Night Phase Research Articles

Examining the Capability of the VLF Technique for Nowcasting Solar Flares Based on Ground Measurements in Antarctica

Measurements of Very-Low-Frequency (VLF) transmitter signals have been widely used to investigate the effects of various space weather events on the D-region ionosphere, including nowcasting solar flares. Previous studies have established a method to nowcast solar flares using VLF measurements, but only using measurements from dayside propagation paths, and there remains limited focus on day–night mixed paths, which are important for method applicability. Between March and May of 2022, the Sun erupted a total of 56 M-class and 6 X-class solar flares, all of which were well captured by our VLF receiver in Antarctica. Using these VLF measurements, we reexamine the capability of the VLF technique to nowcast solar flares by including day–night mixed propagation paths and expanding the path coverage in longitude compared to that in previous studies. The amplitude and phase maximum changes are generally positively correlated with X-ray fluxes, whereas the time delay is negatively correlated. The curve-fitting parameters that we obtain for the X-ray fluxes and VLF signal maximum changes are consistent with those in previous studies for dayside paths, even though different instruments are used, supporting the flare-nowcasting method. Moreover, the present results show that, for day–night mixed paths, the amplitude and phase maximum changes also scale linearly with the logarithm of the flare X-ray fluxes, but the level of change is notably different from that for dayside paths. The coefficients used in the flare-nowcasting method need to be updated for mixed propagation paths.

Continental-scale patterns in diel flight timing of high-altitude migratory insects.

Many insects depend on high-altitude, migratory movements during part of their life cycle. The daily timing of these migratory movements is not random, e.g. many insect species show peak migratory flight activity at dawn, noon or dusk. These insects provide essential ecosystem services such as pollination but also contribute to crop damage. Quantifying the diel timing of their migratory flight and its geographical and seasonal variation, are hence key towards effective conservation and pest management. Vertical-looking radars provide continuous and automated measurements of insect migration, but large-scale application has not been possible because of limited availability of suitable devices. Here, we quantify patterns in diel flight periodicity of migratory insects between 50 and 500 m above ground level during March-October 2021 using a network of 17 vertical-looking radars across Europe. Independent of the overall daily migratory movements and location, peak migratory movements occur around noon, during crepuscular evening and occasionally the morning. Relative daily proportions of insect migration intensity and traffic during the diel phases of crepuscular-morning, day, crepuscular-evening and night remain largely equal throughout May-September and across Europe. These findings highlight, extend, and generalize previous regional-scale findings on diel migratory insect movement patterns to the whole of temperate Europe. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'.

Voluntary exercise fails to prevent metabolic dysfunction-associated steatotic liver disease progression in male rats fed a high-fat high-cholesterol diet.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a major public health issue with a worldwide prevalence of 30%-32%. In animal models, voluntary exercise may be an alternative to forced physical activity, avoiding stress, potential injuries, and being logistically simpler. Here, we assessed voluntary exercise (Vex) in Sprague-Dawley rats fed a high-fat, high-cholesterol diet for 18 weeks to induce MASLD. We quantified workload (speed and distance) using exercise wheels and evaluated energy expenditure using calorimetric cages. MASLD progression was assessed using circulating and hepatic biochemical and gene markers of steatosis, inflammation, and fibrosis. The animals ran an average of 301 km during the study period, with the average daily distance peaking at 4937 m/day during Weeks 3-4 before decreasing to 757 m/day by the end of the study. Rats exposed to Vex showed no improvement in any of the MASLD-associated features, such as steatosis, inflammation, or fibrosis. Rats exposed to Vex exhibited a higher total energy expenditure during the night phase (+0.35 kcal/h; p = 0.003) without resulting in any effect on body composition. We conclude that, in our experimental conditions, Vex failed to prevent MASLD progression in male Sprague-Dawley rats exposed to a high-fat high-cholesterol diet for 18 weeks.

Increased Yangtze finless porpoise presence in urban Wuhan waters of the Yangtze River during fishing closures.

