Effect Of Intermittent Light Research Articles

Turning Ultraviolet Light Traps On and Off Increases Their Attraction to House Flies (Diptera: Muscidae).

Pairs of electrocutor-grid ultraviolet light traps were assigned to three treatments to evaluate the effects of illumination events, e.g., light traps turned on, on house fly, Musca domestica L., attraction as indicated by numbers of flies captured by the traps. Both traps in treatment 1 were illuminated constantly (no illumination event). Both traps in treatment 2 were turned on, illuminated for 1 h, then turned off for 1 h, then repeated (1 illumination event every 2 h). Traps in treatment 3 were operated singularly. One trap was turned on for 1 h, then turned off. As it turned off, the other trap turned on for 1 h, then turned off, then repeated (1 illumination event every hour). The mean number of flies attracted per trap pair was significantly greater in treatment 1 than in treatments 2 or 3. However, in treatment 3, with one trap illuminated at a time and hourly illumination events, the mean fly catch was just 27% less, numerically, than the mean number of flies attracted to treatment 1 with both traps illuminated constantly. The effects of intermittent lighting and its potential use are discussed.

暗期中断における間欠照明とその光質がキクの花芽分化抑制に及ぼす影響

キクの暗期中断における間欠照明の花芽分化抑制に対する有効性を赤色光（以下R光と略す）および赤色光 + 遠赤色光（以下R + FR光と略す）を用いて検証した．同一照射時間帯（22:00～2:00） で連続照明と間欠照明を比較したところ，R光およびR + FR光ともにDuty比が低下するにつれて花芽分化抑制効果が低下した．またR光の連続照明とDuty比0.5で積算の放射照度を連続照明に対して1.0および0.5に設定した間欠照明の効果を比較したところ，1.0区は連続照明と同等であったが，0.5区は連続照明に比較して効果が劣った．このことから，本実験ではキクの同一時間帯での連続照明に対する間欠照明の優位性は確認できなかった．次に，同一積算照射時間において短時間の連続光（18分） と間欠により3時間に照射時間帯を拡張した間欠照明を比較した場合では，R光は間欠照明の効果が認められなかったが，R + FR光では連続照明に比較して間欠照明の花芽分化抑制効果が高くなった．これは短時間照明（18分） の場合，R + FR光の連続照明は，R + FR光によるフィトクロムの低Pfrレベルにより，暗期中断の効果が低下することによると考えられた．また，連続照明の時間帯を変えることで暗期中断の効果が変化したことから，同一積算照射時間の場合は，キクの暗期中断に対する感度が時間帯で変化することに注意する必要があると考えられた．実際のキク電照栽培では，暗期中断の時間がR + FR光での低Pfrによる花芽分化抑制効果の低下が発現する時間よりも比較的長時間であるために，間欠電照の優位性はほとんどないと考えられた．

Effect of intermittent light on photoreceptor cells in the rabbit retina

The objective of the present study was to determine what histological changes occur in the photoreceptor layer of male rabbits exposed to intermittent light of different intensities. Twelve adult male rabbits were randomly divided into three groups: control group (CON), experimental group I (EXP-1), and experimental group II (EXP-2). The EXP-1 and EXP-2 groups were exposed to a 3-h/3-h light-dark cycle, with light provided by a 60-W or 200-W fluorescent bulb, respectively. The eyes of the rabbits were removed, routinely fixed, and studied by transmission electron microscopy. The EXP-1 rabbits showed the least photoreceptor damage, such as only slight vacuolization in the inner segment, but normal appearance in the other layers. The EXP-2 rabbits showed disorganization and distention in the outer segments and sublethal injury in the inner segment, such as vacuolization, mitochondrial distention and disorganization, increased extracellular space, and distention of cisternae in the rough endoplasmic reticulum. In the EXP-2 group, the outer limiting membrane was absent at some sites, and swelling and pyknosis were present. These observations suggest that intermittent high-intensity light causes more damage in the photoreceptor layer of the rabbit than does intermittent low-intensity light.

