Social Anxiety and Cannabis-Related Impairment: The Roles of Anxiety Sensitivity and Intolerance of Uncertainty

Cannabis use is associated with many negative consequences. Identification of factors associated with cannabis could inform prevention and treatment efforts. Social anxiety appears to be one risk factor for cannabis-related problems. Thus, it is important to identify malleable cognitive vulnerability factors that may play a role in the social anxiety-cannabis problems relationship. Anxiety sensitivity (AS) is the fear of anxiety-related bodily sensations and is composed of three subfacets: physical, cognitive, and social concerns. AS is associated with greater social anxiety and may play a role in cannabis-related impairment. Intolerance of uncertainty (IU) refers to a tendency to respond negatively to uncertain situations. IU is associated with social anxiety and may play a role in cannabis-related problems. The current study sought to examine the associations of AS subfacets and IU with cannabis problems as well as the direct and indirect (via AS subfacets and IU) effects of social anxiety on cannabis problems among 220 current (i.e., past three-month) cannabis users. Consistent with prior research, social anxiety was positively related to cannabis problems. All AS subfacets and IU were positively related to cannabis problems. Social anxiety was indirectly related to cannabis problems through AS-social concerns and IU but not through AS-physical concerns or AS cognitive concerns. When AS-social concerns and IU were tested simultaneously, social anxiety remained indirectly related to cannabis problems only through IU. Results highlight the importance of considering IU in treatment efforts for individuals experiencing cannabis-related impairment

A Randomized Controlled Trial of a Hatha Yoga Intervention for Smokers

Despite well-documented negative effects of smoking, many individuals continue to smoke. Anxiety and depression are associated with poorer cessation outcomes. Three transdiagnostic factors may explain the anxiety/depression-smoking link: anxiety sensitivity (AS), distress tolerance (DT), anhedonia (Anh; Leventhal & Zvolensky, 2015). It therefore follows that changing AS, DT, and Anh could aid cessation efforts. Thus, the current study tested the efficacy of hatha yoga for reducing craving, smoking, AS, and Anh and increasing DT, and whether anxiety/depression moderates these relationships. Participants were 55 community-recruited smokers (62% male, 71% non-Hispanic White, Mage = 28.16) motivated to reduce or quit smoking. We randomized participants to one session of hatha yoga (n = 25) or wellness control (n = 30) on their intervention day (when they planned to begin to reduce or quit smoking). We asked them to use the provided intervention materials daily for a week. Hatha yoga was associated with less post-intervention craving but not fewer follow-up cigarettes per day than control. Anxiety/depression did not moderate these relationships. Hatha yoga was associated with less follow-up AS than the control condition. We found a significant Condition x Anxiety/Depression interaction, such that among participants with high anxiety/depression, those in the hatha yoga condition reported less follow-up AS than those in the control condition. Hatha yoga did not impact DT or Anh. In sum, hatha yoga acutely reduces craving but does not impact smoking. Hatha yoga decreased AS, especially among individuals with higher anxiety/depression, a group at particular risk for poorer smoking cessation outcomes

Ages, distances, and the initial mass functions of stellar clusters

We provide a review of the current status of several topics on the ages, distances, and mass functions of open clusters, with a particular emphasis on illuminating the areas of uncertainty. Hipparcos has obtained parallaxes for nearby open clusters that have expected accuracies much better than has been previously achievable. By using the lithium depletion boundary method and isochrone fitting based on much improved new theoretical evolutionary models for low mass stars, it is arguable that we will soon have have much better age scales for clusters and star-forming regions. With improved optical and near-IR cameras, we are just now beginning to extend the mass function of open clusters like the Pleiades into the regime below the hydrogen burning mass limit. Meanwhile, observations in star-forming regions are in principle capable of identifying objects down to of order 10 Jupiter masses

Do open star clusters evolve toward energy equipartition?

We investigate whether open clusters (OCs) tend to energy equipartition, by means of direct N-body simulations with a broken power-law mass function. We find that the simulated OCs become strongly mass segregated, but the local velocity dispersion does not depend on the stellar mass for most of the mass range: the curve of the velocity dispersion as a function of mass is nearly flat even after several half-mass relaxation times, regardless of the adopted stellar evolution recipes and Galactic tidal field model. This result holds both if we start from virialized King models and if we use clumpy sub-virial initial conditions. The velocity dispersion of the most massive stars and stellar remnants tends to be higher than the velocity dispersion of the lighter stars. This trend is particularly evident in simulations without stellar evolution. We interpret this result as a consequence of the strong mass segregation, which leads to Spitzer's instability. Stellar winds delay the onset of the instability. Our simulations strongly support the result that OCs do not attain equipartition, for a wide range of initial conditions