Wuhan, a highly urbanized and rapidly growing region within China's Yangtze Economic Zone, has historically been identified as a gap area for the critically endangered Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) based on daytime visual surveys. However, there has been a noticeable increase in porpoise sightings since 2020. This study employed passive acoustic monitoring to investigate porpoise distribution in Wuhan between 2020 and 2022. Generalized linear models were used to explore the relationship between shipping, hydrological patterns, light intensity, and porpoise biosonar activity. Over 603 days of effective monitoring, the daily positive rate for porpoise biosonar detection reached 43%, with feeding-related buzz signals accounting for 55% of all porpoise biosonar signals. However, the proportion of minutes during which porpoise presence was detected was 0.18%, suggesting that while porpoises may frequent the area, their visits were brief and mainly focused on feeding. A significant temporal trend emerged, showing higher porpoise biosonar detection during winter (especially in February) and 2022. Additionally, periods without boat traffic correlated with increased porpoise activity. Hydrological conditions and light levels exhibited significant negative correlations with porpoise activity. Specifically, porpoise sonar detections were notably higher during the night, twilight, and new moon phases. It is highly conceivable that both fishing bans and COVID-19 pandemic-related lockdowns contributed to the heightened presence of porpoises in Wuhan. The rapid development of municipal transportation and shipping in Wuhan and resulting underwater noise pollution have emerged as a significant threat to the local porpoise population. Accordingly, it is imperative for regulatory bodies to effectively address this environmental stressor and formulate targeted protection measures to ensure the conservation of the finless porpoise.

Metabolic plasticity and obesity-associated changes in diurnal postexercise metabolism in mice

BackgroundCircadian disruption is widespread and increases the risk of obesity. Timing of therapeutic interventions may promote coherent and efficient gating of metabolic processes and restore energy homeostasis. AimTo characterize the diurnal postexercise metabolic state in mice and to identify the influence of diet-induced obesity on identified outcomes. MethodsC57BL6/NTac male mice (6 wks of age) were fed a standard chow or high-fat diet for 5 weeks. At week 5, mice were subjected to a 60-min (16 m/min, 5 % incline) running bout (or sham) during the early rest (day) or early active (night) phase. Tissue and serum samples were collected immediately post-exercise (n = 6/group). In vivo glucose oxidation was measured after oral administration of 13C-glucose via 13CO2 exhalation analysis in metabolic cages. Basal and isoproterenol-stimulated adipose tissue lipolysis was assessed ex vivo for 1 h following exercise. ResultsLean mice displayed exercise-timing-specific plasticity in metabolic outcomes, including phase-specificity in systemic glucose metabolism and adipose-tissue-autonomous lipolytic activity depending on time of day. Conversely, obesity impaired temporal postexercise differences in whole-body glucose oxidation, as well as the phase- and exercise-mediated induction of lipolysis in isolated adipose tissue. This obesity-induced alteration in diurnal metabolism, as well as the indistinct response to exercise, was observed concomitant with disruption of core clock gene expression in peripheral tissues. ConclusionsOverall, high-fat fed obese mice exhibit metabolic inflexibility, which is also evident in the diurnal exercise response. Our study provides physiological insight into exercise timing-dependent aspects in the dynamic regulation of metabolism and the influence of obesity on this biology.

Blue light at night produces stress-evoked heightened aggression by enhancing brain-derived neurotrophic factor in the basolateral amygdala

Light is an underappreciated mood manipulator. People are often exposed to electronic equipment, which results in nocturnal blue light exposure in modern society. Light pollution drastically shortens the night phase of the circadian rhythm. Preclinical and clinical studies have reported that nocturnal light exposure can influence mood, such as depressive-like phenotypes. However, the effects of blue light at night (BLAN) on other moods and how it alters mood remain unclear. Here, we explored the impact of BLAN on stress-provoked aggression in male Sprague‒Dawley rats, focusing on its influence on basolateral amygdala (BLA) activity. Resident-intruder tests, extracellular electrophysiological recordings, and enzyme-linked immunosorbent assays were performed. The results indicated that BLAN produces stress-induced heightened aggressive and anxiety-like phenotypes. Moreover, BLAN not only potentiates long-term potentiation and long-term depression in the BLA but also results in stress-induced elevation of brain-derived neurotrophic factor (BDNF), mature BDNF, and phosphorylation of tyrosine receptor kinase B expression in the BLA. Intra-BLA microinfusion of BDNF RNAi, BDNF neutralizing antibody, K252a, and rapamycin blocked stress-induced heightened aggressive behavior in BLAN rats. In addition, intra-BLA application of BDNF and 7,8-DHF caused stress-induced heightened aggressive behavior in naïve rats. Collectively, these results suggest that BLAN results in stress-evoked heightened aggressive phenotypes, which may work by enhancing BLA BDNF signaling and synaptic plasticity. This study reveals that nocturnal blue light exposure may have an impact on stress-provoked aggression. Moreover, this study provides novel insights into the BLA BDNF-dependent mechanism underlying the impact of the BLAN on mood.

