Purpose: This article draws from cumulative disadvantage and life course theories to develop a new theory for the social scientific study of aging. Design and Methods: Five axioms of cumulative ...inequality (CI) theory are articulated to identify how life course trajectories are influenced by early and accumulated inequalities but can be modified by available resources, perceived trajectories, and human agency. Results: Although the concept of CI has attracted considerable attention among social scientists, it holds promise for integrating additional disciplinary approaches to the study of aging including, but not limited to, biology, epidemiology, and immunology. The applicability of CI theory to gerontology is illustrated in research on the early origins of adult health. Implications: Primary contributions of the theory to gerontology include greater attention to family lineage as a source of inequality; genes, gestation, and childhood as critical to early and enduring inequalities; the onset, duration, and magnitude of exposures to risk and opportunity; and constraints on generalizations arising from cohort-centric studies.
Globular star clusters are compact and massive stellar systems old enough to have witnessed the entire history of our Galaxy, the Milky Way. Although recent results suggest that their formation may ...have been more complex than previously thought, they still are the best approximation to a stellar population formed over a relatively short timescale (less than 1 Gyr) and with virtually no dispersion in the iron content. Indeed, only one cluster-like system ( Centauri) in the Galactic halo is known to have multiple stellar populations with a significant spread in iron abundance and age. Similar findings in the Galactic bulge have been hampered by the obscuration arising from thick and varying layers of interstellar dust. Here we report that Terzan 5, a globular-cluster-like system in the Galactic bulge, has two stellar populations with different iron contents and ages. Terzan 5 could be the surviving remnant of one of the primordial building blocks that are thought to merge and form galaxy bulges.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Context.
The production of neutrinos by plasma oscillations is the most important energy sink process operating in the degenerate core of low-mass red giant stars. This process counterbalances the ...release of energy induced by nuclear reactions and gravitational contraction, and determines the luminosity attained by a star at the moment of the He ignition. This occurrence coincides with the tip of the red giant branch (RGB), whose luminosity is extensively used as a calibrated standard candle in several cosmological studies.
Aims.
We aim to investigate the possible activation of additional energy sink mechanisms, as predicted by many extensions of the so-called Standard Model. In particular, our objective is to test the possible production of axions or axion-like particles, mainly through their coupling with electrons.
Methods.
By combining
Hubble
Space Telescope and ground-based optical and near-infrared photometric samples, we derived the RGB tip absolute magnitude of 22 galactic globular clusters (GGCs). The effects of varying the distance and the metallicity scales were also investigated. Then we compared the observed tip luminosities with those predicted by state-of-the-art stellar models that include the energy loss due to the axion production in the degenerate core of red giant stars.
Results.
We find that theoretical predictions including only the energy loss by plasma neutrinos are, in general, in good agreement with the observed tip bolometric magnitudes, even though the latter are ∼0.04 mag brighter on average. This small shift may be the result of systematic errors affecting the evaluation of the RGB tip bolometric magnitudes, or, alternatively, it could be ascribed to an axion-electron coupling causing a non-negligible thermal production of axions. In order to estimate the strength of this possible axion sink, we performed a cumulative likelihood analysis using the RGB tips of the whole set of 22 GGCs. All the possible sources of uncertainties affecting both the measured bolometric magnitudes and the corresponding theoretical predictions were carefully considered. As a result, we find that the value of the axion-electron coupling parameter that maximizes the likelihood probability is
g
ae
/10
−13
∼ 0.60
−0.58
+0.32
. This hint is valid, however, if the dominant energy sinks operating in the core of red giant stars are standard neutrinos and axions coupled with electrons. Any additional energy-loss process, not included in the stellar models, would reduce such a hint. Nevertheless, we find that values
g
ae
/10
−13
> 1.48 can be excluded with 95% confidence.
Conclusions.
The new bound we find represents the most stringent constraint for the axion-electron coupling available so far. The new scenario that emerges after this work represents a greater challenge for future experimental axion searches. In particular, we can exclude that the recent signal seen by the XENON1T experiment was due to solar axions.
