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Two-dimensional semiconducting materials are considered as ideal candidates for ultimate device scaling. However, a systematic study on the performance and variability impact of scaling the different device dimensions is still lacking. Here we investigate the scaling behavior across 1300 devices fabricated on large-area grown MoS2 material with channel length down to 30 nm, contact length down to 13 nm and capacitive effective oxide thickness (CET) down to 1.9 nm. These devices show best-in-class performance with transconductance of 185 μS/μm and a minimum subthreshold swing (SS) of 86 mV/dec. We find that scaling the top-contact length has no impact on the contact resistance and electrostatics of three monolayers MoS2 transistors, because edge injection is dominant. Further, we identify that SS degradation occurs at short channel length and can be mitigated by reducing the CET and lowering the Schottky barrier height. Finally, using a power performance area (PPA) analysis, we present a roadmap of material improvements to make 2D devices competitive with silicon gate-all-around devices. [ABSTRACT FROM AUTHOR]

This paper reports a teaching experiment in which two students engaged in tasks that challenged them to describe a final state for a variety of infinite iterative processes. The results from the study indicate that the students used multiple reasoning strategies for addressing these tasks. Refinements in the students' reasoning occurred as students constructed relationships between the problems they were solving and problems they had solved previously, applying some of the reasoning strategies that they used for one problem to make sense of or solve another problem. We discuss how these findings relate to the existing body of research on infinite iterative processes. [ABSTRACT FROM AUTHOR]

Nine prospective secondary mathematics teachers were interviewed about their teaching internship experience. The results of these interviews revealed that 7 of the 9 participants professed to value reform-oriented teaching and conceptual understanding in mathematics, yet all were paired with cooperating teachers who seemed to value traditional instruction and procedural understanding in mathematics. We explored the reasons that some of these student interns had positive experiences with their cooperating teachers and university supervisors while others had negative experiences. We found that the participants valued (a) critical feedback that was constructive and contained concrete recommendations for improvement, (b) freedom to use their own teaching methods, and (c) a friendly and supportive relationship with their mentors. The differing teaching philosophies of student teachers and their cooperating teachers contributed to negative experiences only when student teachers were not allowed freedom in their teaching methods. [ABSTRACT FROM AUTHOR]

In this paper, we discuss our experiences with an after-school program in which we engaged middle-school students with low socioeconomic status from an urban community in mathematical problem solving. We document that these students participated in many aspects of problem solving, including the posing of problems, constructing justifications, developing and implementing problem-solving heuristics and strategies, and understanding and evaluating the solutions of others. We then delineate what aspects of our environment encouraged the students to take part in these activities, particularly emphasising the proactive role of the teacher, the tasks the students completed, and the social norms of our after-school sessions. Finally, we discuss the relationship between our study and the literature on equity research in mathematics education. [ABSTRACT FROM AUTHOR]

Recent theories suggest that the quasiparticles that populate certain quantum Hall states should exhibit exotic braiding statistics that could be used to build topological quantum gates. Confined systems that support such states at a filling fraction ν=5/2 are of particular interest for testing these predictions. Here, we report transport measurements of just such a system, which consists of a quantum point contact (QPC) in a two-dimensional GaAs/AlGaAs electron gas that itself exhibits a well-developed fractional quantum Hall effect at a bulk filling fraction νbulk=5/2. We observe plateau-like features at an effective filling fraction of νQPC=5/2 for lithographic contact widths of 1.2 μm and 0.8 μm, but not 0.5 μm. Transport near νQPC=5/2 in the QPCs is consistent with a picture of chiral Luttinger-liquid edge states with inter-edge tunnelling, suggesting that an incompressible state at νQPC=5/2 forms in this confined geometry. [ABSTRACT FROM AUTHOR]

Two-dimensional semiconducting materials of the transition-metal-dichalcogenide family, such as MoS2 and WSe2, have been intensively investigated in the past few years, and are considered as viable candidates for next-generation electronic devices. In this paper, for the first time, we study scaling trends and evaluate the performances of polarity-controllable devices realized with undoped mono- and bi-layer 2D materials. Using ballistic self-consistent quantum simulations, it is shown that, with the suitable channel material, such polarity-controllable technology can scale down to 5 nm gate lengths, while showing performances comparable to the ones of unipolar, physically-doped 2D electronic devices. [ABSTRACT FROM AUTHOR]

A correction to the article "Refinements in mathematics undergraduate students' reasoning on completed infinite iterative processes" that is published in this issue is presented.