405 research outputs found

    Unification Theory of Angular Magnetoresistance Oscillations in Quasi-One-Dimensional Conductors

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    We present a unification theory of angular magnetoresistance oscillations, experimentally observed in quasi-one-dimensional organic conductors, by solving the Boltzmann kinetic equation in the extended Brillouin zone. We find that, at commensurate directions of a magnetic field, resistivity exhibits strong minima. In two limiting cases, our general solution reduces to the results, previously obtained for the Lebed Magic Angles and Lee-Naughton-Lebed oscillations. We demonstrate that our theoretical results are in good qualitative and quantitative agreement with the existing measurements of resistivity in (TMTSF)2_2ClO4_4 conductor.Comment: 6 pages, 2 figure

    Quantum Limit in a Parallel Magnetic Field in Layered Conductors

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    We show that electron wave functions in a quasi-two-dimensional conductor in a parallel magnetic field are always localized on conducting layers. Wave functions and electron spectrum in a quantum limit, where the "sizes" of quasi-classical electron orbits are of the order of nano-scale distances between the layers, are determined. AC infrared measurements to investigate Fermi surfaces and to test Fermi liquid theory in Q2D organic and high-Tc materials in high magnetic fields, H = 10-45 T, are suggested.Comment: 9 pages, 2 figures; Submitted to Physical Review Letter

    Soliton Wall Superlattice in Quasi-One-Dimensional Conductor (Per)2Pt(mnt)2

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    We suggest a model to explain the appearance of a high resistance high magnetic field charge-density-wave (CDW) phase, discovered by D. Graf et al. [Phys. Rev. Lett. v. 93, 076406 (2004)] in (Per)2Pt(mnt)2. In particular, we show that the Pauli spin-splitting effects improve the nesting properties of a realistic quasi-one-dimensional electron spectrum and, therefore, a high resistance Peierls CDW phase is stabilized in high magnetic fields. In low and very high magnetic fields, a periodic soliton wall superlattice (SWS) phase is found to be a ground state. We suggest experimental studies of the predicted phase transitions between the Peierls and SWS CDW phases in (Per)2Pt(mnt)2 to discover a unique SWS phase.Comment: 10 pages, 3 figures. Submitted to Physical Review Letters (February 19, 2007

    The Informal Politics of Legislation: Explaining Secluded Decision-Making in the European Union

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    This article investigates a widespread yet understudied trend in EU politics: the shift of legislative decision making from public inclusive to informal se- cluded arenas and the subsequent adoption of legislation as “early agree- ments.” Since its introduction in 1999, “fast-track legislation” has increased dramatically, accounting for 72% of codecision files in the Sixth European Parliament. Drawing from functionalist institutionalism, distributive bargain- ing theory, and sociological institutionalism, this article explains under what conditions informal decision making is likely to occur. The authors test their hypotheses on an original data set of all 797 codecision files negotiated between mid-1999 and mid-2009. Their analysis suggests that fast-track leg- islation is systematically related to the number of participants, legislative workload, and complexity. These findings back a functionalist argument, emphasizing the transaction costs of intraorganizational coordination and in- formation gathering. However, redistributive and salient acts are regularly decided informally, and the Council presidency’s priorities have no significant effect on fast-track legislation. Hence, the authors cannot confirm explana- tions based on issue properties or actors’ privileged institutional positions. Finally, they find a strong effect for the time fast-track legislation has been used, suggesting socialization into interorganizational norms of cooperation

    A multifaceted strategy using mobile technology to assist rural primary healthcare doctors and frontline health workers in cardiovascular disease risk management: protocol for the SMARTHealth India cluster randomised controlled trial

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    BACKGROUND: Blood Pressure related disease affected 118 million people in India in the year 2000; this figure will double by 2025. Around one in four adults in rural India have hypertension, and of those, only a minority are accessing appropriate care. Health systems in India face substantial challenges to meet these gaps in care, and innovative solutions are needed. METHODS: We hypothesise that a multifaceted intervention involving capacity strengthening of primary healthcare doctors and non-physician healthcare workers through use of a mobile device-based clinical decision support system will result in improved blood pressure control for individuals at high risk of a cardiovascular disease event when compared with usual healthcare. This intervention will be implemented as a stepped wedge, cluster randomised controlled trial in 18 primary health centres and 54 villages in rural Andhra Pradesh involving adults aged ≥40 years at high cardiovascular disease event risk (approximately 15,000 people). Cardiovascular disease event risk will be calculated based on World Health Organisation/International Society of Hypertension's region-specific risk charts. Cluster randomisation will occur at the level of the primary health centres. Outcome analyses will be conducted blinded to intervention allocation. EXPECTED OUTCOMES: The primary study outcome is the difference in the proportion of people meeting guideline-recommended blood pressure targets in the intervention period vs. the control period. Secondary outcomes include mean reduction in blood pressure levels; change in other cardiovascular disease risk factors, including body mass index, current smoking, reported healthy eating habits, and reported physical activity levels; self-reported use of blood pressure and other cardiovascular medicines; quality of life (using the EQ-5D); and cardiovascular disease events (using hospitalisation data). Trial outcomes will be accompanied by detailed process and economic evaluations. SIGNIFICANCE: The findings are likely to inform policy on a scalable strategy to overcome entrenched inequities in access to effective healthcare for under-served populations in low and middle income country settings. TRIAL REGISTRATION: Clinical Trial Registry India CTRI/2013/06/003753

