539 research outputs found

    The resource curse without natural resources: expectations of resource booms and their impact

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    Many resource rich countries have experienced a range of negative economic and political effects from natural resource extraction, often lumped together as the ‘resource curse’. This article investigates to what extent future expectations of natural resource booms in São Tomé e Príncipe and Madagascar led to ‘resource curse’ effects even though these countries did not experience the expected natural resource booms. It finds that both countries did experience resource curse effects as a result of future expectations, including volatile economic growth and deteriorated governance. The article demonstrates that shared aspirations and expectations alone may make for material political and economic outcomes even when they become visibly divorced from reality. Thus, there is much more to resource curse effects than simply the product of the material extraction of natural endowments. At a time of extremely volatile prices for primary commodities, and the relatively easy availability of investment capital and credit to support speculative ventures that in turn incentivize resource hype, it is likely that a growing number of countries may suffer the malign effects of a resource curse without natural resource extraction

    Rebuttal to "Comment by V.M. Krasnov on 'Counterintuitive consequence of heating in strongly-driven intrinsic junctions of Bi2Sr2CaCu2O8+d Mesas' "

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    In our article [1], we found that with increasing dissipation there is a clear, systematic shift and sharpening of the conductance peak along with the disappearance of the higher-bias dip/hump features (DHF), for a stack of intrinsic Josephson junctions (IJJs) of intercalated Bi2Sr2CaCu2O8+{\delta} (Bi2212). Our work agrees with Zhu et al [2] on unintercalated, pristine Bi2212, as both studies show the same systematic changes with dissipation. The broader peaks found with reduced dissipation [1,2] are consistent with broad peaks in the density-of-states (DOS) found among scanning tunneling spectroscopy [3] (STS), mechanical contact tunneling [4] (MCT) and inferred from angle (momentum) resolved photoemission spectroscopy [5] (ARPES); results that could not be ignored. Thus, sharp peaks are extrinsic and cannot correspond to the superconducting DOS. We suggested that the commonality of the sharp peaks in our conductance data, which is demonstrably shown to be heating-dominated, and the peaks of previous intrinsic tunneling spectroscopy (ITS) data implies that these ITS reports might need reinterpretation.Comment: Rebuttal to Comment of Krasnov arXiv:1007.451

    Pressure and isotope effect on the anisotropy of MgB2_{2}

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    We analyze the data for the pressure and boron isotope effect on the temperature dependence of the magnetization near TcT_{c}. Invoking the universal scaling relation for the magnetization at fixed magnetic field it is shown that the relative shift of TcT_{c}, induced by pressure or boron isotope exchange, mirrors essentially that of the anisotropy. This uncovers a novel generic property of anisotropic type II superconductors, inexistent in the isotropic case. For MgB2_{2} it implies that the renormalization of the Fermi surface topology due to pressure or isotope exchange is dominated by a mechanism controlling the anisotropy.Comment: 7 pages, 3 figure

    Low temperature vortex phase diagram of Bi2Sr2CaCu2O8 : a magnetic penetration depth study

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    We report measurements of the magnetic penetration depth \lambda_m(T) in the presence of a DC magnetic field in optimally doped BSCCO-2212 single crystals. Warming, after magnetic field is applied to a zero-field cooled sample, results in a non-monotonic \lambda_m(T), which does not coincide with a curve obtained upon field cooling, thus exhibiting a hysteretic behaviour. We discuss the possible relation of our results to the vortex decoupling, unbinding, and dimensional crossover.Comment: M2S-HTSC-V

    Pulled apart, pushed together: diversity and unity within the Congress of South African Trade Unions

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    This is a study of horizontal and vertical solidarity within a national labour movement, based on a nationwide survey of members of affiliated unions of the Congress of South African Trade Unions. On the one hand, the survey reveals relatively high levels of vertical and horizontal solidarity, despite the persistence of some cleavages on gender and racial lines. On the other hand, the maintenance and deepening of existing horizontal and vertical linkages in a rapidly changing socio-economic context, represents one of many challenges facing organized labour in an industrializing economy. COSATU’s strength is contingent not only on an effective organizational capacity, and a supportive network linking key actors and interest groupings, but also on the ability to meet the concerns of existing constituencies and those assigned to highly marginalized categories of labour

    On the Reconstructed Fermi Surface in the Underdoped Cuprates

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    The Fermi surface topologies of underdoped samples the high-Tc superconductor Bi2212 have been measured with angle resolved photoemission. By examining thermally excited states above the Fermi level, we show that the Fermi surfaces in the pseudogap phase of underdoped samples are actually composed of fully enclosed hole pockets. The spectral weight of these pockets is vanishingly small at the anti-ferromagnetic zone boundary, which creates the illusion of Fermi "arcs" in standard photoemission measurements. The area of the pockets as measured in this study is consistent with the doping level, and hence carrier density, of the samples measured. Furthermore, the shape and area of the pockets is well reproduced by a phenomenological model of the pseudogap phase as a spin liquid.Comment: 4 pages, 4 figures. Submitted to Physics Review Letter

    Anisotropy of Transverse Sound in the Heavy-Fermion Superconductor UPt_3

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    We report the first measurements of the attenuation of ultrasound in the basal plane of superconducting UPt_3. Transverse sound propagating along the b axis shows a marked anisotropy in its temperature dependence when the polarization is rotated in and out of the basal plane. For polarization in the basal plane the attenuation varies linearly with temperature down to 35 mK and the slope scales as the square of the frequency. Our results appear to indicate the presence of an additional attenuation mechanism when compared with recent theories of anisotropic superconductors in the dirty limit
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