Diurnal Variation Research Articles

Dietary macronutrient composition and its effect on 24-h substrate oxidation: A study of diurnal variations in carbohydrate and fat intake

IntroductionIn recent times, the complexity of food styles and meal content has increased, leading to significant variations in macronutrient composition between meals. This has coincided with a rise in obesity rates. ObjectiveTo determine if a larger variation in macronutrient composition between meals results in lower fat oxidation. MethodsA cross-over study was conducted on 13 healthy young male individuals using whole-body indirect calorimetry to test energy metabolic responses under three conditions: regular meals (R), high-carbohydrate breakfast (CB), or high-fat breakfast (FB), each with different macronutrient contents. R included three meals daily with the same macronutrient composition. CB included a high-carbohydrate meal at breakfast, a high-fat meal at lunch, and a high-carbohydrate meal at dinner. FB included a high-fat meal at breakfast, a high-carbohydrate meal at lunch, and a high-carbohydrate meal at dinner. The daily macronutrient compositions were similar across the three conditions, except CB and FB had larger variations in carbohydrate and fat balance between meals than R. The participants were tested in random order. ResultsThere were no significant differences in the measures of energy expenditure among the three conditions. However, after adjusting for the sleeping respiratory quotient (RQ) on the preceding day, the 24-hour RQ was lower under FB than under R (β=−0.0087, P=0.0077) or CB conditions (β=−0.0078, P=0.016). There was no difference in the magnitude of the 5-hour RQ change from lunch to dinner under the CB condition and in the magnitude of change from breakfast to lunch under the FB condition. ConclusionsA large variation in carbohydrate and fat balance between meals does not decrease daily fat oxidation. A FB may increase daily fat oxidation compared to a CB when the daily food quotient is equal, but this impact may not involve radical acceleration of fat oxidation.

Sex and circadian regulation of metabolic demands in the rat kidney: A modeling analysis.

Renal hemodynamics, renal transporter expression levels, and urine excretion exhibit circadian variations. Disruption of these diurnal patterns is associated with the pathophysiology of hypertension and chronic kidney disease. Renal hemodynamics determines oxygen delivery, whereas renal transport and metabolism determines oxygen consumption; the balance between them yields renal oxygenation which also demonstrates 24-h periodicity. Another notable modulator of kidney function is sex, which has impacts on renal hemodynamics and transport function that are regulated by as well as independent of the circadian clock. The goal of this study was to investigate the diurnal and sexual variations in renal oxygen consumption and oxygenation. For this purpose, we developed computational models of rat kidney function that represent sexual dimorphism and circadian variation in renal hemodynamics and transporter activities. Model simulations predicted substantial differences in tubular Na+ transport and oxygen consumption among different nephron segments. We also simulated the effect of loop diuretics, which are used in the treatment of renal hypoxia, on medullary oxygen tension. Our model predicted a significantly higher effect of loop diuretics on medullary oxygenation in female rats compared to male rats and when administered during the active phase.

Monitoring the Vertical Variations in Chlorophyll-a Concentration in Lake Chaohu Using the Geostationary Ocean Color Imager

Due to the external environment and the buoyancy of cyanobacteria, the inhomogeneous vertical distribution of phytoplankton in eutrophic lakes affects remote sensing reflectance (Rrs) and the inversion of surface chlorophyll-a concentration (Chla). In this study, vertical profiles of Chla(z) (where z is the water depth) and field Rrs (Rrs_F) were collected and utilized to retrieve the vertical profiles of Chla in Lake Chaohu in China. Chla(z) was categorized into vertically uniform (Type 1: N = 166) and vertically non-uniform (Type 2: N = 58) types. Based on the validation of the atmospheric correction performance of the Geostationary Ocean Color Imager (GOCI), a Chla(z) inversion model was developed for Lake Chaohu from 2011 to 2020 using GOCI Rrs data (Rrs_G). (1) Five functions of non-uniform Chla(z) were compared, and the best result was found for Chla(z) = a × exp(b × z) + c (R2 = 0.98, RMSE = 38.15 μg/L). (2) A decision tree of Chla(z) was established with the alternative floating algae index (AFAIRrs), the fluorescence line height (FLH), and wind speed (WIN), where the overall accuracy was 89% and the Kappa coefficient was 0.79. The Chla(z) inversion model for Type 1 was established using the empirical relationship between Chla (z = surface) and AFAIRrs (R2 = 0.58, RMSE = 10.17 μg/L). For Type 2, multivariate regression models were established to estimate the structural parameters of Chla(z) combined with Rrs_G and environmental parameters (R2 = 0.75, RMSE = 72.80 μg/L). (3) There are obvious spatial variations in Chla(z), especially from the water surface to a depth of 0.1 m; the largest diurnal variations were observed at 12:16 and 13:16 local time. The Chla(z) inversion method can determine Chla in different layers of each pixel, which is important for the scientific assessment of phytoplankton biomass and lake carbon and can provide vertical information for the short-term prediction of algal blooms (and the generation of corresponding warnings) in lake management.

