Effect of Spatial Charge Inhomogeneity on 1/f Noise Behavior in Graphene

Scattering mechanisms in graphene are critical to understanding the limits of signal-to-noise-ratios of unsuspended graphene devices. Here we present the four-probe low frequency noise (1/f) characteristics in back-gated single layer graphene (SLG) and bilayer graphene (BLG) samples. Contrary to the expected noise increase with the resistance, the noise for SLG decreases near the Dirac point, possibly due to the effects of the spatial charge inhomogeneity. For BLG, a similar noise reduction near the Dirac point is observed, but with a different gate dependence of its noise behavior. Some possible reasons for the different noise behavior between SLG and BLG are discussed.Comment: 28 pages, 3 figures + 3 supplement figure

You Say Bully, I Say Bullied: School Culture and Definitions of Bullying in Two Elementary Schools

Purpose This chapter examines the definitions of bullying used by students and adults in elementary schools and the effects that these definitions had within the broader school culture. Design/methodology/approach I combine interviews with 53 students and 10 adults and over 430 hours of participant observation with fifth grade students at two rural elementary schools. Findings Definitions of bullying held by those in these schools typically differed from those used by researchers. Even when individuals held definitions that were in line with those used by researchers, however, a focus on identifying bullies rather than on behaviors that fit definitions of bullying contributed to a school culture in which negative interactions were normalized and student reports of these behaviors were discouraged. Research limitations/implications This study is limited to two elementary schools in the rural Midwest and cannot be seen as representative of all schools. Support for my findings from other research combined with similar definitions and school cultures in both schools, however, suggest that these definitions and practices are part of a broader cultural context of bullying in the United States. Practical implications These findings suggest that schools might be better served by focusing less on labels like bully and more on particular behaviors that are to be taken seriously by students, teachers, staff members, and principals. Originality/value Although other researchers have studied definitions of bullying, none have combined these definitions with observational data on the broader school contexts in which those definitions are created and used

Towards a sociocultural understanding of children’s voice

While ‘voice’ is frequently invoked in discussions of pupils’ agency and empowerment, less attention has been paid to the dialogic dynamics of children’s voices and the sociocultural features shaping their emergence. Drawing on linguistic ethnographic research involving recent recordings of ten and eleven year-old children’s spoken language experience across the school day, this article examines how pupils’ voices are configured within institutional interactional contexts which render particular kinds of voice more or less hearable, and convey different kinds of value. Analysis shows how children appropriate and reproduce the authoritative voices of education, popular culture and parents in the course of their induction into social practices. At the same time they also express varying degrees of commitment to these voices and orchestrate their own and other people’s voices within accounts and anecdotes, making voice appropriation an uneven, accumulative process shot through with the dynamics of personal and peer-group experience. The examination of children’s dialogue from different contexts across the school day highlights the situated semiotics of voice and the heteroglossic development of children’s speaking consciousness

Chemically-induced Mobility Gaps in Graphene Nanoribbons: A Route for Upscaling Device Performances

We report a first-principles based study of mesoscopic quantum transport in chemically doped graphene nanoribbons with a width up to 10 nm. The occurrence of quasibound states related to boron impurities results in mobility gaps as large as 1 eV, driven by strong electron-hole asymmetrical backscattering phenomena. This phenomenon opens new ways to overcome current limitations of graphene-based devices through the fabrication of chemically-doped graphene nanoribbons with sizes within the reach of conventional lithography.Comment: Nano Letters (in press

Escalating Terror: Communicative Strategies in a Preschool Classroom Dispute

This paper describes the pragmatic and stategic communicative work of some young boys in a preschool classroom as they made themselves observable and hearable as owners of block area and members of specific activities. Using a transcript of a video-recorded episode of the boys engaged in a dispute about who could play in block area, analysis shows how the boys generated and escalated images of terror until the targeted child left the area or was evicted from the group by the other boys. In the course of escalating the terror, the boys used a range of commumicative resources to construct group membership affiliation and, at the same time, to assert their individual identities. The work of the boys established and displayed credentials as to who was able to play in the block area, and who was able to determine and justify why others could or could not play. This detailed analysis ofhow the boys formed collaborations and strategic partnerships in the course of their dispute gives us a way of appreciating the communicative competencies that underpin membership in a local social order that is in a state of flux