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This study aims to measure the daily melatonin secretory rhythms of people living in high-, mid-, and low-latitude regions characterised by different day lengths and global solar-radiation conditions. In Poland, a high-latitude region, the amount of melatonin secretion is greater, with secretion occurring earlier (exemplifying phase advance). On the other hand, in Vietnam, a low-latitude region, the level is lower and occurs later (phase delay). Japan, a mid-latitude region, shows behaviour intermediate between these two. Melatonin secretory rhythm in Vietnam is closely related to Day length and Global Solar Radiation, though no such relationship is observed in Poland or Japan, making it necessary for other factors to be considered. The results of this study have important implications considering the impacts of light pollution and lighting-related conditions of modern life. [ABSTRACT FROM AUTHOR]

Circadian rhythms, which respond to the day-night cycle on the earth, arise from the endogenous timekeeping system within organisms, called the "biological clock." For accurate circadian rhythms, daily fluctuations in light and temperature are considered one of the important time cues. In social insects, both abiotic and biotic factors (i.e., social interactions) play a significant role in activity-rest rhythm regulation. However, it is challenging to monitor individual activity-rest rhythms in a colony because of the large group size and small body size. Therefore, it is unclear whether individuals in a colony exhibit activity-rest rhythms and how social interactions regulate their activity-rest rhythms in the colony. This study developed an image-based tracking system using 2D barcodes for Diacamma cf. indicum from Japan (a monomorphic ant) and measured the locomotor activities of all colony members under laboratory colony conditions. We also investigated the effect of broods on activity-rest rhythms by removing all broods under colony conditions. Activity-rest rhythms appeared only in isolated ants, not under colony conditions. In addition, workers showed arrhythmic activities after brood removal. These results suggested that a mixture of social interactions, and not light and temperature, induces the loss of activity-rest rhythms. These results contribute to the knowledge of a diverse pattern of circadian activity rhythms in social insects. [ABSTRACT FROM AUTHOR]

Many species show rhythmicity in activity, from the timing of flowering in plants to that of foraging behavior in animals. The free-running periods and amplitude (sometimes called strength or power) of circadian rhythms are often used as indicators of biological clocks. Many reports have shown that these traits are highly geographically variable, and interestingly, they often show latitudinal or longitudinal clines. In many cases, the higher the latitude is, the longer the free-running circadian period (i.e., period of rhythm) in insects and plants. However, reports of positive correlations between latitude or longitude and circadian rhythm traits, including free-running periods, the power of the rhythm and locomotor activity, are limited to certain taxonomic groups. Therefore, we collected a cosmopolitan stored-product pest species, the red flour beetle Tribolium castaneum, in various parts of Japan and examined its rhythm traits, including the power and period of the rhythm, which were calculated from locomotor activity. The analysis revealed that the power was significantly lower for beetles collected in northern areas than southern areas in Japan. However, it is worth noting that the period of circadian rhythm did not show any clines; specifically, it did not vary among the sampling sites, despite the very large sample size (n = 1585). We discuss why these cline trends were observed in T. castaneum. [ABSTRACT FROM AUTHOR]

Background: Sleep health-related issues, such as poor subjective sleep quality during the night and nocturnal wakefulness, have been a focus of recent research on frailty. However, current trends regarding the chronotypes of older individuals with frailty have not been well documented, and information on the impact of frailty on circadian rest-activity patterns is limited. The aim of this research was to clarify the relationship among frailty, nonparametric rest-activity patterns, and chronotype in older community-dwelling subjects. Method: A survey was conducted between June and December 2018, and the participants of this study were recruited from among community-dwellers aged 60 years or older living in Akita prefecture, Japan. The frailty phenotype defined by the National Center for Geriatrics and Gerontology Study of Geriatric Syndromes (NCGG-SGS) was used to evaluate the frailty status of each participant. To evaluate nonparametric rest-activity rhythm (RAR) parameters (e.g., interdaily stability [IS], intradaily variability [IV], and relative amplitude [RA]), each participant wore an Actiwatch Spectrum Plus device on his or her non-dominant wrist for seven continuous days without removal. The Munich chronotype questionnaire-Japanese version (MCTQ-J) was also used to measure the midpoint of sleep in free days (MSF). Results: The final study cohort was composed of 105 participants (85.7% women) and was divided into 58 non-frail subjects, 45 pre-frail subjects, and 2 frail subjects. According to a binomial logistic regression analysis, the pre-frail individuals had a weaker grip strength (coefficient [beta], −0.18; odds ratio, 0.84; 95% confidence interval [CI], 0.76–0.93; p =.001) and a lower RA (beta, −8.78; odds ratio, 0.0002; 95% CI, 0.00–0.15; p =.01). In addition, correlation analyses also showed that the MSF was negatively associated with the RA in the pre-frail group (r = −0.30, p <.05) and positively correlated with the RA in the non-frail group (r = 0.26, p <.05); furthermore, the MSF of the pre-frail group occurred at a later time than that of the non-frail one (p =.03). Conclusion: The present study provides grounds for our proposal that pre-frailty is significantly associated with a low grip power and relative imbalance between rest and active statuses as indexed using nonparametric RAR parameters. Furthermore, elderly individuals with pre-frailty or frailty may have a later MSF time. However, these potential findings need to be validated in future research. [ABSTRACT FROM AUTHOR]

