598 research outputs found
Symmetry breaking in commensurate graphene rotational stacking; a comparison of theory and experiment
Graphene stacked in a Bernal configuration (60 degrees relative rotations
between sheets) differs electronically from isolated graphene due to the broken
symmetry introduced by interlayer bonds forming between only one of the two
graphene unit cell atoms. A variety of experiments have shown that non-Bernal
rotations restore this broken symmetry; consequently, these stacking varieties
have been the subject of intensive theoretical interest. Most theories predict
substantial changes in the band structure ranging from the development of a Van
Hove singularity and an angle dependent electron localization that causes the
Fermi velocity to go to zero as the relative rotation angle between sheets goes
to zero. In this work we show by direct measurement that non-Bernal rotations
preserve the graphene symmetry with only a small perturbation due to weak
effective interlayer coupling. We detect neither a Van Hove singularity nor any
significant change in the Fermi velocity. These results suggest significant
problems in our current theoretical understanding of the origins of the band
structure of this material.Comment: 7 pages, 6 figures, submitted to PR
A wide band gap metal-semiconductor-metal nanostructure made entirely from graphene
A blueprint for producing scalable digital graphene electronics has remained
elusive. Current methods to produce semiconducting-metallic graphene networks
all suffer from either stringent lithographic demands that prevent
reproducibility, process-induced disorder in the graphene, or scalability
issues. Using angle resolved photoemission, we have discovered a unique one
dimensional metallic-semiconducting-metallic junction made entirely from
graphene, and produced without chemical functionalization or finite size
patterning. The junction is produced by taking advantage of the inherent,
atomically ordered, substrate-graphene interaction when it is grown on SiC, in
this case when graphene is forced to grow over patterned SiC steps. This
scalable bottomup approach allows us to produce a semiconducting graphene strip
whose width is precisely defined within a few graphene lattice constants, a
level of precision entirely outside modern lithographic limits. The
architecture demonstrated in this work is so robust that variations in the
average electronic band structure of thousands of these patterned ribbons have
little variation over length scales tens of microns long. The semiconducting
graphene has a topologically defined few nanometer wide region with an energy
gap greater than 0.5 eV in an otherwise continuous metallic graphene sheet.
This work demonstrates how the graphene-substrate interaction can be used as a
powerful tool to scalably modify graphene's electronic structure and opens a
new direction in graphene electronics research.Comment: 11 pages, 7 figure
“I just let him cry...”: Designing socio-technical interventions in families to prevent mental health disorders
Interventions that help children develop protective factors against mental health disorders are an inherently social endeavour, relying on a number of actors from within the family as well as the school context. Little work thus far in CSCW and HCI has examined the potential of technology to support or enhance such interventions. This paper provides the first steps to unpacking this socio-technical design space, focusing on emotional regulation (ER) as a specific instance of a protective factor. We combine a user-centred approach to understanding lived experiences of families (interviews, design workshops) with an expert-led understanding of what makes interventions psychologically effective. Our findings suggest the potential of technology to enable a shift in how prevention interventions are designed and delivered: empowering children and parents through a new model of ‘child-led, situated interventions’, where participants learn through actionable support directly within family life, as opposed to didactic in-person workshops and a subsequent ‘skills application’. This conceptual model was then instantiated in a technology probe, which was deployed with 14 families. The promising field study findings provide an initial proof-of-concept validation of the proposed approach
Silicon intercalation into the graphene-SiC interface
In this work we use LEEM, XPEEM and XPS to study how the excess Si at the
graphene-vacuum interface reorders itself at high temperatures. We show that
silicon deposited at room temperature onto multilayer graphene films grown on
the SiC(000[`1]) rapidly diffuses to the graphene-SiC interface when heated to
temperatures above 1020. In a sequence of depositions, we have been able to
intercalate ~ 6 ML of Si into the graphene-SiC interface.Comment: 6 pages, 8 figures, submitted to PR
Mapping FoodHCI Futures
Recognizing the significant potential impact that HCI has on food practices and experiences, researchers and practitioners are undertaking a growing number of explorations of novel computing technology and food combinations. These explorations have so far primarily emphasized technology-driven systems and taken a human-centric perspective. We propose a Special Interest Group (SIG) in "foodHCI futures"that creates a space for researchers to discuss the boundaries of food incorporating HCI, and with the simultaneous aims of reconciling food with technology and extending our visions for human-food interactions towards anthropocentrism. Specifically, the SIG will be a beginning of developing a structured conceptual map of the possibilities for future technology interventions in food systems. In developing this map, we hope to encourage democratized debate, provoke new and divergent thoughts on the opportunities for foodHCI, and ultimately gain unique insights that contribute to preferable food futures
EQUIPT: protocol of a comparative effectiveness research study evaluating cross-context transferability of economic evidence on tobacco control
This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial.This article has been made available through the Brunel Open Access Publishing Fund.Tobacco smoking claims 700 000 lives every year in Europe and the cost of tobacco smoking in the EU is estimated between €98 and €130 billion annually; direct medical care costs and indirect costs such as workday losses each represent half of this amount. Policymakers all across Europe are in need of bespoke information on the economic and wider returns of investing in evidence-based tobacco control, including smoking cessation agendas. EQUIPT is designed to test the transferability of one such economic evidence base-the English Tobacco Return on Investment (ROI) tool-to other EU member states
The Future of Human-Food Interaction
There is an increasing interest in food within the HCI discipline, with many interactive prototypes emerging that augment, extend and challenge the various ways people engage with food, ranging from growing plants, cooking ingredients, serving dishes and eating together. Grounding theory is also emerging that in particular draws from embodied interactions, highlighting the need to consider not only instrumental, but also experiential factors specific to human-food interactions. Considering this, we are provided with an opportunity to extend human-food interactions through knowledge gained from designing novel systems emerging through technical advances. This workshop aims to explore the possibility of bringing practitioners, researchers and theorists together to discuss the future of human-food interaction with a particular highlight on the design of experiential aspects of human-food interactions beyond the instrumental. This workshop extends prior community building efforts in this area and hence explicitly invites submissions concerning the empirically-informed knowledge of how technologies can enrich eating experiences. In doing so, people will benefit not only from new technologies around food, but also incorporate the many rich benefits that are associated with eating, especially when eating with others
Anomalous spectral weight in photoemission spectra of the hole doped Haldane chain Y2-xSrxBaNiO5
In this paper, we present photoemission experiments on the hole doped Haldane
chain compound . By using the photon energy dependence of
the photoemission cross section, we identified the symmetry of the first
ionisation states (d type). Hole doping in this system leads to a significant
increase in the spectral weight at the top of the valence band without any
change in the vicinity of the Fermi energy. This behavior, not observed in
other charge transfer oxides at low doping level, could result from the
inhomogeneous character of the doped system and from a Ni 3d-O 2p hybridization
enhancement due to the shortening of the relevant Ni-O distance in the
localized hole-doped regions.Comment: 5 pages, 4 figure
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