3,444 research outputs found

    Doppler shift on local density of states and local impurity scattering in the vortex state

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    The vortex state thermal and transport properties of the high T_c copper oxides can be understood in a d-wave gap model and are dominated by the extended quasiparticle states that exist along the nodal directions in momentum space. The Doppler shift on these states due to the circulating supercurrents around the vortex core, introduces new van Hove ridges into the energy dependent local density of states (LDOS) as a function of distance in the region between cores. We emphasize the topology of these ridges and the effect on them of local impurity scattering in Born and unitary limit. We treat possible orthorhombicity. Effective local scttering rates are also obtaines.Comment: 19 pages, 7 Figure

    On the thermal stability of transonic accretion discs

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    Nonlinear time-dependent calculations have been carried out in order to study the evolution of the thermal instability for optically thick, transonic, slim accretion discs around black holes. In the present calculations we have investigated only the original version of the slim disc model with low viscosity. This version does not yet contain several important non-local effects but our aim is to use it as a standard reference against which to compare the results from forthcoming studies in which additional effects will be added one by one thus giving a systematic way of understanding the contribution from each of them. A range of results for different cases is presented showing a number of interesting features. One preliminary conclusion is that the stabilizing effect of advection seems not to be strong enough in these low viscosity models to allow for limit cycle behaviour to occur.Comment: 23 pages, Latex, 11 Postscript figures, accepted by MNRA

    Andreev interferometry as a probe of superconducting phase correlations in the pseudogap regime of the cuprates

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    Andreev interferometry - the sensitivity of the tunneling current to spatial variations in the local superconducting order at an interface - is proposed as a probe of the spatial structure of the phase correlations in the pseudogap state of the cuprate superconductors. To demonstrate this idea theoretically, a simple tunneling model is considered, via which the tunneling current is related to the equilibrium phase-phase correlator in the pseudogap state. These considerations suggest that measurement of the low-voltage conductance through mesoscopic contacts of varying areas provides a scheme for accessing phase-phase correlation information. For illustrative purposes, quantitative predictions are made for a model of the pseudogap state in which the phase (but not the amplitude) of the superconducting order varies randomly, and does so with correlations consistent with certain proposed pictures of the pseudogap state.Comment: 9 pages, 5 figures; 3 references adde

    Near-Field Microwave Microscopy of Materials Properties

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    Near-field microwave microscopy has created the opportunity for a new class of electrodynamics experiments of materials. Freed from the constraints of traditional microwave optics, experiments can be carried out at high spatial resolution over a broad frequency range. In addition, the measurements can be done quantitatively so that images of microwave materials properties can be created. We review the five major types of near-field microwave microscopes and discuss our own form of microscopy in detail. Quantitative images of microwave sheet resistance, dielectric constant, and dielectric tunability are presented and discussed. Future prospects for near-field measurements of microwave electrodynamic properties are also presented.Comment: 31 pages, 9 figures, lecture given at the 1999 NATO ASI on Microwave Superconductivity Changes suggested by editor, including full reference

    EU Cohesion policy 2007-13 and the implications for Spain : who gets what, when and how?

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    The recent negotiation of the EU budget and the associated reform of EU Cohesion policy have had major policy implications for Spain, the country in receipt of most Cohesion policy support in the current programming period (2000-06). EU enlargement, combined with relatively rapid growth in Spain, impacted on the eligibility of Spanish regions for Cohesion support while also taking the country as a whole beyond the eligibility threshold for the Cohesion Fund. As a result, based on the original Commission budget proposals of February 2004, Spain was facing a reduced Cohesion policy budget of at least a half (to below €30 billion). This paper first reviews the budget negotiations from a Spanish (Cohesion policy) perspective, identifying the key negotiating goals and the extent to which they were achieved. It then looks at the outcome of the negotiations for Spain, initially at the national level and then in the regions. It highlights the significant differential impacts of the cutbacks in Cohesion policy allocations at the regional level and the pressures on the Spanish government to modulate the regional impact of the budgetary changes. Having considered the direct funding implications of the new Cohesion policy, the second half of the paper is concerned with the regulatory, institutional and economic impacts of the new policy regime. Many of the reform proposals fit with Spanish priorities, not least the new rationale for Cohesion policy (with its stress on the Lisbon and Gothenburg agendas) and the new policy architecture (with all regions eligible for some form of support and with a related shift from a geographic to more of a thematic focus). The retention of the key Structural Funds principles has also been welcomed in Spain, unsurprising given the wealth of experience and expertise built up over three (high-spending) programming cycles. As in most Member States, the main regulatory concern relates to the extent to which a more simplified and devolved approach to Funds' implementation will be achieved in practice. As regards policy and institutional impacts, the paper brings together regional views on the new budgetary and regulatory frameworks and reviews how the new regulations are being implemented in practice. A discussion of the developing National Strategic Reference Framework and the related Operational Programmes makes clear that the strong emphasis on the Lisbon agenda is not viewed as a constraint in Spain; rather, it is felt to fit well with recent Spanish developments and goals. Finally, the paper considers the economic implications of the reductions in Cohesion policy support. On the basis of evaluation studies, it highlights the positive impact the Funds have had in the past and the potentially quite varied regional impacts the reductions in funding may have in the future