Fear of missing out (FoMO) describes the concern of missing out on a rewarding experience. Though research demonstrates anxiety and depression severity are related to FoMO, there are gaps in the ...literature regarding mediating factors between these variables which may explain why not everyone is equally inclined to experience FoMO. Specifically, boredom proneness and anxiety attachment may provide further understanding of how FoMO intensity is not uniform for individuals of similar anxiety and depression severity. The aims of this study were to test if boredom proneness mediates the relations of both anxiety and depression severity with FoMO. An additional aim was to examine if anxiety attachment mediates the relationship between boredom proneness and FoMO. To this end, we recruited 450 adults from across the United States who completed multiple survey measures. By use of Structural Equation Modeling (SEM) we tested multiple theoretical models. Results indicated anxiety attachment influences how boredom proneness predicts FoMO. Additionally, boredom proneness appears to regulate the activation of anxiety attachment by mediating anxiety and depression severity. Boredom proneness also mediated the relations of anxiety and depression severity with FoMO. As not everyone is equally inclined to FoMO, the current research contributes to the empirical literature by highlighting individual differences which further explain the apprehensions that one is missing out. We discuss the multi-dimensional nature of FoMO and the theoretical basis for our results. Limitations and suggestions for future research is outlined.
•Boredom proneness mediated the relationship of FoMO with anxiety and depression.•Boredom proneness predicted FoMO.•Anxiety Attachment mediated the relationship of boredom proneness and FoMO.•Boredom proneness mediated the relations of both anxiety and depression severity with anxiety attachment.
Globular star clusters that formed at the same cosmic time may have evolved rather differently from the dynamical point of view (because that evolution depends on the internal environment) through a ...variety of processes that tend progressively to segregate stars more massive than the average towards the cluster centre. Therefore clusters with the same chronological age may have reached quite different stages of their dynamical history (that is, they may have different 'dynamical ages'). Blue straggler stars have masses greater than those at the turn-off point on the main sequence and therefore must be the result of either a collision or a mass-transfer event. Because they are among the most massive and luminous objects in old clusters, they can be used as test particles with which to probe dynamical evolution. Here we report that globular clusters can be grouped into a few distinct families on the basis of the radial distribution of blue stragglers. This grouping corresponds well to an effective ranking of the dynamical stage reached by stellar systems, thereby permitting a direct measure of the cluster dynamical age purely from observed properties.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Discrimination is pernicious in many ways, but there are inconsistent findings regarding whether it is harmful to cognitive function in later life. To address the inconsistency, we use two closely ...related concepts of everyday discrimination to predict cognitive trajectories in a diverse sample. Using data from the Health and Retirement Study (HRS), we examine whether the frequency of discrimination, measured at baseline with six questions, is related to poorer cognitive function and change in function over time (2008-2016). Age at baseline ranged from 53 to 100. Growth curve models of initial cognitive function and change in function were estimated. Everyday global discrimination was associated with poorer initial cognition and slower declines over time, and these relationships were not moderated by race and ethnicity. By contrast, the relationship between everyday racial discrimination and cognition was moderated by race: more frequent everyday racial discrimination was associated with better initial cognitive function among Black adults but not among Hispanic and White adults. Discrimination is a multifaceted concept, and specific types of discrimination manifest lower or higher cognitive function during later life for White, Black, and Hispanic adults.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
We present a detailed analysis of the kinematic properties of the multiple populations (MPs) in the low-mass Galactic globular cluster (GC) NGC 6362 based on a sample of about 500 member ...stars for which radial velocities (RVs), and Fe and Na abundances have been homogeneously derived. At distances from the cluster center larger than about 0.5
r
h
, we find that first-generation (FG–Na-poor) and second-generation (SG–Na-rich) stars show hints of different line-of-sight velocity dispersion profiles, with FG stars being dynamically hotter. This is the first time that differences in the velocity dispersion of MPs are detected using only RVs. While kinematic differences between MPs in GCs are usually described in terms of anisotropy differences driven by the different radial distributions, this explanation hardly seems viable for NGC 6362, where SG and FG stars are spatially mixed. We demonstrate that the observed difference in the velocity dispersion profiles can be accounted for by the effect of binary stars. In fact, thanks to our multi-epoch RV measurements, we find that the binary fraction is significantly larger in the FG sample (
f
∼ 14%) than in the SG population (
f
< 1%), and we show that such a difference can inflate the velocity dispersion of FG with respect to SG by the observed amount in the relevant radial range. Our results nicely match the predictions of state-of-the art
N
-body simulations of the co-evolution of MPs in GCs that include the effects of binaries.
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