Changes In Variability Research Articles

The impact of working night shifts on cardiac autonomic nervous regulation during the six-minute walk test in nurses

BackgroundClinical nurses frequently face the necessity of working night shifts, often with insufficient opportunities for timely sleep recovery, which may negatively impact autonomic nervous system regulation. The aim of this study was to evaluate changes in heart rate variability (HRV) after the six-minute walk test (6MWT) in nurses post-night shift and to explore the impact of night shift work on cardiac autonomic regulation.MethodsThirty-five female nurses, with a mean age of 28.7 years (range 21.0–37.0 years), participated in this study. On the first and second mornings after a night shift, the nurses performed the 6MWT. During the test, electrocardiogram (ECG) signals, blood pressure, and walking distance were recorded simultaneously.ResultsCompared with the second postshift morning, on the first postshift morning, nurses presented higher ratings of perceived exertion (RPE), higher Borg scale scores, and a slower pulse rate before and after the 6MWT but covered a shorter walking distance. Additionally, HRV indicators such as the SDNN, RMSSD, pNN50, TP, VLF, LF, and HF were all higher on the first postshift morning. Regarding the amplitude of cardiac autonomic nervous regulation, variations in the RMSSD and pNN50 were both greater during the 6MWT on the first postshift morning, although there was no significant difference in post-6MWT recovery.ConclusionsNight shifts appear to increase the activity of the autonomic nervous system in nurses on the first postshift morning and exert a greater inhibitory effect on parasympathetic activity during the 6MWT. Therefore, it is important to ensure timely recovery sleep and improve autonomic regulation after working night shifts.KeywordsHeart rate variability; Night shift; Autonomic nervous system; Six-minute walk test; Nurses.Trial registrationThis study was retrospectively registered in the Clinicaltrials.gov. Registration Date: August 1, 2024. Clinicaltrials.gov ID: NCT06542510.

Influence of heart rate variability on platelet hemostasis by average aggregate size in patients with chronic coronary heart disease in combination with COVID-19

BACKGROUND. In order to prevent complications of coronavirus infection (platelet hemostasis disorders, heart rate variability and QT interval dispersion, which increase the risk of thromboembolic complications and fatal arrhythmias), it is promising to study the relationship between heart rate variability and platelet hemostasis in patients with coronary artery disease (CAD) in combination with coronavirus disease (COVID-19). OBJECTIVE. The aim of the study was to investigate the impact of COVID-19 on the interdependence of changes in platelet hemostasis and heart rate variability in patients with CAD. MATERIALS AND METHODS. We examined 102 patients divided into three groups: group 1 – CAD without COVID-19 (n=32); group 2 – CAD in combination with COVID-19 (n=35); group 3 – COVID-19 without CAD (n=35). The control group included 30 conditionally healthy individuals. Changes in platelet hemostasis were studied according to laser aggregometry by the Born method and analysis of the average size of aggregates with an assessment of spontaneous aggregation and aggregation induced by adenosine diphosphate (ADP), arachidonic acid, epinephrine, collagen, ristomycin. Heart rate variability parameters and QT interval variability characteristics were determined by the results of 24-hour Holter electrocardiogram monitoring. RESULTS AND DISCUSSION. The time for spontaneous aggregation was longer in all patients compared to the control group, with the highest values observed in groups 2 and 3 (with COVID-19). In ADP aggregation, the control group showed higher results. The rate of aggregation in ADP was lowest in group 2. Collagen-induced aggregation was higher in COVID-19 cases. All groups exhibited lower values of adrenaline-induced aggregation, with the lowest values in group 3. The time of aggregation under adrenaline was shortest in group 2. Ristocetin induced greater aggregation in the control group, but the lowest rate in group 2, and the shortest time in group 1 (СAD without COVID-19). In СAD with COVID-19, an inverse relationship was observed between the parasympathetic nervous system and adrenaline-induced aggregation, as well as between sympathetic activity and ristocetin-induced aggregation. The degree of platelet aggregation induced by ADP had a direct correlation with the corrected QT interval. The rate of aggregation with ADP had an inverse correlation with the mean QT. The time of platelet aggregation activated by ristocetin had an inverse correlation with the standard deviation of QT(NN). The mode of QT had an inverse correlation with the degree of aggregation with ristocetin. CONCLUSIONS. In СAD and COVID-19, platelet hemostatic function is impaired, as confirmed by laser aggregometry data. Autonomous dysregulation and prolonged QT interval have been identified. A complex interaction between platelet hemostasis and heart rate variability is observed. Considering platelet hemostatic function, heart rate variability, and QT dispersion is crucial for treating this cohort of patients.