X-ray Emission From Nearby M-dwarfs: the Super-saturation Phenomenon

A rotation rate and X-ray luminosity analysis is presented for rapidly rotating single and binary M-dwarf systems. X-ray luminosities for the majority of both single & binary M-dwarf systems with periods below $\simeq 5-6$ days (equatorial velocities, V$_{eq}>$ 6 km~s$^{-1}$) are consistent with the current rotation-activity paradigm, and appear to saturate at about $10^{-3}$ of the stellar bolometric luminosity. The single M-dwarf data show tentative evidence for the super-saturation phenomenon observed in some ultra-fast rotating ($>$ 100 km~s$^{-1}$) G & K-dwarfs in the IC 2391, IC 2602 and Alpha Persei clusters. The IC 2391 M star VXR60b is the least X-ray active and most rapidly rotating of the short period (P$_{rot}<$ 2 days) stars considered herein, with a period of 0.212 days and an X-ray activity level about 1.5 sigma below the mean X-ray emission level for most of the single M-dwarf sample. For this star, and possibly one other, we cautiously believe that we have identified the first evidence of super-saturation in M-dwarfs. If we are wrong, we demonstrate that only M-dwarfs rotating close to their break up velocities are likely to exhibit the super-saturation effect at X-ray wavelengths.Comment: 12 pages, 4 figures, accepted by MNRA

The Gaia-ESO Survey: Dynamical analysis of the L1688 region in Ophiuchus

The Gaia ESO Public Spectroscopic Survey (GES) is providing the astronomical community with high-precision measurements of many stellar parameters including radial velocities (RVs) of stars belonging to several young clusters and star-forming regions. One of the main goals of the young cluster observations is to study their dynamical evolution and provide insight into their future, revealing whether they will eventually disperse to populate the field rather than evolve into bound open clusters. In this paper we report the analysis of the dynamical state of L1688 in the ? Ophiuchi molecular cloud using the dataset provided by the GES consortium. We performed the membership selection of the more than 300 objects observed. Using the presence of the lithium absorption and the location in the Hertzspung-Russell diagram, we identify 45 already known members and two new association members. We provide accurate RVs for all 47 confirmed members. A dynamical analysis, after accounting for unresolved binaries and errors, shows that the stellar surface population of L1688 has a velocity dispersion s ~ 1.14 ± 0.35 km s-1 that is consistent with being in virial equilibrium and is bound with a ~80% probability. We also find a velocity gradient in the stellar surface population of ~1.0 km s-1 pc-1 in the northwest-southeast direction, which is consistent with that found for the pre-stellar dense cores, and we discuss the possibility of sequential and triggered star formation in L1688

The Gaia-ESO Survey: Galactic evolution of lithium at high metallicity

Context. Reconstructing the Galactic evolution of lithium (Li) is the main tool used to constrain the source(s) of Li enrichment in the Galaxy. Recent results have suggested a decline in Li at supersolar metallicities, which may indicate reduced production. Aims. We exploit the unique characteristics of the Gaia-ESO Survey open star cluster sample to further investigate this issue and to better constrain the evolution of Li at high metallicity. Methods. We trace the upper envelope of Li abundance versus metallicity evolution using 18 clusters and considering members that should not have suffered any Li depletion. Results. At variance with previous claims, we do not find any evidence of a Li decrease at high metallicity. The most metal-rich clusters in the sample ([Fe/H] = ~0.3) actually show the highest Li abundances, with A(Li) > 3.4. Our results clearly show that previous findings, which were based on field stars, were affected by selection effects. The metal-rich population in the solar neighbourhood is composed of relatively old and cool stars that have already undergone some Li depletion; hence, their measured Li does not represent the initial interstellar medium abundance, but a lower limit to it

The Gaia-ESO Survey: a kinematical and dynamical study of four young open clusters

ContextThe origin and dynamical evolution of star clusters is an important topic in stellar astrophysics. Several models have been proposed in order to understand the formation of bound and unbound clusters and their evolution, and they can be tested by examining the kinematical and dynamical properties of clusters over a wide range of ages and masses.AimsWe use the Gaia-ESO Survey products to study four open clusters (IC 2602, IC 2391, IC 4665, and NGC 2547) that lie in the age range between 20 and 50 Myr.MethodsWe employ the gravity index ? and the equivalent width of the lithium line at 6708 Å together with effective temperature Teff and the metallicity of the stars in order to discard observed contaminant stars. Then we derive the cluster radial velocity dispersions sc, the total cluster mass Mtot, and the half mass radius rhm. Using the Gaia-DR1 TGAS catalogue, we independently derive the intrinsic velocity dispersion of the clusters from the astrometric parameters of cluster members.ResultsThe intrinsic radial velocity dispersions derived by the spectroscopic data are higher than those derived from the TGAS data, possibly due to the different masses of the considered stars. Using Mtot and rhm we derive the virial velocity dispersion svir and we find that three out of four clusters are supervirial. This result is in agreement with the hypothesis that these clusters are dispersing, as predicted by the “residual gas expulsion” scenario. However, recent simulations show that the virial ratio of young star clustersmay be overestimated if it is determined using the global velocity dispersion, since the clusters are not fully relaxed