Background Stress Research Articles

Fault Friction Derived From Fault Bend Influence on Coseismic Slip During the 2019 Ridgecrest Mw 7.1 Mainshock

AbstractThe variation of stress on faults is important for our understanding of fault friction and the dynamics of earthquake ruptures. However, we still have little observational constraints on their absolute magnitude, or their variations in space and in time over the seismic cycle. Here we use a new geodetic imaging technique to measure the 3D coseismic slip vectors along the 2019 Ridgecrest surface ruptures and invert them for the coseismic stress state. We find that the coseismic stresses show an eastward rotation that becomes increasingly transtensional from south‐to‐north along the rupture, that matches the known background stress state. We find that the main fault near the Mw 7.1 mainshock hypocenter was critically stressed. Coseismic slip was maximum there and decreased gradually along strike as the fault became less optimally oriented due its curved geometry. The variations of slip and stress along the curved faults are used to infer the static and dynamic fault friction assuming Mohr‐Coulomb failure. We find shear stresses of 4–9 MPa in the shallow crust (∼1.3 km depth) and that fault friction drops from a static, Byerlee‐type, value of 0.61 0.14 to a dynamic value of 0.29 0.04 during seismic slip. These values explain quantitatively the slip variations along a transpressional fault bend.

Seismic analysis of the Xiluodu reservoir area and insights into the geometry of seismogenic faults

The Xiluodu (XLD) reservoir is the second largest reservoir in China and the largest in the Jinsha River basin. The occurrence of two M > 5 earthquakes after reservoir impoundment has aroused great interest among seismologists and plant operators. We comprehensively analyzed the seismicity of the XLD reservoir area using precise earthquake relocation results and focal mechanism solutions and found that the seismicity of this area was weak before impoundment. Following impoundment, earthquake activity increased significantly. The occurrence of M ≥ 3.5 earthquakes within five years of impoundment also appear to be closely related to rapid rises and falls in water level, though this correlation weakened after five years because earthquake activity was far from the reservoir area. Earthquakes in the XLD reservoir area are clustered; near the dam (Area A), small faults are intermittently distributed along the river, while Area B is composed of multiple NW-trending left-lateral strike-slip faults and a thrust fault and Area C is composed of a NW-trending left-lateral strike-slip main fault and a nearly EW-trending right-lateral strike-slip minor fault. The geometries of the deep and the shallow parts of the NW-trending fault differ. Under the action of the NW-trending background stress field, a series of NW-trending left-lateral strike-slip faults and NE-trending thrust faults in critical stress states were dislocated due to the stress caused by reservoir impoundment. The two largest earthquakes in the XLD reservoir area were tectonic earthquakes that were directly triggered by impoundment.

Long‐Term Fluid Injection Can Expedite Fault Reactivation and Development: Riedel Shear Structures Illuminated by Induced Earthquakes in Alberta, Canada

AbstractRiedel shear structures (RSS) are often observed in the embryonic stage of strike‐slip fault development, which can be depicted in the field through outcrops and coseismic surface ruptures. It is a critical concept linking the geomechanical behavior of individual earthquakes to structural geology at both local and regional scales. However, the influence of long‐term fluid injections on the developing process of RSS, as manifested by the common occurrences of injection‐induced earthquakes, has been rarely addressed. Here we document for the first‐time subsurface RSS expedited by long‐term wastewater disposal injections in western Canada. We study an earthquake sequence consisting of 187 events (ML ranging 1.3–3.9) between 1 January 2018 and 15 July 2021 in an area without any previous seismic history. According to 31 well‐constrained focal mechanism solutions, the injection‐related earthquake sequence exhibits various faulting types with the vast majority (87%) being compatible with the background stress regime (SHmax azimuth = N38°E). The orientation of derived nodal planes collectively indicates a model of RSS that consists of four primary strike‐slip structures striking 19° (R′), 79° (R), 94° (PDZ), and 109° (P), respectively. Moreover, six fault segments delineated from the relocated local seismicity are parallel to the substructures of RSS. Mohr‐Coulomb failure analysis further suggests a cumulative stress perturbation of up to 10.0 MPa. Our observations suggest that long‐term fluid injection can expedite the development of local fault systems. Therefore, it is probably important to consider the dimension of local/regional RSS in the assessment of the overall seismic hazard due to fluid injections.

