The effects of long-term stress exposure on aging cognition: a behavioral and EEG investigation

A large field of research seeks to explore and understand the factors that may cause different rates of age-related cognitive decline within the general population. However, the impact of experienced stress on the human aging process has remained an under-researched possibility. This study explored the association between cumulative stressful experiences and cognitive aging, addressing whether higher levels of experienced stress correlate with impaired performance on 2 working memory tasks. Behavioral performance was paired with electroencephalographic recordings to enable insight into the underlying neural processes impacted on by cumulative stress. Thus, the electroencephalogram was recorded while both young and elderly performed 2 different working memory tasks (a Sternberg and N-back paradigm), and cortical oscillatory activity in the theta, alpha, and gamma bandwidths was measured. Behavioral data indicated that a higher stress score among elderly participants related to impaired performance on both tasks. Electrophysiological findings revealed a reduction in alpha and gamma event-related synchronization among high-stress-group elderly participants, indicating that higher levels of experienced stress may impact on their ability to actively maintain a stimulus in working memory and inhibit extraneous information interfering with successful maintenance. Findings provide evidence that cumulative experienced stress adversely affects cognitive aging

Measures Matter: Scales for Adaptation, Cultural Distance, and Acculturation Orientation Revisited

Building upon existing measures, four new brief acculturation scales are presented, measuring sociocultural adaptation, psychological adaptation, perceived cultural distance, and acculturation orientation. Following good scale reliability in initial samples, the English scales were translated into nine different languages (Chinese, French, German, Italian, Japanese, Portuguese, Spanish, Thai, and Turkish). The translated scales were administered to a large sample of sojourners (N = 1,929), demonstrating good reliability and adequate structural equivalence across languages. In line with existing theory, sociocultural adaptation and psychological adaptation were positively correlated, and showed a negative association with perceived cultural distance. General measures of well-being were correlated with adaptation and distance, with better adaptation relating to higher well-being, and more distance relating to lower well-being. Acculturation orientation toward the home and host culture were measured separately and a weak negative correlation was found between the two, supporting their independence. Arguing against dichotomization, these subscales were analyzed as continuous variables. Regression analysis showed sojourners to be better adapted, if they were oriented more toward the host culture and less toward the home culture. These new scales are proposed as alternatives to existing measures

PPAR Agonist-Induced Reduction of Mcp1 in Atherosclerotic Plaques of Obese, Insulin-Resistant Mice Depends on Adiponectin-Induced Irak3 Expression

Synthetic peroxisome proliferator-activated receptor (PPAR) agonists are used to treat dyslipidemia and insulin resistance. In this study, we examined molecular mechanisms that explain differential effects of a PPARα agonist (fenofibrate) and a PPARγ agonist (rosiglitazone) on macrophages during obesity-induced atherogenesis. Twelve-week-old mice with combined leptin and LDL-receptor deficiency (DKO) were treated with fenofibrate, rosiglitazone or placebo for 12 weeks. Only rosiglitazone improved adipocyte function, restored insulin sensitivity, and inhibited atherosclerosis by decreasing lipid-loaded macrophages. In addition, it increased interleukin-1 receptor-associated kinase-3 (Irak3) and decreased monocyte chemoattractant protein-1 (Mcp1) expressions, indicative of a switch from M1 to M2 macrophages. The differences between fenofibrate and rosiglitazone were independent of Pparγ expression. In bone marrow-derived macrophages (BMDM), we identified the rosiglitazone-associated increase in adiponectin as cause of the increase in Irak3. Interestingly, the deletion of Irak3 in BMDM (IRAK3(-/-) BMDM) resulted in activation of the canonical NFκB signaling pathway and increased Mcp1 protein secretion. Rosiglitazone could not decrease the elevated Mcp1 secretion in IRAK3(-/-) BMDM directly and fenofibrate even increased the secretion, possibly due to increased mitochondrial reactive oxygen species production. Furthermore, aortic extracts of high-fat insulin-resistant LDL-receptor deficient mice, with lower adiponectin and Irak3 and higher Mcp1, showed accelerated atherosclerosis. In aggregate, our results emphasize an interaction between PPAR agonist-mediated increase in adiponectin and macrophage-associated Irak3 in the protection against atherosclerosis by PPAR agonists

OSIRIS-REx Precision Orbit Determination

No abstract availabl

OSIRIS-REx Orbit Determination Performance During the Navigation Campaign

The OSIRIS-REx mission Navigation Campaign consists of three sub-phases: Approach,Preliminary Survey, and Orbital A. Approach was designed for initial characterization ofBennu while matching Bennu's heliocentric velocity. Preliminary Survey provided the firstspacecraft-based estimate of Bennu's mass. This phase consisted of five target flybys witha close approach distance of about 7 km. Orbital A was a two-month phase devoted to theNavigation Team learning the close proximity operations dynamics and environment aroundBennu and transitioning from center-finding optical navigation to landmark feature-basednavigation. This paper provides a detailed summary of the orbit determination performancethroughout the Navigation Campaign

A tight spot: How personality moderates the impact of social norms on sojourner adaptation