A prospective, self-controlled study of sub-plateau heart rate variability in healthy adults

BackgroundThe low-pressure, hypoxic environment characteristic of high-altitude regions significantly affects the cardiovascular and autonomic nervous system functions of individuals, consequently impairing their sleep quality. Heart rate variability, a non-invasive indicator of autonomic nervous system activity and balance within the cardiovascular system, has not been thoroughly investigated in terms of its patterns during acclimatization and de-acclimatization phases for individuals traveling to and residing in high-altitude areas and its relationship with sleep stability.MethodsData was collected from 22 medical staff members who traveled from Chengdu to Yecheng, with measurements taken before leaving Chengdu, 1 week in Yecheng, 3 months in Yecheng, and 1 week after returning to Chengdu. The study analyzed changes in heart rate variability during acclimatization and de-acclimatization at 1,400 m above sea level. It also examined arrhythmia and sleep disorders based on circadian groups.Results1. Following 1 week of acclimatization to the sub-plateau environment of Yecheng, significant decreases were observed in SDANN, SDNN and SD2 indices compared to departure from Chengdu (P < 0.05). After 3 months of sub-plateau acclimatization, these indices significantly increased (P < 0.05). Upon returning to Chengdu and undergoing de-acclimatization for 1 week, these indices further significantly increased (P < 0.05). 2. During the period of sub-plateau acclimatization and de-acclimatization, significant changes were noted in average heart rate and minimum heart rate (P < 0.05), with the average heart rate showing a continuous decrease and the minimum heart rate exhibiting an initial increase followed by a decrease. No significant changes were observed in maximum heart rate or the incidence of arrhythmias (P > 0.05). 3. When stratified by day and night, the trends for SDANN, RMSSD, and TP were consistent with the overall trend at night (P < 0.05), but opposite during the day (P < 0.05). 4. During the sub-plateau acclimatization period, stable sleep duration was significantly reduced, and increased markedly after de-acclimatization, although it did not return to pre-acclimatization levels (P < 0.05).ConclusionAcclimatization to the sub-plateau environment of Yecheng affects the autonomic nervous system, heart rate, and sleep in healthy adults. De-acclimatization can ameliorate these effects. Furthermore, the impact of sub-plateau acclimatization on the autonomic nervous system exhibits a distinct circadian rhythmicity.

Projected Changes in Dry and Wet Spells over West Africa during Monsoon Season Using Markov Chain Approach

This study examines projected changes in dry and wet spell probabilities in West Africa during the July–August–September monsoon season using a Markov chain approach. Four simulations of regional climate models from the CORDEX-Africa program were used to analyze projected changes in intraseasonal variability. The results show an increase in the probability of having a dry day, a dry day preceding a wet day, and a dry day preceding a dry day, and a decrease in the probability of wet days in the Sahel region under anthropogenic forcing scenarios RCP4.5 and RCP8.5. The decrease in wet days is stronger in the far future and under the RCP8.5 scenario (up to −30%). The study also finds that the probability of consecutive dry days (lasting at least 7 days and 10 days) is expected to increase in western Sahel, central Sahel, and the Sudanian Area under both scenarios, with stronger increases in the RCP8.5 scenario. In contrast, a decrease is expected over the Guinea Coast, with the changes being more important under the RCP4.5. Dry spell probabilities increasing in the Sahel areas and in the northern Sudanian Area is linked to the increase in the very wet days (R95P) in the daily rainfall intensity index (SDII). These changes in dry and wet spell probabilities are important for water management decisions and risk reduction in the energy and agricultural sectors. This study also highlights the need for decision-makers to implement mitigation and adaptation policies to minimize the adverse effects of climate change.

