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  1. This mixed-methods observational study analyzes Advanced Placement (AP) Biology teachers’ engagement in microblogging for their professional development (PD). Data from three hashtag-based Twitter communities, #apbiochat, #apbioleaderacad, and #apbioleaderacademy (121 users; 2,253 tweets), are analyzed using methodological approaches including educational data mining, qualitative two-cycle content analysis, social network analysis, linear and logistic regression analyses, and hierarchical linear modeling. Results indicate that Twitter adheres to standards of high-quality PD and has the potential to complement more traditional PD activities. Notably, Twitter’s non-hierarchical leadership affords shared content creation and distribution. Additionally, Twitter allows for different temporal participation patterns and supports the personalization of learning experiences aligned to teachers’ needs and preferences. Furthermore, teachers frame their interactions on Twitter positively, thus, creating a supportive environment for professional learning that might reduce teachers’ perceived isolation. Therefore, policy makers and school leaders should feel empowered to encourage teachers to use microblogging complementary to other PD activities. 
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  2. This empirical study explored participation patterns of 1,733 Advanced Placement (AP) Physics teachers in the online AP teacher community (APTC) following the redesigned AP science examinations in the United States. We identified profiles of teachers with different levels of engagement in this peer-based online learning community. Our results provide insight into underrepresented user groups and the development of more personalized online teacher support systems. Our analysis suggested that teachers’ knowledge and experience, the enactment of AP practices, challenges with the AP redesign, and AP workload were all significantly associated with changes in the probability of teachers becoming APTC users. This indicated that the APTC attracted a non-representative population sample of all AP physics teachers. However, most teacher, teaching, and school characteristics provided no indication as to whether APTC users were posters or lurkers. 
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  3. This paper describes a study using a quasi-experimental design to examine teachers’ preparations in low-income schools for a revised version of the AP Biology and AP Chemistry examinations, and explores variables associated with student scores on the AP science examinations that are better than would be predicted based on their PSAT scores. Considering the frequently-measured achievement gap on high-stakes examinations, identifying “what works” to raise student performance of at-risk students is an urgent area for research. The analyses indicate that (a) districts per-student funding allocations, (b) teachers’ knowledge and experience, and (c) teachers’ participation in professional development activities with a responsive agenda and effective support for teaching the redesigned AP science course are significantly associated with higher students’ average performance on the AP science exams than would be predicted. 
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  4. Abstract

    An overview of the Community Earth System Model Version 2 (CESM2) is provided, including a discussion of the challenges encountered during its development and how they were addressed. In addition, an evaluation of a pair of CESM2 long preindustrial control and historical ensemble simulations is presented. These simulations were performed using the nominal 1° horizontal resolution configuration of the coupled model with both the “low‐top” (40 km, with limited chemistry) and “high‐top” (130 km, with comprehensive chemistry) versions of the atmospheric component. CESM2 contains many substantial science and infrastructure improvements and new capabilities since its previous major release, CESM1, resulting in improved historical simulations in comparison to CESM1 and available observations. These include major reductions in low‐latitude precipitation and shortwave cloud forcing biases; better representation of the Madden‐Julian Oscillation; better El Niño‐Southern Oscillation‐related teleconnections; and a global land carbon accumulation trend that agrees well with observationally based estimates. Most tropospheric and surface features of the low‐ and high‐top simulations are very similar to each other, so these improvements are present in both configurations. CESM2 has an equilibrium climate sensitivity of 5.1–5.3 °C, larger than in CESM1, primarily due to a combination of relatively small changes to cloud microphysics and boundary layer parameters. In contrast, CESM2's transient climate response of 1.9–2.0 °C is comparable to that of CESM1. The model outputs from these and many other simulations are available to the research community, and they represent CESM2's contributions to the Coupled Model Intercomparison Project Phase 6.

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  5. null (Ed.)
    Two additions impacting tables 3 and 4 in ref. [1] are presented in the following. No significant impact is found for other results or figures in ref. [1]. 
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  6. null (Ed.)