Cordyceps militaris,which is a precious edible fungus,contains effective ingredients such as cordycepin and adenosine,and can treat a variety of diseases.However,light has the greatest effect on the growth of C.milita...Cordyceps militaris,which is a precious edible fungus,contains effective ingredients such as cordycepin and adenosine,and can treat a variety of diseases.However,light has the greatest effect on the growth of C.militaris in the process of artificial cultivation.In this study,the effects of light time,light intensity and light color on the growth,physiology,yield and quality of C.militaris were discussed to provide reference for the efficient artificial cultivation of C.militaris.展开更多
Human activities modulate the impact of environmental forcing in general and of climate in particular.Information on the spatial and temporal patterns of human activities is in high demand,but scarce in sparsely popul...Human activities modulate the impact of environmental forcing in general and of climate in particular.Information on the spatial and temporal patterns of human activities is in high demand,but scarce in sparsely populated and data-poor regions such as Northern Africa.The intensity and spatial distribution of nighttime lights provide useful information on human activities and can be observed by space-borne imaging radiometers.Our study helps to bridge the gap between the DMSP-OLS data available until 2013 and the NPP-VIIRS data available since 2013.The approach to calibrate the OLS data includes three steps:a)inter-calibrate the OLS DN data acquired by different sensors in 1992-2013;b)cali-brate the OLS DN data using VIIRS data in 2013;c)generate syn-thetic OLS radiance data by degrading the VIIRS data in 2013-2020.We generated a)a time series of calibrated OLS nighttime light radiance data(1992-2013);b)mean annual VIIRS radiance on stable lights at the OLS spatial resolution for 2013-2020;c)synthetic OLS radiance data generated using VIIRS radiance data degraded to match the radiometric specifications of OLS for 2013-2020.The evaluation of these data products in 2013 documented their accu-racy and consistency.展开更多
A real-time double-ring neutron time-of-flight(TOFII) spectrometer system has been proposed to achieve plasma diagnosis on HL-2M tokamak with a relatively high count rate and sufficient energy resolution.The TOFII sys...A real-time double-ring neutron time-of-flight(TOFII) spectrometer system has been proposed to achieve plasma diagnosis on HL-2M tokamak with a relatively high count rate and sufficient energy resolution.The TOFII system is in its development stage,and this work describes its characteristics in terms of design principle,system structure,electronic system design,preliminary tests,and neutron transport simulation.The preliminary test results illustrate that the TOFII system can demonstrate the realtime dynamic spectrum every 10 ms.The results also show that based on the support vector machine method,the n-γ discrimination algorithm achieves the discrimination accuracy of 99.1%with a figure of merit of 1.30,and the intrinsic timing resolution of the system is within 0.3%.The simulated flight time spectrums from 1 to 5 MeV are obtained through the Monte Carlo tool Geant4,which also provide the reasonable results.The TOFII system will then be calibrated on mono-energetic neutron sources for further verification.展开更多
With the increasing popularity of solid sate lighting devices, Visible Light Communication (VLC) is globally recognized as an advanced and promising technology to realize short-range, high speed as well as large capac...With the increasing popularity of solid sate lighting devices, Visible Light Communication (VLC) is globally recognized as an advanced and promising technology to realize short-range, high speed as well as large capacity wireless data transmission. In this paper, we propose a prototype of real-time audio and video broadcast system using inexpensive commercially available light emitting diode (LED) lamps. Experimental results show that real-time high quality audio and video with the maximum distance of 3 m can be achieved through proper layout of LED sources and improvement of concentration effects. Lighting model within room environment is designed and simulated which indicates close relationship between layout of light sources and distribution of illuminance.展开更多
