Age Gradient Research Articles

COVID-19 Age-Mortality Curves for 2020 are Flatter in Developing Countries Using Both Official Death Counts and Excess Deaths

Background: Previous studies have found a pattern of flatter COVID-19 age-mortality curves among low- and middle-income countries using only official COVID-19 death counts. This study examines this question by comparing the age gradient of COVID-19 mortality in a broad set of countries using both official COVID-19 death counts and excess mortality estimates for 2020.Methods: The analysis uses official COVID-19 death counts for 64 countries and excess death estimates for 41 countries. A standardized population analysis was conducted to assess the extent to which variation across countries in the age distribution of COVID-19 deaths was driven by variation in the population age distribution.Findings: A higher share of pandemic-related deaths in 2020 were at younger ages in middle-income countries compared to high-income countries. People under age 65 constituted on average (1) 11 percent of both official deaths and excess deaths in high-income countries, (2) 40 percent of official deaths and 37 percent of excess deaths in upper-middle-income countries, and (3) 54 percent of official deaths in lower-middle-income countries. These contrasting profiles are due only in part to differences in population age structure.Interpretation: These findings are driven by some combination of variation in age patterns of infection rates and infection fatality rates. They indicate that COVID-19 is not just a danger to older people in developing countries, where a large share of victims are people of working age, who are caregivers and breadwinners for their families.Funding Information: None.Declaration of Interests: The authors declare no competing interests.Ethics Approval Statement: Ethics approval was not sought as the study presents results of an analysis of secondary data and does not involve human participants.

On the flaring of thick discs of galaxies: insights from simulations

ABSTRACT Using simulated galaxies in their cosmological context, we analyse how the flaring of mono-age populations (MAPs) influences the flaring and the age structure of geometrically defined thick discs. We also explore under which circumstances the geometric thin and thick discs are meaningfully distinct components, or are part of a single continuous structure as in the Milky Way. We find that flat thick discs are created when MAPs barely flare or have low surface density at the radius where they start flaring. When looking at the vertical distribution of MAPs, these galaxies show a continuous thin/thick structure. They also have radial age gradients and tend to have quiescent merger histories. Those characteristics are consistent with what is observed in the Milky Way. Flared thick discs, on the other hand, are created when the MAPs that flare have a high surface density at the radius where they start flaring. The thick discs’ scale heights can either be dominated by multiple MAPs or just a few, depending on the mass and scale height distribution of the MAPs. In a large fraction of these galaxies, thin and thick discs are clearly distinct structures. Finally, flared thick discs have diverse radial age gradients and merger histories, with galaxies that are more massive or that have undergone massive mergers showing flatter age radial gradients in their thick disc.

Left Atrial Mechanical Function Predicts Postoperative AF in Patients with Rheumatic Mitral Valve Disease Who Underwent Mitral Valve Surgery.

Postoperative atrial fibrillation (PoAF) is a common complication after surgical mitral valve replacement. Late PoAF is independently associated with long-term mortality. This study aimed to test the utility of preoperative left atrial mechanical function as a predictor of early and late PoAF in clinical practice. Patients (N = 150) with a rheumatic mitral valve who underwent mitral valve replacement with or without tricuspid valvuloplasty and who were in stable sinus rhythm were included. Baseline characteristics and transthoracic echocardiographic assessment information on the day before surgery were collected. Em, Em´, and Ei´ indicate early diastolic peak velocity of the mitral valve, early diastolic velocity at the lateral wall of the mitral annulus, and early diastolic velocity at the interventricular septal annulus, respectively. Early PoAF was present in 59 of 150 patients (39.3%), and 32 of 150 patients (21.3%) developed late PoAF within 1 year after surgery. Among all of the variables examined, age, diabetes, early mitral filling velocity (Mitral E), left atrial mechanical function (Mitral A), Em/Em´, Em/Ei´, and mitral transvalvular gradient showed a significant correlation with PoAF. Only age, Mitral A, and mitral transvalvular gradient showed strong, significant correlations with the occurrence of late PoAF. In a multivariate analysis, predictors of late PoAF recurrence included early PoAF and Mitral A. Routine evaluation of Mitral A is feasible and useful to predict early and late PoAF in patients with a rheumatic mitral valve undergoing surgical mitral valve replacement.

