Exotic orbits due to spin-spin coupling around Kerr black holes

We report exotic orbital phenomena of spinning test particles orbiting around a Kerr black hole, i.e., some orbits of spinning particles are asymmetrical about the equatorial plane. When a nonspinning test particle orbits around a Kerr black hole in a strong field region, due to relativistic orbital precessions, the pattern of trajectories is symmetrical about the equatorial plane of the Kerr black hole. However, the patterns of the spinning particles' orbit are no longer symmetrical about the equatorial plane for some orbital configurations and large spins. We argue that these asymmetrical patterns come from the spin-spin interactions between spinning particles and Kerr black holes, because the directions of spin-spin forces can be arbitrary, and distribute asymmetrically about the equatorial plane.Comment: 15 pages, 20 figure

Improving sustainability performance through supplier relationship management in the tobacco industry

Purpose: The purpose of this study is to explore how tobacco manufacturing companies can improve their sustainability performance via effective supplier relationship management (SRM). Design/methodology/approach: This study has adopted a single case study of an international tobacco company. The primary data involved semi-structured interviews with participants from the case company who are familiar with sustainable SRM in the tobacco industry and are engaging in various techniques to improve sustainability performance. Findings: The drivers for sustainable SRM commonly identified in literature are observable within the case company. There is also clear evidence of integrating sustainability in its SRM processes. However, the perception of sustainability as a requirement to meet stringent regulations limits its scope and drive in pursuing sustainable SRM. It has also limited supplier sustainability evaluation and performance metrics. Furthermore, the findings of this paper reinforce the importance of a procurement team’s ability to work with other functional teams in implementing sustainable SRM. The findings also contribute to the emerging literature on the impact of sustainability on supplier segmentation and multi-tier supplier management. Research limitations/implications: This study provides insight into the varying SRM methods used in the tobacco industry to ensure compliance and improve sustainability performance. However, further research is required to explore the generalisability of the findings of this study derived from a single case study. Originality/value: The tobacco industry is an under-researched industry, particularly in terms of sustainable operations and supply chain management practices. The findings of this study seem to be relevant to those comparable industries with stringent regulations as well

Distributed entanglement induced by dissipative bosonic media

We describe a scheme with analytic result that allows to generate steady-state entanglement for two atoms over a dissipative bosonic medium. The resonant coupling between the mediating bosonic mode and cavity modes produces three collective atomic decay channels. This dissipative dynamics, together with the unitary process induced by classical microwave fields, drives the two atoms to the symmetric or asymmetric entangled steady state conditional upon the choice of the phases of the microwave fields. The effects on the steady-state entanglement of off-resonance mediating bosonic modes are analyzed. The entanglement can be obtained with high fidelity regardless of the initial state and there is a linear relation in the scaling of the fidelity with the cooperativity parameter. The fidelity is insensitive to the fluctuation of the Rabi frequencies of the classical driving fields.Comment: to appear in Europhysics Letter