Influence of regional background stress fields on the spontaneous rupture of the major faults around Xiluodu dam, China

Simulations of the spontaneous rupture of potential earthquakes in the vicinity of reservoir dams can provide accurate parameters for seismic resilience assessment, which is essential for improving the seismic performance of reservoir dams. In simulations of potential spontaneous ruptures, fault geometry, regional stress fields, constitutive parameters of the fault friction law, and many other factors control the slip rate, morphology, and dislocation of the rupture, thereby affecting the simulated ground motion parameters. The focus of this study was to elucidate the effects of the background stress field on the nucleation and propagation of spontaneous ruptures based on the factors influencing potential M > 7 earthquake events on the Leibo Middle Fault (LBMF) and the Mabian-Yanjing Fault (MB-YJF) in the Xiluodu dam (XLD) region. Our simulation results show that the magnitude of the regional background stress field plays a decisive role in whether a destructive earthquake exceeding the critical magnitude will occur. We found that the direction and magnitude of the regional stress significantly affect the range of rupture propagation on the fault plane, and fault geometry affects the spatial distribution of the rupture range. Under the same regional stress field magnitude and orientation, a more destructive, high-magnitude earthquake is more likely to occur on the LBMF than on the MB-YJF.

Heat stress and incidence of acute kidney injury among agricultural workers in Spain

BACKGROUND AND AIM Heat stress (HS) is associated with adverse health outcomes among agricultural workers, including acute kidney injury (AKI). The aim on this study was to estimate the incidence of AKI over the course of the work shift and the association with HS among agricultural workers in Spain, where summer temperatures are high and heat waves are expected to be more frequent. METHODS Male agricultural workers were enrolled in the study in two different periods and provinces: summer harvesting season in Alacant (n=43, September 2018) and winter harvesting season in Tarragona (n=52, November 2018 and January 2019). For each participant we estimated exposure to HS during a work shift based on the wet bulb globe temperature (WBGT) index (ISO 7243:2017) and AKI cross-shift incidence, defined as an increase in post-shift serum creatinine by at least 0.3 mg/ dl or at least 1.5 times the pre-shift serum creatinine levels. We collected information on potential confounders. For a subsample of participants (n=54), we measured neutrophil gelatinase-associated lipocalin (NGAL) levels before and after the working shift. We used regression models to assess if heat stress is a risk factors for AKI and increase in NGAL levels. RESULTS Mean WBGT was 24.5 ᵒC (20.2-27.1) during the summer harvesting season and 14.2 ᵒC (8.0-20.7) during the winter harvesting season. Nine percent of workers harvesting during the summer months were exposed to HS. Incidence of AKI was higher during the summer harvesting season (33% versus 4%). HS was associated with cross-shift incidence of AKI [Age adjusted OR (95%CI) =9.6 (1.4, 67.9)]. No differences in NGAL levels were observed between participants exposed to HS. CONCLUSIONS Heat stress is a risk factor for AKI among agricultural workers in Spain even when environmental temperatures are not extremely hot. KEYWORDS Heat stress, Acute kidney injury, Agricultural workers, Mediterranean region

Adverse childhood events and health-related quality of life among women undergoing hysterectomy for uterine leiomyoma

