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Creators/Authors contains: "Zheng, Xiang"

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  1. Abstract Historically Black Colleges and Universities (HBCUs) play a foundational role in promoting equality in U.S. higher education and society. Studying faculty transitions and research dynamics at HBCUs is crucial to understanding and addressing these institutions’ challenges, such as the brain drain and its relationships with faculty research practices. By tracking the affiliation changes of 139 professors and their research outcomes (consisting of 4,269 publications) and comparing them with a matched control group with similar backgrounds, we revealed a moving penalty for professors moving from Predominantly White Institutions (PWIs) to HBCUs, who experienced declines in research productivity and citation impact. In contrast, professors transitioning from HBCUs to PWIs benefited from the moving premium of increasing high-impact publications. Professors at HBCUs tend to increase their collaborations with PWIs before transitioning, while those moving to PWIs reduce their collaborations with HBCUs. Our findings highlight the ongoing challenges HBCUs face and underscore the need for comprehensive strategies to strengthen these institutions’ research functionality and ultimately their overall academic standing. 
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  2. Abstract The relative significance of various geodynamic mechanisms that drive supercontinent breakup is unclear. A previous analysis of extensional stress during supercontinent breakup demonstrated the importance of the plume‐push force relative to the dragging force of subduction retreat. Here, we extend the analysis to basal traction (shear stress) and cross‐lithosphere integrations of both extensional and shear stresses, aiming to understand more clearly the relevant importance of these mechanisms in supercontinent breakup. More importantly, we evaluate the effect of preexisting orogens (mobile belts) in the lithosphere on supercontinent breakup process. Our analysis suggests that a homogeneous supercontinent has extensional stress of 20–50 MPa in its interior (<40° from the central point). When orogens are introduced, the extensional stress in the continents focuses on the top 80‐km of the lithosphere with an average magnitude of ~160 MPa, whereas at the margin of the supercontinent the extensional stress is 5–50 MPa. In both homogeneous and orogeny‐embedded cases, the subsupercontinent mantle upwellings act as the controlling factor on the normal stress field in the supercontinent interior. Compared with the extensional stress, shear stress at the bottom of the supercontinent is 1–2 order of magnitude smaller (0–5 MPa). In our two end‐member models, the breakup of a supercontinent with orogens can be achieved after the first extensional stress surge, whereas for a hypothetical supercontinent without orogens it starts with more diffused local thinning of the continental lithospheric before the breakup, suggesting that weak orogens play a critical role in the dispersal of supercontinents. 
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