The generalized two-dimensional correlation analysis based on time-resolved light scattering patterns （2D TRLS） has been employed to study the phase separation process of an epoxy-amine-polyethersulfone blend in whi...The generalized two-dimensional correlation analysis based on time-resolved light scattering patterns （2D TRLS） has been employed to study the phase separation process of an epoxy-amine-polyethersulfone blend in which the secondary phase separation takes place. The results of the 2D TRLS provided more detailed information that was not readily observed in the 1D TRLS patterns. （i） During the first process of phase separation, the sequential order of coarsening in size of the domains among the larger and smaller ones has been reversed between the diffusion regime and the hydrodynamic regime. （ii） The change of the larger domains in size, due to the hydrodynamic flow in the late stage of the first phase separation process, keeps on taking place earlier than that of the new domains appeared in the secondary phase separation process. （iii） During the secondary phase separation process the size growth of the smaller domains takes place earlier than that of the larger ones, probably due to the assumption that the coarsening mode could decrease the interface tension more quickly.展开更多
We show that as the dimensions of the Multiverse increase so does its density. This increase in density has the effect of decreasing the speed of light, slowing down time, and increasing the life span of each higher d...We show that as the dimensions of the Multiverse increase so does its density. This increase in density has the effect of decreasing the speed of light, slowing down time, and increasing the life span of each higher dimension and the life span of human beings occupying that higher dimension. We use the tenth dimension as the highest dimension as a special case but show that it is not possible to exactly determine its value because of varying factors that can end the Multiverse, sending all the Energy back into the original levels of the Quantum of the void that started the creation process.展开更多
Background: It was well established that exposure to nighttime light was responsible of a diverse negative health effect. Therefore, the aim of this study was to assess the epidemiologic exposure to artificial light a...Background: It was well established that exposure to nighttime light was responsible of a diverse negative health effect. Therefore, the aim of this study was to assess the epidemiologic exposure to artificial light at night time and negative health consequences that associated with prolonged nighttime lighting exposure. Methodology: This is a cross-sectional survey, involving a total of 266 Saudi residents living in the city of Hail, Northern KSA. Essential information regarding exposure to light at night time was obtained. Results: The overall incidence of nighttime light exposure in the present study was 65.8% for general population, was 61.5% males and was 38.5% for females. About 75.6% persons used to sleep for Conclusion: Prolonged exposure to the light at nighttime is prevalent in Saudi Arabia. This exposure usually results from late sleep in the nighttime and the late awake in the daytime.展开更多
A new approach for studying the time-evolution law of a chaotic light field in a damping-gaining coexisting process is presented. The new differential equation for determining the parameter of the density operator p（...A new approach for studying the time-evolution law of a chaotic light field in a damping-gaining coexisting process is presented. The new differential equation for determining the parameter of the density operator p（t） is derived and the solution of f for the damping and gaining processes are studied separately. Our approach is direct and the result is concise since it is not necessary for us to know the Kraus operators in advance.展开更多
The phase time of p-polarized light pulses passing through a glass plate is investigated. We do this by converting the problem into a l-dimensional quantum-mechanical counterpart, a potential well with a position-depe...The phase time of p-polarized light pulses passing through a glass plate is investigated. We do this by converting the problem into a l-dimensional quantum-mechanical counterpart, a potential well with a position-dependent effective mass. We find that the phase time and the lateral shift have the negative characteristics.展开更多
With the technology of coincidence method, transit time spreads (TTSs) of PMTs are measured with Cherenkov light on the photocathode window of photomultiplier tube (PMT) produced by cascade γ radiation source, 60Co. ...With the technology of coincidence method, transit time spreads (TTSs) of PMTs are measured with Cherenkov light on the photocathode window of photomultiplier tube (PMT) produced by cascade γ radiation source, 60Co. TTSs with single and multi-photoelectron which are analyzed by convolution of Poisson and Gaussian are obtained. The study to XP2020 and XP2020Q PMTs shows that TTSs are consistent with data supplied by Philips. TTSs are inversely proportional to the square roots of number of photoelectrons. The method is feasible when single and multi-photoelectron can be distinguished.展开更多