Background and Aim Psychosocial stress may increase fibroid risk, but associations with symptom severity, which often influence clinical management decisions, have been underexamined. Our objective is to examine associations between adverse childhood experiences (ACE) and symptom severity and symptom impact on health-related quality of life (HRQL) among women undergoing hysterectomy for treatment of their leiomyomas (fibroids). Methods We recruited 103 premenopausal women into the Fibroids, Observational Research on Genes and the Environment (FORGE) study who were seeking evaluation of fibroids at the Medical Faculty Associates in Washington D.C. and intending to undergo hysterectomy at the George Washington University Hospital. For exposure classification, we assessed eight ACE categories related to child abuse and household challenges. For outcome classification, we used the Uterine Fibroid Symptom and Quality of Life (UFS-QOL). The five-level Likert scale responses were summed to create composite scores; a lower symptom severity score indicated fewer symptoms, while a higher HRQL score indicated better quality of life. We ran quasi-poisson regressions (log-link) to examine associations between ACE scores and UFS-QOL composite scores adjusting for age, race/ethnicity, and education (N=89). Results The majority of participants were Black (73%); about half had private insurance (55%) and a college degree (49%). Cumulative ACE and symptom severity scores were higher among Black compared to non-Black women (p ≤ 0.03). History of substance abuse in the household was associated with greater symptom severity (relative risk (RR) = 1.31, 95% CI: 1.07, 1.61), and worse HRQL (RR = 0.74, 95% CI: 0.55, 1.00). History of sexual abuse was also associated with worse HRQL (RR = 0.67, 95% CI: 0.48, 0.92). Conclusions Our study adds to the growing evidence that early life exposures to chronic stress may influence gynecologic health, including symptom-related quality of life. Keywords. Women’s health, gynecological health, health disparities, social-structural stressors

Is mindfulness one-size-fits-all?: Consulting community members and stakeholders to adapt mindfulness for communities with low-income and economic marginalization

Background and purposeAlthough stress is pertinent to all people, individuals with low-income and economic marginalization (LIEM) tend to experience greater psychosocial stressors as well as different relationship stressors than individuals with higher income. While mindfulness may be a particularly useful tool for individuals with LIEM, it has yet to be adapted for this community. Using a community-based participatory research (CBPR) approach, the present study conducted focus groups with community members with LIEM to identify effective dissemination strategies. Materials and methodsThirteen individuals with LIEM were recruited to participate in one of two focus groups. The focus groups collected information on how individuals with LIEM cope with stress, how these individuals perceive mindfulness, and how to reduce barriers to participating in a brief mindfulness intervention for stress. Focus groups were transcribed and coded by four coders using thematic analysis within a grounded theory framework. ResultsTwelve themes were identified: movement-based coping, behavioral/tactile coping, interest in mindfulness, familiarity with mindfulness, tangible mindfulness, narrow understanding of practicing mindfulness, relaxing, affiliation, alliance with healthcare facility, storytelling, breaking bread, and mental health treatment stigma. ConclusionThemes derived from the focus groups were discussed with community stakeholders. Findings from this study informed clinical considerations for using mindfulness with individuals with LIEM.

Imagery Rescripting as a stand-alone treatment for posttraumatic stress disorder related to childhood abuse: A randomized controlled trial

Background and objectivesPosttraumatic stress disorder (PTSD) related to childhood abuse (CA) is associated with high symptom complexity. This study examined the efficacy of Imagery Rescripting (ImRs) as a stand-alone treatment versus a sequenced approach with Skills training in Affective and Interpersonal Regulation (STAIR) followed by ImRs for CA-related PTSD. MethodsOutpatients of two mental health clinics with CA-related PTSD (N = 61) were randomly assigned to ImRs (16 sessions; n = 21), STAIR/ImRs (8 STAIR-sessions followed by 16 ImRs-sessions; n = 20), or Waitlist (8 weeks; n = 20). Patients of the waitlist condition were also randomized to the two active conditions for comparison of STAIR/ImRs (total n for this condition = 31) and ImRs (total n for this condition = 30) and started treatment after waitlist completion. Assessments took place at pre-treatment, after each treatment phase and at 12-week post-intervention follow-up. PTSD symptoms and diagnosis were primary outcome measures, and depression, emotion regulation and interpersonal functioning were secondary outcomes. ResultsImRs showed greater reduction of PTSD severity (effect sizes [ES] 1.40–1.63) than STAIR (ES, 0.23–0.33) as compared to waitlist. When comparing STAIR/ImRs and ImRs directly, (i.e. including re-randomized Waitlist-patients), PTSD symptoms reduced significantly (within condition ES, 1.64–2.10) and improved further to 12-week follow-up (within-condition ES, 2.33–2.66), with no significant difference between both conditions (between-condition ES, 0.21–0.45). Loss of PTSD diagnosis was achieved by 70% in the ImRs condition and 86% in the STAIR/ImRs condition. LimitationsThe sample size was relatively small. ConclusionsResults show that ImRs is an effective treatment for CA-related PTSD, whereby the current data do not convincingly show an additive effect of STAIR.

