We report on our recent progress in the manipulation and cooling of a magnetically guided, high-flux beam of 87 Rb atoms. Typically, 7 ϫ 10 9 atoms per second propagate in a magnetic guide providing a transverse gradient of 800 G / cm, with a temperature ϳ550 K, at an initial velocity of 90 cm/ s. The atoms are subsequently slowed down to ϳ60 cm/ s using an upward slope. The relatively high collision rate ͑5 s −1 ͒ allows us to start forced evaporative cooling of the beam, leading to a reduction of the beam temperature by a factor of 4, and a tenfold increase of the on-axis phase-space density.

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A theory, bridging the free-volume and shear-transformation zone concepts through mean field theory, is established to predict the failure threshold of bulk metallic glasses (BMGs), and the physical mechanism of slip is investigated. A linear relation between the increment of free-volume and strain rate at small time intervals is found to describe inhomogeneous flow. The room-temperature theoretical failure threshold, Smax, follows a universal material-dependent criterion Smax∼Tgη, where Tg is the glass-transition temperature and η is a constant related to the serrated flow. This criterion is in good accordance with experimental results and provides a quantitative understanding of the failure mechanisms highly dependent on the serrations in BMGs, which is helpful to enhance plasticity via tuning the failure threshold.