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Protecting populations contending with co-occurring stressors requires a better understanding of how multiple early-life stressors affect the fitness of natural systems. However, the complexity of such research has limited its advancement and prevented us from answering new questions. In human studies, cumulative risk models predict adult health risk based on early adversity exposure. We apply a similar framework in wild yellow-bellied marmots (Marmota flaviventer). We tested cumulative adversity indices (CAIs) across different adversity types and time windows. All CAIs were associated with decreased pup survival and were well supported. Moderate and acute, but not standardized CAIs were associated with decreased lifespan, supporting the cumulative stress hypothesis and the endurance of early adversity. Multivariate models showed that differences in lifespan were driven by weaning date, precipitation, and maternal loss, but they performed poorly compared with CAI models. We highlight the development, utility, and insights of CAI approaches for ecology and conservation.

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Background and Objectives: Drawing from cumulative inequality theory and the weathering hypothesis, this study examined the relationship between life-course stress exposure (measured cumulatively and by domains) and the onset of disability in later life among White, Black, U.S.-born Hispanic, and foreign-born Hispanic older adults. Research Design and Methods: Cross-sectional and longitudinal models were estimated using nationally representative data from the Health and Retirement Study (N = 11,483). We used logistic regression models to examine associations between stress exposure and Wave 1 disability (i.e., occurrence), and Weibull-accelerated failure-time models to examine the relationship between stress exposure and age of onset of disability 12-14 years later (i.e., incidence). We tested for moderation between stress and disability by race, ethnicity, and Hispanic nativity. Results: At Wave 1, higher odds of disability occurrence were associated with cumulative stress burden (CSB; odds ratio [OR] = 4.93, 95% confidence interval [CI]: 2.95-8.23). In a model specifying domains of stressors, disability occurrence was associated with childhood financial strain (OR = 1.22, CI: 1.01-1.46), lifetime traumatic events (OR = 1.92, CI: 1.41-2.62), neighborhood disadvantage (OR = 1.32, CI: 1.01-1.73), and major lifetime discrimination (OR = 1.64, CI: 1.12-2.41). Over time, earlier onset of disability was associated with CSB (ß = -0.39), childhood traumatic events (ß = -0.16), adult financial strain (ß = -0.17), everyday discrimination (ß = -0.15), and major lifetime discrimination (ß = -0.13). The effect of childhood traumatic events on the transition to disability was stronger for U.S.-born Hispanic adults than White adults (occurring 33% earlier). Discussion and Implications: To reduce racial, ethnic, and nativity disparities in disability, it is important to consider the historical and structural disadvantages associated with stress exposure across the life course. It is also important to acknowledge that nativity influences stratification processes associated with disparities in racial and ethnic health trajectories.

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The recent polycrisis (COVID-19, Ukraine war, climate change, economic crisis) has been associated with mental health through cumulative stress, with young people being particularly vulnerable. We surveyed 403 college students from Poland to examine their psychological responses to the experienced crises. The results showed that polycrisis was associated with worse mental health of college students from disadvantaged groups (based on gender, sexual orientation, and financial situation) compared to other college students, in four areas: sense of proximity to the crises, stress caused by the crises, sense of responsibility for mitigating the crises, and experiencing everyday moral dilemmas regarding the crises. These young adults also suffered more in terms of negative affectivity, depressive symptoms, and subjective physical and mental health. Our findings suggest that when discussing public mental health perspectives, it is important to consider consequences of cumulative stress and its greater impact on young people from disadvantaged groups.

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OBJECTIVE: Using a large longitudinal sample of adults from the Midlife in the United States (MIDUS) study, the present study extended a recently developed hierarchical model to determine how best to model the accumulation of stressors, and to determine whether the rate of change in stressors or traditional composite scores of stressors are stronger predictors of health outcomes. METHOD: We used factor analysis to estimate a stress-factor score and then, to operationalize the accumulation of stressors we examined five approaches to aggregating information about repeated exposures to multiple stressors. The predictive validity of these approaches was then assessed in relation to different health outcomes. RESULTS: The prediction of chronic conditions, body mass index, difficulty with activities of daily living, executive function, and episodic memory later in life was strongest when the accumulation of stressors was modeled using total area under the curve (AUC) of estimated factor scores, compared to composite scores that have traditionally been used in studies of cumulative stress, as well as linear rates of change. CONCLUSIONS: Like endogenous, biological markers of stress reactivity, AUC for individual trajectories of self-reported stressors shows promise as a data reduction technique to model the accumulation of stressors in longitudinal studies. Overall, our results indicate that considering different quantitative models is critical to understanding the sequelae and predictive power of psychosocial stressors from midlife to late adulthood.