    Queering Jesus: LGBTQI Dangerous Remembering and Imaginative Resistance

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    Queering Jesus is a call to remember the danger of the story of Jesus. The primary aim of this article is to offer a comprehensive survey of the representation of queer Jesus. Building upon the deconstructive work of Johannes Baptist Metz and the notion of the dangerous memories of Jesus’s suffering and death (memoria passsionis), this article tries to make sense of the deconstruction of heteronormative and cisgender constructions of a white, male Jesus that supports the exclusion and oppression of queer folks. Queer constructions of Jesus in biblical interpretation and popular media are accused of being blasphemous fictions, while the same charge can be levied against the constructions of heteronormative and cisgender Christian churches who marginalize and stigmatize LGBTQI people. The imaginative remembering of the dangerous story of Jesus empowers queer folks to liberate and create a queer Jesus who allows LGBTQI Christians to experience the liberating presence of Jesus, to experience themselves as beloved, and to empower them to take back an inclusive Christianity

    Early estimates of seasonal influenza vaccine effectiveness in Europe among target groups for vaccination: results from the I-MOVE multicentre case-control study, 2011/12

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    Colaboração de: Baltazar Nunes, investigador do DEPTo provide an early estimate of 2011/12 influenza vaccine effectiveness (VE), we conducted a multicentre case–control study based on seven sentinel surveillance networks. We included influenza-like illness cases up to week 7/2012 from the vaccination target groups, swabbed less than eight days after symptom onset. Laboratory-confirmed influenza A(H3) cases were compared to negative controls. Adjusted VE was 43% (95% confidence interval: -0.4 to 67.7), suggesting low to moderate VE against influenza A(H3) in the early 2011/12 season

    Policy democracy? Social and material participation in biodiesel policy-making processes in India

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    Following its 2003 biodiesel mission, the Indian national government released its controversial policy on biodiesel in December 2009. Viewing the policy as a set of propositions that have been progressively assembled and constituted by many voices, we study its making on the basis of 72 qualitative interviews and ethnographic fieldwork. We consider the policy-making process to constitute policy democracy if its propositions were well-articulated. A well-articulated proposition is one that has registered the voices of many different human and nonhuman entities, including those that were hitherto mute. In addition, a well-articulated proposition must have allowed the entities to challenge and recompose it. And it must not have turned the entities’ actions and voices into a repetitive singularity. Finally, a well-articulated proposition is not easily transferrable between different socio-ecological situations. We argue that the Indian government attempted to perform policy democracy, by being partially responsive to some entities’ recalcitrance. However, it failed to register crucial voices associated with biodiesel production such as those of water and CO2. It also turned many voices into repetitive singularities, discounting the different relations that allow an entity to speak in multiple voices. The policy’s propositions remained easily transferrable between diverse socio-ecological situations, ignoring the immense diversity of India’s lands, their inhabitants and their practices associated with biodiesel production. Finally, due to a severe disconnect between the various voices registered in its different propositions, we argue that the policy lacked overall consistency

    Utilizing Astroinformatics to Maximize the Science Return of the Next Generation Virgo Cluster Survey

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    The Next Generation Virgo Cluster Survey is a 104 square degree survey of the Virgo Cluster, carried out using the MegaPrime camera of the Canada-France-Hawaii telescope, from semesters 2009A-2012A. The survey will provide coverage of this nearby dense environment in the universe to unprecedented depth, providing profound insights into galaxy formation and evolution, including definitive measurements of the properties of galaxies in a dense environment in the local universe, such as the luminosity function. The limiting magnitude of the survey is g_AB = 25.7 (10 sigma point source), and the 2 sigma surface brightness limit is g_AB ~ 29 mag arcsec^-2. The data volume of the survey (approximately 50 terabytes of images), while large by contemporary astronomical standards, is not intractable. This renders the survey amenable to the methods of astroinformatics. The enormous dynamic range of objects, from the giant elliptical galaxy M87 at M(B) = -21.6, to the faintest dwarf ellipticals at M(B) ~ -6, combined with photometry in 5 broad bands (u* g' r' i' z'), and unprecedented depth revealing many previously unseen structures, creates new challenges in object detection and classification. We present results from ongoing work on the survey, including photometric redshifts, Virgo cluster membership, and the implementation of fast data mining algorithms on the infrastructure of the Canadian Astronomy Data Centre, as part of the Canadian Advanced Network for Astronomical Research (CANFAR).Comment: 8 pages, 2 figures. Accepted for the Joint Workshop and Summer School: Astrostatistics and Data Mining in Large Astronomical Databases, La Palma, May 30th - June 3rd 2011. A higher resolution version is available at http://sites.google.com/site/nickballastronomer/publication
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