutes to decades, accounting for all timescales that have so far been resolved or covered by irradiance measurements. We demonstrate that no other sources of variability are required to explain the data. Recent measurements of Sun-like stars by the COnvection ROtation and planetary Transits (CoRoT)13 and Kepler14 missions uncovered brightness variations similar to that of the Sun, but with a much wider variety of patterns15. Our finding that solar brightness variations can be replicated in detail with just two well-known sources will greatly simplify future modelling of existing CoRoT and Kepler as well as anticipated Transiting Exoplanet Survey Satellite16 and PLAnetary Transits and Oscillations of stars (PLATO)17 data.

  18. 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.

  19. A new method for imaging faint objects nearby a bright source

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In astronomical observation, it is difficult to obtain the image of faint objects in the peripheral area around a bright celestial body. In order to solve the problem, a new method is designed and experimented, which is called the separation readout technique (SRT). SRT is different from either the traditional coronagraphy or the newly-developed anti-blooming CCD technique, and allows an enough-long exposure to the faint objects in the area around a bright celestial body with the well-preserved bright body's image in one frame. This paper describes in detail the principle of SRT, the computer simulation, the experimental devising and result of SRT observation on a telescope.

  20. A possible low-level explanation of "temporal dynamics of brightness induction and White's illusion"

    CERN Document Server

    Karmakar, Subhajit

    2009-01-01

    Based upon physiological observation on time dependent orientation selectivity in the cells of macaque's primary visual cortex together with the psychophysical studies on the tuning of orientation detectors in human vision we suggest that time dependence in brightness perception can be accommodated through the time evolution of cortical contribution to the orientation tuning of the ODoG filter responses. A set of Difference of Gaussians functions has been used to mimic the time dependence of orientation tuning. The tuning of orientation preference and its inversion at a later time have been considered in explaining qualitatively the temporal dynamics of brightness perception observed in "Brief presentations reveal the temporal dynamics of brightness induction and White's illusion" for 58 and 82 ms of stimulus exposure.

  1. CCD Photometry of bright stars using objective wire mesh

    Energy Technology Data Exchange (ETDEWEB)

    Kamiński, Krzysztof; Zgórz, Marika [Astronomical Observatory Institute, Faculty of Physics, A. Mickiewicz University, Słoneczna 36, 60-286 Poznań (Poland); Schwarzenberg-Czerny, Aleksander, E-mail: chrisk@amu.edu.pl [Copernicus Astronomical Centre, ul. Bartycka 18, PL 00-716 Warsaw (Poland)

    2014-06-01

    Obtaining accurate photometry of bright stars from the ground remains problematic due to the danger of overexposing the target and/or the lack of suitable nearby comparison stars. The century-old method of using objective wire mesh to produce multiple stellar images seems promising for the precise CCD photometry of such stars. Furthermore, our tests on β Cep and its comparison star, differing by 5 mag, are very encouraging. Using a CCD camera and a 20 cm telescope with the objective covered by a plastic wire mesh, in poor weather conditions, we obtained differential photometry with a precision of 4.5 mmag per two minute exposure. Our technique is flexible and may be tuned to cover a range as big as 6-8 mag. We discuss the possibility of installing a wire mesh directly in the filter wheel.

  2. Testing sky brightness models against radial dependency: a dense two dimensional survey around the city of Madrid, Spain

    CERN Document Server

    Zamorano, Jaime; Ocaña, Francisco; Pila-Diez, Berenice; Castaño, José Gómez; Pascual, Sergio; Tapia, Carlos; Gallego, Jesús; Fernandez, Alberto; Nievas, Miguel

    2015-01-01

    We present a study of the night sky brightness around the extended metropolitan area of Madrid using Sky Quality Meter (SQM) photometers. The map is the first to cover the spatial distribution of the sky brightness in the center of the Iberian peninsula. These surveys are neccessary to test the light pollution models that predict night sky brightness as a function of the location and brightness of the sources of light pollution and the scattering of light in the atmosphere. We describe the data-retrieval methodology, which includes an automated procedure to measure from a moving vehicle in order to speed up the data collection, providing a denser and wider survey than previous works with similar time frames. We compare the night sky brightness map to the nocturnal radiance measured from space by the DMSP satellite. We find that i) a single source model is not enough to explain the radial evolution of the night sky brightness, despite the predominance of Madrid in size and population, and ii) that the orograph...

  3. Testing sky brightness models against radial dependency: A dense two dimensional survey around the city of Madrid, Spain

    Science.gov (United States)

    Zamorano, J.; Sánchez de Miguel, A.; Ocaña, F.; Pila-Díez, B.; Gómez Castaño, J.; Pascual, S.; Tapia, C.; Gallego, J.; Fernández, A.; Nievas, M.

    2016-09-01

    We present a study of the night sky brightness around the extended metropolitan area of Madrid using Sky Quality Meter (SQM) photometers. The map is the first to cover the spatial distribution of the sky brightness in the centre of the Iberian peninsula. These surveys are necessary to test the light pollution models that predict night sky brightness as a function of the location and brightness of the sources of light pollution and the scattering of light in the atmosphere. We describe the data-retrieval methodology, which includes an automated procedure to measure from a moving vehicle in order to speed up the data collection, providing a denser and wider survey than previous works with similar time frames. We compare the night sky brightness map to the nocturnal radiance measured from space by the DMSP satellite. We find that (i) a single source model is not enough to explain the radial evolution of the night sky brightness, despite the predominance of Madrid in size and population and (ii) that the orography of the region should be taken into account when deriving geo-specific models from general first-principles models. We show the tight relationship between these two luminance measures. This finding sets up an alternative roadmap to extended studies over the globe that will not require the local deployment of photometers or trained personnel.

  4. An Extremely Bright Echo Associated With SN 2002hh

    CERN Document Server

    Welch, D L; Campbell, Amy; Barlow, M J; Sugerman, Ben E K; Meixner, Margaret; Bank, S H R

    2007-01-01

    We present new, very late-time optical photometry and spectroscopy of the interesting Type II-P supernova, SN 2002hh, in NGC 6946. Gemini/GMOS-N has been used to acquire visible spectra at six epochs between 2004 August and 2006 July, following the evolution of the SN from age 661 to 1358 days. Few optical spectra of Type II supernovae with ages greater than one year exist. In addition, g'r'i' images were acquired at all six epochs. The spectral and photometric evolution of SN 2002hh has been very unusual. Measures of the brightness of this SN, both in the R and I bands as well as in the H-alpha emission flux, show no significant fading over an interval of nearly two years. The most straightforward explanation for this behavior is that the light being measured comes not only from the SN itself but also from an echo off of nearby dust. Echoes have been detected previously around several SNe but these echoes, at their brightest, were ~8 mag below the maximum brightness of the SN. At V~21 mag, the putative echo ...

  5. Bright PanSTARRS Nuclear Transients – what are they?

    Directory of Open Access Journals (Sweden)

    Smartt S.

    2012-12-01

    Full Text Available We present an initial analysis of 49 bright transients occurring in the nuclei of galaxies with no previous known Active Galactic Nucleus (AGN. They have been discovered as part of the PanSTARRs 3π survey, and followed up with the Liverpool Telescope. Based on colours, light curve shape, and a small number with optical spectra, these transients seem to fall into three groups. Red/fast transients are nuclear supernovae of various types. Some bright nuclear transients are blue and decay on a timescale of a few months; these may be candidates for tidal disruption events. However most of the events we have found are blue and are either still rising or decaying slowly, on a timescale of years; the few spectra we have show AGN at z ∼ 1. We argue that these transients are background AGN microlensed by stars in foreground galaxies by a factor 10–100. Monitoring such events gives us very promising prospects for measuring the structure of AGN and so testing current theories.

