80 research outputs found
Calculating the energy spectra of magnetic molecules: application of real- and spin-space symmetries
The determination of the energy spectra of small spin systems as for instance
given by magnetic molecules is a demanding numerical problem. In this work we
review numerical approaches to diagonalize the Heisenberg Hamiltonian that
employ symmetries; in particular we focus on the spin-rotational symmetry SU(2)
in combination with point-group symmetries. With these methods one is able to
block-diagonalize the Hamiltonian and thus to treat spin systems of
unprecedented size. In addition it provides a spectroscopic labeling by
irreducible representations that is helpful when interpreting transitions
induced by Electron Paramagnetic Resonance (EPR), Nuclear Magnetic Resonance
(NMR) or Inelastic Neutron Scattering (INS). It is our aim to provide the
reader with detailed knowledge on how to set up such a diagonalization scheme.Comment: 29 pages, many figure
Quantum oscillations of the critical current and high-field superconducting proximity in ballistic graphene
Graphene-based Josephson junctions provide a novel platform for studying the
proximity effect due to graphene's unique electronic spectrum and the
possibility to tune junction properties by gate voltage. Here we describe
graphene junctions with a mean free path of several micrometres, low contact
resistance and large supercurrents. Such devices exhibit pronounced
Fabry-P\'erot oscillations not only in the normal-state resistance but also in
the critical current. The proximity effect is mostly suppressed in magnetic
fields below 10mT, showing the conventional Fraunhofer pattern. Unexpectedly,
some proximity survives even in fields higher than 1 T. Superconducting states
randomly appear and disappear as a function of field and carrier concentration,
and each of them exhibits a supercurrent carrying capacity close to the
universal quantum limit. We attribute the high-field Josephson effect to
mesoscopic Andreev states that persist near graphene edges. Our work reveals
new proximity regimes that can be controlled by quantum confinement and
cyclotron motion
Qualitative study on the implementation of professional pharmacy services in Australian community pharmacies using framework analysis
Abbreviations: BCT, Behavioural change techniques taxonomy; BCW, Behavioural change wheel; CFIR, Consolidated
framework for implementation research; EPOC, Cochrane effective practice and organisation of care; FISpH, Framework
for the implementation of services in pharmacy; GIF, Generic implementation framework; KPI, Key performance
indicator; TDF, Theoretical domains frameworkBackground: Multiple studies have explored the implementation process and influences, however it appears there
is no study investigating these influences across the stages of implementation. Community pharmacy is attempting
to implement professional services (pharmaceutical care and other health services). The use of implementation
theory may assist the achievement of widespread provision, support and integration. The objective was to investigate
professional service implementation in community pharmacy to contextualise and advance the concepts of a generic
implementation framework previously published.
Methods: Purposeful sampling was used to investigate implementation across a range of levels of implementation in
community pharmacies in Australia. Twenty-five semi-structured interviews were conducted and analysed using a
framework methodology. Data was charted using implementation stages as overarching themes and each stage
was thematically analysed, to investigate the implementation process, the influences and their relationships. Secondary
analyses were performed of the factors (barriers and facilitators) using an adapted version of the Consolidated
Framework for Implementation Research (CFIR), and implementation strategies and interventions, using the
Expert Recommendations for Implementing Change (ERIC) discrete implementation strategy compilation.
Results: Six stages emerged, labelled as development or discovery, exploration, preparation, testing, operation
and sustainability. Within the stages, a range of implementation activities/steps and five overarching influences
(pharmacys' direction and impetus, internal communication, staffing, community fit and support) were identified.
The stages and activities were not applied strictly in a linear fashion. There was a trend towards the greater the
number of activities considered, the greater the apparent integration into the pharmacy organization. Implementation
factors varied over the implementation stages, and additional factors were added to the CFIR list and definitions
modified/contextualised for pharmacy. Implementation strategies employed by pharmacies varied widely.