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Based on a multiwave, two-year prospective design, this study is the first to examine the extent to which multilocus hypothalamic-pituitary-adrenal axis (HPA axis)-related genetic variants, childhood maltreatment, and recent stress jointly predicted prospective changes in adolescent depressive symptoms. A theory-driven multilocus genetic profile score (MGPS) was calculated to combine the effects of six common polymorphisms within HPA-axis related genes (CRHR1, NR3C1, NR3C2, FKBP5, COMT, and HTR1A) in a sample of Chinese Han adolescents (N = 827; 50.2% boys; Mage = 16.45 ± 1.36 years). The results showed that the three-way interaction of HPA-axis related MGPS, childhood maltreatment and recent interpersonal, but not noninterpersonal, stress significantly predicted prospective changes in adolescent depressive symptoms. For adolescents with high but not low HPA-axis related MGPS, exposure to severe childhood maltreatment predisposed individuals more vulnerable to recent interpersonal stress, exhibiting greater prospective changes in adolescent depressive symptoms. The findings provide preliminary evidence for the cumulative risk mechanism regarding gene-by-environment-by-environment (G × E1 × E2) interactions that underlie the longitudinal development of adolescent depressive symptoms and show effects specific to interpersonal stress.

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BACKGROUND: The cumulative stress toll on nurses increased during the COVID-19 pandemic. An evidence-based practice (EBP) project was conducted to understand what is known about the impacts of cumulative stress within nursing and if there are ways to mitigate stress during a nurse's shift. AIM/IMPLEMENTATION: A project team from three clinical units completed an extensive literature review and identified the need to promote detachment while supporting parasympathetic recovery. Based on this review, leaders from three pediatric clinical units (neonatal intensive care unit, cardiovascular intensive care unit, and acute pulmonary floor) implemented respite rooms. OUTCOMES: Follow-up outcomes showed a statistically significant stress reduction. For all shifts combined, the Wilcoxon Signed-Rank Test revealed that perceived stress scores from an 11-point Likert scale (0 = no stress and 10 = maximum perceived stress) were significantly lower in the post-respite room (Md = 3, n = 68) compared to in the pre-respite room (Md = 6, n = 68), Z = -7.059, p < .001, with a large effect size, r = .605. Nurses and other staff frequently utilized respite rooms during shifts. IMPLICATIONS FOR PRACTICE: Clinical inquiry and evidence-based practice processes can mitigate cumulative stress and support staff wellbeing. Respite rooms within the hospital can promote a healthy work environment among nurses and promote a self-care culture change. Evidence-based strategies to mitigate cumulative stress using respite rooms are a best practice to promote nurse wellbeing and mitigate cumulative stress.

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BACKGROUND: African American (AA) women navigate the world with multiple intersecting marginalized identities. Accordingly, AA women have higher cumulative stress burden or allostatic load (AL) compared to other women. Studies suggest that AA women with a college degree or higher have lower AL than AA women with less than a high school diploma. We examined the joint effect of educational attainment and AL status with long-term risk of cancer mortality, and whether education moderated the association between AL and cancer mortality. METHODS: We performed a retrospective analysis among 4,677 AA women within the National Health and Nutrition Examination Survey (NHANES) from 1988 to 2010 with follow-up data through December 31, 2019. We fit weighted Cox proportional hazards models to estimate adjusted hazard ratios (aHRs) of cancer death between educational attainment/AL (adjusted for age, income, and smoking status). RESULTS: AA women with less than a high school diploma living with high AL had nearly a 3-fold increased risk (unadjusted HR: 2.98; 95%C CI: 1.24-7.15) of cancer death compared to AA college graduates living with low AL. However, after adjusting for age, this effect attenuated (age-adjusted HR: 1.11; 95% CI: 0.45-2.74). AA women with high AL had 2.3-fold increased risk of cancer death (fully adjusted HR: 2.26; 95% CI: 1.10-4.57) when compared to AA with low AL, specifically among women with high school diploma or equivalent and without history of cancer. CONCLUSIONS: Our findings suggest that high allostatic load is associated with a higher risk of cancer mortality among AA women with lower educational attainment, while no such association was observed among AA women with higher educational attainment. Thus, educational attainment plays a modifying role in the relationship between allostatic load and the risk of cancer death for AA women. Higher education can bring several benefits, including improved access to medical care and enhanced medical literacy, which in turn may help mitigate the adverse impact of AL and the heightened risk of cancer mortality among AA women.