This paper considers a Manpower system where “exits” of employed personnel produce some wastage or loss. This system monitors these wastages over the sequence of exit epochs {t0 = 0 and tk;k = 1, 2,…} that form a r...This paper considers a Manpower system where “exits” of employed personnel produce some wastage or loss. This system monitors these wastages over the sequence of exit epochs {t0 = 0 and tk;k = 1, 2,…} that form a recurrent process and admit recruitment when the cumulative loss of man hours crosses a threshold level Y, which is also called the breakdown level. It is assumed that the inter-exit times Tk = tk-1 - tk, k = 1, 2,… are independent and identically distributed random variables with a common cumulative distribution function (CDF) B(t) = P(Tk t) which has a tail 1 – B(t) behaving like t-v with 1 v as t → ∞. The amounts {Xk} of wastages incurred during these inter-exit times {Tk} are independent and identically distributed random variables with CDF P(Xk X) = G(x) and Y is distributed, independently of {Xk} and {tk}, as an exponentiated exponential law with CDF H(y) = P(Y y) = (1 - e-λy)n. The mean waiting time to break down of the system has been obtained assuming B(t) to be heavy tailed and as well as light tailed. For the exponential case of G(x), a comparative study has also been made between heavy tailed mean waiting time to break down and light tailed mean waiting time to break down values. The recruitment policy operating under the heavy tailed case is shown to be more economical in all types of manpower systems.展开更多
[ Objective ] The paper was to confirm the effect of mating and black light treatment on cryptochromes mRNA expression of Hclicoverpa armigera. [ Method ] Quantitative real-time PCR （ SYBR Green） technique was appli...[ Objective ] The paper was to confirm the effect of mating and black light treatment on cryptochromes mRNA expression of Hclicoverpa armigera. [ Method ] Quantitative real-time PCR （ SYBR Green） technique was applied to detect the expression of cryptochromes gene （ cryl and cry2 ） of H. armigera under different conditions. Total RNA was extracted from the head of H. armigera, and carried out reverse transcription to synthesize cDNA after digested by DNase I. Specific primers were used to carry out quantitative real-time PCR on cryl, cry2 and EF-Ict gene, respectively. [ Result] The expression of cryl mRNA of H. ar- migera significantly decreased after exposure to black light for 2 h, the mRNA expression of cry2 was smaller than control, they had no significant difference with each other. Mating had significant effect on mRNA expression of cryl and cry2 of H. armigera, and the mRNA expression of cryl and cry2 of male and female adults showed decreasing trend with the prolongation of time after mating. [ Conclusion] The result had important significance for further studying on function of cry gene and the control of cotton bollwonn.展开更多
Human depression patients often show abnormal pupillary reflex with morphological changes in hippo campus and prefrontal cortex. This study aimed to find the relationship between the prolonged pupillary light reflex ...Human depression patients often show abnormal pupillary reflex with morphological changes in hippo campus and prefrontal cortex. This study aimed to find the relationship between the prolonged pupillary light reflex （PLR） which had been shown by confined sows with chronic stress or depression and morphological changes in brain, in order to provide theoretical basis for that the confined environment should lead to sows＇ depression. A total of 637 sows of Durac, Landrace and Large White breeds with various parities were observed, and the pupil light reflex （PLR） was measured and the actual pupillary light reflex time （PLRT） were recorded. All the PLRTs were grouped based on the results of confidence interval： t〉10% as group A, 5% 〈t〈10% as group B, 1%〈t〈5% as group C and t〈l% as group D. Three individuals were randomly selected from each group （12 sows in total） and the white tissues of hippocampus and the prefrontal cortex were prepared for HS staining slices （three slices/per tissue） for observation on tissue structure and pathological changes with high magnification （400X） of electronic microscope. The results showed that in group A （t〉10%） pathological change was found in hippocampus, however, as PLRT increased from group B to group D, pathological changes in hippocampus tissues tended to be deteriorated with the increase of inflammatory cells and nuclear pyknosis phenomena. The same as those shown in hippocampus as the increasing of PLRT from groups A to D, more inflammatory cells appeared in prefrontal cortex for groups B and D. The results suggested that the tissue lesions of hippocampus and prefrontal cortex of the confined sows with prolonged PLRT might be the results of chronic stress or depression.展开更多