Future seasonal surface temperature predictability with and without ARISE-stratospheric aerosol injection-1.5

Abstract To help reduce anthropogenic climate change impacts, various forms of solar radiation modification have been proposed to reduce the rate of warming. One method to intentionally reflect sunlight into space is through the introduction of reflective particles into the stratosphere, known as stratospheric aerosol injection (SAI). Previous research has shown that SAI implementation could lead to future climate impacts beyond surface temperature, including changes in ENSO variability. This response has the potential to modulate midlatitude variability and predictability through atmospheric teleconnections. Here, we explore possible differences in seasonal surface temperature predictability under a future with and without SAI implementation, using neural networks and the ARISE-SAI-1.5 simulations. We find significant future predictability changes in both boreal summer and winter under SSP2-4.5 with and without SAI. However, during boreal winter when SAI is implemented, seasonal predictability is more similar to the base climate than when SAI is not implemented, particularly in regions impacted by ENSO teleconnections.

Weather- and climate-driven power supply and demand time series for power and energy system analyses

Reaching net-zero carbon emissions requires large shares of intermittent renewable energy and the electrification of end-use consumption, such as heating, making the future energy system highly dependent on weather variability and climate change. Weather exhibits fluctuations on temporal scales ranging from sub-hourly to yearly while climate variations occur on decadal scales. To investigate the intricate interplay between weather patterns, climate variations, and power systems, we developed a database of time series of wind and solar power generation, hydropower inflow, heating and cooling demand using an internally consistent modeling framework. Here we focused on the European continent and generated country level time series extending between 1940 and 2100. Our database can be used for analyses aimed at understanding and addressing the challenges posed by the evolving energy landscape in the face of deep decarbonization and climate change.

Present Variability and Future Change in Onset and Cessation of the Rainy Season Over Peru

ABSTRACTChanges in patterns of accumulated rainfall, as well as the rainy season onset, cessation and duration, can impact the availability of water resources and sectors such as agriculture, affecting the livelihoods of the population. The knowledge of these changes is crucial for regions driven by strong precipitation variability such as the Andean countries. Therefore, the aim of this work is to determine the present and future spatio‐temporal patterns of the onset, cessation and duration of the rainy season in Peru. For this purpose, we analysed in a first step the present variability and trends in 11 homogeneous regions using data from 377 ground stations for the period 1981–2019. The results showed significant trends (1981–2019) of earlier onset and increased duration only in the Southern Peruvian Amazon (Madre de Dios River basin). Furthermore, the accumulated rainfall has significant trends of increases in North East Andes, Northern and Southern Amazon. In a second step, we assessed future changes of the rainy season from an ensemble of statistically downscaled CMIP6 climate scenarios. A two‐tailed Student t‐test was used to evaluate the significance of changes. Two future time slices (2031–2060 and 2071–2100) relative to the reference period (1981–2010) were analysed. Future changes of the rainy season showed significant delays in the onset for the Central East Andes, South West Andes and Amazon regions in the period 2071–2100. Likewise, the rainy season duration presents future significant reductions in regions of the central and southern Andes under the SSP2‐4.5 scenario. Moreover, the accumulated precipitation is projected to increase significantly in the Pacific slope and Andes regions, mainly under the SSP5‐8.5 scenario. These findings are particularly important for sectors like agriculture, energy and water resources management.