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BACKGROUND: Allostatic load (AL) is associated with a heightened predisposition to disease due to prolonged activation of biological stress-response systems. Alcohol use disorder (AUD) is known to activate these systems. The primary aim of the current study was to examine the relationship between AL and AUD. METHODS: Participants were males (100%) with DSM-IV Alcohol Dependence (n = 48) and healthy participants with no history of substance use disorder (n = 17). Participants with AUD were 4-6 weeks abstinent. The AL index used cortisol, interleukin-6 (IL-6), fibrinogen, tumor necrosis factor-alpha (TNFα), C-reactive protein (CRP), glucose, insulin, leptin, pulse, systolic blood pressure readings, diastolic blood pressure readings, and body mass index (BMI). Physiological dysregulation for each biological measure was determined based on values within the 25th or 75th percentiles; AL was calculated as the total number of physiologically dysregulated biological measures. RESULTS: No differences in mean AL scores between the cases and controls [t(63) = .48, p = .633] were observed. Among cases, AL was not associated with lifetime drinks per drinking day (F(2,42) = .42, p = .662), lifetime total drinks (F(2,42) = 0.48, p = .620), total drinks 6 months prior to participating in the study (F(2,43) = 0.58, p = .563), or drinks per drinking day at 3-month follow-up (F(2,35) = 1.93, p = .161). AL was negatively associated with drinks per drinking day 6 months prior to study participation (F(2,42) = 3.71, p = .033). CONCLUSIONS: The hypotheses were not supported. Given that alcohol is likely to lead to physiological dysregulation, the apparent absence of a relationship between biomarkers of cumulative stress as indicated by AL and drinking status was both unanticipated and remarkable. Based on the results, AL in the context of drinking status or drinking among males with AUD may not be applicable.

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In 2021, there were close to 37 million children displaced worldwide. There were 13.7 million refugees and an additional 22.8 million internally displaced. In Europe, this included 23,255 unaccompanied minors seeking asylum, up 72% compared with 2020 (13,550). The objective was to review the current literature regarding PTSD in unaccompanied refugee minors (URM). The authors searched Ovid Medline, Embase, and Cochrane Library from 1 January 2008 through 15 January 2019. Thirty full texts were chosen that specifically studied unaccompanied refugee minors (URM). The results showed that URM had a prevalence of post-traumatic stress disorder (PTSD of 17-85% across the studies reviewed. There were numerous factors that contributed to PTSD, including cumulative stress and trauma, guilt, shame, and uncertainty about legal status. Protective factors included resilience, a trusted mentor, belonging to a social network, religion, having an adult mentor, and having a family (even if far away). Immigrant youth can thrive most easily in multiculturally affirming countries. Five interventions demonstrated effectiveness, comprising trauma-focused cognitive behavioral therapy (TF-CBT); "Mein Weg", a TF-CBT combined with a group-processing mixed therapy approach; teaching recovery techniques (TRT), narrative exposure therapy for children (KIDNET), and expressive arts intervention (EXIT). The significant mental health conditions include depression, anxiety, internalizing and externalizing behaviors, and frequently PTSD. It is fair to conclude that the high levels of mental health problems experienced in URM are due to exposure to traumatic experiences, separation from parents, and lack of social support.