Minimum wall shear stress points and their underlying intra-aneurysmal flow structures of unruptured cerebral aneurysms on 4D flow MRI

Background and purposeMinimum wall shear stress (Min-WSS) points may be associated with wall instability of unruptured cerebral aneurysms. We aimed to investigate the relationship between the locations of Min-WSS points and their underlying intra-aneurysmal flow structure patterns in unruptured cerebral aneurysms using four-dimensional (4D) flow magnetic resonance imaging (MRI). Materials and methodsMin-WSS points and the intra-aneurysmal flow structure patterns were identified in 50 unruptured aneurysms by 4D flow MRI. ResultsThe Min-WSS points were located around a vortex core tip in 31 (62.0%) aneurysms and on an intra-bleb vortex center in 7 (14.0%). Sixteen (32.0%) aneurysms had the Min-WSS points on the aneurysmal apex, and in 24 (48.0%) were on the neck. The Min-WSS values of aneurysms with the Min-WSS points on an intra-bleb flow were significantly lower than those of the other groups (P = 0.030). Aneurysms with the Min-WSS points on the neck had significantly higher Min-WSS values than the other aneurysms (P = 0.008). ConclusionsThe location of the Min-WSS point was corresponding to the vortex core or center in 76% of all aneurysms. The underlying intra-aneurysmal flow structure and location of the Min-WSS point affect the Min-WSS value. Further studies are needed to characterize Min-WSS points to identify aneurysms with a higher risk of wall instability.

Quality of Life in Patients With Inflammatory Bowel Disease: Importance of Psychological Symptoms.

BackgroundDepressive, anxiety, and stress symptoms are prevalent in patients with inflammatory bowel disease (IBD) and may negatively influence the disease course and quality of life. The study aimed to assess the relationship between psychological factors and patients’ quality of life (QoL).Materials and methodsA cross-sectional study with the use of a structured questionnaire among 38 patients with Crohn’s disease and 30 with ulcerative colitis was conducted. The inflammatory bowel disease questionnaire (IBDQ-32) was used to evaluate the patients’ quality of life, and the Depression, Anxiety, Stress Scale (DASS21) was used to evaluate these psychological factors. Pearson descriptive statistics and multiple regression analyses were performed.ResultsAccording to the findings of the multiple regression analysis, depressive, anxiety, and stress symptoms were negatively associated with quality of life. Participants with higher scores of anxiety had inferior QoL in intestinal symptoms (p=0.013) and in systemic symptoms (p=0.013), with higher scores of depression had inferior QoL in emotional function (p<0.001), and higher scores of stress had inferior QoL in the domain of social support (p=0.002). Psychological symptoms of emotional disorders appear to be associated with lower quality of life in IBD patients.ConclusionThis study examined levels of depression, anxiety, and stress in Greek patients with IBD, which were associated with lower levels of their quality of life. Interventions to improve QoL in patients with IBD should consider the effect of psychological symptoms.