Changes in heart rate variability after rhinosurgical interventions

Purpose: to study changes in heart rate variability (HRV), as an indicator of the stress response, after rhinosurgical interventions.Material and methods. A study of heart rate variability was conducted in 98 patients in the perioperative period who underwent open rhinoplasty (1st group, 33 patients), open rhinoplasty with simultaneous septoplasty (2nd group, 33 patients), and septoplasty (3rd group, 32 patients). Heart rate variability was assessed before surgery, 3, 6, 24 and 48 hours after surgery. The low frequency component (LF), high frequency component (HF), and very low frequency component (VLF) of HRV were studied.Results. In the 3rd group of patients, compared with the data before surgery, the high-frequency component of HRV significantly decreased on the 3rd and 24th hours after surgery (p < 0.001), but increased after two days (p < 0.001). 3 hours after surgery, HF HRV in patients of 1st group was significantly higher than in patients of groups 2nd and 3rd (p < 0.001). In the second group, a significant decrease in HF was noted in the first 3 (p < 0.001), 6 hours (p < 0.01), 24 hours (p < 0.05) and 48 hours (p < 0.001) of the postoperative period, compared with data before surgery. In 3rd group, at intervals after surgery of 3 and 24 hours (p < 0.001), as well as 6 hours (p < 0.001), LF was significantly lower than before septoplasty. 3 hours after surgery, the VLF in the rhinoplasty group was significantly higher than in the other groups (p < 0.001). At the 6th hour there were no differences between the groups. After 24 hours, in the septoplasty group, VLF was significantly lower than in 11st and 2nd groups (p <0.01).Conclusion. Septoand rhinosptoplasty provoke an inadequate low response from the sympathetic nervous system in the first hours after surgery, which is manifested by low LF power and indicates a violation of adaptive responses maladaptation. A decrease in VLF power in the first 3 hours after septoand rhinoseptoplasty indicates a pronounced stressor effect, which leads to low adaptive capabilities compared to rhinoplasty, that is, maladaptation within the specified period.

Changes in glucose variability and diabetes control in children and young adults with type 1 diabetes on routine continuous glucose monitoring and continuous subcutaneous insulin therapy following a switch to hybrid closed-loop therapy (MiniMed 780G) – retrospective study

IntroductionAdvanced hybrid closed loop (AHCL) insulin delivery systems offer considerable benefits to individuals with type 1 diabetes (T1D) in terms of glucose control and quality of life. With increasing numbers of regular users, real-life long-term data on long-term AHCL effectiveness become available.Material and methodsThis was a single-centre retrospective study. We included children and young adults (age 5–25 years ) with established T1D (≥ 3 m) who started MiniMed780G therapy between January 2021 and April 2022. We excluded those naïve to continuous glucose monitoring (CGM) or insulin pumps, as well as those without good-quality baseline CGM data. Included patients were followed for 12 months, with CGM and pump data retrieved from 14-day periods before transition and 3, 6, 9, and 12 months following the start of automode. Clinical data (body weight, height, glycated haemoglobin concentration) were recorded from the most recent outpatient visits.ResultsAmong 81 patients who started AHCL therapy, 46 met the criteria for analysis (mean age 11.5 ±4.4 years, diabetes duration 4.4 ±3.6 years, mean glycated haemoglobin 7.0 ±1.0%). Over the year following transition, we noted a significant improvement in time in target range 70–180 mg/dl (TIR, baseline: 69.1 ±12.0% to 12 m: 76.9 ±8.5%, <i>p</i> < 0.0001) and time in tight range 70–140 mg/dl (baseline: 45.3 ±14.2% to 12 m: 53.3 ±10.4%, <i>p</i> < 0.0001). Time below target range 70 mg/dl (TBR70 mg/dl) decreased significantly for 24-hour records (<i>p</i> = 0.0020). Importantly, those improvements were not accompanied by an increase in daily dose of insulin or body mass index.ConclusionsA prolonged 12-month-long observation in a routine care setting demonstrates that for young CGM- and pump users with T1D, switch AHCL offers sustained benefits in glucose variability.