Dissecting the stellar content of Leo I: a dwarf irregular caught in transition

ABSTRACT Leo I is considered one of the youngest dwarf spheroidals (dSph) in the Local Group. Its isolation, extended star formation history (SFH), and recent perigalacticon passage (∼1 Gyr ago) make Leo I one of the most interesting nearby stellar systems. Here, we analyse deep photometric Hubble Space Telescope data via colour–magnitude diagram fitting techniques to study its global and radially resolved SFH. We find global star formation enhancements in Leo I ∼13, 5.5, 2.0, and 1.0 Gyr ago, after which it was substantially quenched. Within the context of previous works focused on Leo I, we interpret the most ancient and the youngest ones as being linked to an early formation (surviving reionization) and the latest perigalacticon passage (transition from dIrr to dSph), respectively. We clearly identify the presence of very metal poor stars ([Fe/H] ∼ −2) ageing ∼5–6 and ∼13 Gyr old. We speculate with the possibility that this metal-poor population in Leo I is related to the merging with a low-mass system (possibly an ultra-faint dwarf). This event would have triggered star formation (peak of star formation ∼5.5 Gyr ago) and accumulated old, metal-poor stars from the accreted system in Leo I. Some of the stars born during this event would also form from accreted gas of low-metallicity (giving rise to the 5–6 Gyr low-metallicity tail). Given the intensity and extension of the 2.0 Gyr burst, we hypothesize that this enhancement could also have an external origin. Despite the quenching of star formation around 1 Gyr ago (most probably induced by ram pressure stripping with the Milky Way halo at pericentre), we report the existence of stars as young as 300–500 Myr. We also distinguish two clear spatial regions: the inner ∼190 pc presents a homogeneous stellar content (size of the gaseous star forming disc in Leo I from ∼4.5 to 1 Gyr ago), whereas the outer regions display a clear positive age gradient.

Age and Socioeconomic Gradients in Frailty Among Older Adults in India

Although individuals with frailty and lower socioeconomic status (SES) are vulnerable to morbidity and early mortality, few studies have investigated this association. We intend to fill this gap with a study using older adults aged ≥ 50 years from the SAGE WAVE II in India. The Aim of study is to examine the association of frailty with SES and how this association varies across different age groups. A modified Fried phenotype approach with five frailty indicators was used to categorize 6560 older adults as frail, pre-frail or robust who had more than two, one or zero indicators, respectively: grip strength, exhaustion, weight loss, walking speed and physical activity. Multinomial logistic regression estimated the likelihood of being pre-frail and frail for various levels of SES, controlling and not controlling for confounders. This study also shows the overall socioeconomic gradients and age patterns of socioeconomic gradients of frailty indicators using predicted probabilities. Approximately 26%, 55% and 20% participants were robust, pre-frail and frail, respectively. The number of frailty indicators was positively associated with lower income and education levels in the case of controlling and not controlling for confounders. Also, among the higher age groups, individuals with low SES had higher chances of being frail.Overall, the results in this research indicated a negative low SES and frailty association as found in previous studies worldwide. This highlights the need for comprehensive and centered public health interventions for older adults with low SES.

Allostatic Load Among U.S.- and Foreign-Born Whites, Blacks, and Latinx

The objective of this study is to examine how allostatic load, a multidimensional measure of the body's cumulative response to stressors experienced throughout the life course, has changed over time and by age among U.S.- and foreign-born Whites, Blacks, and Latinx. Data were from 26,818 adult participants in the 2005-2018 National Health and Nutrition Examination Survey, a national repeated cross-sectional study. Allostatic load was measured based on 10 indicators of cardiovascular, metabolic, and immunologic risk. The analyses were conducted in March 2020. Allostatic load increased over time across all groups. The difference between the first and last survey cycle was greatest among U.S.-born Black women (from 2.74 in 2005-2006 to 3.02 in 2017-2018), U.S.-born Latino men (from 2.69 to 3.09) and foreign-born Latino men (from 2.58 to 2.87). Aging gradients in allostatic load were steepest among foreign-born Blacks of both genders and foreign-born Latina women and flattest among U.S.-born and foreign-born Whites. Chronic exposure to stressors leads to an erosion of health that is particularly severe among foreign-born Blacks and Latinx. Policies should seek to reduce exposure to structural and environmental risks and to ensure equitable opportunities to achieve optimal health among racial/ethnic minorities and immigrants.