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The demand for soybeans in Europe motivates breeders, researchers, and growers to find suitable cultivars to adapt and extend the soybean crop to improper climate areas. Weed control is a crucial aspect of crop technology in organic agriculture, but particularly for soybean crops. In laboratory conditions, the cumulative stress index for seedlings was determined to identify the susceptible cultivars. A field experiment with 14 soybean accessions and 2 sowing dates was conducted under organic farming conditions over the course of three years, from 2020 to 2022. Plant population density was found to be significantly (p < 0.01 and p < 0.1) negatively correlated to the degree of resistance to low temperature as well as infestation degree with weeds (for p < 0.05 and p < 0.1), with the exception of early sowing in 2021. Yield was significantly (p < 0.05, p < 0.01, p < 0.1) correlated with plant population density, with the exception of optimal sowing in 2022. Early sowing variants emerged with vigor in the first two years, breeding lines and registered varieties showed low input, and organic agriculture systems showed low yields in the drought years of 2020 and 2022. Although early sowing even in the first two years proved to be a practice that increased the cultivars' performance, in 2022, due to the long period of chilling stress in the field, this option had negative effects on yield due to the high weed frequency. Therefore, the early sowing strategy for the soybean crop in this particular case of non-irrigated conditions in a temperate continental area proved to be a risky practice.

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Sexual minorities (SM) have higher chronic physiologic stress as indicated by allostatic load (AL), which may be explained in part by consistent experiences of discriminatory practices. This is one of the first studies to examine the joint effects of SM status and AL on the association with long-term risk for cancer death. Retrospective analyses were conducted on 12,470 participants using National Health and Nutrition Examination Survey (NHANES) from years 2001 through 2010 linked with the National Death Index through December 31, 2019. Cox proportional hazards models estimated adjusted hazard ratios (aHRs) of cancer deaths between groups of SM (those reporting as gay, lesbian, bisexual, or having same-sex sexual partners) status and AL. SM adults living with high AL (n = 326) had a 2-fold increased risk of cancer death (aHR: 2.55, 95% CI: 1.40-4.65) when compared to straight/heterosexual adults living with low AL (n = 6674). Among those living with high AL, SM (n = 326) had a 2-fold increased risk of cancer death (aHR: 2.26, 95% CI: 1.33-3.84) when compared to straight/heterosexual adults with high AL (n = 4957). SM with high AL have an increased risk of cancer mortality. These findings highlight important implications for promoting a focused agenda on cancer prevention with strategies that reduce chronic stress for SM adults.

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Rapidly changing conditions alter disturbance patterns, highlighting the need to better understand how the transition from pulse disturbances to more persistent stress will impact ecosystem dynamics. We conducted a global analysis of the impacts of 11 types of disturbances on reef integrity using the rate of change of coral cover as a measure of damage. Then, we evaluated how the magnitude of the damage due to thermal stress, cyclones, and diseases varied among tropical Atlantic and Indo-Pacific reefs and whether the cumulative impact of thermal stress and cyclones was able to modulate the responses of reefs to future events. We found that reef damage largely depends on the condition of a reef before a disturbance, disturbance intensity, and biogeographic region, regardless of the type of disturbance. Changes in coral cover after thermal stress events were largely influenced by the cumulative stress of past disturbances and did not depend on disturbance intensity or initial coral cover, which suggests that an ecological memory is present within coral communities. In contrast, the effect of cyclones (and likely other physical impacts) was primarily modulated by the initial reef condition and did not appear to be influenced by previous impacts. Our findings also underscore that coral reefs can recover if stressful conditions decrease, yet the lack of action to reduce anthropogenic impacts and greenhouse gas emissions continues to trigger reef degradation. We uphold that evidence-based strategies can guide managers to make better decisions to prepare for future disturbances.