  6. The first world atlas of the artificial night sky brightness

    CERN Document Server

    Cinzano, P; Elvidge, C D

    2001-01-01

    We present the first World Atlas of the zenith artificial night sky brightness at sea level. Based on radiance calibrated high resolution DMSP satellite data and on accurate modelling of light propagation in the atmosphere, it provides a nearly global picture of how mankind is proceeding to envelope itself in a luminous fog. Comparing the Atlas with the U.S. Department of Energy (DOE) population density database we determined the fraction of population who are living under a sky of given brightness. About two thirds of the World population and 99% of the population in US (excluding Alaska and Hawaii) and EU live in areas where the night sky is above the threshold set for polluted status. Assuming average eye functionality, about one fifth of the World population, more than two thirds of the US population and more than one half of the EU population have already lost naked eye visibility of the Milky Way. Finally, about one tenth of the World population, more than 40% of the US population and one sixth of the E...

  7. Some Activities with Polarized Light from a Laptop LCD Screen

    Science.gov (United States)

    Fakhruddin, Hasan

    2008-01-01

    The LCD screen of a laptop computer provides a broad, bright, and extended source of polarized light. A number of demonstrations on the properties of polarized light from a laptop computer screens are presented here.

  8. Some Activities with Polarized Light from a Laptop LCD Screen

    Science.gov (United States)

    Fakhruddin, Hasan

    2008-01-01

    The LCD screen of a laptop computer provides a broad, bright, and extended source of polarized light. A number of demonstrations on the properties of polarized light from a laptop computer screens are presented here.

  9. Suggestive correlations between the brightness of Neptune, solar variability, and Earth's temperature

    Science.gov (United States)

    Hammel, H. B.; Lockwood, G. W.

    2007-04-01

    Long-term photometric measurements of Neptune show variations of brightness over half a century. Seasonal change in Neptune's atmosphere may partially explain a general rise in the long-term light curve, but cannot explain its detailed variations. This leads us to consider the possibility of solar-driven changes, i.e., changes incurred by innate solar variability perhaps coupled with changing seasonal insolation. Although correlations between Neptune's brightness and Earth's temperature anomaly-and between Neptune and two models of solar variability-are visually compelling, at this time they are not statistically significant due to the limited degrees of freedom of the various time series. Nevertheless, the striking similarity of the temporal patterns of variation should not be ignored simply because of low formal statistical significance. If changing brightnesses and temperatures of two different planets are correlated, then some planetary climate changes may be due to variations in the solar system environment.

  10. Estimating all-sky night brightness maps from finite sets of SQM measurements

    Science.gov (United States)

    Tilve Rúa, V.; Ling, J. F.; Bará, S.; Sánchez de Miguel, A.; Nievas, M.; Zamorano, J.

    2015-05-01

    The all-sky night brightness distributions recorded at observing sites with moderate to high levels of light pollution can be efficiently described by polynomial series or relatively low order. This opens the way for estimating these continuous distributions from discrete sets of measurements made in different directions of the sky with photometric detectors of low spatial resolution as, e.g. the Sky Quality Meter, SQM^{TM} (10° HWHM). Modal estimations of the night sky brightness can be obtained by expanding their equal-area projection maps as a series of orthonormal functions, in particular Zernike polynomials, and fitting the unknown modal coefficients to the measurements provided by the detector. Least squares and minimum variance estimators can be easily developed once the linear functional relationship between the measurements and the actual sky brightness distribution is established.

  11. Splitting between bright and dark excitons in transition metal dichalcogenide monolayers

    Science.gov (United States)

    Echeverry, J. P.; Urbaszek, B.; Amand, T.; Marie, X.; Gerber, I. C.

    2016-03-01

    The optical properties of transition metal dichalcogenide monolayers such as the two-dimensional semiconductors MoS2 and WSe2 are dominated by excitons, Coulomb bound electron-hole pairs. The light emission yield depends on whether the electron-hole transitions are optically allowed (bright) or forbidden (dark). By solving the Bethe-Salpeter equation on top of G W wave functions in density functional theory calculations, we determine the sign and amplitude of the splitting between bright and dark exciton states. We evaluate the influence of the spin-orbit coupling on the optical spectra and clearly demonstrate the strong impact of the intra-valley Coulomb exchange term on the dark-bright exciton fine structure splitting.

  12. Night sky brightness at sites from DMSP-OLS satellite measurements

    CERN Document Server

    Cinzano, P

    2004-01-01

    We apply the sky brightness modelling technique introduced and developed by Roy Garstang to high-resolution DMSP-OLS satellite measurements of upward artificial light flux and to GTOPO30 digital elevation data in order to predict the brightness distribution of the night sky at a given site in the primary astronomical photometric bands for a range of atmospheric aerosol contents. This method, based on global data and accounting for elevation, Earth curvature and mountain screening, allows the evaluation of sky glow conditions over the entire sky for any site in the World, to evaluate its evolution, to disentangle the contribution of individual sources in the surrounding territory, and to identify main contributing sources. Sky brightness, naked eye stellar visibility and telescope limiting magnitude are produced as 3-dimensional arrays whose axes are the position on the sky and the atmospheric clarity. We compared our results to available measurements.

  13. 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.

  14. Improving sodium laser guide star brightness by polarization switching

    Science.gov (United States)

    Fan, Tingwei; Zhou, Tianhua; Feng, Yan

    2016-01-01

    Optical pumping with circularly polarized light has been used to enhance the brightness of sodium laser guide star. But the benefit is reduced substantially due to the precession of sodium atoms in geomagnetic field. Switching the laser between left and right circular polarization at the Larmor frequency is proposed to improve the return. With ESO’s laser guide star system at Paranal as example, numerical simulation shows that the return flux is increased when the angle between geomagnetic field and laser beam is larger than 60°, as much as 50% at 90°. The proposal is significant since most astronomical observation is at angle between 60° and 90° and it only requires a minor addition to the delivery optics of present laser system. PMID:26797503

  15. Sharp and Bright Photoluminescence Emission of Single Crystalline Diacetylene Nanoparticles

    CERN Document Server

    Kima, Seokho; Kima, Hyeong Tae; Cuic, Chunzhi; Park, Dong Hyuk

    2016-01-01

    Amorphous nanoparticles (NPs) of diacetylene (DA) molecules were prepared by using a reprecipitation method. After crystallization through solvent-vapor annealing process, the highly crystalline DA NPs show different structural and optical characteristics compared with the amorphous DA NPs. The single crystal structure of DA NPs was confirmed by high-resolution transmission electron microscopy (HR-TEM) and wide angle X-ray scattering (WAXS). The luminescence color and photoluminescence (PL) characteristics of the DA NPs were measured using color charge-coupled device (CCD) images and high-resolution laser confocal microscope (LCM). The crystalline DA NPs emit bright green light emission compared with amorphous DA NPs and the main PL peak of the crystalline DA NPs exhibits relative narrow and blue shift phenomena due to enhanced interaction between DA molecular in the nano-size crystal structure.

  16. Source brightness fluctuation correction of solar absorption Fourier Transform mid infrared spectra

    Directory of Open Access Journals (Sweden)

    T. Ridder

    2011-01-01

    Full Text Available Solar absorption Fourier Transform infrared spectrometry is considered a precise and accurate method for the observation of trace gases in the atmosphere. The precision and accuracy of such measurements are dependent on the stability of the light source. Fluctuations in the source brightness reduce the precision and accuracy of the trace gas concentrations, but cannot always be avoided. Thus, a strong effort is made within the community to reduce the impact of source brightness fluctuations by applying a correction on the spectra following the measurements. So far, it could be shown that the precision and accuracy of CO2 total column concentrations could be improved by applying a source brightness fluctuation correction to spectra in the near infrared spectral region.

    The analysis of trace gas concentrations obtained from spectra in the mid infrared spectral region is fundamental. However, spectra 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 a source brightness fluctuation correction.

    Here, we show a method of source brightness fluctuation correction, which can be applied on spectra in the whole infrared spectral region including spectra measured with a MCT detector. We present a solution to remove the unknown offset in MCT interferograms allowing MCT spectra for an application of source brightness fluctuation correction. This gives an improvement in the quality of MCT spectra and we demonstrate an improvement in the retrieval of O3 profiles and total column concentrations.

    For a comparison with previous studies, we apply our source brightness fluctuation correction method on spectra in the near infrared spectral region and show an improvement in the retrieval of CO2 total column concentrations.