Information provision and financial incentives in Catalonia's public primary care (2010–2019): an interrupted time series analysis

The relative efficacy of information provision versus financial incentives in improving primary care quality remains a critical, unresolved question. We investigated these two strategies in Catalonia's public primary care system from 2010 to 2019: an innovative online platform providing real-time quality indicator information and targeted economic incentives for achieving indicator goals. We conducted a comprehensive interrupted time series regression analysis on data from 272 primary care practices (5,628,080 patients). This analysis used linear regression models with Newey-West standard errors, and a sensitivity analysis including logit transformations to address ceiling effects. We evaluated 1) immediate post-intervention changes (step changes) in indicator results and inter-practice variability (coefficient of variation, CV), and 2) shifts in pre-intervention trends (slopes). We scrutinized 39 indicators after rigorous quality control: 23 novel (12 informed, 11 incentivized) and 16 derived from existing incentivized indicators. Robustness checks included 14 consistently incentivized and 10 non-intervened indicators. Overall, we assessed 63 indicators: 18 control, 13 follow-up, 9 quaternary prevention, 7 treatment, 7 diagnosis, 6 screening and 3 vaccination indicators. Informed indicators showed positive impacts in 75% (9/12) of cases, and incentivized indicators in 64% (7/11) of cases. Incentivized indicators displayed improvements in annual trends ranging from 6.66 to 1.25 percentage points, with step changes up to 8.87 percentage points. Information led to step changes ranging from 19.67 to 1.07 percentage points, along with trend improvements between 1.09 and 0.34 percentage points annually. Both interventions were associated with step reductions in variability (up to-0.18 CV reduction) and significant trend improvements. Derived indicators showed limited improvements in results or variability (31%, 5/16), with minor step increases up to 2.22 percentage points. Our findings reveal that information provision alone can match or even surpass the impact of financial incentives in improving care quality and reducing practice variability. This challenges conventional wisdom and offers a cost-effective, scalable approach to primary care quality enhancement, with far-reaching implications for global health policy. European Union, Horizon Europe.

Analysis of the response of AXL and/or MITF melanoma subpopulations to immunotherapy

BackgroundTumor heterogeneity is a hurdle to effective therapy, as illustrated by the “mixed responses” frequently seen in immunotherapy-treated patients. Previously, AXL+ tumor cells were identified to be highly resistant to targeted therapy, whereas more differentiated MITF+ tumor cells do respond to RAF and MEK inhibitors. MethodsIn this study we analyzed tumor heterogeneity, and explored the presence of the previously described AXL+ or MITF+ melanoma subpopulations, both at the mRNA and protein level, in metastatic tissues by Nanostring gene expression analysis, single-cell RNA sequencing, and by in situ multiplex immunofluorescence, respectively. Furthermore, we analyzed how these subpopulations correlate with immunological pressure and response to immunotherapy (immunomodulating antibodies or autologous tumor lysate-loaded dendritic cell vaccination). ResultsOur data demonstrate large inter patient variability and variable therapy-induced changes independent of the type of therapy. We identify the presence of previously described AXL+ and MITF+ subpopulations in metastatic tissues both at the mRNA and in situ at the protein level, and demonstrate that MITF+ melanoma cells are significantly decreased upon immunotherapy, while AXL+ melanoma cells numbers are stable. MITF+ tumor cells showed the most significant inverse correlation with CD8+ T cells. Our patient cohort also shows that immunotherapy-induced changes in the abundance of AXL+ or MITF+ tumor cells did not correlate with improved survival. ConclusionOverall, this study suggests that more differentiated MITF+ tumors are efficiently targeted by immunotherapy, while AXL+ tumor cells may be more resistant, analogous to their response to targeted therapy.

Coastal vertical land motion across Southeast Asia derived from combining tide gauge and satellite altimetry observations

Vertical land motion (VLM) is complex in Southeast Asia because this region is subject to a range of natural processes (e.g., earthquakes) and anthropogenic activities (e.g., groundwater withdrawal) that can change land heights. To aid in coastal management, long-term observations of VLM are as crucial as observations for climate-induced sea surface height changes; however, such long-term observations are sparse for Southeast Asian coasts. To fill this observational gap, here we derive monthly VLM time series from 1993 to 2020 at 50 coastal sites across Southeast Asia by combining tide-gauge records and newly generated satellite altimetry observations. These altimetry observations are reproduced sea-level products using new altimetry standards and more accurate geophysical corrections. Our 27-year-long VLM dataset shows high spatial variability and non-linear temporal changes in VLM across Southeast Asia. We identify several major sources that dominate the regional land-height changes, which include large subsidence due to groundwater extraction in Manila and Bangkok, land uplift in Indonesia and subsidence in Thailand from postseismic deformation resulting from the sequence of large Sumatran earthquakes since 2004, and land subsidence as a result of sediment compaction in Malaysia. Those signals are quantitatively or qualitatively consistent with observations from other sources. This VLM dataset can be used to advance our understanding of the physical mechanisms behind land-height changes and to improve sea level projections in the region.