Light plays an essential role in psychobiological and psychophysiological processes,such as alertness.The alerting effect is influenced by light characteristics and the timing of interventions.This meta-analysis is th...Light plays an essential role in psychobiological and psychophysiological processes,such as alertness.The alerting effect is influenced by light characteristics and the timing of interventions.This meta-analysis is the first to systematically review the effect of light intervention on alertness and to discuss the optimal protocol for light intervention.In this meta-analysis,registered at PROSPERO(Registration ID:CRD42020181485),we conducted a systematic search of the Web of Science,PubMed,and PsycINFO databases for studies published in English prior to August 2021.The outcomes included both subjective and objective alertness.Subgroup analyses considered a variety of factors,such as wavelength,correlated color temperature(CCT),light illuminance,and timing of interventions(daytime,night-time,or all day).Twenty-seven crossover studies and two parallel-group studies were included in this meta-analysis,with a total of 1210 healthy participants(636(52%)male,mean age 25.62 years).The results revealed that light intervention had a positive effect on both subjective alertness(standardized mean difference(SMD)=-0.28,95%confidence interval(CI):-0.49 to-0.06,P=0.01)and objective alertness in healthy subjects(SMD=-0.34,95%CI:-0.68 to-0.01,P=0.04).The subgroup analysis revealed that cold light was better than warm light in improving subjective alertness(SMD=-0.37,95%CI:-0.65 to-0.10,P=0.007,I2=26%)and objective alertness(SMD=-0.36,95%CI:-0.66 to-0.07,P=0.02,I2=0).Both daytime(SMD=-0.22,95%CI:-0.37 to-0.07,P=0.005,I2=74%)and night-time(SMD=-0.32,95%CI:-0.61 to-0.02,P=0.04,I2=0)light exposure improved subjective alertness.The results of this meta-analysis and systematic review indicate that light exposure is associated with significant improvement in subjective and objective alertness.In addition,light exposure with a higher CCT was more effective in improving alertness than light exposure with a lower CCT.Our results also suggest that both daytime and night-time light exposure can improve subjective alertness.展开更多
基金Supported by Science and Technology Planning Project of Guangxi,China(Guike AD19245169,Guike AD18281072,Guike AA17202037,Guike AB16380164).
文摘Cordyceps militaris,which is a precious edible fungus,contains effective ingredients such as cordycepin and adenosine,and can treat a variety of diseases.However,light has the greatest effect on the growth of C.militaris in the process of artificial cultivation.In this study,the effects of light time,light intensity and light color on the growth,physiology,yield and quality of C.militaris were discussed to provide reference for the efficient artificial cultivation of C.militaris.
基金supported by the National Natural Science Foundation of China project(Grant No.41661144022)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA19030203),the Chinese Academy of Sciences President’s International Fellowship Initiative(Grant No.2020VTA0001),and the MOST High-Level Foreign Expert program(Grant No.GL20200161002).
文摘Human activities modulate the impact of environmental forcing in general and of climate in particular.Information on the spatial and temporal patterns of human activities is in high demand,but scarce in sparsely populated and data-poor regions such as Northern Africa.The intensity and spatial distribution of nighttime lights provide useful information on human activities and can be observed by space-borne imaging radiometers.Our study helps to bridge the gap between the DMSP-OLS data available until 2013 and the NPP-VIIRS data available since 2013.The approach to calibrate the OLS data includes three steps:a)inter-calibrate the OLS DN data acquired by different sensors in 1992-2013;b)cali-brate the OLS DN data using VIIRS data in 2013;c)generate syn-thetic OLS radiance data by degrading the VIIRS data in 2013-2020.We generated a)a time series of calibrated OLS nighttime light radiance data(1992-2013);b)mean annual VIIRS radiance on stable lights at the OLS spatial resolution for 2013-2020;c)synthetic OLS radiance data generated using VIIRS radiance data degraded to match the radiometric specifications of OLS for 2013-2020.The evaluation of these data products in 2013 documented their accu-racy and consistency.