Effects of Frequency and Duty Ratio on the Growth of Potato Plantlets In Vitro Using Light-emitting Diodes

Effects of intermittent light on photomixotrophic growth of potato plantlets in vitro and the electrical savings that could be realized by adjusting the frequency and duty ratio of light-emitting diodes (LEDs) were investigated and compared to the use of conventional tubular fluorescent lamps (TFLs). TFLs provide continuous fluctuating light at 60 Hz and LEDs provide continuous nonfluctuating or intermittent/pulse light depend on the preset frequency and duty ratio. In total, eight treatments were investigated with varying light source, frequency, duty ratio and photoperiod. Results indicated that if growth rate is the only concern, LEDs at 720 Hz [1.4 milliseconds (ms)] and 50% duty ratio with 16-h light/8-h dark photoperiod stimulated plant growth the most. However, if energy consumption is the major concern, using LEDs at 180 Hz (5.5 ms) and 50% duty ratio with 16-h light/8-h dark photoperiod would be the best choice for illuminating potato plantlets without significantly sacrificing plant growth, especially when energy for heat removal is also considered.

Tank cultivation of the red alga Palmaria palmata: Effects of intermittent light on growth rate, yield and growth kinetics

Tank cultivation of marine macroalgaeinvolves air-agitation of the algal biomassand intermittent light conditions,i.e.periodic, short light exposure of thethalli in the range of 10 s at the watersurface followed by plunging to low lightor darkness at the tank bottom andrecirculation back to the surface in therange of 1–2 min. Open questions relate toeffects of surface irradiance on growthrate and yield in such tumble cultures andthe possibility of chronic photoinhibitionin full sunlight. A specially constructedshallow-depth tank combined with a darktank allowed fast circulation times ofapproximately 5 s, at a density of 4.2 kgfresh weight (FW) m-2s-1. Growthrate and yield of the red alga Palmaria palmata increased over a widerange of irradiances, with no signs ofchronic photoinhibition, up to agrowth-saturating irradiance ofapproximately 1600 μmol m-2s-1 in yellowish light supplied by asodium high pressure lamp at 16 h light perday. Maximum growth rate ranged at 12% FWd-1, and maximum yield at 609 gFW m-2 d-1. This shows that highgrowth rates of individual thalli may bereached in a dense tumble culture, if highsurface irradiances and short circulationtimes are supplied. Another aspect ofintermittent light relates to possiblechanges of basic growth kinetics, ascompared to continuous light. For thispurpose on-line measurements of growth ratewere performed with a daily light reductionby 50% in light-dark cycles of 1, 2 or 3min duration during the daily light period.Growth rates at 10 °C and 50 μmolphoton m-2 s-1 dropped in allthree intermittent light regimes duringboth the main light and dark periods andreached with all three periodicitiesapproximately 50% of the control , with noapparent changes in basic growth kinetics,as compared to continuous light.

Effect of intermittent lighting, light intensity and source on the performance and welfare of broilers

Broilers are currently reared under nearly continuous lighting (CL) schedules. However, the suitability of such lighting regimens may be questioned in terms of performance and welfare. This paper reviews the literature concerning the effects of intermittent lighting (IL) schedules on these issues. Final body weights at market age of broilers reared under IL schedules are equal to, or even higher than, those of broilers reared under CL schedules. However, endogenous (genotype and sex) and exogenous (dietary composition, feeder space, etc.) factors may interact with the lighting schedule. In contrast, feed conversion is consistently improved with IL, partly as a consequence of a more concave growth curve (initial growth depression followed by compensatory growth). Inconsistencies in the literature concerning the effect of IL on (abdominal) fat content and dressing yield are caused by interactions with other factors. However, it is clearly demonstrated that IL reduces leg abnormalities, in particular the incidence of twisted legs. Additional welfare benefits of IL are found in reduced physiological stress and improved eye condition. An increase in the amount of catching damage has been observed with IL, but this may be avoided by modifying light management before commencement of the catching operation. The importance of light is not restricted to the lighting schedule; aspects of the light quality are also important. Although the data related to light intensity are conflicting, it is generally recommended that an intensity of 5 lux should be provided. Whilst fluorescent light does not affect broiler performance adversely, its lower use of electricity compared with incandescent lighting does reduce input costs. More research is needed to evaluate the impact of these qualitative aspects of lighting on poultry welfare.