Internal variability of the winter North Atlantic Oscillation longitudinal displacements

The winter North Atlantic Oscillation (NAO), one of the leading modes of atmospheric variability in the Northern Hemisphere and key driver of surface climate anomalies, was long considered to be spatially stable. Yet, its northern center-of-action – the Icelandic Low (IL) – shifted eastward in the late 1970s compared to the preceding decades of the mid-20th century. The responsible processes are still uncertain, particularly after the decline of the positive NAO trend in the 21st century. Here, we present observational and model evidence that the NAO-IL moves naturally alternating between two preferential locations, west/east of Iceland, with no need for changes in anthropogenic forcing or low-frequency oceanic variability. These recurrent longitudinal displacements of the NAO pattern appear linked to zonal changes in the fluctuations (not mean-state) of transient-eddy activity, emphasizing the relevance of internal atmospheric variability, and could represent a major source of uncertainty in regional climate prediction and projection.

Sensitivity of groundwater levels to low-frequency climate variability in a large watershed

Groundwater level (GWL) can vary over a wide range of timescales. Previous studies highlighted that low-frequency variability (interannual (2–8 years) to decadal (>10 years)) originating from large-scale climate variability, represents a significant part of GWL variance. It remains an open question, however, how GWL, including extremes, may respond to changes in large-scale climate forcing, affecting precipitation variability. Focusing on the Seine River basin, this study therefore aims to assess how GWLs respond to changes in interannual to decadal climate variability.We implemented an empirical numerical approach, which enables an assessment of the GWL sensitivity to changes in precipitation variability over a range of timescales (up to decadal), using the Seine hydrosystem as a case study. The approach consists in: i) identifying and modifying the spectral content of precipitation in the low-frequency range; ii) using these perturbed precipitation fields as input in the physically-based hydrological/hydrogeological CaWaQS model for the Seine River basin to simulate the corresponding GWL response; iii) comparing the spectral content, mean, variance and extremes of perturbed GWLs with reference (i.e. unperturbed) GWLs. Two interannual (2–4 yr and 5–8 yr) and one decadal (15 yr) timescales were modified individually by either increasing or decreasing their amplitude by 50 %. This led to six scenarios of perturbed low-frequency precipitation variability, which were subsequently used as CaWaQS inputs to assess the GWL response.Results indicated increased (decreased) GWL up to 5 m when low-frequency precipitation variability increased (decreased) by 50 %. This led to an increased occurrence of groundwater floods (droughts) with increased severity and decreased occurrence of groundwater droughts (floods) with decreased severity, respectively. These results indicate: i) how using biased climate data, in terms of low-frequency variability, leads to large deviations in the GWL simulation, ii) to what extent potential changes in low-frequency climate variability may affect future GWL, and particularly drought and flood occurrence and severity.

Evolution of the subtropical surface wind in the north-east Atlantic under climate change

The climate of western Europe and northwest Africa strongly depends on the Azores anticyclone strength, location, and shape and, locally, also on the characteristics of the Iberia and Sahara summer thermal lows. EC-EARTH3 global simulations are here used to assess the predicted behaviour of these two relevant surface pressure systems and associated surface wind, by the end of XXI century (2071–2100), considering two climate change scenarios. Additionally, a high-resolution Weather Research and Forecasting (WRF) simulation centred on Madeira Island is used to assess the influence of climate change on the surface wind at smaller scales, in a region well known for its perturbed flows. Results indicate a general mean wind speed decrease over a sector of the North-Atlantic, associated with a flatter Azores anticyclone. However, the predicted intensification of the Iberia and Sahara thermal lows imposes an increasing surface wind speed near west Iberia and northwest Africa, in summer. Southwest of Iberia, Madeira Island is also predicted to experience a summer intensification of its tip-jets. The projected changes in low-level wind speed and variability will impact on different sectors of activity, either directly as are the cases of aeronautical operation and offshore renewable energy, or indirectly through changes in the ocean circulation.

