•The temporal dynamic of the effects of stress on decision making was tested.•Five or 18min of stress exposure caused less risky decision making.•In contrast, 28min after stress onset, decision ...making was more risky.•Moderate increases of catecholamines may be beneficial for decisions under risk.•Increasing cortisol concentrations may lead to riskier decision making.
Stress has been shown to impair decision making. However the temporal development of this phenomenon remains poorly understood. We speculated that the rapid stress induced increase in norepinephrine and the delayed increase in cortisol might exert opposing effects on decision making under risk. Therefore, three different experimental groups underwent the Trier Social Stress Test (TSST) and performed the Game of Dice Task (GDT) at different time points in relation to the stressor, which lasted approximately 18min. The first group performed the GDT 5min after stress onset, the second and third group performed the GDT either 18 or 28min after TSST onset. Decision-making performance of the control group was measured after a respective resting time. Results confirmed a rapid activation of the sympathetic nervous system and a somewhat slower response of the hypothalamic pituitary adrenal axis. In the GDT an improvement of decision-making performance in the 5 and 18min stress groups compared to controls and the 28min stress group occurred. Descriptively, decision making of the 28min after stress group was more risky than decision making of the control group. Our findings are in line with the idea that a moderate increase in catecholamines enhances decision-making performance, while elevated cortisol concentrations may negatively affect decision making presumably via rapid nongenomic mechanisms.
TRAPPIST-1 is a fantastic nearby (∼39.14 light years) planetary system made of at least seven transiting terrestrial-size, terrestrial-mass planets all receiving a moderate amount of irradiation. To ...date, this is the most observationally favourable system of potentially habitable planets known to exist. Since the announcement of the discovery of the TRAPPIST-1 planetary system in 2016, a growing number of techniques and approaches have been used and proposed to characterize its true nature. Here we have compiled a state-of-the-art overview of all the observational and theoretical constraints that have been obtained so far using these techniques and approaches. The goal is to get a better understanding of whether or not TRAPPIST-1 planets can have atmospheres, and if so, what they are made of. For this, we surveyed the literature on TRAPPIST-1 about topics as broad as irradiation environment, planet formation and migration, orbital stability, effects of tides and Transit Timing Variations, transit observations, stellar contamination, density measurements, and numerical climate and escape models. Each of these topics adds a brick to our understanding of the likely—or on the contrary unlikely—atmospheres of the seven known planets of the system. We show that (i) Hubble Space Telescope transit observations, (ii) bulk density measurements comparison with H
2
-rich planets mass-radius relationships, (iii) atmospheric escape modelling, and (iv) gas accretion modelling altogether offer solid evidence against the presence of hydrogen-dominated—cloud-free and cloudy—atmospheres around TRAPPIST-1 planets. This means that the planets are likely to have either (i) a high molecular weight atmosphere or (ii) no atmosphere at all. There are several key challenges ahead to characterize the bulk composition(s) of the atmospheres (if present) of TRAPPIST-1 planets. The main one so far is characterizing and correcting for the effects of stellar contamination. Fortunately, a new wave of observations with the James Webb Space Telescope and near-infrared high-resolution ground-based spectrographs on existing very large and forthcoming extremely large telescopes will bring significant advances in the coming decade.
Stress promotes a shift from goal-directed action-outcome learning toward habitual stimulus-response learning. This shift is mediated by an interaction of noradrenergic activity and glucocorticoid ...stress hormones. In the present experiment, we examined the neural correlates of the stress (hormone)-induced shift from goal-directed to habit learning in the human brain. Healthy participants were administered hydrocortisone, the α2-adrenoceptor antagonist yohimbine, or both before they were trained in two instrumental actions leading to two distinct food rewards. After training, one of the rewards was devalued by feeding participants to satiety on that food. Finally, participants were presented the two instrumental actions in extinction. We collected functional magnetic resonance images both during instrumental training and during extinction testing. Our behavioral data confirmed that the simultaneous administration of hydrocortisone and yohimbine renders instrumental behavior insensitive to the outcome devaluation (and thus habitual), whereas hydrocortisone or yohimbine alone have no such effect. At the neural level, the combined administration of hydrocortisone and yohimbine reduced the sensitivity of the orbitofrontal and medial prefrontal cortex to changes in outcome value. Brain areas that have been previously implicated in habit learning were not modulated by hydrocortisone and yohimbine. These findings suggest that concurrent glucocorticoid and noradrenergic activity disrupts the neural bases of goal-directed action and thus renders behavior habitual.