  17. Emittance measurement of high-brightness microbeams

    Energy Technology Data Exchange (ETDEWEB)

    Ishizuka, Hiroshi; Nakahara, Yuriko (Fukuoka Inst. of Tech. (Japan)); Kawasaki, Sunao; Musyoki, S.; Shimizu, Hiroshi; Watanabe, Akihiko; Shiho, Makoto

    1994-09-01

    Arrays of microtriodes have recently become available due to the development of microfabricated field-emission electron sources. Computer simulation has shown that the brightness of beams emitted by them is significantly higher than that of the common microbeams, and possible application of the accelerated beam to free electron lasers has been discussed. Experimentation on beam generation has started, but methods for diagnosing the beam have not yet been established. Difficulty is predicted, because of the high brightness, in applying the conventional methods of emittance measurement. In this paper we propose a new method that determines the emittance without using apertures. The cross section of a converging beam is elongated by a quadrupole lens, and parameters of the emittance ellipse are obtained from the beam size on a screen when changing either the strength or the axial position of the quadrupole lens. (author).

  18. Human CD56bright NK Cells

    DEFF Research Database (Denmark)

    Michel, Tatiana; Poli, Aurélie; Cuapio, Angelica

    2016-01-01

    Human NK cells can be subdivided into various subsets based on the relative expression of CD16 and CD56. In particular, CD56(bright)CD16(-/dim) NK cells are the focus of interest. They are considered efficient cytokine producers endowed with immunoregulatory properties, but they can also become...... cytotoxic upon appropriate activation. These cells were shown to play a role in different disease states, such as cancer, autoimmunity, neuroinflammation, and infection. Although their phenotype and functional properties are well known and have been extensively studied, their lineage relationship with other...... NK cell subsets is not fully defined, nor is their precise hematopoietic origin. In this article, we summarize recent studies about CD56(bright) NK cells in health and disease and briefly discuss the current controversies surrounding them....

  19. The bright optical flash from GRB 060117

    CERN Document Server

    Jel'inek, M; Kubánek, P; Hudec, R; Nekola, M; Grygar, J; Castro-Tirado, A J; Gorosabel, J; Hrabovsk'y, M; Mandat, D; Nosek, D; Palatka, M; Pandey, S B; Pech, M; Schovanek, P; De Postigo, A U; Vítek, S; Jel\\'inek, Martin; Prouza, Michael; Kub\\'anek, Petr; Hudec, Ren\\'e; Nekola, Martin; R}\\'idk\\'y, Jan {; Grygar, Ji{r}\\'i; Castro-Tirado, Alberto J.; Gorosabel, Javier; Hrabovsk\\'y, Miroslav; Mand\\'at, Du{s}an; Nosek, Dalibor; Palatka, Miroslav; Pandey, Shashi B.; Pech, Miroslav; Schov\\'anek, Petr; S}m\\'ida, Radom\\'ir {; Postigo, Antonio de Ugarte; V\\'itek, Stanislav

    2006-01-01

    We present a discovery and observation of an extraordinarily bright prompt optical emission of the GRB 060117 obtained by a wide-field camera atop the robotic telescope FRAM of the Pierre Auger Observatory from 2 to 10 minutes after the GRB. We found rapid average temporal flux decay of alpha = -1.7 +- 0.1 and a peak brightness R = 10.1 mag. Later observations by other instruments set a strong limit on the optical and radio transient fluxes, unveiling an unexpectedly rapid further decay. We present an interpretation featuring a relatively steep electron-distribution parameter p ~ 3.0 and providing a straightforward solution for the overall fast decay of this optical transient as a transition between reverse and forward shock.

  20. Brightness of synchrotron radiation from wigglers

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2014-12-15

    According to literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so called 'depth-of-field' effects. In fact, the particle beam cross section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. In the geometrical optics limit computations can be performed analytically. Within this limit, we restrict ourselves to the case of the beam size-dominated regime, which is typical for synchrotron radiation facilities in the X-ray wavelength range. We give a direct demonstration of the fact that the apparent horizontal source size is broadened in proportion to the beamline opening angle and to the length of the wiggler. While this effect is well-understood, a direct proof appears not to have been given elsewhere. We consider the problem of the calculation of the wiggler source size by means of numerical simulations alone, which play the same role of an experiment. We report a significant numerical disagreement between exact calculations and approximations currently used in literature.

  1. Modular Zero Energy. BrightBuilt Home

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, Robb [Steven Winter Associates, Inc., Norwalk, CT (United States); Butterfield, Karla [Steven Winter Associates, Inc., Norwalk, CT (United States)

    2016-03-01

    With funding from the Building America Program, part of the U.S. Department of Energy Building Technologies Office, the Consortium for Advanced Residential Buildings (CARB) worked with BrightBuilt Home (BBH) to evaluate and optimize building systems. CARB’s work focused on a home built by Black Bros. Builders in Lincolnville, Maine (International Energy Conservation Code Climate Zone 6). As with most BBH projects to date, modular boxes were built by Keiser Homes in Oxford, Maine.

  2. Extreme Ultraviolet Explorer Bright Source List

    Science.gov (United States)

    Malina, Roger F.; Marshall, Herman L.; Antia, Behram; Christian, Carol A.; Dobson, Carl A.; Finley, David S.; Fruscione, Antonella; Girouard, Forrest R.; Hawkins, Isabel; Jelinsky, Patrick

    1994-01-01

    Initial results from the analysis of the Extreme Ultraviolet Explorer (EUVE) all-sky survey (58-740 A) and deep survey (67-364 A) are presented through the EUVE Bright Source List (BSL). The BSL contains 356 confirmed extreme ultraviolet (EUV) point sources with supporting information, including positions, observed EUV count rates, and the identification of possible optical counterparts. One-hundred twenty-six sources have been detected longward of 200 A.

  3. Fate of E. coli O157:H7, Salmonella spp. and potential surrogate bacteria on apricot fruit, following exposure to UV-C light.

    Science.gov (United States)

    Yun, Juan; Yan, Ruixiang; Fan, Xuetong; Gurtler, Joshua; Phillips, John

    2013-09-16

    Some soft fruit, such as tree-ripened apricots, cannot be washed with aqueous sanitizers, due to their innate softness and delicate surfaces. In this study, ultraviolet-C (UV-C) light was investigated for its efficacy in inactivating 4-5 individual strains of Escherichia coli O157:H7 and Salmonella spp. on apricots, in addition to a four-strain composite of Shiga toxin-negative E. coli O157:H7 and a cocktail of three attenuated strains of Salmonella Typhimurium and Salmonella Typhimurium LT2. Also, the survival of E. coli O157:H7 and Salmonella spp. after exposure to 74 and 442 mJ/cm² of UV-C was evaluated during post-UV storage at 2 and 20 °C. The fruit was spot inoculated and the areas (ca. 1.5 cm²) of fruit surface with the inoculated bacteria were exposed to UV-C at 7.4 mW/cm². E. coli O157:H7 and Salmonella spp. populations decreased rapidly (1-2 logs) (PSalmonella spp. During storage at 2 or 20 °C, populations of pathogenic E. coli O157:H7 and Salmonella spp. on untreated fruit decreased slowly; however, populations on fruit treated with 442 mJ/cm² decreased rapidly at both temperatures. After 8 days at 20 °C or 21 days at 2 °C, E. coli O157:H7 and Salmonella spp. populations on UV-C treated fruit were at least 2 log CFU/g lower than on non-treated controls. Our results suggest that surface-inoculated bacteria survived poorly following UV-C treatment of apricots.

  4. The night sky brightness at Potsdam-Babelsberg including overcast and moonlit conditions

    Science.gov (United States)

    Puschnig, Johannes; Schwope, Axel; Posch, Thomas; Schwarz, Robert

    2014-05-01

    We analyze the results of 2 years (2011-2012) of night sky photometry performed at the Leibniz Institute for Astrophysics in Potsdam-Babelsberg. This institute is located 23 km to the southwest of the center of Berlin. Our measurements have been performed with a Sky Quality Meter. We find night sky brightness values ranging from 16.5 to 20.3 magSQM arcsec-2; the latter value corresponds to 4.8 times the natural zenithal night sky brightness. We focus on the influence of clouds and of the moon on the night sky brightness. It turns out that Potsdam-Babelsberg, despite its proximity to Berlin, still shows a significant correlation of the night sky brightness with the lunar phases. However, the light-pollution-enhancing effect of clouds dominates the night sky brightness by far: overcast nights (up to 16.5 magSQM arcsec-2) are much brighter than clear full moon nights (18-18.5 magSQM arcsec-2).