Endoplasmic reticulum stress promotes nuclear translocation of calmodulin, which activates phenotypic switching of vascular smooth muscle cells

Background and aimsIncreased endoplasmic reticulum (ER) stress is strongly associated with the phenotypic switching of vascular smooth muscle cells (VSMCs) in atherosclerosis. Depletion of the ER Ca2+ content is one of the leading causes of increased ER stress in VSMCs. The ryanodine receptor (RyR) is a major Ca2+ release channel in the sarcoplasmic reticulum membrane. Calmodulin (CaM), which binds to RyR (CaM-RyR), stabilizes the closed state of RyR in the resting state in normal cells. Defective CaM-RyR interactions can cause abnormal Ca2+ leakage through RyR, resulting in decreased Ca2+ content, indicating that defective CaM-RyR interactions may be a cause of increased ER stress. Herein, we used a mouse VSMCs to assess whether CaM-RyR plays a pivotal role in VSMCs phenotypic switching, which is caused by ER stress, and whether dantrolene, which enhances the binding affinity of CaM to RyR, affects VSMCs phenotypic switching. Methods and resultsTunicamycin was used to mimic ER stress in vitro. Tunicamycin-induced ER stress caused CaM to dissociate from the RyR and translocate to the nucleus, which stimulated phenotypic switching through the activation of MEF2 and KLF5. Dantrolene suppressed tunicamycin-induced apoptosis, ER stress (restoring ER Ca2+ content), and phenotypic switching of VSMCs. Suramin, which directly unbinds CaM from RyR, promoted nuclear CaM accumulation with parallel VSMCs phenotypic switching, and dantrolene prevented these effects. ConclusionsWe observed that ER stress causes CaM translocation to the nucleus and drives the phenotypic switching of VSMCs. Thus, restoration of the binding affinity of CaM to RyR may be a therapeutic target for atherosclerosis.

3D geomechanical modeling of the Xianshuihe fault zone, SE Tibetan Plateau: Implications for seismic hazard assessment

The Xianshuihe fault on the southeastern margin of the Tibetan Plateau is one of the most active intracontinental faults worldwide. At least 16 strong earthquakes (M > 6.5) have occurred on this fault since 1327 CE. To reasonably assess the future seismic hazard of this fault region, it is essential to gain a comprehensive knowledge of the fault kinematics and stress state. In this study, we developed a fine 3D geomechanical model of the Xianshuihe fault and its adjacent area, and obtained a spatially continuous contemporary kinematics and crustal background stress field of this region. Our modeled results show that the slip rate of the Xianshuihe fault is as high as 11 mm/a on the northwestern segment and generally decreases to ~9 mm/a on the southeastern segment (i.e. Moxi fault). The Yulongxi fault, a branch oblique to the Moxi fault, has different slip senses in different segments with a very low horizontal slip rate (<0.6 mm/a). In terms of stress, the study area is dominated by a transtensional faulting stress regime with E-W-trending maximum horizontal stress SH, indicating the study area is mainly subjected to an E-W compression and N-S extension. Localized normal and thrust faulting regimes appear alternately along the Xianshuihe fault, showing an inhomogeneous stress state. The high normal stresses on the Songlinkou-Selaha segment and the Moxi fault combined with their relatively high slip rates, make us speculate that these two segments have the potential to produce strong earthquakes in the future. A relatively high seismic hazard is also ascribed to the Yulongxi fault based on the analysis of its geological and geodynamic environment.

Emotion regulation strategies and perceived stress during pregnancy in expectant mothers and fathers

