The Role of Savoring Positive Experiences When Faced with Challenge and Hindrance Demands: A Longitudinal Study

The goal of the present study was to examine the moderating effects of savoring and both challenge and hindrance job demands on the longitudinal relationship between job resources and engagement and burnout, mediated by personal resources, represented by psychological capital (PsyCap). Building upon previous research (Xanthopoulou et al., 2007; Xanthopoulou et al., 2009), Time 1 job resources were positively related to Time 2 engagement and negatively related to Time 2 burnout through Time 1 personal resources. In addition, Time 1 savoring was found to significantly interact with Time 1 job resources to predict Time 2 burnout, whereby savoring magnified the negative relationship between Time 1 job resources and Time 2 burnout. However, the moderating effects of challenge and hindrance demands were not found in the smaller matched sample. In the larger Time 1 sample, challenge demands enhanced the positive relationship between job resources and engagement, as well as enhanced the negative relationship between personal resources and burnout. Hindrance demands also significantly interacted with personal resources and job resources to predict engagement. Finally, in the larger Time 1 sample, savoring again amplified the negative relationship between job resources and burnout. These findings first demonstrate that the presence of challenge and hindrance job demands may significantly affect employees’ work engagement and symptoms of burnout given the availability of job resources. Furthermore, savoring positive experiences may be beneficial to employees’ mental health by diminishing symptoms of burnout when more job resources are available

The MHD Kelvin-Helmholtz Instability III: The Role of Sheared Magnetic Field in Planar Flows

We have carried out simulations of the nonlinear evolution of the magnetohydrodynamic (MHD) Kelvin-Helmholtz (KH) instability for compressible fluids in $2\frac{1}{2}$-dimensions, extending our previous work by Frank et al (1996) and Jones \etal (1997). In the present work we have simulated flows in the x-y plane in which a ``sheared'' magnetic field of uniform strength ``smoothly'' rotates across a thin velocity shear layer from the z direction to the x direction, aligned with the flow field. We focus on dynamical evolution of fluid features, kinetic energy dissipation, and mixing of the fluid between the two layers, considering their dependence on magnetic field strength for this geometry. The introduction of magnetic shear can allow a Cat's Eye-like vortex to form, even when the field is stronger than the nominal linear instability limit given above. For strong fields that vortex is asymmetric with respect to the preliminary shear layer, however, so the subsequent dissipation is enhanced over the uniform field cases of comparable field strength. In fact, so long as the magnetic field achieves some level of dynamical importance during an eddy turnover time, the asymmetries introduced through the magnetic shear will increase flow complexity, and, with that, dissipation and mixing. The degree of the fluid mixing between the two layers is strongly influenced by the magnetic field strength. Mixing of the fluid is most effective when the vortex is disrupted by magnetic tension during transient reconnection, through local chaotic behavior that follows.Comment: 14 pages including 9 figures (4 figures in degraded jpg format), full paper with original quality figures available via anonymous ftp at ftp://canopus.chungnam.ac.kr/ryu/mhdkh2d.uu, to appear in The Astrophysical Journa

Implicit and Explicit Attitudes Towards Mental Health Treatment

The present study assessed implicit and explicit attitudes toward mental health treatment, and whether the different attitude assessments were related to treatment-seeking. Undergraduate students (N=192) completed three Implicit Association Tests (IAT), which were computer-based reaction time tasks where participants responded to terms for mental health and medical treatments that were paired with the attributes good versus bad, effective versus ineffective, and honoring versus humiliating. Survey items assessed explicit ratings of mental health treatment and medical treatment on these attributes, as well as more general attitudes toward mental health treatment. The IAT results revealed a significant negative implicit bias toward mental health treatment as being less effective, good, and honoring than medical treatment. Explicit survey measures also showed more negative responses toward mental health treatment. Some correspondence was also obtained between the implicit biases reflected by the IAT and the explicit biases shown on the self-report survey. Finally, students who had sought mental health treatment had more positive explicit attitudes toward mental health treatment than those who had not sought treatment, but no differences were obtained on the implicit attitude measures. The current study helps to progress research working to reduce stigma towards mental health treatment and increase treatment-seeking behaviors