When living abroad, how do you navigate the norms of your new culture? Taking an interactionalist perspective, we examine how contextual factors and personality traits jointly affect sojourner's adaptation. We hypothesized that tightness (strong, rigidly imposed norms) of the host culture would be associated with lower levels of adaptation, and that tightness of the home culture would be associated with higher levels of adaptation. Further, we proposed that the impact of tightness should be dependent on personality traits associated with navigating social norms (agreeableness, conscientiousness, and honesty-humility). Longitudinal data were analyzed from intercultural exchange students (N = 889) travelling from and to 23 different countries. Multilevel Modeling showed that sojourners living in a tighter culture had poorer adaptation than those in a looser culture. In contrast, sojourners originating from a tighter culture showed better adaptation. The negative effect of cultural tightness was moderated by agreeableness and honesty-humility, but not conscientiousness

Hemispherical differences in the shape and topography of asteroid (101955) Bennu

We investigate the shape of near-Earth asteroid (101955) Bennu by constructing a high-resolution (20 cm) global digital terrain model from laser altimeter data. By modeling the northern and southern hemispheres separately, we find that longitudinal ridges previously identified in the north extend into the south but are obscured there by surface material. In the south, more numerous large boulders effectively retain surface materials and imply a higher average strength at depth to support them. The north has fewer large boulders and more evidence of boulder dynamics (toppling and downslope movement) and surface flow. These factors result in Bennu’s southern hemisphere being rounder and smoother, whereas its northern hemisphere has higher slopes and a less regular shape. We infer an originally asymmetric distribution of large boulders followed by a partial disruption, leading to wedge formation in Bennu’s history

Interleukin-1 Receptor-Associated Kinase-3 Is a Key Inhibitor of Inflammation in Obesity and Metabolic Syndrome

BACKGROUND: Visceral obesity is associated with the rising incidence of type 2 diabetes and metabolic syndrome. Low-grade chronic inflammation and oxidative stress synergize in obesity and obesity-induced disorders. OBJECTIVE: We searched a cluster of molecules that support interactions between these stress conditions in monocytes. METHODS: RNA expressions in blood monocytes of two independent cohorts comprising 21 and 102 obese persons and 46 age-matched controls were determined by microarray and independently validated by quantitative RT-PCR analysis. The effect of three-month weight loss after bariatric surgery was determined. The effect of RNA silencing on inflammation and oxidative stress was studied in human monocytic THP-1 cells. RESULTS: Interleukin-1 receptor-associated kinase-3 (IRAK3), key inhibitor of IRAK/NFκB-mediated chronic inflammation, is downregulated in monocytes of obese persons. Low IRAK3 was associated with high superoxide dismutase-2 (SOD2), a marker of mitochondrial oxidative stress. A comparable expression profile was also detected in visceral adipose tissue of the same obese subjects. Low IRAK3 and high SOD2 was associated with a high prevalence of metabolic syndrome (odds ratio: 9.3; sensitivity: 91%; specificity: 77%). By comparison, the odds ratio of high-sensitivity C-reactive protein, a widely used marker of systemic inflammation, was 4.3 (sensitivity: 69%; specificity: 66%). Weight loss was associated with an increase in IRAK3 and a decrease in SOD2, in association with a lowering of systemic inflammation and a decreasing number of metabolic syndrome components. We identified the increase in reactive oxygen species in combination with obesity-associated low adiponectin and high glucose and interleukin-6 as cause of the decrease in IRAK3 in THP-1 cells in vitro. CONCLUSION: IRAK3 is a key inhibitor of inflammation in association with obesity and metabolic syndrome. Our data warrant further evaluation of IRAK3 as a diagnostic and prognostic marker, and as a target for intervention

Early Navigation Performance of the OSIRIS-REx Approach to Bennu

The New Frontiers-class OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) mission is the first American endeavor to return a sample from an asteroid. In preparation for retrieving the sample, OSIRIS-REx is conducting a campaign of challenging proximity-operations maneuvers and scientific observations, bringing the spacecraft closer and closer to the surface of near-Earth asteroid (101955) Bennu. Ultimately, the spacecraft will enter a 900-meter-radius orbit about Bennu and conduct a series of reconnaissance flybys of candidate sample sites before being guided into contact with the surface for the Touch and Go sample collection event. Between August and December 2018, the OSIRIS-REx team acquired the first optical observations of Bennu and used them for navigation. We conducted a series of maneuvers with the main engine, Trajectory Correction Maneuver, and Attitude Control System thruster sets to slow the OSIRIS-REx approach to Bennu and achieve rendezvous on December 3, 2018. This paper describes the trajectory design, navigation conops, and key navigation results from the Approach phase of the OSIRIS-REx mission

Experienced stress produces inhibitory deficits in old adults’ Flanker task performance: First evidence for lifetime stress effects beyond memory

Studies regarding aged individuals' performance on the Flanker task differ with respect to reporting impaired or intact executive control. Past work has explained this discrepancy by hypothesising that elderly individuals use increased top-down control mechanisms advantageous to Flanker performance. This study investigated this mechanism, focussing on cumulative experienced stress as a factor that may impact on its execution, thereby leading to impaired performance. Thirty elderly and thirty young participants completed a version of the Flanker task paired with electroencephalographic recordings of the alpha frequency, whose increased synchronisation indexes inhibitory processes. Among high stress elderly individuals, findings revealed a general slowing of reaction times for congruent and incongruent stimuli, which correlated with alpha desynchronisation for both stimulus categories. Results found high performing (low stress) elderly revealed neither a behavioural nor electrophysiological difference compared to young participants. Therefore, rather than impacting on top-down compensatory mechanisms, findings indicate that stress may affect elderly participants' inhibitory control in attentional and sensorimotor domains