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Stress has a detrimental impact on memory, the hippocampus, and psychological health. Psychopathology research on stress has centered mainly on psychiatric diagnoses rather than symptom dimensions, and less attention has been given to the neurobiological factors through which stress might be translated into psychopathology. The present work investigates the transdiagnostic relationship of cumulative stress with episodic memory and the hippocampus (both structure and function) and explores the extent to which stress mediates the relationship between personality psychopathology and hippocampal size and activation. Cumulative lifetime stress was assessed in a sample of females recruited to vary in stress exposure and severity of personality psychopathology. Fifty-six participants completed subjective and objective tests of episodic memory, a T2-weighted high-resolution magnetic resonance imaging (MRI) scan of the medial-temporal lobe, and functional MRI (fMRI) scanning during a learning and recognition memory task. Higher cumulative stress was significantly related to memory complaints (but not episodic memory performance), lower bilateral hippocampal volume, and greater encoding-related hippocampal activation during the presentation of novel stimuli. Furthermore, cumulative stress significantly mediated the relationship between personality psychopathology and both hippocampal volume and activation, whereas alternative mediation models were not supported. The findings suggest that structural and functional activation differences in the hippocampus observed in case-control studies of psychiatric diagnoses may share cumulative stress as a common factor, which may mediate broadly reported relationships between psychopathology and hippocampal structure and function.

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BACKGROUND: The effect of multiple stressors on immigrant young adults' endocrine functioning and health outcomes has not been comprehensively investigated. AIMS: This study tested a theoretical model of cumulative and current stressor effects on the hypothalamic-pituitary-adrenocortical (HPA) axis functioning and health-related quality of life (HRQL) among Arab American young adults. METHODS: Using a cross-sectional design, we recruited 160 participants, ages 18 to 24 years, from an urban university in the Midwest. Cumulative stress was assessed by self-report measures of childhood adversity, bullying victimization, and perceived ethnic discrimination. Current perceived stress was measured using the Perceived Stress Scale (PSS) while cortisol levels were measured in participants' hair. Structural equation modeling tested the effects of cumulative and current stress on cortisol and HRQL. RESULTS: Cumulative stress was negatively associated with HRQL (standardized path coefficient = -.51, p < .05). Interestingly, however, cumulative stress was inversely associated with hair cortisol level (standardized path coefficient = -.51, p < .05). Current stress was positively associated with cortisol level (standardized path coefficient = .43, p < .05) and negatively associated with the mental HRQL (standardized path coefficient < -.37, p < .05). CONCLUSION: Cumulative stress exhibited a different effect on HPA functioning from current perceived stress. Mental health was significantly impaired by both cumulative and current perceived stress. Implications for mental health nursing practice and research among Arab Americans are discussed.

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Background: Several studies suggest that chronic stress may be associated with increased risk of cancer mortality. Our study sought to determine the association between allostatic load (AL), a measure of cumulative stress, and risk of cancer death; and whether these associations varied by race/ethnicity. Methods: We performed retrospective analysis using National Health and Nutrition Examination Survey (NHANES) years 1988 through 2010 linked with the National Death Index through December 31, 2019. We fit Fine & Gray Cox proportional hazards models to estimate sub-distribution hazard ratios (SHRs) of cancer death between high and low AL status (models adjusted for age, sociodemographics, and comorbidities). Results: In fully adjusted models, high AL was associated with a 14% increased risk of cancer death (adjusted (SHR): 1.14, 95% CI: 1.04-1.26) among all participants and a 18% increased risk of cancer death (SHR:1.18, 95% CI: 1.03-1.34) among Non-Hispanic White (NH-White) adults. When further stratified by age (participants aged <40 years), high AL was associated with a 80% increased risk (SHR: 1.80, 95% CI: 1.35-2.41) among all participants; a 95% increased risk (SHR: 1.95, 95% CI: 1.22-3.12) among NH-White adults; a 2-fold (SHR: 2.06, 95% CI: 1.27-3.34) increased risk among Non-Hispanic Black (NH-Black) adults; and a 36% increased risk among Hispanic adults (SHR: 1.36, 95% CI: 0.70-2.62). Conclusions: Overall, the risk of cancer death was associated with high AL; however, when stratified among NH-Black and Hispanic adults this association was slightly attenuated. Impact: High AL is associated with increased risk of overall cancer death, and future studies should delineate the association between AL and cancer-specific mortality to better understand the causal mechanisms between cumulative stress and cancer.