Effects of landscape composition and site land-use intensity on secondary succession in a tropical dry forest

Regenerating forests after agricultural land abandonment are increasingly common in human-modified tropical landscapes. These secondary forests preserve biodiversity and provide multiple ecosystem services, but such important roles depend on their recovery rates, which can be difficult to predict. Recovery is expected to occur faster when landscape composition favors seed dispersal to the regenerating site, and when previous land-use does not significantly reduce propagule bank or future plant growth. Here, we test such expectations for the recovery of a Mexican tropical dry forest during secondary succession. For this purpose, we measured several indicators of landscape composition and site land-use intensity in 30 regenerating sites located along gradients of age of abandonment and amount of surrounding forest. Generalized linear models and redundancy analysis were fitted to test if values of four vegetation properties (aboveground biomass, total and dominant species diversity, and species composition) were indicative of such effects. We found evidence that, as expected, species richness recovers faster in sites surrounded by higher forest cover, while aboveground biomass recovers slower as surrounding pasture cover increases. Species composition was also significantly but poorly explained by the interaction between age of abandonment and the amount of forest cover. Contrary to our expectations, we found weak evidence on the impact of site land-use intensity on all vegetation properties, except on the number of dominant species, which showed higher values in sites with higher land-use intensity. Our findings show that landscape context plays a major role in structuring successional plant communities in this tropical dry region, even stronger than site land-use intensity. This seems to be related to the influence of landscape patterns on dispersal and recruitment limitation, but also on the likelihood of further human disturbances. Therefore, conserving landscape quality is paramount to enhance forest recovery and its contribution to the preservation of biodiversity and ecosystem services.

Demographic variations and temporal trends in prenatal use of multiple micronutrient supplements in Beijing, 2013-2017.

To provide updated information about demographic variations and temporal trends in the prenatal use of multiple micronutrient (MMN) supplements in the metropolitan areas of China. Descriptive analysis of routine prenatal healthcare data between 2013 and 2017. Chaoyang District, Beijing, China. A total of 197 346 pregnant women who attended their first prenatal care visit and provided information about MMN supplementation during the periconceptional period. Of these pregnant women, 60·6 % reported consuming prenatal MMN supplements. In multivariate-adjusted models, there were significant gradients of age, education and parity in prenatal MMN supplementation, with the highest likelihood of MMN use among the oldest, the most highly educated and nulliparous women (Pfor trend < 0·001). Compared with that among unemployed women, prenatal MMN supplementation was more common among the employed, especially those engaged in business (adjusted relative risks (95 % CI): 1·08 (1·06, 1·10)) and management (1·10 (1·08, 1·12)). The proportion of prenatal MMN supplementation was 57·0 % in 2013, which increased to 63·5 % in 2017 (Pfor trend < 0·001). The trends varied by age, education and parity (Pfor heterogeneity < 0·001), whereas no significant difference was observed in trends across subgroups of ethnicity or occupation. The greatest magnitude increase in MMN supplement use occurred in women of age < 25 years (annual percent change: 5·7 %), less than high school education (9·6 %), parity ≥ 2 (6·8 %) or unemployment (6·1 %). Approximately two-thirds of women consumed prenatal MMN supplements during the periconceptional period in the central area of Beijing and the proportion increased over time, indicating a need to evaluate the effectiveness and safety and to develop a guideline for relatively well-nourished women.

