Rotating a Bose-Einstein condensate by shaking an anharmonic axisymmetric magnetic potential

We present an experimental method for rotating a Bose-Einstein condensate trapped in an axisymmetric magnetic potential. This method is based on the anharmonicity of the trapping potential, which couples the center-of-mass motion of the condensate to its internal motion. By circularly shaking the trapping potential, we generate a circular center-of-mass motion of the condensate around the trap center. The circulating condensate undergoes rotating shape deformation and eventually relaxes into a rotating condensate with a vortex lattice. We discuss the vortex nucleation mechanism and in particular, the role of the thermal cloud in the relaxation process. Finally, we investigate the dependence of the vortex nucleation on the elliptical polarization of the trap shaking. The response of the condensate is asymmetric with respect to the sign of the shaking polarization, demonstrating the gauge field effect due to the spin texture of the condensate in the magnetic potential.Comment: 8 pages, 9 figure

Testing Magnetic Field Models for the Class 0 Protostar L1527

For the Class 0 protostar, L1527, we compare 131 polarization vectors from SCUPOL/JCMT, SHARP/CSO and TADPOL/CARMA observations with the corresponding model polarization vectors of four ideal-MHD, non-turbulent, cloud core collapse models. These four models differ by their initial magnetic fields before collapse; two initially have aligned fields (strong and weak) and two initially have orthogonal fields (strong and weak) with respect to the rotation axis of the L1527 core. Only the initial weak orthogonal field model produces the observed circumstellar disk within L1527. This is a characteristic of nearly all ideal-MHD, non-turbulent, core collapse models. In this paper we test whether this weak orthogonal model also has the best agreement between its magnetic field structure and that inferred from the polarimetry observations of L1527. We found that this is not the case; based on the polarimetry observations the most favored model of the four is the weak aligned model. However, this model does not produce a circumstellar disk, so our result implies that a non-turbulent, ideal-MHD global collapse model probably does not represent the core collapse that has occurred in L1527. Our study also illustrates the importance of using polarization vectors covering a large area of a cloud core to determine the initial magnetic field orientation before collapse; the inner core magnetic field structure can be highly altered by a collapse and so measurements from this region alone can give unreliable estimates of the initial field configuration before collapse.Comment: 43 pages, 9 figures, 4 tables. Accepted by the Astrophysical Journa

The role of cool versus warm colors in B2B versus B2C firm-generated content for boosting positive eWOM

While the importance of electronic Word-of-Mouth (eWOM) for Business-to-Business (B2B) firms is increasing, the use of B2B firm-generated content for driving positive eWOM is less understood. Given the emergence of image-oriented social media platforms, this study investigates how color features increase positive eWOM in the B2B versus B2C context by analyzing 13,356 images on Instagram. The results reveal key differences in color features in the contexts of B2B and B2C. Specifically, cool colors are more appealing in B2B content, while warm colors work better in B2C content. Further, darkness, saturation, and colorfulness moderate the cool effect in B2B content, such that darker, less saturated, and more varied colors increase the effect of cool color. In the B2C context, only colorfulness increases the effect of warm color. The findings of this research contribute to the literature examining the different drivers of eWOM between B2B and B2C social media and offer managerial implications for B2B and B2C firms on ways to encourage positive eWOM