Evaluating the impact of individuals' morningness-eveningness on the effectiveness of a habit-formation intervention for a simple and a complex behavior.

Planning-based interventions are often used to help individuals form habits. Existing literature suggests a one-size-fits all approach to habit formation, but planning interventions may be optimized if tailored to individual differences and/or behavioral complexity. We test the hypothesis that planning to do a relatively complex behaviour (exercise) at a time that matches an individuals' diurnal preference will facilitate behavioral engagement; whereas for a simpler behaviour (calcium supplementation), the optimal time-of-day for a new behavior will occur in the morning. Young, women volunteers (N = 317) were randomly assigned to take calcium supplements or to exercise for 4 weeks and to control (no planning) or to one of three planning interventions (morning plan; evening plan; unassigned-time plan). Participants reported diurnal preference at baseline and habit strength and behavioral frequency weekly. Fitbit Zips and Medication Event Monitoring System Caps (MEMS) were used to objectively assess behavioral engagement. Multilevel modelling found that calcium-supplementation was greatest for morning-types in the morning-cue condition, whereas exercise was greatest for morning-types with morning cues and evening-types with evening cues. Habit-formation strategies may depend on diurnal preference and behavioral complexity. Future research can evaluate the role of other individual differences.

Diurnal and Daily Symptom Variation in Patients with End Stage Kidney Disease: An Ecological Momentary Assessment Study.

Patients with end-stage kidney disease (ESKD) on hemodialysis (HD) experience a high symptom burden which is compounded by unpredictable fluctuations in symptom severity. Few studies have used ecological momentary assessment (EMA) to determine how symptoms vary over time. This study aimed to characterize the diurnal and day-to-day variability in symptoms among HD patients. Patients enrolled in the Technology Assisted Collaborative Care (TĀCcare) trial rated the intensity of physical, cognitive, and mood symptoms using an automated telephone-administered version of the Daytime Insomnia Symptom Scale (DISS) at four time-points (morning, early afternoon, late afternoon, evening) for seven consecutive days at baseline. Confirmatory factor analysis (CFA) was used to verify the original four-factor solution for the DISS: sleepiness/fatigue (SF), alert cognition (AC), positive mood (PM), and negative mood (NM). Symptom domain scores were calculated for each time point and mixed modeling with random patient effects was used to examine differences in daily symptoms daily time points between HD and non-HD days after controlling for age, gender, race, and comorbidity burden. One hundred and sixty patients were enrolled (mean±SD age 58±14 years, 45% women, 52% White). Diurnal symptom variation existed; trends were non-linear and differed by HD vs. non-HD days. Day-to-day symptom variation also existed; patients endorsed better physical, cognitive, and mood states (i.e., higher AC and PM) as well as lower symptom burden (i.e., lower SF and NM) on non-HD days compared to HD days at all time-points. The greatest day-to-day mean differences (MDs) were observed in the early afternoon for all symptom domains: AC (MD=0.17 p<0.001), PM (MD=0.28, p<0.001), SF (MD=-0.66, p<0.001), and NM (MD=-0.26, p<0.001). Patients with ESKD demonstrate diurnal variation in symptoms and greater symptom burden on HD days compared to non-HD days, with the most extreme differences in symptom severity occurring in the early afternoon.