  5. The Bright SHARC Survey The Cluster Catalog

    CERN Document Server

    Romer, A K; Holden, B P; Ulmer, M P; Pildis, R A; Merrelli, A J; Adami, C; Burke, D J; Collins, C A; Metevier, A J; Kron, Richard G; Commons, K

    1999-01-01

    We present the Bright SHARC (Serendipitous High-Redshift Archival ROSAT Cluster) Survey, which is an objective search for serendipitously detected extended X-ray sources in 460 deep ROSAT PSPC pointings. The Bright SHARC Survey covers an area of 178.6 sq.deg and has yielded 374 extended sources. We discuss the X-ray data reduction, the candidate selection and present results from our on-going optical follow-up campaign. The optical follow-up concentrates on the brightest 94 of the 374 extended sources and is now 97% complete. We have identified thirty-seven clusters of galaxies, for which we present redshifts and luminosities. The clusters span a redshift range of 0.0696Bright SHARC clusters have not been listed in any previously ...

  6. On the origin of facular brightness

    CERN Document Server

    Kostik, R

    2016-01-01

    This paper studies the dependence of the CaIIH line core brightness on the strength and inclination of photospheric magnetic field, and on the parameters of convective and wave motions in a facular region at the solar disc center. We use three simultaneous datasets obtained at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife): (1) spectra of BaII 4554 A line registered with the instrument TESOS to measure the variations of intensity and velocity through the photosphere up to the temperature minimum; (2) spectropolarimetric data in FeI 1.56 $\\mu$m lines (registered with the instrument TIP II) to measure photospheric magnetic fields; (3) filtergrams in CaIIH that give information about brightness fluctuations in the chromosphere. The results show that the CaIIH brightness in the facula strongly depends on the power of waves with periods in the 5-min range, that propagate upwards, and also on the phase shift between velocity oscillations at the bottom photosphere and around the temperature min...

  7. Brightness illusion in the guppy (Poecilia reticulata).

    Science.gov (United States)

    Agrillo, Christian; Miletto Petrazzini, Maria Elena; Bisazza, Angelo

    2016-02-01

    A long-standing debate surrounds the issue of whether human and nonhuman species share similar perceptual mechanisms. One experimental strategy to compare visual perception of vertebrates consists in assessing how animals react in the presence of visual illusions. To date, this methodological approach has been widely used with mammals and birds, while few studies have been reported in distantly related species, such as fish. In the present study we investigated whether fish perceive the brightness illusion, a well-known illusion occurring when 2 objects, identical in physical features, appear to be different in brightness. Twelve guppies (Poecilia reticulata) were initially trained to discriminate which rectangle was darker or lighter between 2 otherwise identical rectangles. Three different conditions were set up: neutral condition between rectangle and background (same background used for both darker and lighter rectangle); congruent condition (darker rectangle in a darker background and lighter rectangle in a lighter background); and incongruent condition (darker rectangle in a lighter background and lighter rectangle in a darker background). After reaching the learning criterion, guppies were presented with the illusory pattern: 2 identical rectangles inserted in 2 different backgrounds. Guppies previously trained to select the darker rectangle showed a significant choice of the rectangle that appears to be darker by human observers (and vice versa). The human-like performance exhibited in the presence of the illusory pattern suggests the existence of similar perceptual mechanisms between humans and fish to elaborate the brightness of objects.

  8. BRIGHT BROADBAND AFTERGLOWS OF GRAVITATIONAL WAVE BURSTS FROM MERGERS OF BINARY NEUTRON STARS

    Energy Technology Data Exchange (ETDEWEB)

    Gao He; Ding Xuan; Wu Xuefeng [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Zhang Bing [Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States); Dai Zigao, E-mail: xfwu@pmo.ac.cn, E-mail: zhang@physics.unlv.edu, E-mail: dzg@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

    2013-07-10

    If double neutron star mergers leave behind a massive magnetar rather than a black hole, then a bright early afterglow can follow the gravitational wave burst (GWB) even if there is no short gamma-ray burst (SGRB)-GWB association or if there is an association but the SGRB does not beam toward Earth. Besides directly dissipating the proto-magnetar wind, as suggested by Zhang, here we suggest that the magnetar wind could push the ejecta launched during the merger process and, under certain conditions, would reach a relativistic speed. Such a magnetar-powered ejecta, when interacting with the ambient medium, would develop a bright broadband afterglow due to synchrotron radiation. We study this physical scenario in detail and present the predicted X-ray, optical, and radio light curves for a range of magnetar and ejecta parameters. We show that the X-ray and optical light curves usually peak around the magnetar spin-down timescale ({approx}10{sup 3}-10{sup 5} s), reaching brightnesses readily detectable by wide-field X-ray and optical telescopes, and remain detectable for an extended period. The radio afterglow peaks later, but is much brighter than the case without a magnetar energy injection. Therefore, such bright broadband afterglows, if detected and combined with GWBs in the future, would be a probe of massive millisecond magnetars and stiff equations of state for nuclear matter.

  9. Estimation of the space density of low surface brightness galaxies

    NARCIS (Netherlands)

    Briggs, FH

    1997-01-01

    The space density of low surface brightness and tiny gas-rich dwarf galaxies are estimated for two recent catalogs: the Arecibo Survey of Northern Dwarf and Low Surface Brightness Galaxies and the Catalog of Low Surface Brightness Galaxies, List II. The goals are (1) to evaluate the additions to the

  10. Exposure assessment of aluminum arc welding radiation.

    Science.gov (United States)

    Peng, Chiung-yu; Lan, Cheng-hang; Juang, Yow-jer; Tsao, Ta-ho; Dai, Yu-tung; Liu, Hung-hsin; Chen, Chiou-jong

    2007-10-01

    The purpose of this study is to evaluate the non-ionizing radiation (NIR) exposure, especially optical radiation levels, and potential health hazard from aluminum arc welding processes based on the American Conference of Governmental Industrial Hygienists (ACGIH) method. The irradiance from the optical radiation emissions can be calculated with various biological effective parameters [i.e., S(lambda), B(lambda), R(lambda)] for NIR hazard assessments. The aluminum arc welding processing scatters bright light with NIR emission including ultraviolet radiation (UVR), visible, and infrared spectra. The UVR effective irradiance (Eeff) has a mean value of 1,100 microW cm at 100 cm distance from the arc spot. The maximum allowance time (tmax) is 2.79 s according to the ACGIH guideline. Blue-light hazard effective irradiance (EBlue) has a mean value of 1840 microW cm (300-700 nm) at 100 cm with a tmax of 5.45 s exposure allowance. Retinal thermal hazard effective calculation shows mean values of 320 mW cm(-2) sr(-1) and 25.4 mW (cm-2) (380-875 nm) for LRetina (spectral radiance) and ERetina (spectral irradiance), respectively. From this study, the NIR measurement from welding optical radiation emissions has been established to evaluate separate types of hazards to the eye and skin simultaneously. The NIR exposure assessment can be applied to other optical emissions from industrial sources. The data from welding assessment strongly suggest employees involved in aluminum welding processing must be fitted with appropriate personal protection devices such as masks and gloves to prevent serious injuries of the skin and eyes upon intense optical exposure.

  11. ESCA (XPS) study on light-induced yellowing of thermomechanical and chemothermomechanical pulps

    Science.gov (United States)

    Tóth, András; Faix, Oskar; Rachor, Georg; Bertóti, Imre; Székely, Tamás

    1993-11-01

    Thermomechanical and chemothermomechanical pulp samples have been derived from Norway spruce ( Picea abies) and characterized by brightness measurements and ESCA before and after exposure to artificial light irradiation. The surface O/C atomic ratios of the non-irradiated pulps were found to be between 0.3 and 0.37, which was interpreted as being due to their high surface lignin contents. The brightness reversion was accompanied by a considerable increase in the surface O/C ratio, by a decrease in the relative intensity of the C1 component of the C1s peak ( BE = 285.0 eV), and by increases in those of the C2 ( BE = 286.6 eV) and C3 ( BE = 288.2 eV) parts. It had no effect on the shapes of the O 1s peaks. The results were related to the photo-oxidation and photoyellowing of high-yield pulps.