Petrochronology of Wadi Tayin Metamorphic Sole Metasediment, With Implications for the Thermal and Tectonic Evolution of the Samail Ophiolite (Oman/UAE)

AbstractOphiolite metamorphic soles preserve important records of ophiolite emplacement, but there have been few detailed investigations into their non‐mafic portions. We present new thermobarometric and petrochronologic data from a metasediment and mafic restite in the upper Wadi Tayin sole exposure in the Samail (Oman‐UAE) Ophiolite. Thermodynamic modeling suggests metasedimentary garnet nucleation at ~4 kb, ~550°C and final growth at 7.5 ± 1.2 kbar, 665 ± 32°C, occurring by 93.0 ± 0.5 Ma (Lu‐Hf isochron). Zircon U‐Pb dates of 106.9 ± 2.3 (detrital) and 98.7 ± 1.7 to 94.1 ± 1.6 Ma (metamorphic) bracket the initiation of metamorphism, and monazite U‐Pb dates from ~97–89 Ma suggest a lengthy period of growth or recrystallization. A mafic titanite U‐Pb age of 92.2 ± 1.8 Ma records the earliest possible juxtaposition of high‐ and lower‐grade sole rocks. These and other data suggest that (i) the Wadi Tayin sole preserves an inverted metamorphic, metasomatic, and age gradient,(ii) metasediment metamorphism occurred during, or soon after, crystallization of the overlying ophiolite (≤96.5 Ma); and (iii) sole metasediments define a thermal gradient continuous with hotter, higher‐P amphibolites. Some of these data conflict with existing models for sole formation, and we propose several hypotheses to explain them. Cooling of the sole below Ar closure by ~92 Ma suggests that strain rapidly partitioned away from the sole, leading to large‐scale, thin‐skinned thrust emplacement of the ophiolite &gt;100 km across the continental margin and the late, cool underthrusting of the continental margin.

SDSS-IV MaNGA: Global and local stellar population properties of elliptical galaxies

Context.We study the spatially resolved properties of 343 elliptical galaxies with the Mapping Nearby Galaxies at the Apache Point Observatory (MaNGA) survey.Aims.Our goal is to understand the fundamental processes of formation and quenching of elliptical galaxies.Methods.We used the DESI Legacy Imaging Surveys for accurate morphological classification. Based on integrated spectroscopic properties and colors, we classified seven classes of elliptical galaxies. We inferred the stellar age and metallicity gradients out to a 1.5 effective radius (Reff) of classical “red and dead”, recently quenched, and blue star-forming ellipticals (CLEs, RQEs, and BSFs), corresponding to 73%, 10%, and 4% of the sample, respectively. Additionally, we reconstructed their global and radial histories of star formation and mass growth.Results.The mass- and luminosity-weighted age gradients of CLEs are nearly flat or mildly negative, with small differences between both ages. The respective metallicity gradients are negative (∇log[Zmw] = −0.11−0.08+0.07dex/Reffand ∇log[Zlw] = −0.11−0.07+0.06dex/Reff, respectively), being flatter as the mass is smaller. The more massive CLEs formed stars earlier and quenched faster than the less massive ones. The CLEs show a weak inside-out growth and a clear inside-out quenching. They finished their quenching globally 3.8 ± 1.2 Gyr ago on average, with quenching time-scales of 3.4 ± 0.8 Gyr. AtM⋆&lt; 1011 M⊙, the age andZgradients of the RQEs and BSFs are flatter than those of the CLEs, but with larger scatters. They show very weak inside-out growth and quenching, which is slow and not even completed atz ∼ 0 for the BSFs. Instead, the massive RQEs show an outside-in quenching and positive gradients in the luminosity-weighted age and stellar metallicities. The RQEs of all masses quenched 1.2 ± 0.9 Gyr ago on average.Conclusions.Our results for the CLEs are consistent with a two-phase scenario where their inner parts formed by an early and coeval dissipative collapse with a consequent burst of star formation and further quenching, whereas the outer parts continued their assembly, likely by dry mergers. We also discuss some evolutionary scenarios for the RQE and BSF galaxies that would agree with the generic results.

SQuIGG E Survey: Massive z ∼ 0.6 Post-starburst Galaxies Exhibit Flat Age Gradients

Abstract We present Gemini Multi-Object Spectrograph (GMOS) integral field unit (IFU) observations of six massive (M ⋆ ≥ 1011 M ⊙) A-star dominated post-starburst galaxies at z ∼ 0.6. These galaxies are a subsample of the Survey, which selects intermediate-redshift post-starbursts from the Sloan Digital Sky Survey spectroscopic sample (DR14) with spectral shapes that indicate they have recently shut off their primary epoch of star formation. Using Hδ A absorption as a proxy for stellar age, we constrain five of the galaxies to have young (∼600 Myr) light-weighted ages at all radii and find that the sample on average has flat age gradients. We examine the spatial distribution of mass-weighted properties by fitting our profiles with a toy model including a young, centrally concentrated burst superimposed on an older, extended population. We find that galaxies with flat Hδ A profiles are inconsistent with formation via a central secondary starburst. This implies that the mechanism responsible for shutting off this dominant episode of star formation must have done so uniformly throughout the galaxy.