Features of Stress-Induced Changes in Heart Rate Variability During Blockade of Central and Stimulation of Peripheral Serotonin and Dopamine Receptors in Rats.

The dynamics of heart rate variability (HRV) during acute stress was studied in male nonlinear rats that received single injection of serotonin (200 μg/kg) or dopamine (60 μg/kg), regular (4-fold) injections of central serotonin receptor blockers (ketanserin and granisetron, 0.1 mg/kg each) or central dopamine receptor blockers (0.1 mg/kg SCH-23390 and 10 mg/kg sulpiride), as well as a combination of central receptor blockers with the administration of serotonin or dopamine, respectively. During stress against the background of serotonin receptors blockade, a weak tachycardia, low stress index, high rhythm variability, especially in the low-frequency range were recorded; against the background of dopamine receptors blockade, increased reactivity to stress at high HR, an initial increase in the stress index, and a decrease in rhythm variability, followed by an increase in the proportion of very low frequency waves in the spectrum were revealed. Serotonin and dopamine, by stimulating peripheral receptors, predominantly weakened stress-induced changes in HRV (especially serotonin), but in combination with blockade of the corresponding central receptors contributed to maintaining tachycardia, reduced rhythm variability, and potentiated the effects of blockers in relation to stress induced changes in the wave structure of the HRV spectrum. We believe that central and peripheral serotoninergic and dopaminergic structures are involved in the formation of HRV by modulating the activity of components of the autonomous and central circuits of HR regulation, respectively.

The effects of COVID-19 lockdown and reopening on rest-activity rhythms in Singaporean working adults: A longitudinal age group comparison study

Study objectivesCOVID-19 mobility restrictions disrupted daily rhythms worldwide, but how this rhythm disruption differs across age groups is unclear. We examined the course of age-related differences in trajectories of rest-activity rhythm during the COVID-19 pandemic lockdown and reopening in Singapore. We also evaluated the association of these patterns with mental well-being. Methods24-hour step count data (Fitbit) were obtained from 617 younger (age range: 21-40) and 602 older adults (age range: 55-70) from January 2020 (baseline) through lockdown (April 2020) and reopening periods until August 2021. Nonparametric rest-activity rhythm metrics: interdaily stability, intradaily variability and most active 10-hour period (M10) were computed. Longitudinal changes in rest-activity rhythm, age-related differences in changes, and the associations between mental well-being and these changes were assessed using nonlinear latent-growth models. ResultsIn younger adults, mobility restrictions during lockdown caused significant decline in interdaily stability and M10, alongside significant increase in intradaily variability. However, in older adults, changes were confined to increased intradaily variability and decreased M10. Older adults also showed less change in intradaily variability and M10 compared to younger adults. Gradual recovery of rest-activity rhythm metrics during reopening was observed, with interdaily stability and M10 remaining lower after 15months post-lockdown. In younger but not older adults, a larger decline in interdaily stability was associated with poorer mental well-being 15months post-lockdown. ConclusionYounger adults appear more vulnerable than older adults to mobility restrictions as reflected in their rest-activity rhythm metrics. A significant disruption of daily routine may have long-lasting effects on younger adults’ mental well-being. Statement of significanceAlthough stringent mobility restrictions imposed to curb the spread of COVID-19 were imposed primarily to protect older adults, we found that younger adults were more vulnerable to rhythm disruption arising from mobility restrictions. Disrupted rhythm stability was associated with poorer mental well-being 15months after the lockdown ended in younger but not older adults. These asymmetric long-term effects on mental health on younger relative to older adults should be kept in mind when planning for large-scale catastrophes linked to mobility restrictions.