Ribosome profiling in the Symbiodiniacean dinoflagellate Fugacium kawagutii shows coordinated protein synthesis of enzymes in different pathways at different times of day.

Dinoflagellates respond to daily changes in light and dark by changes in cellular metabolism, yet the mechanisms used are still unclear. For example, Fugacium (previously Symbiodinium) kawagutii shows little difference in the transcriptome between day and night suggesting little transcriptional control over gene expression. Here, we have performed ribosome profiling at 2 h intervals over a daily light-dark cycle to assess the degree to which protein synthesis rates might change over the daily cycle. The number of F. kawagutii coding sequences with significant differences in the number of ribosome-protected fragments (RPF) over the 24-h cycle was 2923 using JTK_Cycle and 3655 using ECHO. The majority of the regulated transcripts showed peak translation at the onset of the dark period. The regulated sequences were assigned to different KEGG pathways and transcripts that were translated at roughly the same time were termed concurrently regulated. Both analyses revealed concurrent regulation of many transcripts whose gene products were involved in spliceosome or lysosome biogenesis with peak translation rates around the onset of the dark period, while others, involved in nitrate metabolism and ribosomal proteins, were preferentially translated around the onset of the day phase or the end of the night phase, respectively. In addition, some sequences involved in DNA synthesis were preferentially translated at the end of the day. We conclude that light-dark cycles seem able to synchronize translation of some transcripts encoding proteins involved in a range of different cellular processes, and propose that these changes may help the cells adapt and alter their metabolism as a function of the time of day.

Chronotoxicity of Acrylamide in Mice Fed a High-Fat Diet: The Involvement of Liver CYP2E1 Upregulation and Gut Leakage.

Acrylamide (ACR) is produced under high-temperature cooking of carbohydrate-rich foods via the Maillard reaction. It has been reported that ACR has hepatic toxicity and can induce liver circadian disorder. A high fat diet (HFD) could dysregulate liver detoxification. The current study showed that administration of ACR (100 mg/kg) reduced the survival rate in HFD-fed mice, which was more pronounced when treated during the night phase than during the day phase. Furthermore, ACR (25 mg/kg) treatment could cause chronotoxicity in mice fed a high-fat diet, manifested as more severe mitochondrial damage of liver during the night phase than during the day phase. Interestingly, HFD induced a higher CYP2E1 expressions for those treated during the night phase, leading to more severe DNA damage. Meanwhile, the expression of gut tight junction proteins also significantly decreases at night phase, leading to the leakage of LPSs and exacerbating the inflammatory response at night phase. These results indicated that a HFD could induce the chronotoxicity of ACR in mice liver, which may be associated with increases in CYP2E1 expression in the liver and gut leak during the night phase.

Altered transposable elements expression and gene networks remodeling precede disruptions in sleep/wake cycles in a tauopathy mouse model of AD