The Effect of a Pine Looper Moth Outbreak on the Radial Growth Rate of Pine

This study compares the 1945–2015 time series of the radial growth rate of pine Pinus sylvestris L. damaged by the 1974–1978 outbreak of the pine looper moth Bupalus piniarius L. and those of the undisturbed Krasnoturansk pine forest. It is proposed to employ regulatory characteristics of time series, including the order of autoregression (lag value n) and standard deviation of the amplitude of time series oscillation s (number of the first differences of radial growth s), to estimate differences between radial growth rates of trees in damaged and intact stands. These indicators allow for a quantitative assessment of the lag of the processes regulating the radial growth rate. Only the first differences of the series of radial growth rate are assessed, inasmuch as the regulatory characteristics can be correctly calculated only for the stationery time series. Trees exposed to insect outbreak either have no lag in the dynamics of the first differences of the series in the radial growth rate or they have high values of autoregression order n. At the same time, the oscillations of the current radial growth rate of damaged trees in relation to the age gradient are significantly larger than in undisturbed trees. We estimate the speed of the growth-rate recovery in damaged trees as a function of regulatory characteristics of time series of the radial growth rate before the damage. These data could be used to assess the pest hazard in the stands and recovery rates of forests damaged by insect outbreaks.

Age Differences in Material Deprivation in Finland: How do Consensus and Prevalence-Based Weighting Approaches Change the Picture?

While material deprivation is often used to measure poverty, analyses focusing on the measurement of material deprivation are scarce. This study provides new information on material deprivation by analyzing how differences in the considerations of necessities and possession of deprivation items among all respondents and within population subgroups affect group-level differences in material deprivation in Finland. In line with many previous studies on material deprivation, this study focused on age groups. There is a significant age gradient regarding considerations of necessities, possession, and deprivation of many deprivation items. On average, younger adults experience material deprivation more often than older adults do. This study considers the differences in the considerations of necessities and possession of deprivation items using different weighting approaches. The study found that these differences are not largely transmitted to deprivation indices. Two causes of this finding were found: (1) individuals, on average, are not deprived of items in which there are differences between age groups regarding consensus and prevalence and (2) in those items in which deprivation is high, the consensus and the prevalence rates are often lower compared to other items. The results provide new information on which factors are important when using weighting approaches to measure material deprivation.

Variations in Soil Erosion Resistance of Gully Head Along a 25-Year Revegetation Age on the Loess Plateau

The effects of vegetation restoration on soil erosion resistance of gully head, along a revegetation age gradient, remain poorly understood. Hence, we collected undisturbed soil samples from a slope farmland and four grasslands with different revegetation ages (3, 10, 18, 25 years) along gully heads. Then, these samples were used to obtain soil detachment rate of gully heads by the hydraulic flume experiment under five unit width flow discharges (2–6 m3 h). The results revealed that soil properties were significantly ameliorated and root density obviously increased in response to restoration age. Compared with farmland, soil detachment rate of revegetated gully heads decreased 35.5% to 66.5%, and the sensitivity of soil erosion of the gully heads to concentrated flow decreased with revegetation age. The soil detachment rate of gully heads was significantly related to the soil bulk density, soil disintegration rate, capillary porosity, saturated soil hydraulic conductivity, organic matter content and water stable aggregate. The roots of 0–0.5 and 0.5–1.0 mm had the highest benefit in reducing soil loss of gully head. After revegetation, soil erodibility of gully heads decreased 31.0% to 78.6%, and critical shear stress was improved by 1.2 to 4.0 times. The soil erodibility and critical shear stress would reach a stable state after an 18-years revegetation age. These results allow us to better evaluate soil vulnerability of gully heads to concentrated flow erosion and the efficiency of revegetation.

