University-wide chronotyping shows late-type students have lower grades, shorter sleep, poorer well-being, lower self-regulation, and more absenteeism

A person's preferred timing of nocturnal sleep (chronotype) has important implications for cognitive performance. Students who prefer to sleep late may have a selective learning disadvantage for morning classes due to inadequate sleep and circadian desynchrony. Here, (1) we tested whether late-type students perform worse only for morning classes, and (2) we investigated factors that may contribute to their poorer academic achievement. Chronotype was determined objectively in 33,645 university students (early, n=3,965; intermediate, n=23,787; late, n=5,893) by analyzing the diurnal distribution of their logins on the university's Learning Management System (LMS). Late-type students had lower grades than their peers for courses held at all different times of day, and during semesters when they had no morning classes. Actigraphy studies (n=261) confirmed LMS-derived chronotype was associated with students' sleep patterns. Nocturnal sleep on school days was shortest in late-type students because they went to bed the latest and woke up early compared with non-school days. Surveys showed that late-type students had lower self-rated health and mood (n=357), and lower metacognitive self-regulation (n=752). Wi-Fi connection data for classrooms (n=17,356) revealed that late-type students had lower lecture attendance than their peers for classes held in both the morning and the afternoon. Our findings suggest that multiple factors converge to impair learning in late-type students. Shifting classes later can improve sleep and circadian synchrony in late-type students but is unlikely to eliminate the performance gap. Interventions that focus on improving students' well-being and learning strategies may be important for addressing the late-type academic disadvantage.

The Use of Cluster Analysis to Evaluate the Impact of COVID-19 Pandemic on Daily Water Demand Patterns

Proper determination of unitary water demand and diurnal distribution of water consumption (water consumption histogram) provides the basis for designing, dimensioning, and all analyses of water supply networks. It is important in the case of mathematical modelling of flows in the water supply network, particularly during the determination of nodal water demands in the context of Extended Period Simulation (EPS). Considering the above, the analysis of hourly water consumption in selected apartment buildings was performed to verify the justification of the application of grouping by means of k-means clustering. The article presents a detailed description of the adopted methodology, as well as the obtained results in the form of synthetic distributions of hourly water consumption, and the effect of the COVID-19 pandemic on their change.

Analysis of diurnal, seasonal, and annual distribution of urban sub-hourly to hourly rainfall extremes in Germany

The timing of short extreme rainstorm, which was usually thought to occur on midsummer afternoons, was investigated to improve future mitigation options for infrastructure and safety from localised flash flooding. Using a peak-over-threshold approach, the timing of 10- and 60-min extreme events was filtered from high-resolution rainfall series assessing diurnal, seasonal, and annual distributions and analysed for spatial variations and prevailing atmospheric circulation types (CTs). The diurnal distribution showed a clear deviation from that of the entire rainfall regime. A complex spatial pattern was identified with distinct timing signatures of storms in the northern (mostly afternoon) and southern regions (a bimodal distribution with a second peak in the early morning) of Germany and a more homogenous diurnal distribution of events across the central regions. Most storms occurred in summer, but 42% of 10-min events occurred outside the summer months (June–July–August). A distinct annual clustering of extremes was identified, which varied distinctly between the 10- and 60-min extremes, indicating that the sub-hourly and hourly events were far from running conterminously. The timing of extreme events on the investigated time scales was not dominated by the occurrence of specific CTs in most cases, suggesting that other factors control these extremes.

Evaluation of local weather observations as predictors of fog and low-level stratiform clouds at the airport of Odessa