AbstractBackgroundAlzheimer’s Disease (AD) is an widespread neurodegenerative disorder, common in elder and Veterans communities, culminating in dementia with non‐cognitive behavioral and metabolic symptoms, such as hyperactivity and altered sleep/wake patterns. In demented patients, sleep/wake cycle disruptions facilitate weight loss, which is associated with adverse outcomes like accelerated AD progression and higher institutionalization. Tg4510 mice, which express a P301L mutant variant of human tau, develop both cognitive and non‐cognitive symptoms. Several mouse models of tau deposition, including Tg4510 mice, also have negative energy balance. To identify early factors affecting AD, we measured locomotor, sleep/wake patterns in vivo, and analyzed RNA‐seq data from Tg4510 mice to identify gene and transposable elements (TE) expression changes involved in behavioral derangements in AD.MethodLocomotor activity, sleep and wake intervals and patterns were measured using in vivo metabolic cages for two weeks over 24 hr and day and night cycles from Tg4510 mice (n = 5‐7) vs. controls (n = 7‐10) before and after the onset of tauopathy (at 2 and 7 months of age respectively). In additional experiments, we analyzed RNA‐seq from hippocampi of Tg4510 mice (n = 5) vs. controls (n = 6). Using our established TTESA bioinformatics pipeline, reads were aligned to reference genome and expression of genes or TEs was measured with featureCounts. Pathway enrichment analysis using Visual Annotation Display was used to discover common functional and disease pathways using Gene Ontology, Protein Ontology, and Mammalian Phenotype Ontology.ResultWe observed altered locomotor and sleep patterns during the night phase starting in young Tg4510 vs. controls. TTESA results detected the majority of significantly differentially expressed TEs were retrotransposons (70%), which consisted mainly of long terminal repeats (LTRs; 70%) and some LINE retroelements (30%) and SINEs (<8%) in transgenic mice. VLaD pathway analysis revealed several biological processes upregulated in transgenic mice, including non‐cognitive behavioral pathways were downregulated, such as the regulation of circadian sleep/wake cycle with changes in the expression levels of Per2, Per3 (p<0.0001).ConclusionEarly dysregulation of TEs may be involved in rewiring gene expression networks underlying behavioral changes in wake and sleep cycles and other circadian patterns of behavior in this humanized mouse model of AD.

Impact of Solar Energy and Energy Storage on a Still’s Nocturnal Output

Abstract Solar stills represent one of the effective solutions in remote regions that suffer from the problem of lack of fresh water, but the disadvantage of their type of distillation technologies is the low productivity of pure water per square meter of evaporation surface. During the night, the brine cools down because of the absence of solar radiation, which causes a discontinuity in the operation of the solar still, which no longer produces freshwater. Therefore, the current work aims to achieve the highest performance of solar stills. To achieve these, in the present work, the thermal behavior of a simple greenhouse solar still is coupled to a sensible heat storage tank to ensure the heating of the brine by energy stored and therefore to improve the performance of the solar still by the night production of distilled water. The results obtained are encouraging because the improvement rate was 27.70 % compared to the daily light sentence and the thermal efficiency of our system during the night phase was stable between 60 and 61 %.

Daily rhythms in the behavioural stress response of the zebrafish Danio rerio

In nature, animals are exposed to stressors that occur with different likelihood throughout the day, such as risk of predation and human disturbance. Hence, the stress response is expected to vary plastically to adaptively match these challenges. Several studies have supported this hypothesis in a wide range of vertebrate species, including some teleost fish, mostly through evidence of circadian variation in physiology. However, in teleost fish, circadian variation in behavioural stress responses is less understood. Here, we investigated the daily rhythm of stress response at the behavioural level in the zebrafish Danio rerio. We exposed individuals and shoals to an open field test every 4 h over a 24 h cycle, recording three behavioural indicators of stress and anxiety levels in novel environments (thigmotaxis, activity and freezing). Thigmotaxis and activity significantly varied throughout the day with a similar pattern, in line with a stronger stress response in the night phase. The same was suggested by analysis of freezing in shoals, but not in individual fish, in which variation appeared mostly driven by a single peak in the light phase. In a control experiment, we observed a set of subjects after familiarisation with the open-field apparatus. This experiment indicated that activity and freezing might present a daily rhythmicity that is unrelated to environmental novelty, and thus to stress responses. However, the thigmotaxis was constant through the day in the control condition, suggesting that the daily variation of this indicator is mostly attributable to the stress response. Overall, this research indicates that behavioural stress response of zebrafish does follow a daily rhythm, although this may be masked using behavioural indicators other than thigmotaxis. This rhythmicity can be relevant to improve welfare in aquaculture and reliability of behavioural research in fish models.

Analysis of circadian rhythm components in EEG/EMG data of aged mice.