Dust Emissions on Mars From Phoenix Lidar Measurements in Relation to Local Meteorological Conditions

AbstractThe diurnal cycle of dust aerosols on Mars is studied by analyzing lidar observations at the Phoenix landing site under cloud‐ and fog‐free conditions and in the absence of elevated, long‐range transported dust layers. There is a pronounced diurnal cycle in the dust‐layer height with minimum heights of 4–6 km occurring between 11:00 and 17:00 local time. The ratio of the aerosol optical depth (AOD) within the lowermost 2 km to the total AOD reaches peak values at the same time. This can be explained by local dust emissions driven by the diurnal cycle of heating and cooling in the boundary layer. Analysis of wind and pressure measurements show that the gustiness of surface winds and the frequency of convective vortices undergo diurnal variations resembling those of AOD, indicating that these processes are the main drivers for local dust emissions.

Treatment-emergent symptoms during short-term ketamine administration in treatment-resistant bipolar depression: A retrospective cross-sectional descriptive study

Symptoms that emerge during pharmacological treatment of bipolar depression are frequently observed, underscoring the necessity for comprehensive treatment monitoring. This observational study sought to observe the correlation of eight intravenous ketamine infusions with treatment-emergent depressive symptoms in treatment-resistant bipolar depression patients who maintained their baseline psychotropic and chronic somatic treatments. Depressive symptoms were evaluated using the Inventory of Depressive Symptomatology Self-Report 30 (IDS-SR30). Treatment-emergent symptoms TES were defined as symptoms absent at baseline but present at the conclusion of the study. The most common TES included decreased appetite, increased weight, hypersomnia, and diurnal mood variation. Conversely, feelings of sadness, altered perceptions of the future, decreased interest in sex, and physical discomfort were absent in all patients. Notably, 13.6 % of patients reported thoughts of death or suicide. Larger-scale studies, integrating clinician-rated and patient-reported outcome measures, are essential to deepen our understanding of treatment-emergent symptoms. Establishing regulatory or professional definitions for treatment-emergent symptoms is warranted to improve the robustness of future research endeavors.

Copper-induced renal toxicity controlled by period1 through modulation of Atox1 in mice.

Copper (Cu) is known to induce oxidative stress and apoptosis in the liver, kidney, and brain. We previously demonstrated the molecular mechanism underlying the Cu-induced hepatic diurnal variation. However, the cellular molecule(s) involved in Cu-induced renal chronotoxicity remain unknown. In this study, we aimed to elucidate the molecular mechanisms underlying Cu-induced diurnal toxicity in the kidneys. We evaluated cell viability and clock gene expression levels in mouse renal cortex tubular cells (MuRTE61 cells) after Cu treatment. We also examined the Cu homeostasis- and apoptosis-related gene levels after period 1 (Per1) overexpression in MuRTE61 cells. Cu treatment decreased MuRTE61 cell viability in a dose-dependent manner. It increased the Per1 expression levels after 24 h. Notably, Per1 overexpression alleviated the Cu-induced inhibition of MuRTE61 cell viability. Moreover, Per1 overexpression downregulated the cleaved caspase-3 and reduced Cu levels by upregulating the antioxidant 1 copper chaperone (Atox1) levels. These results suggest that Cu-induced renal toxicity is associated with Per1 expression via the regulation of the copper chaperone, Atox1.

Understanding the Dynamics of Source-Apportioned Black Carbon in an Urban Background Environment

This study aims to delineate the characteristics of black carbon (BC) in the atmosphere over the urban background environment in Vilnius (Lithuania) from 1 June 2021 to 31 May 2022 using aethalometer (Magee Scientific) measurements. The annual mean concentrations of BC originating from fossil fuels (BCff) and from biomass burning (BCbb) were found to be 0.63 μg m−3 with a standard deviation (SD) of 0.67 μg m−3 and 0.27 µg m−3 (0.35 μg m−3). The further findings highlight the dominance of fossil-fuel-related BC throughout the study period (71%) and the seasonal variability of BC pollution, with biomass-burning-related BC making the largest contribution during the summer season (41%) and the smallest contribution during autumn (23%). This information provides valuable insights into the sources and dynamics of BC pollution in the region. The sources and composition of BC on the days with the highest pollution levels were influenced by a combination of local and regional factors in every season. Additionally, this study employs an advanced approach to understanding urban BC pollution by focusing on high-pollution days (18), identified based on a daily mean BC mass concentration exceeding the 95th percentile, alongside an analysis of overall seasonal and diurnal variations. This methodology surpasses many those of previous urban BC studies, offering a comprehensive examination of the sources and composition of BC pollution.