  12. Test-retest repeatability of the pupil light response to blue and red light stimuli in normal human eyes using a novel pupillometer

    DEFF Research Database (Denmark)

    Herbst, Kristina; Sander, Birgit; Milea, Dan;

    2011-01-01

    In this study, we evaluated the repeatability of pupil responses to colored light stimuli in healthy subjects using a prototype chromatic pupillometer. One eye of 10 healthy subjects was tested twice in the same day using monochromatic light exposure at two selected wavelengths (660 and 470 nm...... stimulation as the total area between a reference line representing baseline pupil size and the line representing actual pupil size over 20 s (area under the curve). There was no significant difference in the repeated measure compared to the first test for any of the pupil response parameters. In conclusion......, we have developed a novel prototype of color pupillometer which demonstrates good repeatability in evoking and recording the pupillary response to a bright blue and red light stimulus....

  13. The radio properties of bright Seyfert galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Giuricin, G.; Mardirossian, F.; Mezzetti, M.; Bertotti, G. (Centro Interuniversitario Regionale per l' Astrofisica e la Cosmologia (Italy) Centre for Advanced Research in Space Optics (Italy))

    1990-03-01

    The radio properties of a sample of 69 bright spectroscopically selected Seyfert galaxies, which suffers from little bias toward Markarian galaxies with strong UV excess. At variance with most of the earlier results, generally based on galaxy samples which are strongly biased toward the inclusion of Markarian objects, there is no clear evidence of a significant difference in the major radio properties (radio power, radio-to-optical luminosity ratio, radio spectral index and radio size) of type 1 and type 2 Seyferts. The resulting observational scenario appears now to be more consistent than before with the idea that Seyfert 2 galaxies are simply Seyfert 1 obscured objects. 70 refs.

  14. Rapid Brightness Variations as a Tool to Enhance Satellite Detectability

    Science.gov (United States)

    Laas-Bourez, Myrtille; Klotz, Alain; Ducrotte, Etienne; Boer, Michel; Blanchet, Gwendoline

    2009-03-01

    To preserve the space environment for future generations and ensure the safety of space missions, we have to improve our knowledge of the debris at all altitudes. Since 2004, we have started to observe and study satellites and debris on the geostationary orbit. We use a network of robotic telescopes called TAROT (Télescopes Action Rapide pour les Objets Transitoires - Rapid Action Telescope for Transient Objects) which are located in France and Chile. This system processes the data in real time. Its wide field of view is useful for detection, systematic survey and to follow both catalogued and uncatalogued objects. The TAROTs are 25 cm telescopes with a wide field of view of 1.86deg x 1.86deg. It can detect objects up to 17th magnitude with an integration time of 30 seconds, corresponding to an object of 50cm in the geostationary belt with a 0.2 albedo. Tiny debris are also dangerous for space mission and satellites. To detect them, we need either to increase the TAROT sensitivity or to observe them in optimal light conditions.Last year we detected very important magnitude variations from several geostationary satellites during observations close to equinoxes. The brightness of a geostationary satellite evolves during the night and during the year, depending on the angle between the observer, the satellite and the sun. Geostationary satellites will be brighter near March 1st and of October 10th, at their exit of the shade. In this period the sun crosses the equatorial plan of the Earth, the enlightened surface will reach a maximum during a limited periods of time (about 30 minutes), provoking a short, bright flash. This phenomenon is used in two ways: first, it allows to detect smaller objects, which are usually below the detection limit, enhancing the sensitivity of the survey. Secondly, for longer objects the light curve during and outside the °ash contains information on the object intrinsic geometry and reflectivity. In this paper we discuss how the various

  15. The role of the Fraunhofer lines in solar brightness variability

    CERN Document Server

    Shapiro, A I; Krivova, N A; Tagirov, R V; Schmutz, W K

    2015-01-01

    The solar brightness varies on timescales from minutes to decades. A clear identification of the physical processes behind such variations is needed for developing and improving physics-based models of solar brightness variability and reconstructing solar brightness in the past. This is, in turn, important for better understanding the solar-terrestrial and solar-stellar connections. We estimate the relative contributions of the continuum, molecular, and atomic lines to the solar brightness variations on different timescales. Our approach is based on the assumption that variability of the solar brightness on timescales greater than a day is driven by the evolution of the solar surface magnetic field. We calculated the solar brightness variations employing the solar disc area coverage of magnetic features deduced from the MDI/SOHO observations. The brightness contrasts of magnetic features relative to the quiet Sun were calculated with a non-LTE radiative transfer code as functions of disc position and waveleng...

  16. Photometry of some neglected bright cataclysmic variables and candidates

    Science.gov (United States)

    Bruch, Albert

    2017-04-01

    As part of an effort to better characterize bright cataclysmic variables (CVs) which have received little attention in the past light curves of four confirmed systems (CZ Aql, BO Cet, V380 Oph and EF Tuc) and one candidate (Lib 3) are analyzed. For none of these stars time resolved photometry has been published previously. While no variability was found in the case of Lib 3, which thus cannot be confirmed as a CV, the light curves of all other targets are dominated by strong flickering. Modulations on hourly time scales superimposed on the flickering can probably be related to orbital variations in BO Cet and V380 Oph, but not in CZ Aql and EF Tuc. Variations on the time scale of 10 min in CZ Aql, while not yet constituting convincing evidence, together with previous suspicions of a magnetically channeled accretion flow may point at an intermediate polar nature of this star. Some properties of the flickering are quantified in an effort to enlarge the data base for future comparative flickering studies in CVs and to refine the classification of the target stars.

  17. Photometry of some neglected bright cataclysmic variables and candidates

    CERN Document Server

    Bruch, Albert

    2016-01-01

    As part of an effort to better characterize bright cataclysmic variables (CVs) which have received little attention in the past light curves of four confirmed systems (CZ Aql, BO Cet, V380 Oph and EF Tuc) and one candidate (Lib 3) are analyzed. For none of these stars time resolved photometry has been published previously. While no variability was found in the case of Lib 3, which thus cannot be confirmed as a CV, the light curves of all other targets are dominated by strong flickering. Modulations on hourly time scales superimposed on the flickering can probably be related to orbital variations in BO Cet and V380 Oph, but not in CZ Aql and EF Tuc. Variations on the time scale of 10 minutes in CZ Aql, while not yet constituting convincing evidence, together with previous suspicions of a magnetically channeled accretion flow may point at an intermediate polar nature of this star. Some properties of the flickering are quantified in an effort to enlarge the data base for future comparative flickering studies in ...

  18. Coronal bright points associated with minifilament eruptions

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Junchao; Jiang, Yunchun; Yang, Jiayan; Bi, Yi; Li, Haidong [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Yang, Bo; Yang, Dan, E-mail: hjcsolar@ynao.ac.cn [Also at Graduate School of Chinese Academy of Sciences, Beijing, China. (China)

    2014-12-01

    Coronal bright points (CBPs) are small-scale, long-lived coronal brightenings that always correspond to photospheric network magnetic features of opposite polarity. In this paper, we subjectively adopt 30 CBPs in a coronal hole to study their eruptive behavior using data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. About one-quarter to one-third of the CBPs in the coronal hole go through one or more minifilament eruption(s) (MFE(s)) throughout their lifetimes. The MFEs occur in temporal association with the brightness maxima of CBPs and possibly result from the convergence and cancellation of underlying magnetic dipoles. Two examples of CBPs with MFEs are analyzed in detail, where minifilaments appear as dark features of a cool channel that divide the CBPs along the neutral lines of the dipoles beneath. The MFEs show the typical rising movements of filaments and mass ejections with brightenings at CBPs, similar to large-scale filament eruptions. Via differential emission measure analysis, it is found that CBPs are heated dramatically by their MFEs and the ejected plasmas in the MFEs have average temperatures close to the pre-eruption BP plasmas and electron densities typically near 10{sup 9} cm{sup –3}. These new observational results indicate that CBPs are more complex in dynamical evolution and magnetic structure than previously thought.