基金partially supported by the National Science and Technology Major Project of Ministry of Science and Technology of China(Nos.2014GB109003 and 2015GB111002)the National Natural Science Foundation of China(Nos.11375195,11575184,11375004,and 11775068)
文摘A real-time double-ring neutron time-of-flight(TOFII) spectrometer system has been proposed to achieve plasma diagnosis on HL-2M tokamak with a relatively high count rate and sufficient energy resolution.The TOFII system is in its development stage,and this work describes its characteristics in terms of design principle,system structure,electronic system design,preliminary tests,and neutron transport simulation.The preliminary test results illustrate that the TOFII system can demonstrate the realtime dynamic spectrum every 10 ms.The results also show that based on the support vector machine method,the n-γ discrimination algorithm achieves the discrimination accuracy of 99.1%with a figure of merit of 1.30,and the intrinsic timing resolution of the system is within 0.3%.The simulated flight time spectrums from 1 to 5 MeV are obtained through the Monte Carlo tool Geant4,which also provide the reasonable results.The TOFII system will then be calibrated on mono-energetic neutron sources for further verification.
文摘With the increasing popularity of solid sate lighting devices, Visible Light Communication (VLC) is globally recognized as an advanced and promising technology to realize short-range, high speed as well as large capacity wireless data transmission. In this paper, we propose a prototype of real-time audio and video broadcast system using inexpensive commercially available light emitting diode (LED) lamps. Experimental results show that real-time high quality audio and video with the maximum distance of 3 m can be achieved through proper layout of LED sources and improvement of concentration effects. Lighting model within room environment is designed and simulated which indicates close relationship between layout of light sources and distribution of illuminance.
基金supported by the National Natural Science of Foundation of China(NSFC)(Nos.20674014, 20425415,20274010,50103003,20221402)
文摘The generalized two-dimensional correlation analysis based on time-resolved light scattering patterns （2D TRLS） has been employed to study the phase separation process of an epoxy-amine-polyethersulfone blend in which the secondary phase separation takes place. The results of the 2D TRLS provided more detailed information that was not readily observed in the 1D TRLS patterns. （i） During the first process of phase separation, the sequential order of coarsening in size of the domains among the larger and smaller ones has been reversed between the diffusion regime and the hydrodynamic regime. （ii） The change of the larger domains in size, due to the hydrodynamic flow in the late stage of the first phase separation process, keeps on taking place earlier than that of the new domains appeared in the secondary phase separation process. （iii） During the secondary phase separation process the size growth of the smaller domains takes place earlier than that of the larger ones, probably due to the assumption that the coarsening mode could decrease the interface tension more quickly.
文摘We show that as the dimensions of the Multiverse increase so does its density. This increase in density has the effect of decreasing the speed of light, slowing down time, and increasing the life span of each higher dimension and the life span of human beings occupying that higher dimension. We use the tenth dimension as the highest dimension as a special case but show that it is not possible to exactly determine its value because of varying factors that can end the Multiverse, sending all the Energy back into the original levels of the Quantum of the void that started the creation process.