Advancing Cloud Classification Over the Tibetan Plateau: A New Algorithm Reveals Seasonal and Diurnal Variations

AbstractThe cloud classification algorithm widely used in the International Satellite Cloud Climatology Project (ISCCP) tends to underestimate low clouds over the Tibetan Plateau (TP), often mistaking water clouds for high‐level clouds. To address this issue, we propose a new algorithm based on cloud‐top temperature and optical thickness, which we apply to TP using Advanced Himawari Imager (AHI) geostationary satellite data. Compared with Clouds and the Earth's Radiant Energy System cloud‐type products and ISCCP results obtained from AHI data, this new algorithm markedly improved low‐cloud detection accuracy and better aligned with cloud phase results. Validation with lidar cloud‐type products further confirmed the superiority of this new algorithm. Diurnal cloud variations over the TP show morning dominance shifting to afternoon high clouds and evening mid‐level clouds. Winter is dominated by high clouds, summer by mid‐level clouds, spring by daytime low clouds and nighttime high clouds, and autumn by low and mid‐level clouds.

Time-dependent characteristics of analytical measurands.

Biological variation is a relevant component of diagnostic uncertainty. In addition to within-subject andbetween-subject variation, preanalytical variation also includes components that contribute to biological variability. Among these, daily recurring, i.e.,diurnal physiological variation is of particular importance, as it contains both a random and a non-random component ifthe exact time of blood collection is not known. We introduce four time-dependent characteristics (TDC) of diurnal variations for measurands to assess the relevance and extent of time dependence on the evaluation of laboratory results. TDC address (i)a threshold for considering diurnality, (ii) the expected relative changes per time unit, (iii) the permissible time interval between two blood collections at different daytimes within which the expected time dependence does not exceed a defined analytical uncertainty, and (iv) a rhythm-expanded reference change value. TDC and their importance will be exemplified by the measurands aspartate aminotransferase, creatine kinase, glucose, thyroid stimulating hormone, and total bilirubin. TDCs are calculated for four time slots that reflect known blood collection schedules, i.e.,07:00-09:00, 08:00-12:00, 06:00-18:00, and 00:00-24:00. The amplitude and the temporal location of the acrophase are major determinates impacting the diagnostic uncertainty and thus the medical interpretation, especially within the typical blood collection time from 07:00 to 09:00. We propose to check measurands for the existence of diurnal variations and, if applicable, to specify their time-dependent characteristics as outlined in our concept.

Low-frequency solar radio type II bursts and their association with space weather events during the ascending phase of solar cycle 25

Abstract. Type II solar radio bursts are signatures of the coronal shocks and, therefore, particle acceleration events in the solar atmosphere and interplanetary space. Type II bursts can serve as a proxy to provide early warnings of incoming solar storm disturbances, such as geomagnetic storms and radiation storms, which may further lead to ionospheric effects. In this article, we report the first observation of 32 type II bursts by measuring various plasma parameters that occurred between May 2021 and December 2022 in solar cycle 25. We further evaluated their accompanying space weather events in terms of ionospheric total electron content (TEC) enhancement using the rate of TEC index (ROTI). In this study, we find that at heliocentric distance ∼1–2 R⊙, the shock and the Alfvén speeds are in the range 504–1282 and 368–826 km−1, respectively. The Alfvén Mach number is of the order of 1.2≤MA≤1.8 at the above-mentioned heliocentric distance. In addition, the measured magnetic field strength is consistent with the earlier reports and follows a single power law B(r)=6.07r-3.96G. Based on the current analysis, it is found that 19 out of 32 type II bursts are associated with immediate space weather events in terms of radio blackouts and polar cap absorption events, making them strong indications of space weather disruption. The ROTI enhancements, which indicate ionospheric irregularities, strongly correlate with GOES X-ray flares, which are associated with the type II radio bursts recorded. The diurnal variability in ROTI is proportional to the strength of the associated flare class, and the corresponding longitudinal variation is attributed to the difference in longitude. This article demonstrates that since type II bursts are connected to space weather hazards, understanding various physical parameters of type II bursts helps to predict and forecast the space weather.