Aging disrupts circadian clocks, as evidenced by a reduction in the amplitude of circadian rhythms. Because the circadian clock strongly influences sleep-wake behavior in mammals, age-related alterations in sleep-wake patterns may be attributable, at least partly, to functional changes in the circadian clock. However, the effect of aging on the circadian characteristics of sleep architecture has not been well assessed, as circadian behaviors are usually evaluated through long-term behavioral recording with wheel-running or infrared sensors. In this study, we examined age-related changes in circadian sleep-wake behavior using circadian components extracted from electroencephalography (EEG) and electromyography (EMG) data. EEG and EMG were recorded from 12 to 17-week-old and 78 to 83-week-old mice for 3 days under light/dark and constant dark conditions. We analyzed time-dependent changes in the duration of sleep. Rapid eye movement (REM) and non-REM (NREM) sleep significantly increased during the night phase in old mice, whereas no significant change was observed during the light phase. The circadian components were then extracted from the EEG data for each sleep-wake stage, revealing that the circadian rhythm in the power of delta waves during NREM sleep was attenuated and delayed in old mice. Furthermore, we used machine learning to evaluate the phase of the circadian rhythm, with EEG data serving as the input and the phase of the sleep-wake rhythm (environmental time) as the output. The results indicated that the output time for the old mice data tended to be delayed, specifically at night. These results indicate that the aging process significantly impacts the circadian rhythm in the EEG power spectrum despite the circadian rhythm in the amounts of sleep and wake attenuated but still remaining in old mice. Moreover, EEG/EMG analysis is useful not only for evaluating sleep-wake stages but also for circadian rhythms in the brain.

Accumulation of cyanobacterial photosystem II containing the "rogue" D1 subunit is controlled by FtsH protease and the synthesis of the standard D1 protein.

Unicellular diazotrophic cyanobacteria contribute significantly to the photosynthetic productivity of the ocean and the fixation of molecular nitrogen, with photosynthesis occurring during the day and nitrogen fixation during the night. In species like Crocosphaera watsonii WH8501 the decline in photosynthetic activity in the night is accompanied by the disassembly of oxygen-evolving photosystem II (PSII) complexes. Moreover, in the second half of the night phase a small amount of rogue D1 (rD1), which is related to the standard form of D1 subunit found in oxygen-evolving PSII, but of unknown function, accumulates but is quickly degraded at the start of the light phase. We show here that removal of rD1 is independent of rD1 transcript level, thylakoid redox state and trans-thylakoidal pH but requires light and active protein synthesis. We also found that the maximal level of rD1 positively correlates with the maximal level of chlorophyll biosynthesis precursors and enzymes, which suggests a possible role for rPSII in the activation of chlorophyll biosynthesis just before or upon the onset of light, when new photosystems are synthesized. By studying strains of Synechocystis PCC 6803 expressing Crocosphaera rD1 we found that accumulation of rD1 is controlled by the light-dependent synthesis of the standard D1 protein which triggers the fast FtsH2-dependent degradation of rD1. Affinity purification of FLAG-tagged rD1 unequivocally demonstrated the incorporation of rD1 into a non-oxygen-evolving PSII complex which we term rogue PSII (rPSII). The complex lacks the extrinsic proteins stabilizing the oxygen-evolving Mn4CaO5 cluster but contains the Psb27 and Psb28-1 assembly factors.

Evidence of ancestral nocturnality, locomotor clock regression, and cave zone-adjusted sleep duration modes in a cave beetle

The small carrion beetle Ptomaphagus hirtus is an abundant inhabitant of the exceptionally biodiverse Mammoth Cave system. Previous studies revealed negative phototaxis and the expression of biological clock genes in this microphthalmic cave beetle. Here we present results from probing P. hirtus for the entrainment of locomotor rhythms using the TriKinetics activity monitor setup. Although curtailed by low adjustment frequency of animals to the test environment, the data obtained from successfully monitoring two animals in constant darkness (DD) and six animals exposed to 12 hour light-dark cycles (LD) revealed a strong effect of light on locomotor activity in P. hirtus. In LD, activity was prevalent during the artificial night phases while close to absent during the presumptive day phases, suggesting conserved nocturnality. Upon transitioning LD animals to constant darkness, none displayed detectable evidence of free-running activity rhythms, suggesting complete regression of the central circadian clock. Equally notable, overall locomotor activity of the two DD-monitored animals was about three-fold lower compared to LD animals due to longer rest durations in the former. We, therefore, propose the existence of cave zone-specific energy expenditure modes that are mediated through light schedule responsive modification of sleep duration in P. hirtus.