  19. Internetwork chromospheric bright grains observed with IRIS

    CERN Document Server

    Martínez-Sykora, Juan; Carlsson, Mats; De Pontieu, Bart; Pereira, Tiago M D; Boerner, Paul; Hurlburt, Neal; Kleint, Lucia; Lemen, James; Tarbell, Ted D; Title, Alan; Wuelser, Jean-Pierre; Hansteen, Viggo H; Golub, Leon; McKillop, Sean; Reeves, Kathy K; Saar, Steven; Testa, Paola; Tian, Hui; Jaeggli, Sarah; Kankelborg, Charles

    2015-01-01

    The Interface Region Imaging Spectrograph (IRIS) reveals small-scale rapid brightenings in the form of bright grains all over coronal holes and the quiet sun. These bright grains are seen with the IRIS 1330 \\AA, 1400 \\AA\\ and 2796 \\AA\\ slit-jaw filters. We combine coordinated observations with IRIS and from the ground with the Swedish 1-m Solar Telescope (SST) which allows us to have chromospheric (Ca II 8542 \\AA, Ca II H 3968 \\AA, H\\alpha, and Mg II k 2796 \\AA), and transition region (C II 1334 \\AA, Si IV 1402) spectral imaging, and single-wavelength Stokes maps in Fe I 6302 \\AA at high spatial (0.33"), temporal and spectral resolution. We conclude that the IRIS slit-jaw grains are the counterpart of so-called acoustic grains, i.e., resulting from chromospheric acoustic waves in a non-magnetic environment. We compare slit-jaw images with spectra from the IRIS spectrograph. We conclude that the grain intensity in the 2796 \\AA\\ slit-jaw filter comes from both the Mg II k core and wings. The signal in the C II ...

  20. Spectral evolution of bright NS LMXBs

    CERN Document Server

    Paizis, A; Mainardi, L I; Titarchuk, L

    2010-01-01

    Theoretical and observational support suggests that the spectral evolution of neutron-star LMXBs, including transient hard X-ray tails, may be explained by the interplay between thermal and bulk motion Comptonization. In this framework, we developed a new model for the X-ray spectral fitting XSPEC package which takes into account the effects of both thermal and dynamical (i.e. bulk) Comptonization, CompTB. Using data from the INTEGRAL satellite, we tested our model on broad band spectra of a sample of persistently low magnetic field bright neutron star Low Mass X-ray Binaries, covering different spectral states. The case of the bright source GX 5-1 is presented here. Particular attention is given to the transient powerlaw-like hard X-ray (above 30 keV) tail that we interpret in the framework of the bulk motion Comptonization process, qualitatively describing the physical conditions of the environment in the innermost part of the system.

  1. Sublimation in bright spots on (1) Ceres.

    Science.gov (United States)

    Nathues, A; Hoffmann, M; Schaefer, M; Le Corre, L; Reddy, V; Platz, T; Cloutis, E A; Christensen, U; Kneissl, T; Li, J-Y; Mengel, K; Schmedemann, N; Schaefer, T; Russell, C T; Applin, D M; Buczkowski, D L; Izawa, M R M; Keller, H U; O'Brien, D P; Pieters, C M; Raymond, C A; Ripken, J; Schenk, P M; Schmidt, B E; Sierks, H; Sykes, M V; Thangjam, G S; Vincent, J-B

    2015-12-10

    The dwarf planet (1) Ceres, the largest object in the main asteroid belt with a mean diameter of about 950 kilometres, is located at a mean distance from the Sun of about 2.8 astronomical units (one astronomical unit is the Earth-Sun distance). Thermal evolution models suggest that it is a differentiated body with potential geological activity. Unlike on the icy satellites of Jupiter and Saturn, where tidal forces are responsible for spewing briny water into space, no tidal forces are acting on Ceres. In the absence of such forces, most objects in the main asteroid belt are expected to be geologically inert. The recent discovery of water vapour absorption near Ceres and previous detection of bound water and OH near and on Ceres (refs 5-7) have raised interest in the possible presence of surface ice. Here we report the presence of localized bright areas on Ceres from an orbiting imager. These unusual areas are consistent with hydrated magnesium sulfates mixed with dark background material, although other compositions are possible. Of particular interest is a bright pit on the floor of crater Occator that exhibits probable sublimation of water ice, producing haze clouds inside the crater that appear and disappear with a diurnal rhythm. Slow-moving condensed-ice or dust particles may explain this haze. We conclude that Ceres must have accreted material from beyond the 'snow line', which is the distance from the Sun at which water molecules condense.

  2. Mechanical electrodeposition of bright nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    ZHU ZengWei; ZHU Di; QU NingSong

    2008-01-01

    A new mechanical electrodeposition technology was proposed,and nanocrystal-line nickel deposit with bright and smooth surface was prepared in the bath without any additive agents.Unlike traditional methods,the novel technology employed dynamical hard particles to continuously polish the cathode surface and disturb the nearby solution during electrodepositing.Experimental results showed that the polishing effect of hard particles can effectively prevent the hydrogen bubbles and impurities from adhering on the deposit surface and avoid the production of pits,pinholes and nodules.Furthermore,comparing with the deposit prepared by tradi-tional methods,the one prepared by the novel technology was substantially refined with grain size ranging from 30 to 80 nm.Every diffraction peak's intensity of the deposit was reduced,the preferential orientation degree of (200) decreased and those of (111) and (220) increased.The microhardness notably increased.The magnetic properties were also changed with decreased saturation magnetization and increased coercive force.It was also found that variation of current density and cathode rotational speed could affect the structure and properties of the nickel deposits prepared by this technology.Key.words:electrodeposition,electroforming,hard particle,nanocrystalline,bright nickel deposits prepared by this technology.

  3. Modulation of the initial light reflex during affective picture viewing.

    Science.gov (United States)

    Henderson, Robert R; Bradley, Margaret M; Lang, Peter J

    2014-09-01

    An initial reflexive constriction of the pupil to stimulation-the light reflex-is primarily modulated by brightness, but is attenuated when participants are under threat of shock (i.e., fear-inhibited light reflex). The present study assessed whether the light reflex is similarly attenuated when viewing emotional pictures. Pupil diameter was recorded while participants viewed erotic, violent, and neutral scenes that were matched in brightness; scrambled versions identical in brightness were also presented as an additional control. Compared to viewing neutral scenes, the light reflex was reliably modulated by hedonic content, with significant attenuation both when viewing unpleasant as well as pleasant pictures. No differences in the light reflex were found among scrambled versions. Thus, emotional modulation of the initial light reflex is not confined to a context of fear and is not indicative of brightness differences when viewing pictures of natural scenes. Copyright © 2014 Society for Psychophysiological Research.

  4. Light-stimulated cell expansion in bean (Phaseolus vulgaris L.) leaves. I. Growth can occur without photosynthesis

    Science.gov (United States)

    Van Volkenburgh, E.; Cleland, R. E.

    1990-01-01

    Cell expansion in dicotyledonous leaves is strongly stimulated by bright white light (WL), at least in part as a result of light-induced acidification of the cell walls. It has been proposed that photosynthetic reactions are required for light-stimulated transport processes across plasma membranes of leaf cells, including proton excretion. The involvement of photosynthesis in growth and wall acidification of primary leaves of bean has been tested by inhibiting photosynthesis in two ways: by reducing chlorophyll content of intact plants with tentoxin (TX) and by treating leaf discs with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). Exposure to bright WL stimulated growth of intact leaves of TX-treated plants. Discs excised from green as well as from TX-or DCMU-treated leaves also responded by growing faster in WL, as long as exogenous sucrose was supplied to the photosynthetically inhibited tissues. The WL caused acidification of the epidermal surface of intact TX-leaves, but acidification of the incubation medium by mesophyll cells only occurred when photosynthesis was not inhibited. It is concluded that light-stimulated cell enlargement of bean leaves, and the necessary acidification of epidermal cell walls, are mediated by a pigment other than chlorophyll. Light-induced proton excretion by mesophyll cells, on the other hand, may require both a photosynthetic product (or exogenous sugars) and a non-photosynthetic light effect.