Changes in heart rate variability during an eHealth behavior change intervention program in patients with cardiovascular disease

BackgroundCardiovascular disease (CVD) risk is associated with health behaviors such as physical inactivity, dietary habits, and smoking. The autonomic nervous system plays a key role in this association. The present longitudinal study examines whether ECG-based indices of autonomic nervous system activity change during an eHealth-based behavior intervention program and assesses whether improvements in health behaviors are associated with increases in parasympathetic autonomic nervous system activity. MethodsData from the DoCHANGE-2 (https://clinicaltrials.gov/study/NCT03178305) eHealth-based behavior intervention study in patients with CVD were analyzed for participants with valid ECG recordings (N = 58, mean age = 58.9 [SD = 12.7] years, 21 % women). Heart rate variability (indexed as RMSSD) was calculated from home-recorded (40 s) ECGs over 5-day periods at baseline, 3, and 6 months. Health behaviors, clinical, and psychosocial information was obtained from questionnaires and medical records. Data were analyzed using linear mixed models and general linear models. ResultsOver the 6-month period, RMSSD decreased significantly, with the lowest values at six months (B = -19.336 [95 %CI −36.291; 2.381], p = 0.026). Health behaviors improved significantly during the active (0–3 months) intervention period (B = 13.360 [95 %CI 6.931 19.789], p < 0.001). Higher BMI (B = −0.369 [−0.739; 0.000]; p = 0.05) and older age (B = −0.404 [95 % CI −0.597; − 0.211]; p < 0.001) were associated with lower RMSSD across the three timepoints. No consistent associations were found between changes in health behaviors and changes in RMSSD. ConclusionThis study shows that changes in HRV during an eHealth-based behavioral intervention were not associated with the observed improvements in health behaviors. These findings require replication in larger well-controlled investigations.

Human settlement and destructive activities disrupt the positive contribution of dust to plant biomass growth over the past 2000 years

The dual pressures of global warming and increased anthropogenic activities pose significant threats to terrestrial vegetation ecosystems. To better understand the impacts of climate change and human activities on terrestrial vegetation ecosystems, we reconstructed the changes in vegetation and plant biomass over the past 4500 years using n-alkane records from sediments of two alpine lakes in northwestern China: Xiannv Lake and Tianchi Lake. Our results indicate that changes in the spatial variability of plant biomass are not related to temperature and precipitation. Furthermore, CO2 fertilization and nutrient inputs from dust contributed to the observed changes in plant biomass. We also compared the history of human activities in the Tianshan Mountains, the eastern Silk Road, and the Hunsandak Sandy Land, and find that the demand for plant resources—whether for human settlement, military construction, or warfare—may have caused a sudden decline in terrestrial vegetation, thereby disrupting the positive effects of dust on plant biomass growth.

Historical and Future Asymmetry of ENSO Teleconnections with Extremes

Abstract El Niño–Southern Oscillation (ENSO) is the dominant source of climate variability globally. Many of the most devastating impacts of ENSO are felt through extremes. Here, we present and describe a spatially complete global synthesis of extreme temperature and precipitation relationships with ENSO. We also investigate how these relationships evolve under a future warming scenario under high greenhouse gas emissions using 14 models from phase 6 of Coupled Model Intercomparison Project (CMIP6) ensemble. First, we demonstrate that models broadly capture observed ENSO teleconnections to mean and extreme climate using the Twentieth Century Reanalysis, version 3 (20CRv3). The models project that more regions will experience an amplification of the historical ENSO teleconnection with mean temperature and precipitation than a dampening under a high-emission climate scenario. The response of the ENSO teleconnection with extremes is very similar to the mean response, with even larger changes in some regions. Hence, regions that are predicted to experience an amplification of the ENSO teleconnection under future warming can also expect a comparable amplification in the intensity of extremes. Furthermore, models that suggest greater amplification of ENSO amplitude also tend to exhibit greater intensification of mean and extreme teleconnections. Future changes in regional climate variability may be better constrained if changes in ENSO itself are better understood.