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BACKGROUND: Little is known about women veterans' intimate partner violence (IPV) experiences during the COVID-19 pandemic or the impacts of pandemic-related stress on their mental and physical health. OBJECTIVES: To identify IPV experiences among women veterans prior to and during the pandemic, pandemic-related stressors, and examine their respective contributions to mental and physical health. DESIGN: National sample of women veterans drawn from a larger web-based longitudinal study. Relationships between recent IPV and pandemic-related stressors were tested with linear regressions, controlling for pre-pandemic IPV and mental and physical health symptoms, demographic, and military-related covariates. PARTICIPANTS: One hundred forty-two women veterans (Mage=58.8 years). MAIN MEASURES: We assessed IPV (CTS-2), PTSD (PCL-5), depression (CESD), anxiety (DASS-A), physical health (PHQ-15), and physical health-related quality of life (SF-12) prior to the pandemic (June 2016-December 2016/January 2017) and during the pandemic study period (March 2020-December 2020/January 2021). We assessed pandemic-related stressors (EPII) during the pandemic study period. KEY RESULTS: Over a third (38.7%) of participants experienced IPV during the pandemic study period (psychological: 35.9%, physical: 9.9%, sexual: 4.2%). Overall rates, frequency, and severity of IPV experience did not significantly differ between the pre-pandemic and pandemic study periods. Few participants tested positive for COVID-19 (4.2%); however, most participants reported experiencing pandemic-related stressors across life domains (e.g., social activities: 88%, physical health: 80.3%, emotional health: 68.3%). IPV during the pandemic and pandemic-related stressors were both associated with greater PTSD and depressive symptoms. Pandemic-related stressors were associated with worse anxiety and physical health symptoms. Neither IPV during the pandemic nor pandemic-related stressors were associated with physical health-related quality of life. CONCLUSIONS: IPV experiences during the pandemic were common among women veterans, as were pandemic-related stressors. Although IPV did not increase in the context of COVID-19, IPV experiences during the pandemic and pandemic-related stressors were linked with poorer mental and physical health.

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BACKGROUND: The role of psychosocial stressors in psychiatric disorders and executive dysfunction has been reported, separately. The literature has also suggested the involvement of social support and coping strategies in these relationships. However, there is a lack of research conducted to examine the relationships among multiple stressors and neuropsychiatric comorbidities while considering the presence of social support and coping strategies. This study aims to articulate the roles of multiple psychosocial stressors, social support, and coping strategies in the subsequent occurrence of neuropsychiatric comorbidities. METHODS: Data analyzed were from the 6th data collection of a large-scale, longitudinal population-based cohort from Southwest Montreal in Canada. The cumulative effects of multiple stressors were separately examined by a composite score and latent profile analysis. Multinomial logistic regression models were used to test the relationship between cumulative stressors and neuropsychiatric comorbidities. RESULTS: A total of 210 participants were included in the analyses. The LPA identified a 2-class model for psychosocial stressors (low and high) and executive function (executive dysfunction and no executive dysfunction), respectively. There were 11.8% of participants with neuropsychiatric comorbidities. Both the composite stress score (RR = 1.08, 95%CI = 1.01-1.15) and latent stress groups (RR = 3.65, 95%CI = 1.15-11.57) were associated with neuropsychiatric comorbidities after adjusting for social support and coping strategies. The risk of developing neuropsychiatric comorbidities decreased when the level of social support was high (P < 0.05). CONCLUSIONS: Exposures to multiple stressors increased the risk of subsequent neuropsychiatric comorbidities, but the risk can be modified by a higher level of social support.

