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Creators/Authors contains: "Armstrong, M"

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  1. In 2009, Gaston College launched the SPARC (Student Persistence and Retention through Curriculum, Cohorts, and Centralization) initiative to improve student engagement and enhance transfer student success. The initiative sought to revamp curricula by integrating inquiry-based instruction and introducing a research methods course, centralize STEM student support services, and provide scholarships to cohort students with unmet financial needs. To implement these services and offer scholarships to low-income, academically talented U.S. citizens or permanent residents, the College secured three National Science Foundation (NSF) S-STEM grants. The SPARC model has yielded promising results, with participating students experiencing increased fall-to-fall retention rates and three-year graduation rates. 
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  2. The nuclear two-photon or double-gamma ( 2 γ ) decay is a second-order electromagnetic process whereby a nucleus in an excited state emits two gamma rays simultaneously. To be able to directly measure the 2 γ decay rate in the low-energy regime below the electron-positron pair-creation threshold, we combined the isochronous mode of a storage ring with Schottky resonant cavities. The newly developed technique can be applied to isomers with excitation energies down to 100 keV and half-lives as short as 10 ms . The half-life for the 2 γ decay of the first-excited 0 + state in bare Ge 72 ions was determined to be 23.9(6) ms, which strongly deviates from expectations. Published by the American Physical Society2024 
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  5. X-ray free electron laser (XFEL) sources coupled to high-power laser systems offer an avenue to study the structural dynamics of materials at extreme pressures and temperatures. The recent commissioning of the DiPOLE 100-X laser on the high energy density (HED) instrument at the European XFEL represents the state-of-the-art in combining x-ray diffraction with laser compression, allowing for compressed materials to be probed in unprecedented detail. Here, we report quantitative structural measurements of molten Sn compressed to 85(5) GPa and ∼3500 K. The capabilities of the HED instrument enable liquid density measurements with an uncertainty of ∼1% at conditions which are extremely challenging to reach via static compression methods. We discuss best practices for conducting liquid diffraction dynamic compression experiments and the necessary intensity corrections which allow for accurate quantitative analysis. We also provide a polyimide ablation pressure vs input laser energy for the DiPOLE 100-X drive laser which will serve future users of the HED instrument. 
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