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Later school start times have emerged as a potential policy to improve the sleep and educational outcomes of teenagers. This study uses a quasi-experimental comparative interrupted time series approach to examine a 90-min delay in start times in an urban district in North Carolina. Results show that the later start time resulted in more sleep for students and improved course grades but limited evidence of benefits to other educational outcomes. In addition, the evidence suggests that disruptions from the change may temporarily decrease some educational outcomes, and that these disruption effects are concentrated among low-income students and students of color.

Abstract Acral melanoma is an aggressive type of melanoma with unknown origins. It is the most common type of melanoma in individuals with dark skin and is notoriously challenging to treat. We examine exome sequencing data of 139 tissue samples, spanning different progression stages, from 37 patients. We find that 78.4% of the melanomas display clustered copy number transitions with focal amplifications, recurring predominantly on chromosomes 5, 11, 12, and 22. These complex genomic aberrations are typically shared across all progression stages of individual patients. TERT activating alterations also arise early, whereas MAP-kinase pathway mutations appear later, an inverted order compared to the canonical evolution. The punctuated formation of complex aberrations and early TERT activation suggest a unique mutational mechanism that initiates acral melanoma. The marked intratumoral heterogeneity, especially concerning MAP-kinase pathway mutations, may partly explain the limited success of therapies for this melanoma subtype.

Principal preparation programs play an important role in developing future school leaders’ skills and practices. Internships, or structured opportunities for future leaders to engage in the work of school leadership in hands-on, authentic ways, are among the most essential components of principal preparation. Using longitudinal data from 12 programs in North Carolina, this study extends research on internships by examining the pathways of interns from prior- to post-internship employment. We find that internships are highly localized around interns’ prior- and post-employment schools but not their preparation program, with wide variability in placements between programs. Interns’ demographics do not play a large role in shaping the geography of internship placements. However, we find that preparation program type is strongly related to the geography of internship placements, suggesting that differences in program structure may shape internship placements. We conclude by highlighting the limitations and discussing implications for future research.