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BACKGROUND: Research suggests that non-Hispanic Black (henceforth, Black) women and people with lower educational attainment have higher levels of allostatic load (AL). This study sought to determine the association between educational attainment and AL among a large sample of Black women. METHODS: We analyzed data among 4177 Black women from the National Health and Nutrition Examination Survey years 1999-2018. AL score was defined as the total for abnormal measures of eight biomarkers. We further categorized participants with AL score greater than or equal to 4 as having high AL. We calculated mean estimates of total allostatic load scores using generalized linear models. We performed modified Poisson Regression models with robust variance estimation to estimate prevalence ratios (PRs) of high allostatic load and their associated 95% confidence intervals (CIs) by educational attainment. RESULTS: Black women with a college degree or higher had the lowest prevalence of high allostatic load (31.8% vs. 42.7%, 36.3%, 36.6%), and age adjusted mean allostatic load scores (mean = 1.90 vs. mean = 2.34, mean = 1.99, mean = 2.05) when compared to Black women with less than a high school diploma, high school diploma or GED, and some college or associates degree respectively. Even after accounting for age, poverty-to-income ratio, smoking, congestive heart failure, and heart attack, Black college graduates had an 14.3% lower prevalence of high allostatic load (PR = 0.857, 95% CI 0.839-0.876) when compared to Black women with lower educational attainment. CONCLUSIONS: Black women with a baccalaureate degree or higher educational attainment had lower allostatic load compared to Black women with less than a high school education. This finding further confirms higher education is a social determinant of health. Future research should explore differences in AL by more granular degree types.

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Despite great concern for drought-driven forest mortality, the effects of frequent low-intensity droughts have been largely overlooked in the boreal forest because of their negligible impacts over the short term. In this study, we used data from 6876 permanent plots distributed across most of the Canadian boreal zone to assess the effects of repeated low-intensity droughts on forest mortality. Specifically, we compared the relative impact of sequential years under low-intensity dry conditions with the effects of variables related to the intensity of dry conditions, stand characteristics, and local climate. Then, we searched for thresholds in forest mortality as a function of the number of years between two forest surveys affected by dry conditions of any intensity. Our results showed that, in general, frequent low-intensity dry conditions had stronger effects on forest mortality than the intensity of the driest conditions in the plot. Frequent low-intensity dry conditions acted as an inciting factor of forest mortality exacerbated by stand characteristics and environmental conditions. Overall, the mortality of forests dominated by shade-tolerant conifers was significantly and positively related to frequent low-intensity dry conditions, supporting, in some cases, the existence of thresholds delimiting contrasting responses to drought. In mixtures with broadleaf species, however, sequential dry conditions had a negligible impact. The effects of frequent dry conditions on shade-intolerant forests mainly depended on local climate, inciting or mitigating the mortality of forests located in wet places and dominated by broadleaf species or jack pine, respectively. Our results highlight the importance of assessing not only climate-driven extreme events but also repeated disturbances of low intensity. In the long term, the smooth response of forests to dry conditions might abruptly change leading to disproportional mortality triggered by accumulated stress conditions. Forest and wildlife managers should consider the cumulative effects of climate change on mortality to avoid shortfalls in timber and habitat.

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Antarctica and the Southern Ocean are the most remote regions on Earth, and their quite pristine environmental conditions are increasingly threatened by local scientific, tourism and fishing activities and long-range transport of persistent anthropogenic contaminants from lower latitudes. Plastic debris has become one of the most pervasive and ubiquitous synthetic wastes in the global environment, and even at some coastal Antarctic sites it is the most common and enduring evidence of past and recent human activities. Despite the growing scientific interest in the occurrence of microplastics (MPs) in the Antarctic environment, the lack of standardized methodologies for the collection, analysis and assessment of sample contamination in the field and in the lab does not allow us to establish their bioavailability and potential impact. Overall, most of the Southern Ocean appears to be little-affected by plastic contamination, with the exception of some coastal marine ecosystems impacted by wastewater from scientific stations and tourist vessels or by local fishing activities. Microplastics have been detected in sediments, benthic organisms, Antarctic krill and fish, but there is no clear evidence of their transfer to seabirds and marine mammals. Therefore, we suggest directing future research towards standardization of methodologies, focusing attention on nanoplastics (which probably represent the greatest biological risks) and considering the interactions of MPs with macro- and microalgae (especially sea-ice algae) and the formation of epiplastic communities. In coastal ecosystems directly impacted by human activities, the combined exposure to paint chips, metals, persistent organic pollutants (POPs), contaminants of emerging interest (CEI) and pathogenic microorganisms represents a potential danger for marine organisms. Moreover, the Southern Ocean is very sensitive to water acidification and has shown a remarkable decrease in sea-ice formation in recent years. These climate-related stresses could reduce the resilience of Antarctic marine organisms, increasing the impact of anthropogenic contaminants and pathogenic microorganisms.