Conjugate aurora observations by the Gjøa and Discovery expeditions

Abstract. From 1901 to 1912 – known as the “heroic period” of Arctic and Antarctic exploration – great inroads were made (not only geographic but also scientific) to our knowledge of the continent. At Amundsen's Expedition through the Northwest Passage, measurements of the geomagnetic field and visual auroras were carried out for 19 months at Gjoa Haven (Gjøahavn in Norwegian; geographic coordinates 68°37′10′′ N, 95°53′25′′ W). Scott's Discovery Expedition – at Cape Armitage, McMurdo (coordinates 77.86° S, 166.69° E), Antarctica – carried out the same type of measurements. Their observations were carried out geomagnetically conjugate to Gjoa Haven, with both stations close to 78° magnetic latitude. In addition, measurements were overlapping in time during 1903–1904. However, these two stations are located at different longitudes, so there is a difference in local time between the stations of about 6.5 h. Gjoa Haven and Cape Armitage are conveniently located for separating disturbances in the polar cap regions caused by solar electromagnetic radiations or the solar wind. Auroras were observed during 7 months per year. This gave a unique possibility to compare conjugate characteristics of polar cap auroras. Comparing conjugate geophysical data introduces some difficulties. During the winter season at Gjoa Haven, they had a bright summer in Antarctica, and visa versa. Thus, simultaneous temporal and spatial ionospheric variations can be marked differently. Still, the average diurnal and seasonal variations were similar. The quantity of the auroral data from Cape Armitage was larger because there they had a continuous watch of the sky. The main findings regarding polar cap auroras are the following. Three different auroral forms dominate the polar cap. Low-intensity auroral bands – then called streamers – were the dominating auroral forms morning and afternoon. The number of auroral events in 1903 was nearly twice that in 1902 and 1904. A marked midwinter maximum was observed at both stations. Many displays were observed poleward of the oval. The large fraction was associated with weak magnetic disturbances. Some forms of polar cap aurora have special magnetic signatures and seem to be anti-correlated with Kp. They can be mapped even if they are not seen. According to recent satellite measurements (Newell et al., 2009), they are probably caused by polar rain and/or photoelectrons.

Study on the variation characteristics and influencing factors of stem water content of Acer truncatum during the overwintering period.

Stem water content serves as a pivotal parameter that reflects the plant vitality and maintains their internal water balance. Given the insufficient comprehension regarding the stem water content characteristics and its influencing factors during different stages of the overwintering period, the study focused on Acer truncatum Bunge and developed an Internet of Things (IoT)-based ecological information monitoring system. The system incorporated a proprietary stem water content sensor, allowing non-invasive, in-situ and real time acquisition of stem water content while monitoring diverse environmental parameters. We conducted a detailed elucidation of stem water content variation characteristics and their responses to diverse environmental factors. The results showed: (1) During the overwintering period, stem water content exhibited diurnal variations characterized by " daytime ascent and nighttime descent" across the three stages, exhibiting differences in the moment when the stem water content reaches extremal values and daily fluctuations ranges. Stem water content exhibited minimal fluctuations during deciduous and bud-breaking stages but experienced significant freezing-thawing alternations during the dormant stage, leading to an increased daily fluctuation range. (2) The Pearson correlation coefficients between environmental parameters and stem water content varied dynamically across stages. Path analysis revealed that during the deciduous stage, stem temperature and saturation vapor pressure deficit were dominant factors influencing stem water content; during dormant stage, air temperature and saturation vapor pressure deficit directly impacted stem water content; during the bud-breaking stage, the primary parameters affecting stem water content were saturation vapor pressure deficit and stem temperature. The study provides valuable insights into unveiling the water transport patterns within tree stems tissue and their environmental adaptation mechanisms during the overwintering period, aiding in the scientific development of winter management strategies to protect trees from severe cold and freezing damage, while fostering healthy growth in the subsequent year.

How Critical Is the Accuracy of the Atmospheric Transport Modeling to Improve the Urban CO2 Emission in India?—A Lagrangian‐Based Approach