Blooming of cyanobacteria in turbulent water with steep light gradients: The effect of intermittent light and dark periods on the oxygen evolution capacity of Synechocystis sp. PCC 6803

The influence of intermittent high-light dosage on Synechocystis sp. PCC 6803 with respect to oxygen evolution capacity, fluorescence yield and carotenoid pigment pattern was investigated, using high-light- and low-light-adapted cultures. The results showed that this cyanobacterium was able to survive high light stress for a full day if this stress was applied on and off with intermittently presented recovery periods in darkness. Enhanced respiratory activity in the high-light adapted cells was detected and this may be an important factor in preventing photodamage under high light stress. Cyanobacterial photosynthetic and respiratory electron transfer pathways are both present within the same membrane, and share common electron carriers. The role of respiratory activity in preventing overexcitation of photosystem 2 is discussed with regard to cyanobacterial ecology.

Blooming of cyanobacteria in turbulent water with steep light gradients: The effect of intermittent light and dark periods on the oxygen evolution capacity of Synechocystis sp. PCC 6803

The influence of intermittent high-light dosage on Synechocystis sp. PCC 6803 with respect to oxygen evolution capacity, fluorescence yield and carotenoid pigment pattern was investigated, using high-light- and low-light-adapted cultures. The results showed that this cyanobacterium was able to survive high light stress for a full day if this stress was applied on and off with intermittently presented recovery periods in darkness. Enhanced respiratory activity in the high-light adapted cells was detected and this may be an important factor in preventing photodamage under high light stress. Cyanobacterial photosynthetic and respiratory electron transfer pathways are both present within the same membrane, and share common electron carriers. The role of respiratory activity in preventing overexcitation of photosystem 2 is discussed with regard to cyanobacterial ecology.

Effect of Intermittent Lighting on the Reproductive Performance of First-Year and Recycled Turkey Hens ,

In each of two trials, a 2-by-2 factorial arrangement of treatments was utilized to evaluate the reproductive performance of first-year and recycled turkey hens to intermittent lighting (IL) through an egg-laying period of 20 wk. The IL treatment provided 4 h of light per day given as 2 h light: 12 h dark:2 h light:8 h dark (2L:12D:2L:8D). This treatment group was compared to controls maintained on 16L:8D. Data were collected for BW, feed intake, feed efficiency, time to first egg, eggs per hen fertility, hatchability, egg weight, and poult weight.Consistent age effects included greater BW, egg weight, and poult weight from recycled hens compared to first-year hens as well as a delay in the onset of laying and a reduction in egg production by six eggs per hen in the recycled hens. Feed intake and feed efficiency were similar in both age groups. Intermittent lighting delayed the onset of laying but increased the rate of lay by eight eggs per hen. Late-season fertility, feed efficiency, and egg weight were significantly increased by the IL treatment. The conclusion was that, for turkey hens, intermittent lighting can effectively improve reproductive performance.

Effect of Intermittent Lighting and Time of Hatch on Large Broad-Breasted White Turkeys

To determine if intermittent lighting would reduce leg abnormalities in turkeys, males reared in intermittent lighting of 2 h light:4 h dark were compared to toms subjected to a low intensity, step-down lighting program (15-h photoperiod). Also, to determine if housing poults as soon as possible following hatch would affect later production characteristics, effects of four hatching treatments were assessed.Toms in intermittent as compared with low intensity, step-down lighting programs showed a significant reduction in the incidence of leg abnormalities. There were no significant differences in body weight, feed efficiency, mortality, tibial dyschondroplasia lesions, growth plate closure, and tarsometatarsal length and width for the two lighting programs. Toms exposed to intermittent lighting had heavier testes.It is concluded that intermittent lighting can be used in light-tight, environmentally enclosed turkey houses to reduce leg anomalies without affecting other production traits. Under the experimental conditions employed in the present study, there was no advantage to removing poults from incubator trays as they hatched, as hatching treatments had no effect on production traits of either turkey toms or hens.