Rare autosomal dominant tubulointerstitial kidney disease is caused by mutations in the genes encoding uromodulin (UMOD), hepatocyte nuclear factor-1β (HNF1B), renin (REN), and mucin-1 (MUC1). ...Multiple names have been proposed for these disorders, including ‘Medullary Cystic Kidney Disease (MCKD) type 2’, ‘Familial Juvenile Hyperuricemic Nephropathy (FJHN)’, or ‘Uromodulin-Associated Kidney Disease (UAKD)’ for UMOD-related diseases and ‘MCKD type 1’ for the disease caused by MUC1 mutations. The multiplicity of these terms, and the fact that cysts are not pathognomonic, creates confusion. Kidney Disease: Improving Global Outcomes (KDIGO) proposes adoption of a new terminology for this group of diseases using the term ‘Autosomal Dominant Tubulointerstitial Kidney Disease’ (ADTKD) appended by a gene-based subclassification, and suggests diagnostic criteria. Implementation of these recommendations is anticipated to facilitate recognition and characterization of these monogenic diseases. A better understanding of these rare disorders may be relevant for the tubulointerstitial fibrosis component in many forms of chronic kidney disease.
Conventional definitions of habitability require abundant liquid surface water to exist continuously over geologic timescales. Water in each of its thermodynamic phases interacts with solar and ...thermal radiation and is the cause for strong climatic feedbacks. Thus, assessments of the habitable zone require models to include a complete treatment of the hydrological cycle over geologic time. Here, we use the Community Atmosphere Model from the National Center for Atmospheric Research to study the evolution of climate for an Earth-like planet at constant CO2, under a wide range of stellar fluxes from F-, G-, and K-dwarf main sequence stars. Around each star we find four stable climate states defined by mutually exclusive global mean surface temperatures (Ts); snowball (Ts ≤ 235 K), waterbelt (235 K ≤ Ts ≤ 250 K), temperate (275 K ≤ Ts ≤ 315 K), and moist greenhouse (Ts ≥ 330 K). Each is separated by abrupt climatic transitions. Waterbelt, temperate, and cooler moist greenhouse climates can maintain open-ocean against both sea ice albedo and hydrogen escape processes respectively, and thus constitute habitable worlds. We consider the warmest possible habitable planet as having Ts ∼ 355 K, at which point diffusion limited water-loss could remove an Earth ocean in ∼1 Gyr. Without long timescale regulation of non-condensable greenhouse species at Earth-like temperatures and pressures, such as CO2, habitability can be maintained for an upper limit of ∼2.2, ∼2.4, and ∼4.7 Gyr around F-, G-, and K-dwarf stars respectively, due to main sequence brightening.
Glucocorticoids (GCs) are known to modulate memory in animals and humans. One popular model suggests that stress or GC treatment enhances memory consolidation while impairing delayed memory ...retrieval. Studies in humans have documented that treatment with GCs impairs delayed memory retrieval. Similar alterations after exposure to stress have not been observed thus far. In the present study, 19 young healthy male subjects were exposed to either a standardized psychosocial laboratory stressor (Trier Social Stress Test) or a control condition in a crossover manner. After both treatments, retrieval of a word list (learned 24 h earlier) containing 10 neutral, 10 negative, and 10 positive words was tested. The stressor induced a significant increase in salivary free cortisol and a decrease in mood. Memory retrieval (free recall) was significantly impaired after the stress condition. Follow-up analysis revealed that negative and positive words (i.e., emotionally arousing words) were affected, whereas no effect was observed for neutral words. No changes were detected for cued recall, working memory, or attention. The present study thus demonstrates that psychosocial stress impairs memory retrieval in humans and suggests that emotionally arousing material is especially sensitive to this effect.