Turbulent Convection in Stellar Interiors. II. The Velocity Field

We analyze stellar convection with the aid of 3D hydrodynamic simulations, introducing the turbulent cascade into our theoretical analysis. We devise closures of the Reynolds-decomposed mean field equations by simple physical modeling of the simulations (we relate temperature and density fluctuations via coefficients); the procedure (CABS, Convection Algorithms Based on Simulations) is terrestrially testable and is amenable to systematic improvement. We develop a turbulent kinetic energy equation which contains both nonlocal and time dependent terms, and is appropriate if the convective transit time is shorter than the evolutionary time scale. The interpretation of mixing-length theory (MLT) as generally used in astrophysics is incorrect; MLT forces the mixing length to be an imposed constant. Direct tests show that the damping associated with the flow is that suggested by Kolmogorov. The eddy size is approximately the depth of the convection zone, and this dissipation length corresponds to the "mixing length". New terms involving local heating by turbulent dissipation should appear in the stellar evolution equations. The enthalpy flux ("convective luminosity") is directly connected to the buoyant acceleration, and hence the velocity scale. MLT tends to systematically underestimate this velocity scale. Quantitative comparison with a variety of 3D simulations reveals a previously recognized consistency. Examples of application to stellar evolution will be presented in subsequent papers in this series.Comment: 47 pages, 7 figures, accepted by Ap

Diffusion in supersonic, turbulent, compressible flows

We investigate diffusion in supersonic, turbulent, compressible flows. Supersonic turbulence can be characterized as network of interacting shocks. We consider flows with different rms Mach numbers and where energy necessary to maintain dynamical equilibrium is inserted at different spatial scales. We find that turbulent transport exhibits super-diffusive behavior due to induced bulk motions. In a comoving reference frame, however, diffusion behaves normal and can be described by mixing length theory extended into the supersonic regime.Comment: 11 pages, incl. 5 figures, accepted for publication in Physical Review E (a high-resolution version is available at http://www.aip.de./~ralf/Publications/p21.abstract.html

Theory and Applications of Non-Relativistic and Relativistic Turbulent Reconnection

Realistic astrophysical environments are turbulent due to the extremely high Reynolds numbers. Therefore, the theories of reconnection intended for describing astrophysical reconnection should not ignore the effects of turbulence on magnetic reconnection. Turbulence is known to change the nature of many physical processes dramatically and in this review we claim that magnetic reconnection is not an exception. We stress that not only astrophysical turbulence is ubiquitous, but also magnetic reconnection itself induces turbulence. Thus turbulence must be accounted for in any realistic astrophysical reconnection setup. We argue that due to the similarities of MHD turbulence in relativistic and non-relativistic cases the theory of magnetic reconnection developed for the non-relativistic case can be extended to the relativistic case and we provide numerical simulations that support this conjecture. We also provide quantitative comparisons of the theoretical predictions and results of numerical experiments, including the situations when turbulent reconnection is self-driven, i.e. the turbulence in the system is generated by the reconnection process itself. We show how turbulent reconnection entails the violation of magnetic flux freezing, the conclusion that has really far reaching consequences for many realistically turbulent astrophysical environments. In addition, we consider observational testing of turbulent reconnection as well as numerous implications of the theory. The former includes the Sun and solar wind reconnection, while the latter include the process of reconnection diffusion induced by turbulent reconnection, the acceleration of energetic particles, bursts of turbulent reconnection related to black hole sources as well as gamma ray bursts. Finally, we explain why turbulent reconnection cannot be explained by turbulent resistivity or derived through the mean field approach.Comment: 66 pages, 24 figures, a chapter of the book "Magnetic Reconnection - Concepts and Applications", editors W. Gonzalez, E. N. Parke

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

Performance and Operation of the CMS Electromagnetic Calorimeter

The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented

Physical Processes in Star Formation

© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00693-8.Star formation is a complex multi-scale phenomenon that is of significant importance for astrophysics in general. Stars and star formation are key pillars in observational astronomy from local star forming regions in the Milky Way up to high-redshift galaxies. From a theoretical perspective, star formation and feedback processes (radiation, winds, and supernovae) play a pivotal role in advancing our understanding of the physical processes at work, both individually and of their interactions. In this review we will give an overview of the main processes that are important for the understanding of star formation. We start with an observationally motivated view on star formation from a global perspective and outline the general paradigm of the life-cycle of molecular clouds, in which star formation is the key process to close the cycle. After that we focus on the thermal and chemical aspects in star forming regions, discuss turbulence and magnetic fields as well as gravitational forces. Finally, we review the most important stellar feedback mechanisms.Peer reviewedFinal Accepted Versio

Calibration of the CMS Drift Tube Chambers and Measurement of the Drift Velocity with Cosmic Rays

Peer reviewe