The Impact of the Urban Heat Island on the Sensation of Thermal Comfort and Electricity Consumption in Sfax in Central-Eastern Tunisia during the Hot Season

This study follows on from the work on the urban climate of Sfax and its energy repercussions. The spatial configuration of the urban heat island (UHI) and the spatial distribution of the thermal comfort indices, the heat index (HI), the universal thermal climate index (UTCI) and the temperature humidity wind index (THW), resulting from the car survey method, essentially show the impact of land use and the distance from the coastline on the spatial distribution of air temperatures. A maximum difference of 7 °C between the city centre and the countryside is measured in very hot summer weather. During the night phase, the apparent temperatures are oppressive, particularly in the city centre, where HI and THW comfort indices exceeding 40 °C were calculated. Compared to the HI and UTCI, the THW demonstrates a much stronger variation due to the influence of wind between open areas and the downtown area. The intensity of thermal discomfort decreases as one moves towards the rural area (−15 °C compared to the centre), hence the impact on the consumption of electrical energy dedicated to air conditioning. The central part is the most energy-intensive area compared to the peripheral areas, especially during hot days when the use of air conditioners becomes constant, day and night.

Phase Response Curve to Light under Ambulatory Conditions: A Pilot Study for Potential Application to Daylight Saving Time Transitions.

Several studies have investigated the relationship between daylight saving time (DST) and sleep alterations, psychiatric disorders, cardiovascular events and traffic accidents. However, very few have monitored participants while maintaining their usual lifestyle before and after DST. Considering that DST transitions modify human behavior and, therefore, people's light exposure patterns, the aim of this study was to investigate the potential effects of DST on circadian variables, considering sleep and, for the first time, the human phase response curve to light. To accomplish this, eight healthy adults (33 ± 11 years old, mean ± SD) were recruited to monitor multivariable circadian markers and light exposure by means of a wearable ambulatory monitoring device: Kronowise®. The following night phase markers were calculated: midpoints of the five consecutive hours of maximum wrist temperature (TM5) and the five consecutive hours of minimum time in movement (TL5), sleep onset and offset, as well as sleep duration and light intensity. TM5 for wrist temperature was set as circadian time 0 h, and the balance between advances and delays considering the phase response curve to light was calculated individually before and after both DST transitions. To assess internal desynchronization, the possible shift in TM5 for wrist temperature and TL5 for time in movement were compared. Our results indicate that the transition to DST seems to force the circadian system to produce a phase advance to adapt to the new time. However, the synchronizing signals provided by natural and personal light exposure are not in line with such an advance, which results in internal desynchronization and the need for longer synchronization times. On the contrary, the transition back to ST, which implies a phase delay, is characterized by a faster adaptation and maintenance of internal synchronization, despite the fact that exposure to natural light would favor a phase advance. Considering the pilot nature of this study, further research is needed with higher sample sizes.

Treatment of Circadian Rhythm Sleep-Wake Disorders.

Circadian rhythm sleep-wake disorders (CRSWDs) are a distinct class of sleep disorders caused by alterations to the circadian time-keeping system, its entrainment mechanisms, or a mismatch between the endogenous circadian rhythm and the external environment. The main clinical manifestations are insomnia and excessive daytime sleepiness that often lead to clinically meaningful distress or cause mental, physical, social, occupational, educational, or other functional impairment. CRSWDs are easily mistaken for insomnia or early waking up, resulting in inappropriate treatment. CRSWDs can be roughly divided into two categories, namely, intrinsic CRSWDs, in which sleep disturbances are caused by alterations to the endogenous circadian rhythm system due to chronic changes in the regulation or capture mechanism of the biological clock, and extrinsic circadian rhythm sleep-wake disorders, in which sleep disorders, such as jet lag or shift-work disorder, result from environmental changes that cause a mismatch between sleep-wakefulness times and internal circadian rhythms. Sleep diaries, actigraphy, and determination of day and night phase markers (dim light melatonin onset and core body temperature minimum) have all become routine diagnostic methods for CRSWDs. Common treatments for CRSWD currently include sleep health education, time therapy, light therapy, melatonin, and hypnotic drug therapy. Here, we review the progress in the epidemiology, etiology, diagnostic evaluation, diagnostic criteria, and treatment of intrinsic CRSWD, with emphasis on the latter, in the hope of bolstering the clinical diagnosis and treatment of CRSWDs.