Macrophages have been classified as having plastic phenotypes which exist along a spectrum between M1 (classically activated; pro-inflammatory) and M2 (alternatively activated; regulatory, ...homeostatic). To date, the effects of polarization towards an M1 or M2 phenotype have been studied largely in the context of response to pathogen or cancer. Recently, M1 and M2 macrophages have been shown to play distinct roles in tissue remodeling following injury. In the present study, the M1/M2 paradigm was utilized to examine the role of macrophages in the remodeling process following implantation of 14 biologically derived surgical mesh materials in the rat abdominal wall. In situ polarization of macrophages responding to the materials was examined and correlated to a quantitative measure of the observed tissue remodeling response to determine whether macrophage polarization is an accurate predictor of the ability of a biologic scaffold to promote constructive tissue remodeling. Additionally the ability of M1 and M2 macrophages to differentially recruit progenitor-like cells in vitro, which are commonly observed to participate in the remodeling of those ECM scaffolds which have a positive clinical outcome, was examined as a possible mechanism underlying the differences in the observed remodeling responses. The results of the present study show that there is a strong correlation between the early macrophage response to implanted materials and the outcome of tissue remodeling. Increased numbers of M2 macrophages and higher ratios of M2:M1 macrophages within the site of remodeling at 14days were associated with more positive remodeling outcomes (r2=0.525–0.686, p<0.05). Further, the results of the present study suggest that the constructive remodeling outcome may be due to the recruitment and survival of different cell populations to the sites of remodeling associated with materials that elicit an M1 vs. M2 response. Both M2 and M0 macrophage conditioned media were shown to have higher chemotactic activities than media conditioned by M1 macrophages (p<0.05). A more thorough understanding of these issues will logically influence the design of next generation biomaterials and the development of regenerative medicine strategies for the formation of functional host tissues.
Summary Instrumental action can be controlled by two anatomically and functionally distinct systems: a goal-directed system that learns action–outcome associations and a habit system that learns ...stimulus–response associations without any link to the incentive value of the outcome. Recent evidence indicates that stress before learning modulates these two systems in favor of habitual control. Here, we examined the impact of a stress exposure after learning on instrumental performance. Participants learned to choose two instrumental actions that were associated with the delivery of different food rewards. After learning, one of these food rewards was devalued as participants were saturated with that food. Before being re-exposed to the instrumental actions in extinction, participants were subjected to the socially evaluated cold pressor test or a control procedure. Controls but not stressed participants reduced responding to the action associated with the devalued outcome. That is, acute stress before extinction testing abolished sensitivity of performance to outcome devaluation. Cortisol responses to stress correlated significantly with habitual performance. These findings show that stress induced by the socially evaluated cold pressor test can make behavior habitual without affecting processes involved in learning.
Electrocyclic reactions are characterized by the concerted formation and cleavage of both σ and π bonds through a cyclic structure. This structure is known as a pericyclic transition state for ...thermal reactions and a pericyclic minimum in the excited state for photochemical reactions. However, the structure of the pericyclic geometry has yet to be observed experimentally. We use a combination of ultrafast electron diffraction and excited state wavepacket simulations to image structural dynamics through the pericyclic minimum of a photochemical electrocyclic ring-opening reaction in the molecule α-terpinene. The structural motion into the pericyclic minimum is dominated by rehybridization of two carbon atoms, which is required for the transformation from two to three conjugated π bonds. The σ bond dissociation largely happens after internal conversion from the pericyclic minimum to the electronic ground state. These findings may be transferrable to electrocyclic reactions in general.
Researchers have long noted that individuals occupy consistent spatial positions within animal groups. However, an individual's position depends not only on its own behaviour, but also on the ...behaviour of others. Theoretical models of collective motion suggest that global patterns of spatial assortment can arise from individual variation in local interaction rules. However, this prediction remains untested. Using high-resolution GPS tracking of members of a wild baboon troop, we identify consistent inter-individual differences in within-group spatial positioning. We then apply an algorithm that identifies what number of conspecific group members best predicts the future location of each individual (we call this the individual's neighbourhood size) while the troop is moving. We find clear variation in the most predictive neighbourhood size, and this variation relates to individuals' propensity to be found near the centre of their group. Using simulations, we show that having different neighbourhood sizes is a simple candidate mechanism capable of linking variation in local individual interaction rules—in this case how many conspecifics an individual interacts with—to global patterns of spatial organization, consistent with the patterns we observe in wild primates and a range of other organisms.
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