Disability Incidence Rates for Men and Women in 23 Countries: Evidence on Health Effects of Gender Inequality.

BackgroundInequality in gender varies across social contexts, which may influence the health of both men and women. Based on theories of gender as a social system, we examine whether systematic gender inequality at the macro-level influences health of men and women.MethodUsing harmonized panel data from the Gateway to Global Aging Data in 23 high- and middle-income countries (N = 168 873), we estimate disability prevalence and incidence for men and women ages 55–89 (2000–2016). Within each country or geographic region, we also investigate gender differences in age gradients of the probability of disability onset. We, then, pool data from all countries and test the hypothesis that gender inequality increases the probability of disability onset.ResultsWe found substantial cross-country variation in disability incidence rates, and this variation is greater for women than for men. Among ages 65–69, disability incidence rates ranged from 0.4 to 5.0 for men and from 0.5 to 9.4 for women. Our within-country analysis showed significant gender differences in age gradients of the probability of disability onset in the United States, Korea, Southern Europe, Mexico, and China, but not in Northern, Central, and Eastern Europe, England, and Israel. Testing hypothesized effects of gender inequality, we find that gender inequality is significantly associated with the probability of disability onset for women, but not for men.ConclusionsMacro-level societal gender inequality is significantly associated with the probability of disability onset for women. Reducing and eliminating gender inequality is crucial to achieving good health for women.

Study of Star Clusters in the M83 Galaxy with a Convolutional Neural Network

Abstract We present a study of evolutionary and structural parameters of star cluster candidates in the spiral galaxy M83. For this we use a convolutional neural network trained on mock clusters and capable of fast identification and localization of star clusters, as well as inference of their parameters from multiband images. We use this pipeline to detect 3380 cluster candidates in Hubble Space Telescope observations. The sample of cluster candidates shows an age gradient across the galaxy’s spiral arms, which is in good agreement with predictions of the density wave theory and other studies. As measured from the dust lanes of the spiral arms, the younger population of cluster candidates peaks at the distance of ∼0.4 kpc while the older candidates are more dispersed, but shifted toward ≳0.7 kpc in the leading part of the spiral arms. We find high-extinction cluster candidates positioned in the trailing part of the spiral arms, close to the dust lanes. We also find a large number of dense older clusters near the center of the galaxy and a slight increase of the typical cluster size further from the center.

Subduction accretion, thermal overprinting, and exhumation of high-pressure/low-temperature metasedimentary rocks of the south-central brooks range

ABSTRACT Lithological, petrological and structural observations and measurements of graphite thermometry, Si-in-phengite barometry, and 40Ar/39Ar phengite thermochronology were performed along two transects across the south-central Brooks Range of northern Alaska. The integrated data set reveals a history of accretion, protracted thermal overprinting of high-pressure/low-temperature (HP/LT) metamorphic assemblages, and subsequent exhumation. Tectonic domains characterized by upper greenschist facies metamorphic rocks display a dominant E-W axial planar cleavage/foliation fabric that overprints bedding and earlier metamorphic foliations. Raman maturation thermometry and Si-in-phengite barometry document a southward increase from greenschist facies conditions (ca. 360–400°C; 3–7 kbar) in the Doonerak window and Endicott Mountains allochthon to epidote-blueschist facies conditions (~515°C and 10–13 kbar) within the Schist Belt. Within the Central and Schist belts albite porphyroblasts overgrow the earlier deformation fabric and quartz microstructures exhibit evidence for diffusive recovery. This indicates thermal overprinting of deeper portions of the accretionary complex caused protracted (ca. 25 m.y.) greenschist facies overprinting of HP/LT assemblages within the Ar partial retention zone. The Schist Belt – Central Belt boundary is defined by a singular, penetrative foliation that displays a weak shear-band fabric. 40Ar/39Ar results along this boundary indicate that the fabric records deformation along the lower boundary of a nappe that began to move up the subduction channel as subduction ceased by ~135-130 Ma. Subsequent deformation along the Schist Belt – Phyllite Belt boundary reflects the exhumation of HP/LT rocks along a south-dipping normal-sense shear zone. Phengite 40Ar/39Ar age gradients coupled with the first arrival of coarse-grained Brooks Ranges detritus within the adjacent Yukon Koyukuk Basin indicate that tectonic denudation along this shear zone partly exhumed the Schist and Phyllite belts to mid-crustal depths by 110–105 Ma. Final exhumation of the HP/LT rocks was delayed until the Cenozoic which resulted in < 15 km of additional denudation.