ABSTRACT Background Stress during pregnancy can increase physical and mental health risks in parents and offspring. Emotion regulation (ER) may protect against prenatal stress; however, ER is understudied in expectant parents, particularly expectant fathers. This study aimed to evaluate associations between ER strategies (reappraisal, suppression, ratio of suppression-to-reappraisal) and perceived stress among expectant parents, and also test whether expectant mothers and fathers differed in ER strategy use and perceived stress levels. Methods N = 83 expectant parents (62.7% mothers) in the third trimester completed measures assessing perceived stress,reappraisal, and suppression. ANCOVA, hierarchical regression, and multilevel models were used to evaluate associations between ER strategies and perceived stress, and test for sex differences. Results Controlling for age and education, lower reappraisal and higher suppression were associated with higher perceived stress; in addition, higher suppression-to-reappraisal ratios were associated with greater perceived stress. Mothers and fathers did not differ in perceived stress, reappraisal, or suppression; however, suppression-to-reappraisal ratios significantly differed. Conclusion Increasing ER skills such as reappraisal while reducing suppression may be beneficial for decreasing stress in expectant parents. Expectant fathers report similar levels of perceived stress to mothers and would benefit from prenatal mental health screening and intervention.

The Role of Background Stress State in Fluid‐Induced Aseismic Slip and Dynamic Rupture on a 3‐m Laboratory Fault

AbstractFluid injection stimulates seismicity far from active tectonic regions. However, the details of how fluids modify on‐fault stresses and initiate seismic events remain poorly understood. We conducted laboratory experiments using a biaxial loading apparatus with a 3 m saw‐cut granite fault and compared events induced at different levels of background shear stress. Water was injected at 10 mL/min and normal stress was constant at 4 MPa. In all experiments, aseismic slip initiated on the fault near the location of fluid injection and dynamic rupture eventually initiated from within the aseismic slipping patch. When the fault was near critically stressed, seismic slip initiated only seconds after MPa‐level injection pressures were reached and the dynamic rupture propagated beyond the fluid pressure perturbed region. At lower stress levels, dynamic rupture initiated hundreds of seconds later and was limited to regions where aseismic slip had significantly redistributed stress from within the pressurized region to neighboring locked patches. We found that the initiation of slow slip was broadly consistent with a Coulomb failure stress, but that initiation of dynamic rupture required additional criteria to be met. Even high background stress levels required aseismic slip to modify on‐fault stress to meet initiation criteria. We also observed slow slip events prior to dynamic rupture. Overall, our experiments suggest that initial fault stress, relative to fault strength, is a critical factor in determining whether a fluid‐induced rupture will “runaway” or whether a fluid‐induced rupture will remain localized to the fluid pressurized region.

Using Spiritual Connections to Cope With Stress and Anxiety During the COVID-19 Pandemic.

During the initial phases of the COVID-19 pandemic, stress and anxiety were pervasive among the masses due to high morbidity and mortality. Besides the fear of coronavirus was also particularly driven by social media. Many people started to look for faith and spiritual connections to gain comfort. The role of spiritual ties and religious beliefs in relation to coping with pandemic stress has acquired the attention of researchers in some parts of the world. This cross-sectional survey aimed at assessing the intensity of stress and anxiety symptoms experienced by people and how much they were alleviated by employing spiritual connections. The study sample comprises 795 respondents with 52% males and 48% females living in Saudi Arabia. The brief online study questionnaire collected data about background variables, anxiety and stress scale from DASS-21, and items from the WHOQOL (SRBP) instrument assessed the use of spiritual beliefs to cope. Multiple regression models were tested to determine the role of spiritual connections after adjusting demographic variables. Results illustrated that after adjusting for gender and age, participants’ anxiety symptoms decreased by (β = −0.27; p = 0.000) units with each unit increase in the use of spiritual connections, and participants’ stress symptoms reduce by (β = −0.36; p = 0.000) units with each unit increase in coping with spirituality. Additionally, females’ risk to experience anxiety and stress symptoms was more than males [(β = 0.88; p = 0.01) and (β = 0.92; p = 0.000)], respectively. An increase in age decreases the likelihood of experiencing anxiety symptoms and stress symptoms by (β = −0.75; p = 0.02) and (β = −0.11; p = 0.000) units, respectively. Findings support the protective role of spiritual connections despite small beta coefficients. The social and cultural context in Saudi Arabia favors deep-rooted connections with spirituality and faith. Our findings support the fact that the reliance on spiritual connections helped older people to deal with exaggerated fear during the initial phase of the COVID-19 pandemic and reduces the risk of experiencing anxiety and stress symptoms. Females and younger participants were relatively vulnerable to developing these symptoms. We discussed these findings considering some recent studies that reported similar relationships and made recommendations for future research.

