scholarly journals The lower entrainable limit of rat circadian rhythm to sinusoidal light intensity cycles: A preliminary study

1999 ◽  
Vol 53 (2) ◽  
pp. 215-217 ◽  
Author(s):  
Setsuo Usui ◽  
Terue Okazaki ◽  
Yasuro Takahashi
Keyword(s):  
Circadian Rhythm ◽  
Light Intensity ◽  
Preliminary Study

Preliminary Study of Photosynthetic Bacteria Treating Hydrothermal Liquefaction Wastewater

2014 ◽  
Vol 1073-1076 ◽  
pp. 810-816
Author(s):  
Guo Yang Yuan ◽  
Hai Feng Lu ◽  
Shi Wei Huang ◽  
Yuan Hui Zhang ◽  
Bao Ming Li ◽  
...  
Keyword(s):  
Light Intensity ◽  
Environmental Pollution ◽  
Biomass Production ◽  
Photosynthetic Bacteria ◽  
Resource Recovery ◽  
Inoculum Size ◽  
Hydrothermal Liquefaction ◽  
Treatment Conditions ◽  
Preliminary Study ◽  
Biocrude Oil

Post hydrothermal liquefaction wastewater (PHWW) was generated during biocrude oil production. It contains lots of carbon, nitrogen and phosphorous elements, which can cause environmental pollution and resource waste. Using photosynthetic bacteria (PSB) to treat this kind of wastewater can realize pollutants elimination and resource recovery. In this work, the feasibility of using PSB to treat PHWW was firstly investigated, and the treatment conditions were optimized. Results showed that the PSB can effectively degrade PHWW. The optimal initial COD concentration, inoculum size and light intensity for PSB to treat PHWW were 6000-10000 mg/L, 50 mg/L and 1000-3500 lux, respectively. With the initial COD concentration of 9000 mg/L, inoculum size of 50 mg/L and light intensity of 1000 lux, the COD, NH3-N, TP removal and biomass production reached to 71%, 90%, 47.2% and 773 mg/L, respectively. This showed that using PSB to treat PHWW can be an alternative method for PHWW nutrients recovery and pollutant treatment.

scholarly journals A Review of Silent Substitution Devices for Melanopsin Stimulation in Humans

Photonics ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 121
Author(s):  
Vincent Conus ◽  
Martial Geiser
Keyword(s):  
Circadian Rhythm ◽  
Light Intensity ◽  
Cognitive Functions ◽  
Specific Response ◽  
Light Stimulation ◽  
Sleep Regulation ◽  
Human Relationships ◽  
Silent Substitution ◽  
Optical Setup ◽  
Year 2000

One way to study the specific response of the non-visual melanopsin photoreceptors of the human eye is to silence the response of cones and rods. Melanopsin photoreceptors (ipRGC), highlighted in the early 2000s, are intimately linked to the circadian rhythm and therefore to our sleep and wakefulness. Rest and sleep regulation, health and cognitive functions are all linked to ipRGC and play an important role in work and human relationships. Thus, we believe that the study of ipRGC responses is important.We searched and reviewed scientific articles describing instrumentation dedicated to these studies. PubMed lists more than 90,000 articles created since the year 2000 that contain the word circadian but only 252 with silent substitution. In relation to melanopsin, we found 39 relevant articles from which only 11 give a device description for humans, which is incomplete in most cases. We did not find any consensus for light intensity description, melanopsin contrast, sequences of melanopsin light stimulation and optical setup to expose the retina to the light.

scholarly journals Optimization of light exposure and sleep schedule for circadian rhythm entrainment

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0251478
Author(s):  
Jiawei Yin ◽  
A. Agung Julius ◽  
John T. Wen
Keyword(s):  
Circadian Rhythm ◽  
Light Intensity ◽  
Process Model ◽  
Light Exposure ◽  
Shift Workers ◽  
Wide Range ◽  
Gradient Descent Algorithm ◽  
Time Optimal ◽  
Sleep Schedule ◽  
Light Input