AbstractAnthropogenic CO2 emission reduction strategies depend on how well we track emission enhancements at the urban scale. The estimation system, based on inverse modeling, relies on our knowledge of atmospheric transport and prior flux distributions. Hence, the analysis framework must account for uncertainties associated with each component in order to interpret the variations in observed CO2. Using an ensemble of simulations, we quantify the uncertainties in simulating anthropogenic CO2 mixing ratio enhancements at 15 locations in India. Differences in the representation of transport mechanisms and prior emission in the forward model induce a consistently large model spread of 62.2% and 41.9%, respectively, in the simulated mixing ratio over cities. The analysis reports an average uncertainty of 2.2 ppm with a maximum of 8 ppm for representing diurnally averaged anthropogenic CO2 enhancement. Diurnal variations in emissions and transport induce a rectification effect in those enhancements. The outcome of this study can thus inform future atmospheric CO2 inversion modeling at an urban scale on the expected forward model uncertainties, which are the essential components in the Bayesian inversion framework, typically lacking in the Indian region. The first‐order inversion experiments show that the change in the transport model induces significant uncertainty (up to 84.9%) in anthropogenic CO2 flux estimation at the national scale. Hence, the confidence level of inverse‐based emission estimation in India depends considerably on the accuracy of atmospheric transport modeling.

Seasonal and diurnal variability of sub-ice platelet layer thickness in McMurdo Sound from electromagnetic induction sounding

Seasonal and diurnal variability of sub-ice platelet layer thickness in McMurdo Sound from electromagnetic induction sounding

Diurnal fluctuations in biochemical parameters related to calcium homeostasis – the Bispebjerg study of diurnal variations

Purpose This aim of this study was to assess the possible association between diurnal oscillations and biochemical markers associated with calcium homeostasis. This included the markers parathyroid hormone (PTH), total calcium, total alkaline phosphatase, phosphate, and 25-hydroxyvitamin D (25-OH-D). By examining the influence of circadian rhythms on these parameters, the study aimed to deepen the understanding of calcium metabolism dynamics and its clinical implications. Patients and methods Blood samples from 24 Caucasian male volunteers aged 20 to 40 (mean age 26) with normal pulse, blood pressure, and BMI were analyzed for biochemical markers related to calcium homeostasis. Data was obtained from the Bispebjerg study of diurnal variations. Blood samples were collected every three hours over a 24-hour period. Patients were fasting from 22:00 to 09:00. The participants spent 24 h in the hospital ward, receiving regular meals and engaging in low-intensity activities. They experienced 15 h of daylight and 9 h of complete darkness during sleep. Diurnal oscillations were analyzed using cosinor analysis with statistical significance set at p < 0.05. Results Total calcium, phosphate, and PTH exhibited significant diurnal variations. Total calcium and PTH were inversely synchronized while PTH and phosphate oscillated in synchronization. The three parameters showed relatively large amplitude/reference range ratios from 25.4% to 41.5%. Conclusion This study found notable fluctuations in total calcium, phosphate, and PTH levels over a 24-hour cycle, while 25-OH-D and total alkaline phosphatase remained consistent. It highlights the importance of considering sampling times for total calcium, PTH, and phosphate in clinical settings.

Descriptive, Hospital-Based, 10-Year Study of Malaria Transmission in Goa, a Southwest Indian State in the Malaria Elimination Phase.

The South Asia International Center of Excellence for Malaria Research, an NIH-funded collaborative program, investigated the epidemiology of malaria in the Indian state of Goa through health facility-based data collected from the Goa Medical College and Hospital (GMC), the state's largest tertiary healthcare facility, between 2012 and 2021. Our study investigated region-specific spatial and temporal patterns of malaria transmission in Goa and the factors driving such patterns. Over the past decade, the number of malaria cases, inpatients, and deaths at the GMC decreased significantly after a peak in 2014-2015. However, the proportion of severe malaria cases increased over the study period. Also, a trend of decreasing average parasitemia and increasing average gametocyte density suggests a shift toward submicroscopic infections and an increase in transmission commitment characteristic of low-transmission regions. Although transmission occurred throughout the year, 75% of the cases occurred between June and December, overlapping with the monsoon (June-October), which featured rainfall above yearly average, minimal diurnal temperature variation, and high relative humidity. Sociodemographic factors also had a significant association with malaria cases, with cases being more frequent in the 15-50-year-old age group, men, construction workers, and people living in urban areas within the GMC catchment region. Our environmental model of malaria transmission projects almost negligible transmission at the beginning of 2025 (annual parasitic index: 0.0095, 95% CI: 0.0075-0.0114) if the current control measures continue undisrupted.