  5. The outer regions of galaxy clusters: Chandra constraints on the X-ray surface brightness

    CERN Document Server

    Ettori, S

    2008-01-01

    (Abridged version) We study the properties of the X-ray surface brightness profiles in a sample of galaxy clusters that are observed with Chandra and have emission detectable with a signal-to-noise ratio larger than 2 at a radius beyond R500 ~ 0.7 R200. Our study aims at measuring the slopes of the X-ray surface brightness and of the gas density profiles in the outskirts of massive clusters. These constraints are then compared to similar results obtained from observations and numerical simulations of the temperature and dark matter density profiles with the intention to present a consistent picture of the outer regions of galaxy clusters. We extract the surface brightness profiles S_b(r) from X-ray exposures obtained with Chandra of 52 X-ray luminous galaxy clusters at z>0.3. We estimate R200 both using a beta-model to reproduce the surface brightness profile and scaling relations from the literature, showing that the two methods converge to comparable values. We evaluate then the radius, R_S2N, at which the ...

  6. INVESTIGATION ON THE CAUSES OF EUCALYPTUS KRAFT PULP BRIGHTNESS REVERSION

    Directory of Open Access Journals (Sweden)

    Kátia M. M. Eiras

    2005-12-01

    Full Text Available Some high brightness eucalyptus Kraft pulps have shown poor brightness stability. In most cases, the causes have notbeen identified and permanent solutions have not been found. This work focused on evaluating the brightness stability profile of pulpsbleached by in sequences such as O(DC(PODD, O(DC(PODP, OD(PODD, OD(PODP, ODHT(PODD, ODHT(PODP, OA/D(PODD, OA/D(PODP, OAD(PODD and O(ZeD(PO. Brightness stability tests induced by according to Tappi UM200 procedureon samples bleached to 90±0.5% ISO. Brightness stability was measured after each bleaching stage of the various sequences andexpressed as brightness loss in % ISO. The results indicate that pulps bleached with sequences ending with a peroxide stage havehigher brightness stability compared to those ending with a chlorine dioxide stage. Pulps bleached with a standard sequence, initiatingwith a (DC stage, show brightness stability similar to that of pulp bleached by an ECF (Elementary chlorine free sequence initiatingwith a regular D0 stage. ECF sequences, initiated with hot stages produce pulps with higher brightness stability than sequencesinitiating with a regular D0 stage. The profile across the bleaching sequences shows a tendency of increased brightness stability inalkaline stages containing peroxide and decreased stability in those stages containing chlorine and/or chlorine dioxide, parallelingpulp carbonyl group content.

  7. 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.

  8. Programmable aperture microscopy: A computational method for multi-modal phase contrast and light field imaging

    Science.gov (United States)

    Zuo, Chao; Sun, Jiasong; Feng, Shijie; Zhang, Minliang; Chen, Qian

    2016-05-01

    We demonstrate a simple and cost-effective programmable aperture microscope to realize multi-modal computational imaging by integrating a programmable liquid crystal display (LCD) into a conventional wide-field microscope. The LCD selectively modulates the light distribution at the rear aperture of the microscope objective, allowing numerous imaging modalities, such as bright field, dark field, differential phase contrast, quantitative phase imaging, multi-perspective imaging, and full resolution light field imaging to be achieved and switched rapidly in the same setup, without requiring specialized hardwares and any moving parts. We experimentally demonstrate the success of our method by imaging unstained cheek cells, profiling microlens array, and changing perspective views of thick biological specimens. The post-exposure refocusing of a butterfly mouthpart and RFP-labeled dicot stem cross-section is also presented to demonstrate the full resolution light field imaging capability of our system for both translucent and fluorescent specimens.

  9. Light-Emitting Diodes in the Solid-State Lighting Systems

    CERN Document Server

    Sparavigna, Amelia Carolina

    2014-01-01

    Red and green light-emitting diodes (LEDs) had been produced for several decades before blue emitting diodes, suitable for lighting applications, were widely available. Today, we have the possibility of combining the three fundamental colours to have a bright white light. And therefore, a new form of lighting, the solid-state lighting, has now become a reality. Here we discuss LEDs and some of their applications in displays and lamps.

  10. 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.

  11. An Increasing Stellar Baryon Fraction in Bright Galaxies at High Redshift

    CERN Document Server

    Finkelstein, Steven L; Behroozi, Peter; Somerville, Rachel S; Papovich, Casey; Milosavljevic, Milos; Dekel, Avishai; Narayanan, Desika; Ashby, Matthew L N; Cooray, Asantha; Fazio, Giovanni G; Ferguson, Henry C; Koekemoer, Anton M; Salmon, Brett W; Willner, S P

    2015-01-01

    Recent observations have shown that the characteristic luminosity of the rest-frame ultraviolet (UV) luminosity function does not significantly evolve at 4 < z < 7 and is approximately M*_UV ~ -21. We investigate this apparent non-evolution by examining a sample of 190 bright, M_UV < -21 galaxies at z=4 to 7, analyzing their stellar populations and host halo masses. Including deep Spitzer/IRAC imaging to constrain the rest-frame optical light, we find that M*_UV galaxies at z=4-7 have similar stellar masses of log(M/Msol)=9.8-9.9 and are thus relatively massive for these high redshifts. However, bright galaxies at z=4-7 are less massive and have younger inferred ages than similarly bright galaxies at z=2-3, even though the two populations have similar star formation rates and levels of dust attenuation. We match the abundances of these bright z=4-7 galaxies to halo mass functions from the Bolshoi Lambda-CDM simulation to estimate the halo masses. We find that the typical halo masses in ~M*_UV galaxie...

  12. Low environmental impact bleaching sequences for attaining high brightness level with eucalyptus SPP pulp

    Directory of Open Access Journals (Sweden)

    M. M. Costa

    2009-03-01

    Full Text Available The alternatives used for minimizing the usage of chlorine dioxide in bleaching sequences included a hot acid hydrolysis (Ahot stage, the use of hot chlorine dioxide (Dhot and ozone stages at medium consistency and high consistency (Zmc and Zhc, in addition to stages with atmospheric hydrogen peroxide (P and pressurized hydrogen peroxide (PO. The results were interpreted based on the cost of the chemical products, bleaching process yields and on minimizing the environmental impact of the bleaching process. In spite of some process restrictions, high ISO brightness levels were kept around 90 % brightness. Additionally, the inclusion of stages like acid hydrolysis, pressurized peroxide and ozone in the bleaching sequences provided an increase in operating flexibility, aimed at reducing environmental impact (ECF Light. The Dhot(EOPD(PO sequence presented lower operating cost for ISO brightness above 92 %. However, this kind of sequence was not allowed for closing the wastewater circuit, even partially. For ISO brightness level around 91%, the AhotZhcDP sequence presented a lower operating cost than the others.

  13. Optical Sky Brightness at Cerro Tololo Inter-American Observatory from 1992 to 2006

    CERN Document Server

    Krisciunas, Kevin; Sanhueza, Pedro; Schwarz, Hugo E; Semler, Dylan R; Suntzeff, Nicholas B; Vera, Sergio

    2007-01-01

    We present optical UBVRI sky brightness measures from 1992 through 2006. The data are based on CCD imagery obtained with the CTIO 0.9-m, 1.3-m, and 1.5-m telescopes. The B- and V-band data are in reasonable agreement with measurements previously made at Mauna Kea, though on the basis of a small number of images per year there are discrepancies for the years 1992 through 1994. Our CCD-based data are not significantly different than values obtained at Cerro Paranal. We find that the yearly averages of V-band sky brightness are best correlated with the 10.7-cm solar flux taken 5 days prior to the sky brightness measures. This implies an average speed of 350 km/sec for the solar wind. While we can measure an enhancement of the night sky levels over La Serena 10 degrees above the horizon, at elevation angles above 45 degrees we find no evidence that the night sky brightness at Cerro Tololo is affected by artificial light of nearby towns and cities.