文摘Background: It was well established that exposure to nighttime light was responsible of a diverse negative health effect. Therefore, the aim of this study was to assess the epidemiologic exposure to artificial light at night time and negative health consequences that associated with prolonged nighttime lighting exposure. Methodology: This is a cross-sectional survey, involving a total of 266 Saudi residents living in the city of Hail, Northern KSA. Essential information regarding exposure to light at night time was obtained. Results: The overall incidence of nighttime light exposure in the present study was 65.8% for general population, was 61.5% males and was 38.5% for females. About 75.6% persons used to sleep for Conclusion: Prolonged exposure to the light at nighttime is prevalent in Saudi Arabia. This exposure usually results from late sleep in the nighttime and the late awake in the daytime.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61141007,11047133,and 11175113)the Natural Science Foundation of Jiangxi Province of China (Grant Nos. 2010GQS0080 and 2010GQW0027)+1 种基金the Research Foundation of the Education Department of Jiangxi Province of China (Grant No. GJJ11339)the Sponsored Program for Cultivating Youths of Outstanding Ability in Jiangxi Normal University
文摘A new approach for studying the time-evolution law of a chaotic light field in a damping-gaining coexisting process is presented. The new differential equation for determining the parameter of the density operator p（t） is derived and the solution of f for the damping and gaining processes are studied separately. Our approach is direct and the result is concise since it is not necessary for us to know the Kraus operators in advance.
文摘The phase time of p-polarized light pulses passing through a glass plate is investigated. We do this by converting the problem into a l-dimensional quantum-mechanical counterpart, a potential well with a position-dependent effective mass. We find that the phase time and the lateral shift have the negative characteristics.
文摘With the technology of coincidence method, transit time spreads (TTSs) of PMTs are measured with Cherenkov light on the photocathode window of photomultiplier tube (PMT) produced by cascade γ radiation source, 60Co. TTSs with single and multi-photoelectron which are analyzed by convolution of Poisson and Gaussian are obtained. The study to XP2020 and XP2020Q PMTs shows that TTSs are consistent with data supplied by Philips. TTSs are inversely proportional to the square roots of number of photoelectrons. The method is feasible when single and multi-photoelectron can be distinguished.
文摘This paper considers a Manpower system where “exits” of employed personnel produce some wastage or loss. This system monitors these wastages over the sequence of exit epochs {t0 = 0 and tk;k = 1, 2,…} that form a recurrent process and admit recruitment when the cumulative loss of man hours crosses a threshold level Y, which is also called the breakdown level. It is assumed that the inter-exit times Tk = tk-1 - tk, k = 1, 2,… are independent and identically distributed random variables with a common cumulative distribution function (CDF) B(t) = P(Tk t) which has a tail 1 – B(t) behaving like t-v with 1 v as t → ∞. The amounts {Xk} of wastages incurred during these inter-exit times {Tk} are independent and identically distributed random variables with CDF P(Xk X) = G(x) and Y is distributed, independently of {Xk} and {tk}, as an exponentiated exponential law with CDF H(y) = P(Y y) = (1 - e-λy)n. The mean waiting time to break down of the system has been obtained assuming B(t) to be heavy tailed and as well as light tailed. For the exponential case of G(x), a comparative study has also been made between heavy tailed mean waiting time to break down and light tailed mean waiting time to break down values. The recruitment policy operating under the heavy tailed case is shown to be more economical in all types of manpower systems.
基金Supported by National"973"Project(No.2006CB102006)Special Research Project in Public Service Sectors(Agriculture)(201103012)~~
文摘[ Objective ] The paper was to confirm the effect of mating and black light treatment on cryptochromes mRNA expression of Hclicoverpa armigera. [ Method ] Quantitative real-time PCR （ SYBR Green） technique was applied to detect the expression of cryptochromes gene （ cryl and cry2 ） of H. armigera under different conditions. Total RNA was extracted from the head of H. armigera, and carried out reverse transcription to synthesize cDNA after digested by DNase I. Specific primers were used to carry out quantitative real-time PCR on cryl, cry2 and EF-Ict gene, respectively. [ Result] The expression of cryl mRNA of H. ar- migera significantly decreased after exposure to black light for 2 h, the mRNA expression of cry2 was smaller than control, they had no significant difference with each other. Mating had significant effect on mRNA expression of cryl and cry2 of H. armigera, and the mRNA expression of cryl and cry2 of male and female adults showed decreasing trend with the prolongation of time after mating. [ Conclusion] The result had important significance for further studying on function of cry gene and the control of cotton bollwonn.