보육교사가 지각한 직무스트레스가 분노조절에 미치는 영향

The purpose of this study was to examine the level of job stress perceived by childcare teachers and to examine the effect of stress on anger control. For this purpose, a survey was conducted on 431 childcare teachers working at daycare centers in Gyeongsangbuk-do, and the results of the study are as follows. First, as a result of analyzing whether there is a difference in the perceived anger control by childcare teachers according to the demographic variables of childcare teachers regarding anger control, significant differences were found in age, career, academic background, and job stress. There was no significant difference in the number of people in charge and working hours. Second, as a result of a study on whether job stress perceived by childcare teachers had a significant effect on anger control after controlling for demographic factors, the group with less than 10 years of experience as a childcare teacher showed higher anger control ability than the group with more than 10 years of experience. However, the higher the job stress of childcare teachers, the lower the ability to control anger. Third, as a result of analyzing the effects of six sub-factors of job stress on anger control, parental relationship stress and peer relationship stress had an effect on anger control, and among them, parental relationship stress had the most negative effect on anger control.&#x0D;

Beyond Stress: Altered Sleep-Wake Patterns are a Key Behavioral Risk Factor for Acute Insomnia During Times of Crisis

ABSTRACT Background Stress is a common precipitant of acute insomnia; however, reducing stress during times of crisis is challenging. This study aimed to determine which modifiable factors, beyond stress, were associated with acute insomnia during a major crisis, the COVID-19 pandemic. Participants/Methods A global online survey assessed sleep/circadian, stress, mental health, and lifestyle factors between April-May 2020. Logistic regression models analyzed data from 1319 participants (578 acute insomnia, 731 good sleepers), adjusted for demographic differences. Results Perceived stress was a significant predictor of acute insomnia during the pandemic (OR 1.23, 95% CI1.19–1.27). After adjusting for stress, individuals who altered their sleep-wake patterns (OR 3.36, CI 2.00–5.67) or increased technology use before bed (OR 3.13, CI 1.13–8.65) were at increased risk of acute insomnia. Other sleep factors associated with acute insomnia included changes in dreams/nightmares (OR 2.08, CI 1.32–3.27), increased sleep effort (OR 1.99, CI1.71–2.31) and cognitive pre-sleep arousal (OR 1.18, CI 1.11–1.24). For pandemic factors, worry about contracting COVID-19 (OR 3.08, CI 1.18–8.07) and stringent government COVID-19 restrictions (OR 1.12, CI =1.07–1.18) were associated with acute insomnia. Anxiety (OR 1.02, CI 1.01–1.05) and depressive (OR 1.29, CI 1.22–1.37) symptoms were also risk factors. A final hierarchical regression model revealed that after accounting for stress, altered sleep-wake patterns were a key behavioral predictor of acute insomnia (OR 2.60, CI 1.68–5.81). Conclusion Beyond stress, altered sleep-wake patterns are a key risk factor for acute insomnia. Modifiable behaviors such as maintaining regular sleep-wake patterns appear vital for sleeping well in times of crisis.

Seasonal terrestrial water load modulation of seismicity at the southeastern margin of the Tibetan Plateau constrained by GNSS and GRACE data

