1,511 research outputs found

    Direct-write, focused ion beam-deposited,7 K superconducting C-Ga-O nanowire

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    We have fabricated C-Ga-O nanowires by gallium focused ion beam-induced deposition from the carbon-based precursor phenanthrene. The electrical conductivity of the nanowires is weakly temperature dependent below 300 K, and indicates a transition to a superconducting state below Tc = 7 K. We have measured the temperature dependence of the upper critical field Hc2(T), and estimate a zero temperature critical field of 8.8 T. The Tc of this material is approximately 40% higher than that of any other direct write nanowire, such as those based on C-W-Ga, expanding the possibility of fabricating direct-write nanostructures that superconduct above liquid helium temperaturesComment: Accepted for AP

    Interference Effects Due to Commensurate Electron Trajectories and Topological Crossovers in (TMTSF)2ClO4

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    We report angle-dependent magnetoresistance measurements on (TMTSF)2ClO4 that provide strong support for a new macroscopic quantum phenomenon, the interference commensurate (IC) effect, in quasi-one dimensional metals. In addition to observing rich magnetoresistance oscillations, and fitting them with one-electron calculations, we observe a clear demarcation of field-dependent behavior at local resistance minima and maxima (versus field angle). Anticipated by a theoretical treatment of the IC effect in terms of Bragg reflections in the extended Brillouin zone, this behavior results from 1D-2D topological crossovers of electron wave functions as a function of field orientation.Comment: 14 page

    Interference Commensurate Oscillations in Q1D Conductors

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    We suggest an analytical theory to describe angular magnetic oscillations recently discovered in quasi-one-dimensional conductor (TMTSF)2PF6 [see Phys. Rev. B, 57, 7423 (1998)] and define the positions of the oscillation minima. The origin of these oscillations is related to interference effects resulting from an interplay of quasi-periodic and periodic ("commensurate") electron trajectories in an inclined magnetic field. We reproduce via calculations existing experimental data and predict some novel effects.Comment: 10 pages, 2 figure

    Theory of Thermodynamic Magnetic Oscillations in Quasi-One-Dimensional Conductors

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    The second order correction to free energy due to the interaction between electrons is calculated for a quasi-one-dimensional conductor exposed to a magnetic field perpendicular to the chains. It is found that specific heat, magnetization and torque oscillate when the magnetic field is rotated in the plane perpendicular to the chains or when the magnitude of magnetic filed is changed. This new mechanism of thermodynamic magnetic oscillations in metals, which is not related to the presence of any closed electron orbits, is applied to explain behavior of the organic conductor (TMTSF)2_2ClO4_4.Comment: 11 pages + 5 figures (included

    Architects of time: Labouring on digital futures

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    Drawing on critical analyses of the internet inspired by Gilles Deleuze and the Marxist autonomia movement, this paper suggests a way of understanding the impact of the internet and digital culture on identity and social forms through a consideration of the relationship between controls exercised through the internet, new subjectivities constituted through its use and new labour practices enabled by it. Following Castells, we can see that the distinction between user, consumer and producer is becoming blurred and free labour is being provided by users to corporations. The relationship between digital technologies and sense of community, through their relationship to the future, is considered for its dangers and potentials. It is proposed that the internet may be a useful tool for highlighting and enabling social connections if certain dangers can be traversed. Notably, current remedies for the lack of trust on the internet are questioned with an alternative, drawing on Zygmunt Bauman and Georg Simmel, proposed which is built on community through a vision of a ‘shared network’

    Phylogenetic distance does not predict competition in green algal communities

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116355/1/ecs214005021.pd

    Influences on the uptake of health and wellbeing apps and curated app portals: a think aloud and interview study

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    Background: Health and wellbeing smartphone apps can be identified through different routes, including via curated health app portals, but little is known about people’s experiences of this. Objective: This study explored how people select health apps online and their views on curated portals. Methods: Eighteen UK-based adults were recruited and asked to verbalise their thoughts whilst searching for a health or wellbeing app online, including on two curated health app portals. This was followed by semi-structured interviews. Data were analysed using Framework Analysis, informed by the COM-B model and the Theoretical Domains Framework. Results: Searching for health and wellbeing apps online was described as a ‘minefield’. App uptake appeared to be influenced by i) capabilities (e.g. app literacy skills, health and app awareness), ii) opportunities (e.g. app aesthetics, cost and social influences) and iii) motivation (e.g. the perceived utility and accuracy of the app, and transparency about data protection). Social influences and the percieved utility of an app, in particular, were important. People were not previously aware of curated portals but found the concept appealing and likely to engender trust and address data protection concerns. While apps listed on these were perceived as more trustworthy, their presentation was considered disappointing. Conclusions: The uptake of health and wellbeing apps appear primarily influenced by social influences and the perceived utility of the app. With curated health app portals perceived as credible, app uptake via such portals may mitigate concerns related to data protection and accuracy, but their implementation must better meet user needs. Clinical Trial: N
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