Effects of intermittent lighting on sleep and activity in the domestic hen

This experiment deals with the effects of two different light-dark regimes on general activity, behavioural patterns and sleep in domestic hens ( Gallus domesticus). The light-dark schemes were composed of a traditional 14 h light-10h dark period and the Biomittent Lighting Program (BMLP), which consists of only 15 min light during every hour of the traditional 14 h photoperiod. Although it was found that hens are more active during the day than during the night, they were much less active under the BMLP-regime compared to the traditional regime. More specifically, there is considerable lowering of their activities during the dark portions of the day; behavioural observations revealed that they spend these periods not with resting behaviour, but with passive wakefulness. They more or less concentrate their daily activities during the 15-min light periods. Under the night period of the BMLP-regime, hens appeared to be more restless. Sleep recordings showed that sleep tended to decrease in favour of more drowsiness. It was concluded that circadian rhythmicity of the hens is maintained under both lighting schemes, although the BMLP-regime imposes more passive wakefulness during the day and slightly more activity during the night.

The Effect of Intermittent Lighting on Growth, Feed:Gain Ratio, and Abdominal Fat Content of Broiler Chickens of Various Genotypes and Sex

Intermittent lighting (IL) regimens were tested for rearing broiler chickens from 2 to 7 weeks of age. In Experiments 1 and 2, the effects of 6 cycles of light (L) and darkness (D) of 1L:3D vs. 12 cycles of .25L:1.75 D were compared on the performance of 2400 broiler chickens. Eight genotypes of 5170 mixed-sex broilers were used to compare effects of 6 cycles of 1L:3D vs. 1 cycle per day of 23.5L:.5D on broiler performance (Experiment 3).The sexes responded differently to two IL regimens in Experiment 1. Males had higher body weight, feed intake, and abdominal fat content with 1L:3D; in females, there was no difference in body weight or feed intake, but abdominal fat content was lower with 1L:3D regimen. In Experiment 2, no significant effect of lighting regimen on broiler performance was observed. In Experiment 3, most genotypes had lower feed intake and abdominal fat content for 1L:3D than for 23.5L:.5D, but response of weight gain was variable; one genotype had higher feed intake and another genotype had higher fat content with 1L:3D. It was concluded that sex and genotype should be considered in planning the use of IL techniques for broiler chickens.

Effect of Intermittent Lighting on Energy Savings and Semen Characteristics of Breeder Tom Turkeys

Large White breeder toms were exposed to one of the following light treatments at 34 weeks of age: 1) 15L:9D (control); 2) 2L:11D:4L:7D; 3) 4L:9D:4L:7D; 4) 2L:11D:2L:9D. After 4, 8, 12, and 18 weeks of exposure to these intermittent light treatments, body weight, feed consumption, and semen quality and quantity were determined. Although they maintain similar body weights, toms on intermittent light consumed less feed, produced equivalent semen volumes with similar sperm numbers, and maintained percent normal sperm more persistently during the summer heat than control toms. Compared to the 15L:9D controls, electrical savings for light as great as 73% was calculated for intermittent light. It was concluded that toms can be maintained more efficiently on intermittent lighting than a standard lighting program of 15 hr of light per day.

The effect of intermittent lighting on the time of oviposition in the domestic fowl.