  14. Loss of Melanopsin Photoreception and Antagonism of the Histamine H3 Receptor by Ciproxifan Inhibit Light-Induced Sleep in Mice

    Science.gov (United States)

    Muindi, Fanuel; Colas, Damien; Ikeme, Jesse; Ruby, Norman F.; Heller, H. Craig

    2015-01-01

    Light has direct effects on sleep and wakefulness causing arousal in diurnal animals and sleep in nocturnal animals. In the present study, we assessed the modulation of light-induced sleep by melanopsin and the histaminergic system by exposing mice to millisecond light flashes and continuous light respectively. First, we show that the induction of sleep by millisecond light flashes is dose dependent as a function of light flash number. We found that exposure to 60 flashes of light occurring once every 60 seconds for 1-h (120-ms of total light over an hour) induced a similar amount of sleep as a continuous bright light pulse. Secondly, the induction of sleep by millisecond light flashes was attenuated in the absence of melanopsin when animals were presented with flashes occurring every 60 seconds over a 3-h period beginning at ZT13. Lastly, the acute administration of a histamine H3 autoreceptor antagonist, ciproxifan, blocked the induction of sleep by a 1-h continuous light pulse during the dark period. Ciproxifan caused a decrease in NREMS delta power and an increase in theta activity during both sleep and wake periods respectively. The data suggest that some form of temporal integration occurs in response to millisecond light flashes, and that this process requires melanopsin photoreception. Furthermore, the pharmacological data suggest that the increase of histaminergic neurotransmission is sufficient to attenuate the light-induced sleep response during the dark period. PMID:26083020

  15. Loss of Melanopsin Photoreception and Antagonism of the Histamine H3 Receptor by Ciproxifan Inhibit Light-Induced Sleep in Mice.

    Directory of Open Access Journals (Sweden)

    Fanuel Muindi

    Full Text Available Light has direct effects on sleep and wakefulness causing arousal in diurnal animals and sleep in nocturnal animals. In the present study, we assessed the modulation of light-induced sleep by melanopsin and the histaminergic system by exposing mice to millisecond light flashes and continuous light respectively. First, we show that the induction of sleep by millisecond light flashes is dose dependent as a function of light flash number. We found that exposure to 60 flashes of light occurring once every 60 seconds for 1-h (120-ms of total light over an hour induced a similar amount of sleep as a continuous bright light pulse. Secondly, the induction of sleep by millisecond light flashes was attenuated in the absence of melanopsin when animals were presented with flashes occurring every 60 seconds over a 3-h period beginning at ZT13. Lastly, the acute administration of a histamine H3 autoreceptor antagonist, ciproxifan, blocked the induction of sleep by a 1-h continuous light pulse during the dark period. Ciproxifan caused a decrease in NREMS delta power and an increase in theta activity during both sleep and wake periods respectively. The data suggest that some form of temporal integration occurs in response to millisecond light flashes, and that this process requires melanopsin photoreception. Furthermore, the pharmacological data suggest that the increase of histaminergic neurotransmission is sufficient to attenuate the light-induced sleep response during the dark period.

  16. Loss of Melanopsin Photoreception and Antagonism of the Histamine H3 Receptor by Ciproxifan Inhibit Light-Induced Sleep in Mice.

    Science.gov (United States)

    Muindi, Fanuel; Colas, Damien; Ikeme, Jesse; Ruby, Norman F; Heller, H Craig

    2015-01-01

    Light has direct effects on sleep and wakefulness causing arousal in diurnal animals and sleep in nocturnal animals. In the present study, we assessed the modulation of light-induced sleep by melanopsin and the histaminergic system by exposing mice to millisecond light flashes and continuous light respectively. First, we show that the induction of sleep by millisecond light flashes is dose dependent as a function of light flash number. We found that exposure to 60 flashes of light occurring once every 60 seconds for 1-h (120-ms of total light over an hour) induced a similar amount of sleep as a continuous bright light pulse. Secondly, the induction of sleep by millisecond light flashes was attenuated in the absence of melanopsin when animals were presented with flashes occurring every 60 seconds over a 3-h period beginning at ZT13. Lastly, the acute administration of a histamine H3 autoreceptor antagonist, ciproxifan, blocked the induction of sleep by a 1-h continuous light pulse during the dark period. Ciproxifan caused a decrease in NREMS delta power and an increase in theta activity during both sleep and wake periods respectively. The data suggest that some form of temporal integration occurs in response to millisecond light flashes, and that this process requires melanopsin photoreception. Furthermore, the pharmacological data suggest that the increase of histaminergic neurotransmission is sufficient to attenuate the light-induced sleep response during the dark period.

  17. Tunneling Dynamics Between Atomic Bright Solitons

    CERN Document Server

    Zhao, Li-Chen; Yang, Zhan-Ying; Yang, Wen-Li

    2016-01-01

    We investigate tunneling behavior between two bright solitons in a Bose-Einstein condensate with attractive contact interactions between atoms. The explicit tunneling properties including tunneling particles and oscillation period are described analytically, which indicates that the periodic tunneling form is a nonlinear Josephson type oscillation. The results suggest that the breathing behavior of solitons comes from the tunneling mechanism in an effective double-well potential, which is quite different from the modulational instability mechanism for Akhmediev breather and K-M breather. Furthermore, we obtain a phase diagram for two soliton interaction which admits tunneling property, particle-like property, interference property, and a resonant interaction case. The explicit conditions for them are clarified based on the defined critical distance $d_c$ and spatial interference period $D$.

  18. Dark Skies, Bright Kids Year 8

    Science.gov (United States)

    Bittle, Lauren E.; Wenger, Trey; Johnson, Kelsey E.; Angell, Dylan; Burkhardt, Andrew; Davis, Blair; Firebaugh, Ariel; Hancock, Danielle; Richardson, Whitney; Rochford Hayes, Christian; Linden, Sean; Liss, Sandra; Matthews, Allison; McNair, Shunlante; Prager, Brian; Pryal, Matthew; Troup, Nicholas William

    2017-01-01

    We present activities from the eighth year of Dark Skies Bright Kids (DSBK), an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in Central Virginia through fun, hands-on activities that introduce basic Astronomy concepts. Over the past seven years, our primary focus has been hosting an 8-10 week after-school astronomy club at underserved elementary and middle schools, and over the past several years, we have partnered with local businesses to host our Annual Central Virginia Star Party, a free event open to the community featuring star-gazing and planetarium shows. This past summer we expanded our reach through a new initiative to bring week-long summer day camps to south and southwest Virginia, home to some of the most underserved communities in the commonwealth.

  19. Coupling Bright and Dark Plasmonic Lattice Resonances

    CERN Document Server

    Rodriguez, S R K; Maes, B; Janssen, O T A; Vecchi, G; Rivas, J Gomez

    2011-01-01

    We demonstrate the coupling of bright and dark Surface Lattice Resonances (SLRs), which are collective Fano resonances in 2D plasmonic crystals. As a result of this coupling, a frequency stop-gap in the dispersion relation of SLRs is observed. The different field symmetries of the low and high frequency SLR bands lead to pronounced differences in their coupling to free space radiation. Standing waves of very narrow spectral width compared to localized surface plasmon resonances are formed at the high frequency band edge, while subradiant damping onsets at the low frequency band edge leading the resonance into darkness. We introduce a coupled oscillator analog to the plasmonic crystal, which serves to elucidate the physics of the coupled plasmonic resonances and to estimate very high quality factors (Q>700) for SLRs, which are the highest known for any 2D plasmonic crystal.

  20. Substructure of Quiet Sun Bright Points

    CERN Document Server

    Andic, Aleksandra; Goode, Phillip R

    2010-01-01

    Since photospheric bright points (BPs) were first observed, there has been a question as to how are they structured. Are they just single flux tubes or a bundle of the flux-tubes? Surface photometry of the quiet Sun (QS) has achieved resolution close to 0.1" with the New Solar Telescope at Big Bear Solar Observatory. This resolution allowed us to detect a richer spectrum of BPs in the QS. The smallest BPs we observed with TiO 705.68 nm were 0.13", and we were able to resolve individual components in some of the BPs clusters and ribbons observed in the QS, showing that they are composed of the individual BPs. Average size of observed BPs was 0.22".