SUMMARY The seasonal terrestrial water load modulation of seismicity is an important phenomenon to understand the mechanism behind earthquake triggering and nucleation. The presence of high-level seismicity and large seasonal water load amplitudes at the southeastern margin of the Tibetan Plateau provides a natural experimental environment for studying the modulation mechanism. The spatiotemporal distribution of the water load was inverted using Global Navigation Satellite System (GNSS) and Gravity Recovery and Climate Experiment (GRACE) data, and an earthquake catalogue (M ≥ 2.5) was declustered to obtain the background seismicity using the Epidemic Type Aftershock Sequences (ETAS) model. The Multichannel Singular-Spectrum Analysis (M-SSA) is adopted to the time-series of monthly averaged terrestrial water load and background seismicity rates, and the results show 1- and 2-yr periodicities in the seismicity rates and water load. The 1-yr periodicity in the seismicity rate is correlated with the rate of change of the monthly averaged water load. To evaluate the seasonal principal stress perturbations on the tectonic background stress orientations, the stress changes caused by the seasonal water load changes are projected onto the tectonic background stress field orientations constraining by 8 yr of earthquake focal mechanism solutions. The results show that the largest change of the seasonal principal stress perturbations is about 16 kPa. The number of excess earthquakes is evaluated with the background seismicity rates for discrete stress intervals. The results indicate a ∼10 per cent increase in the seismicity rates that correlate with the rates of the minimum and mean principal stress perturbations. The results above can be explained by the model of harmonic stress perturbations on rate-and-state fault. Based on this model, the nucleation period of the seasonal seismicity should be less than 1 yr at the southeastern margin of the Tibetan Plateau.

보육교사의 직무스트레스와 자아분화가 우울에 미치는 영향

In this study, to examine the effect of childcare teachers' job stress on depression. For thispurpose, a survey was conducted on 253 childcare teachers working at daycare centers locatedin Seoul. The collected data were analyzed through SPSS 23.0. The main results of this studyare as follows. First, the job stress of childcare teachers was slightly lower level than normal,self-differentiation was at a level above average, and depression was at a lower level thannormal. Second, there were negative correlations between job stress and self-differentiation,self-differentiation and depression, and positive correlations between job stress and depressionof childcare teachers. Third, the general background, job stress, and self-differentiation ofchildcare teachers had a significant effect on depression. Especially, self-differentiation had asignificant effect on depression when the overall background and job stress of childcare teacherswere controlled. These results suggests that in order to reduce the depression of childcareteachers, it is necessary to take measures to reduce job stress along with counseling andeducational support that can increase the level of self-differentiation of childcare teachers.

Hyperthermia and Heat Stress as Risk Factors for Sudden Infant Death Syndrome: A Narrative Review.

Background and ObjectivesHeat stress and hyperthermia are common findings in sudden infant death syndrome (SIDS) victims. It has been suggested that thermal stress can increase the risk of SIDS directly via lethal hyperthermia or indirectly by altering autonomic functions. Major changes in sleep, thermoregulation, cardiovascular function, and the emergence of circadian functions occur at the age at which the risk of SIDS peaks—explaining the greater vulnerability at this stage of development. Here, we review the literature data on (i) heat stress and hyperthermia as direct risk factors for SIDS, and (ii) the indirect effects of thermal loads on vital physiological functions.ResultsVarious situations leading to thermal stress (i.e., outdoors temperatures, thermal insulation from clothing and bedding, the prone position, bed-sharing, and head covering) have been analyzed. Hyperthermia mainly results from excessive clothing and bedding insulation with regard to the ambient thermal conditions. The appropriate amount of clothing and bedding thermal insulation for homeothermia requires further research. The prone position and bed-sharing do not have major thermal impacts; the elevated risk of SIDS in these situations cannot be explained solely by thermal factors. Special attention should be given to brain overheating because of the head's major role in body heat losses, heat production, and autonomic functions. Thermal stress can alter cardiovascular and respiratory functions, which in turn can lead to life-threatening events (e.g., bradycardia, apnea with blood desaturation, and glottal closure). Unfortunately, thermal load impairs the responses to these challenges by reducing chemosensitivity, arousability, and autoresuscitation. As a result, thermal load (even when not lethal directly) can interact detrimentally with vital physiological functions.ConclusionsWith the exception of excessive thermal insulation (which can lead to lethal hyperthermia), the major risk factors for SIDS appears to be associated with impairments of vital physiological functions when the infant is exposed to thermal stress.