Dayside Fe i Emission, Day–Night Brightness Contrast and Phase Offset of the Exoplanet WASP-33b

We report on Fe i in the dayside atmosphere of the ultra-hot-Jupiter WASP-33b, providing evidence for a thermal inversion in the presence of an atomic species. We also introduce a new way to constrain the planet’s brightness variation throughout its orbit, including its day–night contrast and peak phase offset, using high-resolution Doppler spectroscopy alone. We do so by analyzing high-resolution optical spectra of six arcs of the planet’s phase curve, using Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS) on the Canada–France–Hawaii telescope and High Dispersion Spectrograph on the Subaru telescope. By employing a likelihood mapping technique, we explore the marginalized distributions of parameterized atmospheric models, and detect Fe i emission at high significance (>10.4σ) in our combined data sets, located at K p = 222.1 ± 0.4 km s−1 and v sys = −6.5 ± 0.3 km s−1. Our values agree with previous reports. By accounting for WASP-33b’s brightness variation, we find evidence that its nightside flux is <10% of the dayside flux and the emission peak is shifted westward of the substellar point, assuming the spectrum is dominated by Fe i. Our ESPaDOnS data, which cover phases before and after the secondary eclipse more evenly, weakly constrain the phase offset to +22 ± 12 degrees. We caution that the derived volume-mixing ratio depends on our choice of temperature-pressure profile, but note it does not significantly influence our constraints on day–night contrast or phase offset. Finally, we use simulations to illustrate how observations with increased phase coverage and higher signal-to-noise ratios can improve these constraints, showcasing the expanding capabilities of high-resolution Doppler spectroscopy.

Sleep-Wake Behaviour of 200-Mile Ultra-Marathon Competitors: A Case Study.

The aim of this study was to examine the sleep–wake behaviour of 200-mile ultra-marathon runners before, during, and after a competition. A longitudinal, observational study was conducted to collect the sleep data of four (two females; mean age: 45.5 ± 3.1 years) runners competing in a 200-mile ultra-marathon (N = 4). Wrist-worn activity monitors, in conjunction with self-report sleep diaries, were used to measure sleep, beginning seven days prior to the race and concluding seven days following the race (2–19 June 2021). Descriptive analysis of runners’ subjective and objective sleep data was conducted. All runners completed the 200-mile event in an average of 82.5 ± 7.1 h. On average, runners obtained 4.7 ± 3.0 h of sleep from 4.8 ± 2.4 sleep episodes, averaging 59.9 ± 49.2 min of sleep per episode. Runners averaged 6.0 ± 1.3 h of sleep per night in the week before the competition and 6.3 ± 1.3 h per night in the week following the competition. Runners in the 200-mile (326 km) ultra-marathon drastically restricted their sleep. However, obtained sleep, the number of sleep episodes, and sleep episode length were greater than those previously reported with 100-mile (161 km) runners. In-race sleep data suggest an increased need for sleep as race duration increases. Interestingly, runners obtained less than the recommended ~8 h of sleep per night, in both pre-race and post-race phases of the competition.

&amp;lt;italic&amp;gt;In situ&amp;lt;/italic&amp;gt; temperature measurement of shallow lunar soil on the far side of the Moon based on Chang&amp;rsquo;e-4 Mission

<p indent="0mm">The Chang’e-4 lander has completed the first full cycle measurement of lunar soil temperature in the South Pole-Aitken basin on the far side of the Moon. This paper introduces the theory and implementation of measuring the temperature of lunar soil in the shallow layer of the Chang’e-4 lander, as well as the results of three lunar days in orbit and preliminary analysis. The Chang’e-4 lander is outfitted with temperature measuring points that can be buried in the shallow lunar soil at the end of the transfer mechanism. The Chang’e-4 lander surface also has temperature measuring points with a good view of the lunar surface. Furthermore, a comparison was made between the measured low temperature data of lunar soil during the lunar night phase and the calculated results based on NASA’s Apollo 17 data. The measured results enrich the measured data about shallow lunar soil temperature on the surface of the Moon and provide an important basis for the inversion of the lunar thermal characteristics model and future study of lunar soil and lunar interior thermal characteristics.