    Novel Phases in the Field Induced Spin Density Wave State in (TMTSF)_2PF_6

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    Magnetoresistance measurements on the quasi one-dimensional organic conductor (TMTSF)_2PF_6 performed in magnetic fields B up to 16T, temperatures T down to 0.12K and under pressures P up to 14kbar have revealed new phases on its P-B-T phase diagram. We found a new boundary which subdivides the field induced spin density wave (FISDW) phase diagram into two regions. We showed that a low-temperature region of the FISDW diagram is characterized by a hysteresis behavior typical for the first order transitions, as observed in a number of studies. In contrast to the common believe, in high temperature region of the FISDW phase diagram, the hysteresis and, hence, the first order transitions were found to disappear. Nevertheless, sharp changes in the resistivity slope are observed both in the low and high temperature domains indicating that the cascade of transitions between different subphases exists over all range of the FISDW state. We also found that the temperature dependence of the resistance (at a constant B) changes sign at about the same boundary. We compare these results with recent theoretical models.Comment: LaTex, 4 pages, 4 figure

    Paramagnetic Intrinsic Meissner Effect in Layered Superconductors

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    Free energy of a layered superconductor with ξ<d\xi_{\perp} < d is calculated in a parallel magnetic field by means of the Gor'kov equations, where ξ\xi_{\perp} is a coherence length perpendicular to the layers and dd is an inter-layer distance. The free energy is shown to differ from that in the textbook Lawrence-Doniach model at high fields, where the Meissner currents are found to create an unexpected positive magnetic moment due to shrinking of the Cooper pairs "sizes" by a magnetic field. This paramagnetic intrinsic Meissner effect in a bulk is suggested to detect by measuring in-plane torque, the upper critical field, and magnetization in layered organic and high-Tc_c superconductors as well as in superconducting superlattices.Comment: Submitted to Physical Review Letters on February 21st 200

    Machine learning algorithms distinguish discrete digital emotional fingerprints for web pages related to back pain

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    Back pain is the leading cause of disability worldwide. Its emergence relates not only to the musculoskeletal degeneration biological substrate but also to psychosocial factors; emotional components play a pivotal role. In modern society, people are significantly informed by the Internet; in turn, they contribute social validation to a “successful” digital information subset in a dynamic interplay. The Affective component of medical pages has not been previously investigated, a significant gap in knowledge since they represent a critical biopsychosocial feature. We tested the hypothesis that successful pages related to spine pathology embed a consistent emotional pattern, allowing discrimination from a control group. The pool of web pages related to spine or hip/knee pathology was automatically selected by relevance and popularity and submitted to automated sentiment analysis to generate emotional patterns. Machine Learning (ML) algorithms were trained to predict page original topics from patterns with binary classification. ML showed high discrimination accuracy; disgust emerged as a discriminating emotion. The findings suggest that the digital affective “successful content” (collective consciousness) integrates patients’ biopsychosocial ecosystem, with potential implications for the emergence of chronic pain, and the endorsement of health-relevant specific behaviors. Awareness of such effects raises practical and ethical issues for health information providers

    Multiparametric determination of genes and their point mutations for identification of beta-lactamases

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    Far-ultraviolet aurora identified at comet 67P/ Churyumov-Gerasimenko

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    Having a nucleus darker than charcoal, comets are usually detected from Earth through the emissions from their coma. The coma is an envelope of gas that forms through the sublimation of ices from the nucleus as the comet gets closer to the Sun. In the far-ultraviolet portion of the spectrum, observations of comae have revealed the presence of atomic hydrogen and oxygen emissions. When observed over large spatial scales as seen from Earth, such emissions are dominated by resonance fluorescence pumped by solar radiation. Here, we analyse atomic emissions acquired close to the cometary nucleus by the Rosetta spacecraft and reveal their auroral nature. To identify their origin, we undertake a quantitative multi-instrument analysis of these emissions by combining coincident neutral gas, electron and far-ultraviolet observations. We establish that the atomic emissions detected from Rosetta around comet 67P/Churyumov-Gerasimenko at large heliocentric distances result from the dissociative excitation of cometary molecules by accelerated solar-wind electrons (and not by electrons produced from photo-ionization of cometary molecules). Like the discrete aurorae at Earth and Mars, this cometary aurora is driven by the interaction of the solar wind with the local environment. We also highlight how the oxygen line O I at wavelength 1,356 Å could be used as a tracer of solar-wind electron variability
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