Healthy, Wealthy, Wise, and Happy? Assessing Age Differences in Evaluative and Emotional Well-Being Among Mature Adults from Five Low- and Middle-Income Countries

This study assesses the relationship between age and two dimensions of subjective well-being—evaluative and emotional—among mature adults from five low-and middle-income countries. We use data from the World Health Organization’s Study on Global AGEing and Adult Health to contrast the associations of age with subjective well-being when controlling only for gender with the corresponding partial associations when including a richer set of covariates. Adjusting only for gender, we find negative associations of age with evaluative well-being, while the corresponding age gradients for emotional well-being are relatively flat. By contrast, adjusting for further socio-demographic factors results in positive associations of age with both evaluative and emotional well-being. Oaxaca-Blinder decompositions allow us to explore the roles of two factors to account for any unadjusted age differences in subjective well-being: age-group differences in individual characteristics and life circumstances, and age-specific associations of individual characteristics and life circumstances with subjective well-being. While adverse circumstances such as poor health and low income contribute to lower levels of evaluative well-being among older adults, age per se is—ceteris paribus—positively associated with subjective well-being. Even in poorer countries, older age does not need to be a time of low subjective well-being. Policies aimed at preserving income and limiting or compensating old-age disability appear to be key for maintaining subjective well-being among older adults.

Micro-scale investigation of aging gradient within bitumen film around air-binder interface

The aging issue of bitumen is one of the most concerned topics for the bituminous pavement duration. Currently, the laboratory accelerates the aging by applying high temperature and pressure. However, an extremely thin state of bitumen in a real asphalt mixture could induce the interference of aging that happened at two interfaces, namely the air-bitumen interface and the bitumen-aggregate interface. Hence, it is of great importance to explore more deeply about what is happening on the air-bitumen interface. This study performed experimental research on the aging gradient of bitumen during the TFOT test, together with the molecular simulation. To that end, Thin Film Oven Tests (TFOTs) on bitumen with different aging durations (0, 1, 5, 10, 20 h) were conducted and further, the microscopic aging gradient along with the aging depths (11 layers in total) was investigated. The Dynamic Shear Rheometer (DSR) and Fourier Transform Infrared Spectroscopy (FTIR) tests were performed to characterize the aged bitumen samples. From the molecular perspective, this study adopted the molecular dynamic simulation of oxygen and bitumen. The results indicated that the aging of bitumen induced the increase of complex modulus and the generation of chemical functional groups. Experimental data demonstrated the microscopic aging gradient, and the effective depth of thermal oxidation could be within 1000 μm due to the limited oxygen diffusion. The results of molecular dynamics simulation showed consistent conclusions with the experimental results. This research revealed the complicated aging mechanism from the molecular scale and provided further research with fundamental findings.

Does Chronic Stress Moderate Age Differences in Emotional Well-Being? Testing Predictions of Strength and Vulnerability Integration.

The Strength and Vulnerability Integration (SAVI) theory posits boundary conditions, such as chronic stress, which place constraints on positive emotional aging. We examine SAVI's prediction that higher levels of chronic stress will attenuate favorable age gradients for multiple indices of well-being. We used cross-sectional data from a diverse systematic probability sample of adults (n = 260, ages 25-65). Multiple regression analysis was used to examine age gradients and test age × chronic stress interactions on 5 measures of well-being relevant for SAVI's prediction: positive and negative affect, life satisfaction, emotional distress, and rumination. Age was unrelated to well-being unless individual differences in health limitations were statistically controlled, in which case older age was associated with more favorable levels of well-being. Chronic stress significantly interacted with age for negative affect, emotional distress, rumination, and life satisfaction; examination of the interactions indicated that age was no longer associated with more favorable levels of well-being at higher levels of chronic stress. Our findings support a key prediction of SAVI by demonstrating that high levels of chronic stress present a boundary condition for favorable age gradients on well-being. We discuss the implications of these findings for understanding the "paradox" of well-being.