• Development and Reproduction
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• v.12 no.1
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• pp.9-18
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• 2008

All the organisms on the earth are affected by the repeating signals from the ambient environment caused by the movements of the sun and the earth. Their physiological and behavioral activities such as reproduction, functional pathway of various molecules, and developmental stage, are reflected by the cyclicity whether it is daily(circadian) or annual rhythms. An essential function of circadian rhythms is to provide an internal estimate of the external local time, thereby allowing the organism to program its activities so that they occur at an appropriate time in the daily environment. Of many rhythmic patterns, the circadian rhythms are considered in this review, focusing on the limit cycle, which is a model to investigate the entrainment.

• Safety and Health at Work
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• v.15 no.1
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• pp.102-109
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• 2024

Background: In today's modern world, longer working hours, shift work, and working at night have become major causes of the disruption of our natural circadian rhythms. This study aimed to investigate the effects of the type of shift work (rotating vs. fixed day), duty period (on-duty vs. off-duty), and working period within each shift (nighttime vs. daytime) on the circadian rhythm characteristics of nurses who provide direct patient care. Methods: This cross-sectional study used a purposive sampling method. Cosinor analysis was applied to analyze the actigraphy data of nurses providing direct patient care for seven consecutive days. The linear mixed effects model was then used to determine any variances between shift type, duty period, and working period within each shift for the nurses. Results: The mesor value did not differ according to nurses' shift type, duty period, and working period within each shift. The amplitude was statistically higher in on-duty nurses and in daytime working hours. The acrophase was significantly delayed in nighttime working hours. As well as nurses in rotating shift had experience. Conclusion: Our findings revealed that the peak activity of nurses occurs significantly later at night while working and nurses working during nighttime hours may have a weaker or less distinct circadian rhythm. Thus, this study suggests that limits be placed on the number of rotating nighttime shifts for nurses.

• Journal of Digital Convergence
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• v.15 no.7
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• pp.247-257
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• 2017

The purpose of this study was to measure the depression level of college students and to analyze the effects of college life stress and circadian rhythm on depression. A questionnaire survey was conducted to 720 students of college in Gwangju area from October 10, 2016 to October 31, and 687 of the collected questionnaires were analyzed. As this result, 34.5% of the students needed treatment for depression, and 71.6% of the students had mild depression. Second, depression was higher in female students, in higher grade students and students living apart from their parents. Third, evening activity type showed higher depression than morning activity type. Fourth, regression analysis revealed that depression was influenced by stress of value problem, circadian rhythm, academic stress, and getting a job stress. The results of this study suggest that students should be able to detect depression early and run a mental health program to relieve college life stress in college. However, this study is limited to some local college students and is not suitable for generalization. It is necessary to conduct research to compare university students and college students in the future.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.5
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• pp.1154-1161
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• 2005

Yin Yang theory is the first and the last one to interpret diseases apply to treatment in oriental medicine. So it is regarded as the way of heaven and earth, the discipline of all things, the origin of change, the beginning of giving birth and death, the source of spirit. These regulatory passages are needed to compare with western medical physiology and analyzed whether it has scientific bases or not. The Yin Yang theory of traditional oriental medicine are summerized from the descriptions of Scripture of Documents, Ying Wei theory of Huangdi Neijing. Meanwhile up-to-date neurobiological and molecular genetic theories on circadian physiology are reviewed in western medicine. Sunshine is transferred through RGC to SCN, herein the central circadian rhythm is made by zeitgeber and interaction of melatonin secreted from pineal body and orexin from mp pan of hypothalamus. So HPA axis is activated and controlled under the circadian rhythm and affects peripheral tissues and cells of whole body through glucocorticoid hormones. First of all, the circadian rhythm makes the basic patterns of human life in biological and sociological meaning. It is almost same context with the record of the Scripture of Documents. Also the Ying Qi and Wei Qi is basically same with the sleep-awake mechanism, that is melatonin/orexin signal or per/clk/bmal/cry genes with circadian activation and activity of each organ's physiological function. Conclusively it can be said that Yin Yang is a priori principle of living things and the beginning of giving birth and death for activation of them biologically, as is described in Huangdi Neijing.