P-572 Circadian serum progesterone variations on the day of frozen embryo transfer in a modified natural cycle protocol

Abstract Study question Does a circadian variation of serum progesterone (P) on the frozen embryo transfer (FET) day in a modified natural cycle (mNC) exist? Summary answer A statistically significant diurnal variation of serum P on the day of a FET in a mNC protocol exists. What is known already In recent years, the proportion of FET cycles has increased dramatically. To further optimize pregnancy outcomes after FET, recent studies have focused on serum luteal P levels in both natural and artificially prepared FET cycles. Despite the different cut-off values proposed to define low serum P in the natural cycle, it is generally accepted that lower serum P values (&amp;lt;10ng/ml) around the day of FET are associated with negative reproductive outcomes. However, a single serum P measurement on the day of FET is not reliable given that P levels are prone to diurnal fluctuations and are impacted by patients’ characteristics. Study design, size, duration A prospective cohort study was conducted in a single fertility center including 22 patients performing a single blastocyst mNC-FET from August 2022 to August 2023.Serum P levels were measured on the day of transfer at 08:00h,12:00h,16:00h and 20:00h.Differences between P levels were compared using the Wilcoxon signed-rank test.The sample size was calculated to detect a difference of 15% between the first and last P measurements with a 5% false-positive rate and a 95% confidence interval. Participants/materials, setting, methods Patients with a normal BMI, between 18 and 40 years old, without uterine diseases were eligible. Patients utilizing donated oocytes were excluded. The mNC-FET protocol implied monitoring the normal ovarian cycle and triggering ovulation with an injection of 250 mcg of choriogonadotropin alfa when a pre-ovulatory follicle (16-20 mm diameter)was visualized. The blastocyst was transferred seven days later. The patients were not supplemented with exogenous P at any moment before the day of the FET. Main results and the role of chance The mean age and BMI of the study population were 33.6 ± 3.8 years and 22.7 ± 1.8 kg/m2, respectively. Mean P values at 08:00h,12:00h,16:00h, and 20:00h were 14.6 ± 4.5ng/ml, 14.7 ± 4.1ng/ml, 12.9 ± 3.5ng/ml, and 14.6 ± 4.3ng/ml, respectively. The mean P levels at 16:00h were statistically significantly lower compared to all other time points (p &amp;lt; 0.05:p= 0.007 between P at 8:00h and 16:00h;p = 0.003 between P at 12:00h and 16:00h;p=0.007 between P at 16:00h and 20:00h). Absence of a statistically significant fluctuation was observed between P values at the other time points (p = 0.88 between P at 8:00h and 12:00h;p=0.96 between P at 8:00h and 20:00h;p=0.83 between P at 12:00h and 20:00h). This study confirms the existence of an intra-day variation of serum P on the day of mNC-FET, with lower values at 16:00h. This highlights the importance of standardizing P measurement on the day of FET; we propose this should always be assessed in the morning to be more reliable and to allow the time to prescribe additional exogenous progesterone if lower P values (&amp;lt;10ng/ml) are detected. This standardization would allow fertility clinics around the world to compare their results and develop internationally recognized treatment protocols. Limitations, reasons for caution The study’s main limitation include the small sample size that may cause a bias when results are extrapolated to a larger subfertile population undergoing mNC-FET. Ideally, larger prospective trials including a more heterogeneous patient population would be necessary to validate our findings. Wider implications of the findings This study demonstrates the existence of a diurnal fluctuation of serum P on the mNC-FET day highlighting the importance of a standardized time point for its measurement.This is important when clinical actions, like additional exogenous P supplementation, are considered when encountering P values lower than 10ng/ml on the FET day. Trial registration number NCT05511272

Seismotectonic Movements in the Minute Range of Periods Before the Catastrophic Earthquake in Japan March 11, 2011

The vertical movements measured by a broadband seismic stations located around Tohoku earthquake 11.03. 2011 with magnitude 9 are calculated. It is shown that during the 15 years before the earthquake the closest to epicenter MAJO station located 386 km from the epicenter the quiet daily variations was demonstrated. Seismic pulses with the durations of a few minutes and amplitudes bigger 10% of the diurnal variations of tidal velocities were revealed in 2009 year. They appeared under quiet meteorological and geomagnetic conditions. These pulses are not found on the records of the stations remoted more 700 km from epicenter. It is hypothesized that sharp changes in the low frequency seismic noise reflect the tectonic deformations in the lithosphere of Japan and adjoin part of Pacific Ocean.