基金Supported by the National Natural Science Foundation of China(NSFC,31472131/C170109,31201834/C170109)Scientific Research Foundation for Doctorship of Northeast Agricultural University(2010RCB37)
文摘Human depression patients often show abnormal pupillary reflex with morphological changes in hippo campus and prefrontal cortex. This study aimed to find the relationship between the prolonged pupillary light reflex （PLR） which had been shown by confined sows with chronic stress or depression and morphological changes in brain, in order to provide theoretical basis for that the confined environment should lead to sows＇ depression. A total of 637 sows of Durac, Landrace and Large White breeds with various parities were observed, and the pupil light reflex （PLR） was measured and the actual pupillary light reflex time （PLRT） were recorded. All the PLRTs were grouped based on the results of confidence interval： t〉10% as group A, 5% 〈t〈10% as group B, 1%〈t〈5% as group C and t〈l% as group D. Three individuals were randomly selected from each group （12 sows in total） and the white tissues of hippocampus and the prefrontal cortex were prepared for HS staining slices （three slices/per tissue） for observation on tissue structure and pathological changes with high magnification （400X） of electronic microscope. The results showed that in group A （t〉10%） pathological change was found in hippocampus, however, as PLRT increased from group B to group D, pathological changes in hippocampus tissues tended to be deteriorated with the increase of inflammatory cells and nuclear pyknosis phenomena. The same as those shown in hippocampus as the increasing of PLRT from groups A to D, more inflammatory cells appeared in prefrontal cortex for groups B and D. The results suggested that the tissue lesions of hippocampus and prefrontal cortex of the confined sows with prolonged PLRT might be the results of chronic stress or depression.
基金supported by the National Natural Science Foundation of China,No.82172530(to QT)Science and Technology Program of Guangdong,No.2018B030334001(to CRR)Guangzhou Science and Technology Project,No.202007030012(to QT).
文摘Light plays an essential role in psychobiological and psychophysiological processes,such as alertness.The alerting effect is influenced by light characteristics and the timing of interventions.This meta-analysis is the first to systematically review the effect of light intervention on alertness and to discuss the optimal protocol for light intervention.In this meta-analysis,registered at PROSPERO(Registration ID:CRD42020181485),we conducted a systematic search of the Web of Science,PubMed,and PsycINFO databases for studies published in English prior to August 2021.The outcomes included both subjective and objective alertness.Subgroup analyses considered a variety of factors,such as wavelength,correlated color temperature(CCT),light illuminance,and timing of interventions(daytime,night-time,or all day).Twenty-seven crossover studies and two parallel-group studies were included in this meta-analysis,with a total of 1210 healthy participants(636(52%)male,mean age 25.62 years).The results revealed that light intervention had a positive effect on both subjective alertness(standardized mean difference(SMD)=-0.28,95%confidence interval(CI):-0.49 to-0.06,P=0.01)and objective alertness in healthy subjects(SMD=-0.34,95%CI:-0.68 to-0.01,P=0.04).The subgroup analysis revealed that cold light was better than warm light in improving subjective alertness(SMD=-0.37,95%CI:-0.65 to-0.10,P=0.007,I2=26%)and objective alertness(SMD=-0.36,95%CI:-0.66 to-0.07,P=0.02,I2=0).Both daytime(SMD=-0.22,95%CI:-0.37 to-0.07,P=0.005,I2=74%)and night-time(SMD=-0.32,95%CI:-0.61 to-0.02,P=0.04,I2=0)light exposure improved subjective alertness.The results of this meta-analysis and systematic review indicate that light exposure is associated with significant improvement in subjective and objective alertness.In addition,light exposure with a higher CCT was more effective in improving alertness than light exposure with a lower CCT.Our results also suggest that both daytime and night-time light exposure can improve subjective alertness.
