745 research outputs found

    Temperature dependent transport in suspended graphene

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    The resistivity of ultra-clean suspended graphene is strongly temperature dependent for 5K<T<240K. At T~5K transport is near-ballistic in a device of ~2um dimension and a mobility ~170,000 cm^2/Vs. At large carrier density, n>0.5*10^11 cm^-2, the resistivity increases with increasing T and is linear above 50K, suggesting carrier scattering from acoustic phonons. At T=240K the mobility is ~120,000 cm^2/Vs, higher than in any known semiconductor. At the charge neutral point we observe a non-universal conductivity that decreases with decreasing T, consistent with a density inhomogeneity <10^8 cm^-2

    Conductivity of graphene: How to distinguish between samples with short and long range scatterers

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    Applying a quasiclassical equation to carriers in graphene we found a way how to distinguish between samples with the domination of short and long range scatterers from the conductivity measurements. The model proposed explains recent transport experiments with chemically doped as well as suspended graphene.Comment: 6 pages, 3 figures, some references have been corrected and revise

    A journey to client and therapist mutuality in person-centered psychotherapy: a case study

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    This aim of this case study was to build theory on the development of clientā€“therapist mutuality in person-centered psychotherapy. A case study focusing on a 42-year-old female client who had presented for therapy following trauma within interpersonal relationships has been used. A reflective, theory-building, case study method was adopted that used data gathered from verbatim session notes and research interviews between the therapist (first author) and research supervisor (second author). Three primary therapeutic processes that contributed to the development of mutuality are discussed. First, the development of mutual empathy in the relationship; second, strategies for disconnection and staying out of relationship are identified. Third, client agency and mutuality is explored. In conclusion the study proposes that mutuality is a key construct within person-centered psychotherapy and develops as a natural consequence of the presence of Rogersā€™ therapeutic conditions

    Superconductivity coexisting with phase-separated static magnetic order in (Ba,K)Fe2_{2}As2_{2}, (Sr,Na)Fe2_{2}As2_{2} and CaFe2_{2}As2_{2}

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    The recent discovery and subsequent developments of FeAs-based superconductors have presented novel challenges and opportunities in the quest for superconducting mechanisms in correlated-electron systems. Central issues of ongoing studies include interplay between superconductivity and magnetism as well as the nature of the pairing symmetry reflected in the superconducting energy gap. In the cuprate and RE(O,F)FeAs (RE = rare earth) systems, the superconducting phase appears without being accompanied by static magnetic order, except for narrow phase-separated regions at the border of phase boundaries. By muon spin relaxation measurements on single crystal specimens, here we show that superconductivity in the AFe2_{2}As2_{2} (A = Ca,Ba,Sr) systems, in both the cases of composition and pressure tunings, coexists with a strong static magnetic order in a partial volume fraction. The superfluid response from the remaining paramagnetic volume fraction of (Ba0.5_{0.5}K0.5_{0.5})Fe2_{2}As2_{2} exhibits a nearly linear variation in T at low temperatures, suggesting an anisotropic energy gap with line nodes and/or multi-gap effects.Comment: 14 pages 7 figures (4 for main text and 3 for on-line supplementary documents

    Synthesis and Structural Investigation of an \u27Oxazinoquinolinespirohexadienone\u27 That Only Exists as Its Long-Wavelength Ring-Opened Quinonimine Isomer

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    The spirocyclic oxazinoquinolinespirohexadienone (OSHD) photochromes are computationally predicted to be an attractive target as electron deficient analogues of the perimidinespirohexadienone (PSHD) photochromes, for eventual application as photochromic photooxidants. We have found the literature method for their preparation unsuitable and present an alternative synthesis. Unfortunately the product of this synthesis is the long wavelength (LW) ring-opened quinonimine isomer of the OSHD. We have found this isomer does not close to the spirocyclic short wavelength isomer (SW) upon prolonged standing in the dark, unlike other PSHD photochromes. The structure of this long wavelength isomer was found by NMR and X-ray crystallography to be exclusively the quinolinone (keto) tautomer, though experimental cyclic voltammetry supported by our computational methodology indicates that the quinolinol (enol) tautomer (not detected by other means) may be accessible through a fast equilibrium lying far toward the keto tautomer. Computations also support the relative stability order of keto LW over enol LW over SW

    Am I just not good enough? The creation, development and questioning of a high performance coaching identity

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    While the career experiences and trajectories of various sports workers have received increased scholarly attention, those of professional coaches have, in comparison, received scant consideration. This paper focuses on the career experiences of Maeve (a pseudonym), a high performance coach, and the critical incidents related to the creation, development, and, ultimately, questioning of her professional identity. Data were collected through a series of narrative-biographical interviews and were subject to a process of iterative data analysis. The results indicated that her significant investment into her coaching self, combined with the vagaries and uncertain nature of work in high performance coaching, led her to experience a biographical disruption that interrupted the narrative coherence of her coaching life. The findings add further credence to recent critiques of only understanding and representing coaching careers in a linear and chronically staged fashion

    Vibrational Enhancement of the Effective Donor - Acceptor Coupling

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    The paper deals with a simple three sites model for charge transfer phenomena in an one-dimensional donor (D) - bridge (B) - acceptor (A) system coupled with vibrational dynamics of the B site. It is found that in a certain range of parameters the vibrational coupling leads to an enhancement of the effective donor - acceptor electronic coupling as a result of the formation of the polaron on the B site. This enhancement of the charge transfer efficiency is maximum at the resonance, where the effective energy of the fluctuating B site coincides with the donor (acceptor) energy.Comment: 5 pages, 3 figure

    Career orientations and career cultures : individual and organisational approaches to beginning teachersā€™ careers

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    Despite the very large literature on teacher careers from an individual perspective, there is relatively little that links the perspectives of teachers themselves to how schools as organisations approach careers. The aim of this paper is, first, to outline how teachersā€™ orientations towards careers change across three dimensions, and, second, to examine how schools as organisations deal with career, developing a model of organisational responses, including developing a concept of ā€˜career cultureā€™, derived from an analysis of interviews regarding the first three years of teaching conducted with senior leaders and second year teachers themselves. By considering the fit between individualsā€™ career orientations and school career cultures, the paper surfaces both the fluid nature of these orientations and the subsequent potential instability of the fit

    'It would be easier if sheā€™d diedā€™: young people with parents with dementia articulating inadmissible stories

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    In the U.K. context where the emphasis is (quite rightly) on living well with dementia, on positivity and enabling approaches, it can be difficult for researchers to investigate and report negative experiences. Failing to re-present perceptions and experiences as they are lived, however, does a serious disservice to the research endeavor and can prevent policy and service development and positive change. In this article, we present some stories told by participants in an Alzheimerā€™s Society (United Kingdom) Funded project uniquely investigating the perceptions and experiences of children and young people who have a parent with dementia. Sometimes the stories were not easy to hear, especially when they challenged dominant master narratives around dementia. We discuss our view that when the young people we spoke with told us how things were for them, we were ethically bound to respect and disseminate their accounts
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