Non-linear clustering during the BEC dark matter phase transition

Spherical collapse of the Bose-Einstein Condensate (BEC) dark matter model is studied in the Thomas Fermi approximation. The evolution of the overdensity of the collapsed region and its expansion rate are calculated for two scenarios. We consider the case of a sharp phase transition (which happens when the critical temperature is reached) from the normal dark matter state to the condensate one and the case of a smooth first order phase transition where there is a continuous conversion of "normal" dark matter to the BEC phase. We present numerical results for the physics of the collapse for a wide range of the model's space parameter, i.e. the mass of the scalar particle $m_{\chi}$ and the scattering length $l_s$. We show the dependence of the transition redshift on $m_{\chi}$ and $l_s$. Since small scales collapse earlier and eventually before the BEC phase transition the evolution of collapsing halos in this limit is indeed the same in both the CDM and the BEC models. Differences are expected to appear only on the largest astrophysical scales. However, we argue that the BEC model is almost indistinguishable from the usual dark matter scenario concerning the evolution of nonlinear perturbations above typical clusters scales, i.e., $\gtrsim 10^{14}M_{\odot}$. This provides an analytical confirmation for recent results from cosmological numerical simulations [H.-Y. Schive {\it et al.}, Nature Physics, {\bf10}, 496 (2014)].Comment: 11 pages. Final version to appear in EPJ

Preparing the Expatriate Candidate for Global Success: A Best-Practice Analysis of Cross-Culture Adaptation Training

Increased demand for global citizenry has led scholars and educators alike to seek ways to improve intercultural communication competence (ICC). Research has focused on the theoretical underpinnings of ICC and how to implement these theoretical factors into a practical educational model. Yet, there remains a gap in the literature regarding the implementation of ICC education in the ever-increasingly popular online context. This quasi-experimental study provides a look at how online expatriate candidate training might influence ICC. Results indicate that online expatriate candidate training provides an effective model for organizational practitioners with limited time and resources

Matter power spectrum for the generalized Chaplygin gas model: The relativistic case

The generalized Chaplygin gas (GCG) model is the prototype of a unified model of dark energy (DE) and dark matter (DM). It is characterized by equation-of-state (EoS) parameters $A$ and $\alpha$. We use a statistical analysis of the 2dFGRS data to constrain these parameters. In particular, we find that very small (close to zero) and very large values ($\alpha\gg 1$) of the equation-of-state parameter $\alpha$ are preferred. To test the validity of this type of unification of the dark sector we admit the existence of a separate DM component in addition to the Chaplygin gas and calculate the probability distribution for the fractional contributions of both components to the total energy density. This analysis favors a model for which the Universe is nearly entirely made up of the separate DM component with an almost negligible Chaplygin gas part. This confirms the results of a previous Newtonian analysis.Comment: Latex file, 8 pages, 15 figures in eps forma