Evaluations were lacking. Conclusions: The process of implementation and five overarching influences of professional services implementation
in community pharmacy have been outlined. Framework analysis revealed, outside of the five overarching influences,
factors influencing implementation varied across the implementation stages. It is proposed at each stage, for
each domain, the factors, strategies and evaluations should be considered. The Framework for the Implementation of
Services in Pharmacy incorporates the contextualisation of implementation science for pharmacy.The study was funded as part of a University of Technology Sydney (UTS)
Research Excellence Scholarship (RES), comprising of an Australian Postgraduate
Award (APA) Scholarship funded by the Australian Government, plus a Top-up
funded by the University of Technology Sydney, received from the primary
author (JCM)
Student politics, teaching politics, black politics: an interview with Ansel Wong
Ansel Wong is the quiet man of British black politics, rarely in the limelight and never seeking political office. And yet his ‘career’ here – from Black Power firebrand to managing a multimillion budget as head of the Greater London Council’s Ethnic Minority Unit in the 1980s – spells out some of the most important developments in black educational and cultural projects. In this interview, he discusses his identification with Pan-Africanism, his involvement in student politics, his role in the establishment of youth projects and supplementary schools in the late 1960s and 1970s, and his involvement in black radical politics in London in the same period, all of which took place against the background of revolutionary ferment in the Third World and the world of ideas, and were not without their own internal class and ethnic conflicts
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Eyewitness Testimony in Autism Spectrum Disorder: A Review
Autism spectrum disorder (ASD) is estimated to affect around 1% of the population, and is characterised by impairments in social interaction, communication, and behavioural flexibility. A number of risk factors indicate that individuals with ASD may become victims or witnesses of crimes. In addition to their social and communication deficits, people with ASD also have very specific memory problems, which impacts on their abilities to recall eyewitnessed events. We begin this review with an overview of the memory difficulties that are experienced by individuals with ASD, before discussing the studies that have specifically examined eyewitness testimony in this group and the implications for investigative practice. Finally, we outline related areas that would be particularly fruitful for future research to explore
Evidence-based Kernels: Fundamental Units of Behavioral Influence
This paper describes evidence-based kernels, fundamental units of behavioral influence that appear to underlie effective prevention and treatment for children, adults, and families. A kernel is a behavior–influence procedure shown through experimental analysis to affect a specific behavior and that is indivisible in the sense that removing any of its components would render it inert. Existing evidence shows that a variety of kernels can influence behavior in context, and some evidence suggests that frequent use or sufficient use of some kernels may produce longer lasting behavioral shifts. The analysis of kernels could contribute to an empirically based theory of behavioral influence, augment existing prevention or treatment efforts, facilitate the dissemination of effective prevention and treatment practices, clarify the active ingredients in existing interventions, and contribute to efficiently developing interventions that are more effective. Kernels involve one or more of the following mechanisms of behavior influence: reinforcement, altering antecedents, changing verbal relational responding, or changing physiological states directly. The paper describes 52 of these kernels, and details practical, theoretical, and research implications, including calling for a national database of kernels that influence human behavior
Superballistic flow of viscous electron fluid through graphene constrictions
Electron–electron (e–e) collisions can impact transport in a variety of surprising and sometimes counterintuitive ways1,2,3,4,5,6. Despite strong interest, experiments on the subject proved challenging because of the simultaneous presence of different scattering mechanisms that suppress or obscure consequences of e–e scattering7,8,9,10,11. Only recently, sufficiently clean electron systems with transport dominated by e–e collisions have become available, showing behaviour characteristic of highly viscous fluids12,13,14. Here we study electron transport through graphene constrictions and show that their conductance below 150 K increases with increasing temperature, in stark contrast to the metallic character of doped graphene15. Notably, the measured conductance exceeds the maximum conductance possible for free electrons16,17. This anomalous behaviour is attributed to collective movement of interacting electrons, which ‘shields’ individual carriers from momentum loss at sample boundaries18,19. The measurements allow us to identify the conductance contribution arising due to electron viscosity and determine its temperature dependence. Besides fundamental interest, our work shows that viscous effects can facilitate high-mobility transport at elevated temperatures, a potentially useful behaviour for designing graphene-based devices
Excess resistivity in graphene superlattices caused by umklapp electron–electron scattering
In electronic transport, umklapp processes play a fundamental role as the only intrinsic mechanism that allows electrons to transfer momentum to the crystal lattice and, therefore, provide a finite electrical resistance in pure metals1,2. However, umklapp scattering is difficult to demonstrate in experiment, as it is easily obscured by other dissipation mechanisms1–6. Here we show that electron–electron umklapp scattering dominates the transport properties of graphene-on-boron-nitride superlattices over a wide range of temperature and carrier density. The umklapp processes cause giant excess resistivity that rapidly increases with increasing superlattice period and are responsible for deterioration of the room-temperature mobility by more than an order of magnitude as compared to standard, non-superlattice graphene devices. The umklapp scattering exhibits a quadratic temperature dependence accompanied by a pronounced electron–hole asymmetry with the effect being much stronger for holes than electrons. In addition to being of fundamental interest, our results have direct implications for design of possible electronic devices based on heterostructures featuring superlattices. © 2018, The Author(s), under exclusive licence to Springer Nature Limited
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