The circadian rhythm, called Process C, regulates a wide range of biological processes in humans including sleep, metabolism, body temperature, and hormone secretion. Light is the dominant synchronizer of the circadian rhythm—it has been used to regulate the circadian phase to cope with jet-lag, shift work, and sleep disorder. The homeostatic oscillation of the sleep drive is called Process S. Process C and Process S together determine the sleep-wake cycle in what is known as the two-process model. This paper addresses the regulation of both Process C and Process S by scheduling light exposure and sleep based on numerical simulations of circadian rhythm and sleep mathematical models. This is a significant step beyond the existing literature that only considers the entrainment of Process C. Regulation of the two-process model poses several unique features and challenges: 1. Process S is non-smooth, i.e., the homeostatic dynamics are different in the sleep and wake regimes; 2. Light only indirectly affects Process S through Process C; 3. Light does not affect Process C during sleep. We consider two scenarios: optimizing light intensity as the control input with spontaneous (i.e., unscheduled) sleep/wake times and jointly optimizing the light intensity and the sleep/wake times, which allows limited delayed sleep and early waking as part of the decision variables. We solve the time-optimal entrainment problem for the two-process model for both scenarios using an extension of the gradient descent algorithm to non-smooth systems. To illustrate the efficacy of our time-optimal entrainment strategies, we consider two common use cases: transmeridian travelers and shift workers. For transmeridian travelers, joint optimization of the two-process model avoids the unrealistic long wake duration when only Process C is considered. The entrainment time also decreases when both the light input and the sleep schedule are optimized compared to when only the light input is optimized. For shift workers, we show that the entrainment time is significantly shortened by optimizing the night shift working light.

Disruption of melatonin circadian rhythm production is related to multiple sclerosis severity: A preliminary study

2015 ◽  
Vol 353 (1-2) ◽  
pp. 166-168 ◽  
Author(s):  
Alfredo Damasceno ◽  
Adriel Santos Moraes ◽  
Alessandro Farias ◽  
Benito Pereira Damasceno ◽  
Leonilda Maria Barbosa dos Santos ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Circadian Rhythm ◽  
Preliminary Study ◽  
Rhythm Production

Conditioning circadian rhythmic control of betacyanin content in Chenopodium rubrum by temperature and light intensity cycles during germination

1971 ◽  
Vol 49 (11) ◽  
pp. 1981-1985 ◽  
Author(s):  
Edgar Wagner ◽  
Silvia Frosch
Keyword(s):  
Circadian Rhythm ◽  
Light Intensity ◽  
Metabolic Activity ◽  
Time Course ◽  
Chenopodium Rubrum ◽  
Light Conditions ◽  
Dark Light ◽  
Cyclic Temperature ◽  
Free Running ◽  
Specific Phase

Evidence is presented that a circadian rhythm in betacyanin accumulation in Chenopodium rubrum seedlings (ecotype 50°10′ N, 105°35′ W, selection 184) was initiated or synchronized by the cyclic temperature and light conditions that were imposed during germination. This rhythm was probably free-running in the constant light conditions that preceded the imposition of darkness. Rhythmic fluctuations in the time course of betacyanin content during darkness, which are probably due to betacyanin turnover, showed correlations with the alternating germination conditions, thus indicating that the rhythm is not initiated or rephased by the transition from light of 600 or 3000 ft-c to darkness. Light following darkness increased the respective level of betacyanin accumulation but did not alter the phasing of the rhythm as compared with darkness. The metabolic activity of the seedlings in the light, following darkness, depends on the specific phase of the endogenous rhythm at the time of the dark: light transition.

scholarly journals A PRELIMINARY STUDY ON THE ECOLOGY OF THE CORAL REEF OF POMBO ISLAND

2018 ◽  
Vol 17 ◽  
pp. 29-49
Author(s):  
Ono Kurnaen Sumadhiharga
Keyword(s):  
Coral Reef ◽  
Light Intensity ◽  
Ecological Factors ◽  
Commercial Importance ◽  
Preliminary Study ◽  
Live Bait

A preliminary study on the ecology of the coral reef of Pombo Island was carried out in 1975. Pombo Island has a characteristic of an atoll and is considered a good habitat for coral and fish, including live-bait fish of commercial importance, Spratelloides delicatulus. Non-planktonic organisms collected consist of 39 species of corals, 56 species of molluscs, 17 species of echinoderms, 130 species of fishes and a number of crustacean species.Some ecological factors such as bottom condition, turbidity, temperatures, light intensity, and freshwater dilution are described. Population and distribution of corals and coral fishes are discussed.

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