<p>Fog that limit visibility and low-level stratiform clouds represent a significant hazard to aviation especially during takeoff and landing, and also low-level flying of aircrafts, because accidents often occur in reduced visibility conditions and low clouds. Therefore, forecasting fog and low ceilings is one of the most important, but at the same time the most difficult issue, because both phenomena strongly depend on local conditions and unsteady in both time and space. So weather observations can be used for statistical dependencies of fog/ low-level stratiform cloud characteristics on numerical model outputs.</p><p>To study fog and low-level stratiform clouds event characteristics occurring at the airport of Odessa, Ukraine, half hourly observations in the period of 2010-2018 are used. Applying a statistical approach annual, seasonal and diurnal distribution of fog and low stratus and their frequency distribution associated with various meteorological parameters are obtained.</p><p>The monthly distributions of low-level stratiform clouds reveal maximum occurrence frequencies in November and January, and fog most frequently occurs in December. No significant diurnal cycle of stratiform cloud occurrence is discovered, as opposed to fog for which the highest frequency is observed in the hours before sunrise, while when the day sets in, frequencies are declining and increasing at night.</p><p>Fog and low-level stratiform clouds have the same distribution in duration and the mean event duration is 4.5 h while 55% of the events lasted 2 h or less. The most long-lived fog and stratiform clouds can last about 4 days during the December-January period.</p><p>Occurrence of fog and stratiform clouds as function of temperature and relative humidity reveals a close statistical relationship, especially for fog events. More than 33% of all fogs are observed at temperatures of 0°C to 6°C and 96-100% relative humidity, the most frequencies of low-level clouds (13%) occur in the same temperature interval, but at lower values of relative humidity (91-95%).</p><p>Regarding fog density 75% of the events have minimum visibility lower than 400 m, which indicates the severity of the problem, because, despite the season and type of fog, they are usually quite intense and dense.</p><p>In all seasons of the year, the highest frequency of low-level stratiform clouds is in interval of 3...4 m/s, excluding summer, when most often such cloud is registered at higher speeds. The wind directions associated with low-level stratiform clouds are, as a rule, northern and eastern ones, which meant that forming stratiform clouds is also related to cyclonic activity.</p><p>Fogs, on the contrary, most often in all seasons, except winter, are formed at calm, meaning that radiation fogs are the most common type in the Odessa airport. In winter fogs are most commonly associated with northern and easterly winds; in all other seasons the southern wind is the most frequent.</p><p>On this basis, a relationship between the weather conditions near the surface and occurrence of fog and low-level stratiform clouds can be found.</p>

Circadian Variation of Migraine Attack Onset: A Review of Clinical Studies

Several studies suggested that migraine attack onset shows a circadian variation; however, there has not been an overview and synthesis of these findings. A PubMed search with keywords “migraine” AND “circadian” resulted in ten studies directly investigating this topic. Results of these studies mostly show that migraine attacks follow a monophasic 24-hour cyclic pattern with an early morning or late night peak while other studies reported an afternoon peak and also a biphasic 24-hour cycle of attacks. The identified studies showed methodological variation including sample size, inclusion of medication use, comorbidities, and night or shift workers which could have contributed to the contradictory results. Several theories emerged explaining the diurnal distribution of migraine attacks suggesting roles for different phenomena including a morning rise in cortisol levels, a possible hypothalamic dysfunction, a circadian variation of migraine triggers, sleep stages, and a potentially different setting of the circadian pacemaker among migraineurs. At the moment, most studies show an early morning or late night peak of migraine attack onset, but a significant amount of studies reveals contradictory results. Further studies should investigate the arising hypotheses to improve our understanding of the complex mechanism behind the circadian variation of migraine attacks that can shed light on new targets for migraine therapy.

Biodiversity of wild alfalfa pollinators and their temporal foraging characters in Hexi Corridor, Northwest China

Seed production of alfalfa (Medicago sativa L.) is important in determining the effective distribution of new cultivars to farmers. However, little is known about the biodiversity and their community function of native wild pollinators of alfalfa in agronomic systems. We investigated the biodiversity of insects which visited alfalfa flowers and their temporal foraging characters in Hexi Corridor, China. A high biodiversity of insect visitors was discovered, 20 insect taxa in all, including 13 species of Hymenoptera, 3 species of Coleoptera, 3 species of Lepidoptera and 1 species of Diptera. Three native bee species, Andrena squamata, Anthophora melanognatha and Megachile abluta,were validated as the principal pollinators. They showed significant variations in tripping mode and their diurnal distribution patterns. Our results indicated that the native wild bees are diverse and they complement each other. This means they have developed a more complex system for the pollination of alfalfa than has been previously found out.