Background: It is recommended globally that shocks by automated external defibrillators (AEDs) should be delivered immediately when a shockable out-of-hospital cardiac arrest (OHCA) occurs. However, the actual time-interval from collapse to first shock by public-access AED and its impact on subsequent outcome has not been extensively investigated in real-world settings.Methods: OHCA data from 2013 to 2015 were obtained from the All-Japan Utstein Registry. Bystander-witnessed OHCA patients with shockable rhythm who were shocked by public-access AED in public locations were included. The primary endpoint was 1-month survival with favourable neurological outcome, and the association between time-interval from collapse to first shock by public-access AED and subsequent outcome was assessed.Results: During the study period, 28% (2282/8126) of bystander-witnessed OHCA cases with shockable rhythm were shocked by public-access AED in public locations. The proportion of OHCA patients who were shocked by public-access AED within 5 min from collapse was 58% (1323/2282). Among these patients, the proportion of 1-month survival with favourable neurological outcome was 62% (815/1317). The proportion significantly decreased with increased time from collapse to shock by public-access AED (48% for 6-10 min, 38% for 11-15 min, 30% for 16-20 min, and 7% for 21-25 min; p-for-trend <0.001), and no patient survived if shock delivery occurred more than 26 min after OHCA.Conclusion: In Japan, earlier shock by public-access AED led to better outcome after bystander-witnessed OHCA with shockable rhythm in public locations. However, the proportion of OHCA patients who received early shock was still low in public locations. [ABSTRACT FROM AUTHOR]

Digestion time and feeding of the pelagic chaetognath Zonosagitta nagae, which occurs predominantly in warm waters around Japan, were investigated in the laboratory. Young individuals of Z. nagae ranging from 4.1-7.6 mm in body length were used for the experiments with adult females of the copepod Acartia steueri as prey. The mean digestion time of Z. nagae was 115±3 minutes at 20°C. Temporal change in individual's feeding intensity was observed every 1.5 h for 24 h to determine the diel feeding pattern, feeding interval, feeding rates and daily ration. Almost all individuals showed no clear diel rhythm within 24-h at 20°C under 12L:12D cycle; time interval between feeding was 4.5-6 h (mode) for individuals that ingested multiple copepods. The number of copepods ingested by a chaetognath ranged from 0 to 5 and on average 2.6 copepods were consumed a day per individual. Specific daily ration in most individuals corresponded to ca. 50% of its dry weight while some individuals showed the extremes of non-feeding or voracious feeding (>200% d-1), indicating that some of the young Z. nagae had an intermittent feeding mode, which would be adaptive to save energy expenditure at low prey densities and to reduce mortality by lowering the risk of predation. [ABSTRACT FROM AUTHOR]

Listeners rely on native-language rhythm in segmenting speech; in different languages, stress-, syllable- or mora-based rhythm is exploited. The rhythmic similarity hypothesis holds that where two languages have similar rhythm, listeners of each language should segment their own and the other language similarly. Such similarity in listening was previously observed only for related languages (English-Dutch; French-Spanish). We now report three experiments in which speakers of Telugu, a Dravidian language unrelated to Japanese but similar to it in crucial aspects of rhythmic structure, heard speech in Japanese and in their own language, and Japanese listeners heard Telugu. For the Telugu listeners, detection of target sequences in Japanese speech was harder when target boundaries mismatched mora boundaries, exactly the pattern that Japanese listeners earlier exhibited with Japanese and other languages. The same results appeared when Japanese listeners heard Telugu speech containing only codas permissible in Japanese. Telugu listeners' results with Telugu speech were mixed, but the overall pattern revealed correspondences between the response patterns of the two listener groups, as predicted by the rhythmic similarity hypothesis. Telugu and Japanese listeners appear to command similar procedures for speech segmentation, further bolstering the proposal that aspects of language phonological structure affect listeners' speech segmentation. [ABSTRACT FROM AUTHOR]

The article features the dance simulation game "Dance Dance Revolution" or DDR, which is currently an "arcade craze" sustained by on-and offline fan communities. "Dance Dance Revolution" was officially released to U.S. arcades in 2000 and quickly became the most successful of a genre of rhythm action games called Bemani. With specialized input devices rather than the traditional joystick-based game controller, Bemani video games turn players into performers, requiring them to dance, scratch DJ turntables, beat drums, and strum guitars in synchronicity with the game machine. "Dance Dance Revolution" has gone through multiple versions and modes of play since its original release as an arcade game in Japan in 1998. Full releases of the game mingle with song and character upgrades.