• Molecules and Cells
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• v.28 no.2
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• pp.75-80
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• 2009

The cyclic environmental conditions brought about by the 24 h rotation of the earth have allowed the evolution of endogenous circadian clocks that control the temporal alignment of behaviour and physiology, including the uptake and processing of nutrients. Both metabolic and circadian regulatory systems are built upon a complex feedback network connecting centres of the central nervous system and different peripheral tissues. Emerging evidence suggests that circadian clock function is closely linked to metabolic homeostasis and that rhythm disruption can contribute to the development of metabolic disease. At the same time, metabolic processes feed back into the circadian clock, affecting clock gene expression and timing of behaviour. In this review, we summarize the experimental evidence for this bimodal interaction, with a focus on the molecular mechanisms mediating this exchange, and outline the implications for clock-based and metabolic diseases.

• Development and Reproduction
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• v.17 no.3
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• pp.149-177
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• 2013

Living beings are surrounded by various changes exhibiting periodical rhythms in environment. The environmental changes are imprinted in organisms in various pattern. The phenomena are believed to match the external signal with organisms in order to increase their survival rate. The signals are categorized into circadian, seasonal, and annual cycles. Among the cycles, the circadian rhythm is regarded as the most important factor because its periodicity is in harmony with the levels of melatonin secreted from pineal gland. Melatonin is produced by the absence of light and its presence displays darkness. Melatonin plays various roles in creatures. Therefore, this review is to introduce the diverse potential ability of melatonin in manifold aspects in living organism.

• Environmental Analysis Health and Toxicology
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• v.8 no.1_2
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• pp.11-17
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• 1993

Radioactive elements Li/sup +/, Rb/sup +/and Cs/sup +/ effect the period shortening in proportion to the higher concentration on the growth of Neurospora crassa. 1 mM LiCl presented the result of the period length 0.52 h shorter than average circadian rhythm 21.66 h. 1 mM RbCl reduced the period length 1.13 h than control period 21.89 h and 1 mM CsCl reduced 2.12 h than control period 21.89 h. In the equal concentration Cs/sup +/ had an extreme effect. Fatal doses of Li/sup +/, Rb/sup +/ and Cs/sup +/ are 20mM, 30mM and 20mM. In the fatal concentration Neurospora didn't develop more after 7 days and the formation of spores were not given in regular order. Circadian length of Neurospora decreased generally at the last cycle of the growth.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.4
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• pp.1481-1498
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• 2014

Automated activity monitoring has become important in many applications. In particular, automated monitoring is an important issue in large-scale management of group-housed livestock because it can save a significant part of farm workers' time or minimize the damage caused by livestock problems. In this paper, we propose an automated solution for measuring the daily-life activities of pigs by using video data in order to manage the group-housed pigs. Especially, we focus on the circadian rhythm of group-housed pigs under windowless and 24-hour light-on conditions. Also, we derive a cost-effective solution within the acceptable range of quality for the activity monitoring application. From the experimental results with the video monitoring data obtained from two pig farms, we believe our method based on circadian rhythm can be applied for detecting management problems of group-housed pigs in a cost-effective way.

• Journal of the Korean Society of School Health
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• v.34 no.2
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• pp.107-114
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• 2021

Purpose: The aim of this study was to investigate the factors influencing eating attitudes in female nursing students. Methods: A cross-sectional study was conducted on 121 university students in 2016. Data was collected using self reported questionnaires asking about circadian rhythm (Morningness-Eveningness Questionnaire), daytime sleepiness (Epworth Sleepiness Scale), sleep quality (Pittsburgh Sleep Quality Index), and eating attitudes (Eating Attitudes Test-26). Stress resistance was measured with a brain quotient test. The data were analyzed with a t-test, ANOVA, Pearson's correlation analysis and linear regression using SPSS 22.0. Results: Eating attitudes were associated with daytime sleepiness, sleep quality, and stress resistance of the right hemisphere. Among these, daytime sleepiness and sleep quality had a significant effect on eating attitudes. Conclusion: The results of this study suggest that sleep should be taken into account when developing interventions for preventing eating disorders in female nursing students.

• Journal of Integrative Natural Science
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• v.5 no.3
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• pp.198-210
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• 2012

Circadian rhythms govern a remarkable variety of metabolic and physiological functions. Accumulating epidemiological and genetic evidence indicates that the disruption of circadian rhythms might be directly linked to cancer. Intriguingly, several molecular gears constituting the clock machinery have been found to establish functional interplays with regulators of the cell cycle, and alterations in clock function could lead to aberrant cellular proliferation. In addition, connections between the circadian clock and cellular metabolism have been identified that are regulated by chromatin remodelling. This suggests that abnormal metabolism in cancer could also be a consequence of a disrupted circadian clock. Therefore, a comprehensive understanding of the molecular links that connect the circadian clock to the cell cycle and metabolism could provide therapeutic benefit against certain human neoplasias.