Oviposition time of 100 pullets of White Leghorn at 52 weeks of age was observed under intermittent lighting. Birds reared under 6L:18D were transferred to intermittent lighting regimens consisted of two unequal light periods; 6L:8D:2L:8D, 6L:7D:4L:7D, 6L: 6D:6L: 6D, 6L:5D:8L:5D, 6L:4D:10L:4D, 6L:3D:12L:3D, 6L:2D:14L:2D and of two unequal dark periods; 6L:10D:6L:2D, 6L:8D:6L:4D successively for two weeks.Under the photoperiod with two unequal light periods the start of the first 6 hours light period is interpreted as a subjective dawn and a phase shift for time of oviposition was occurred at the time of the reversal of the length of the two light periods. Under the photoperiod with two unequal dark periods ovipositions entrained by the longer dark period. The mean intra-clutch oviposition interval became gradually long under the photoperiod from 6L:18D to 6L:2D:14L:2D, but it became short under the photoperiod of 6L:10D:6L:2D and 6L:8D:6L:4D.It is suggested that on the entrainment of ovipositions by intermittent lighting the difference of two dark periods is more important factor than that of two light periods, and the start of longer dark period is interpreted as the onset of subjective night.

The Effect of Intermittent Light on Carcass Quality, Feed Efficiency, and Growth of Broilers

A total of 2400 broiler chicks of both sexes and of two commercial strains were reared in an environment of either intermittent lighting (IL) of 1 hr light:3 hr dark or extended lighting (EL) of 23.5 hr light:.5 hr dark from 15 to 48 or 55 days of age.The IL significantly (P<.05) reduced leaf fat, percent grade A carcasses, and feed:gain ratio of female broilers at 48 and 55 days. There was no difference in weight gain or carcass weight except that carcass weight of females at 42 days was (P<.05) lower with IL. Male chicks receiving IL had fewer grade A carcasses at 48 days for one of two strains used; lower leaf fat at 55 days and lower feed:gain ratios. There was no difference in body or carcass weights at either age. Results indicate that adoption of IL can enhance carcass quality by reducing carcass fatness and improve efficiency of broiler production.

Effect of Intermittent Light on Broilers Reared under Moderate Temperature Conditions

Commercial broilers reared under an intermittent-lighting regime produced a significantly better feed conversion than broilers reared under a continuous-lighting regime. Body weight gain was not significantly affected by light treatment. However, the number of breast trims, as recorded under commercial processing plant inspection procedures, was significantly higher for broilers reared under an intermittent-lighting regime than for those reared under a continuous-lighting regime in which the light intensity was changed during each 24-hr period.

The Effect of Intermittent Light on Broiler Performance, Dust Production and Litter Moisture

A comparison was made of broiler-type chicks subjected to two light regimes, continuous and intermittent (15 minutes light followed by 90 minutes dark) throughout the growing period. Both males and females grown under the intermittent light schedule were significantly heavier (P<0.05) at 8 weeks of age than those grown under continuous light. Litter moisture and dust production were compared in the two light treatments and no significant differences were detected.

The Effect of Intermittent Lighting Programmes on the Production of Market Chickens and Turkeys

Although not all the reports dealing with the effects of intermittent lighting on the body weight of chickens agree, there is a definite indication that birds grown on intermittent light may be exp...

Rate Constants for Combination of Iodine Atoms in Inert Solvents

The effect of intermittent light on the rate of a chain reaction involving iodine atoms has been used to measure the average life-time of photochemically produced iodine atoms between about 15 and 35 deg in hexane, carbon tetrachloride and hexachlorobutadinie-1,3. Since quantum yields for iodine dissociation previously had been measured by a scavenger technique in the same solvents at the same temperatures, the data can be used to calculate rate constants for the combination of ''old'' iodine atoms that have escaped their original partners. The rate constants are all about 5 x 10/sup 3/ liter/mole sec or greater and are in good agreement with the magnitudes to be expected if the rate of the combination reaction is determined by the rate of diffusion of atoms together. However, the data fail to support the proportionality between viscosity and diffussion coefficient predicted by hydrodynamic theories. Measurements in several laboratories of photostationary atom concentration, life- time, quantum yield and rate constant are all remarkably consistent with each other. Both lifetime measurements with intermittent light and rate constant measurements with flash photolysis offer advantages under certain conditions. (auth)

Effect of intermittent light on the readability of printed matter under conditions of decreasing contrast.

Effect of intermittent light on the readability of printed matter under conditions of decreasing contrast.