4,570 research outputs found

    Central Banking and the Choice of Currency Regime in Accession Countries

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    The subject matter of this paper is the design of appropriate Central Banking arrangements and exchange rate regimes for those former centrally planned Central and East European countries that are candidates for full membership in the European Union. We give an overview of the existing arrangements and point out to which extent monetary arrangements are restricted by conditions for entry both into the European Union and eventually into the European Monetary Union. Furthermore we investigate to which degree countries are fulfilling the accession criteria and compare their performance with the performance of earlier EU joiners like the countries of the Iberian Peninsula, Ireland and Greece.

    Torsional Newton-Cartan Geometry and Lifshitz Holography

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    We obtain the Lifshitz UV completion in a specific model for z=2 Lifshitz geometries. We use a vielbein formalism which enables identification of all the sources as leading components of well-chosen bulk fields. We show that the geometry induced from the bulk onto the boundary is a novel extension of Newton-Cartan geometry with a specific torsion tensor. We explicitly compute all the vevs including the boundary stress-energy tensor and their Ward identities. After using local symmetries/Ward identities the system exhibits 6+6 sources and vevs. The FG expansion exhibits, however, an additional free function which is related to an irrelevant operator whose source has been turned off. We show that this is related to a second UV completion.Comment: v2: 5 pages, matches version published in PR

    Role of multiorbital effects in the magnetic phase diagram of iron-pnictides

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    We elucidate the pivotal role of the bandstructure's orbital content in deciding the type of commensurate magnetic order stabilized within the itinerant scenario of iron-pnictides. Recent experimental findings in the tetragonal magnetic phase attest to the existence of the so-called charge and spin ordered density wave over the spin-vortex crystal phase, the latter of which tends to be favored in simplified band models of itinerant magnetism. Here we show that employing a multiorbital itinerant Landau approach based on realistic bandstructures can account for the experimentally observed magnetic phase, and thus shed light on the importance of the orbital content in deciding the magnetic order. In addition, we remark that the presence of a hole pocket centered at the Brillouin zone's M{\rm M}-point favors a magnetic stripe rather than a tetragonal magnetic phase. For inferring the symmetry properties of the different magnetic phases, we formulate our theory in terms of magnetic order parameters transforming according to irreducible representations of the ensuing D4h_{\rm 4h} point group. The latter method not only provides transparent understanding of the symmetry breaking schemes but also reveals that the leading instabilities always belong to the {A1g,B1g}\{A_{1g},B_{1g}\} subset of irreducible representations, independent of their C2_2 or C4_4 nature.Comment: 11 pages, 6 figure

    Direct observation of interface and nanoscale compositional modulation in ternary III-As heterostructure nanowires

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    Straight, axial InAs nanowire with multiple segments of GaInAs were grown. High resolution X-ray energy-dispersive spectroscopy (EDS) mapping reveal the distribution of group III atoms at the axial interfaces and at the sidewalls. Significant Ga enrichment, accompanied by a structural change is observed at the GaInAs/InAs interfaces and a higher Ga concentration for the early grown GaInAs segments. The elemental map and EDS line profile infer Ga enrichment at the facet junctions between the sidewalls. The relative chemical potentials of ternary alloys and the thermodynamic driving force for liquid to solid transition explains the growth mechanisms behind the enrichment.Comment: 12 Pages, 4 figure

    Accurate DNA assembly and genome engineering with optimized uracil excision cloning

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    Simple and reliable DNA editing by uracil excision (a.k.a. USER cloning) has been described by several research groups, but the optimal design of cohesive DNA ends for multigene assembly remains elusive. Here, we use two model constructs based on expression of <i>gfp</i> and a four-gene pathway that produces β-carotene to optimize assembly junctions and the uracil excision protocol. By combining uracil excision cloning with a genomic integration technology, we demonstrate that up to six DNA fragments can be assembled in a one-tube reaction for direct genome integration with high accuracy, greatly facilitating the advanced engineering of robust cell factories
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