Holography from Conformal Field Theory

The locality of bulk physics at distances below the AdS length is one of the remarkable aspects of AdS/CFT duality, and one of the least tested. It requires that the AdS radius be large compared to the Planck length and the string length. In the CFT this implies a large-N expansion and a gap in the spectum of anomalous dimensions. We conjecture that the implication also runs in the other direction, so that any CFT with a planar expansion and a large gap has a local bulk dual. For an abstract CFT we formulate the consistency conditions, most notably crossing symmetry, and show that the conjecture is true in a broad range of CFT's, to first nontrivial order in 1/N^2: any CFT with a gap and a planar expansion is generated via the AdS/CFT dictionary from a local bulk interaction. We establish this result by a counting argument on each side, and also investigate various properties of some explicit solutions.Comment: 49 pages. Minor corrections. Figure and references adde

Big Data and Changes in Audit Technology: Contemplating a Research Agenda

This study explores the most recent episode in the evolution of audit technology, namely the incorporation of Big Data and Data Analytics (BDA) into audit firm approaches. Drawing on 22 interviews with individuals with significant experience in developing, implementing or assessing the impact of BDA in auditing, together with publicly available documents on BDA published within the audit field, the paper provides a holistic overview of BDA-related changes in audit practice. In particular, the paper focuses on three key aspects, namely the impact of BDA on the nature of the relationship between auditors and their clients; the consequences of the technology for the conduct of audit engagements and the common challenges associated with embedding BDA in the audit context. The study’s empirical findings are then used to establish an agenda of areas suitable for further research on the topic. The study is one of the first empirical accounts providing a perspective on the rise of BDA in auditing

Site characterization and performance assessment for a low-level radioactive waste management site in the American Southwest

The Area 5 Radioactive Waste Management Site located in southern Nevada, has been used for the disposal of low-level radioactive waste since 1961. The site is located in the Mohave Desert of the American Southwest, an extremely arid region receiving as little as 0.1 m/yr of precipitation. Site characterization studies have measured the physical, hydrologic, and geochemical properties of core samples collected from 10 shallow boreholes and 3 deep boreholes that extend through the unsaturated zone to the uppermost aquifer. Results indicate that the unsaturated zone consists of 240 m of dry alluvial sediments and is remarkably uniform with respect to most physical parameters. Measurements of saturated hydraulic conductivity with depth showed no evidence of trends, layering, or anisotropy. Parameters for hydraulic functions were not highly variable and exhibited little trend with depth. Water potential profiles indicate that water movement in the upper alluvium is upward, except immediately following a precipitation event. Below the evaporative zone, the liquid flux was downward and of the same order of magnitude as the upward thermal vapor flux induced by the geothermal gradient. The extreme climatic conditions at the site reduce or eliminate many radionuclide release and transport mechanisms. Downward transport of radionuclides to the uppermost aquifer appears unlikely under current climatic conditions. Important radionuclide transport pathways appear to be limited to upward diffusion and advection of gases and biologically-mediated transport. Conceptual models of disposal site performance have been developed based on site characterization studies. The limited transport pathways and limited land use potential of the site provide reasonable assurance that regulatory performance objectives can be met

Effect of Sn addition in preprecipitation stage in Al-Cu alloys: A correlative transmission electron microscopy and atom probe tomography study

The effect of a trace addition of Sn (0.01 at. pct) in Al-1.7Cu (at. pct) alloy in the preprecipitation stage has been investigated by atom probe tomography (APT) and transmission electron microscopy (TEM). APT demonstrates that Sn clusters form independently of Cu in the as-quenched (AQ) state in Al-1.7Cu-0.01Sn alloy. The Sn clusters lead to the rapid nucleation of β-Sn precipitates during increased temperature aging. The APT analysis also indicates that Cu tends to cluster with Sn when the increased temperature aging commences. The TEM experiments revealed that GP zones formed during the first 30 seconds of aging at 473 K (200 °C) in both alloys. These GP zones were unstable and underwent a reversion reaction such that they were not detected after 180 seconds of aging. This process is thought to arise from heating rate effects and, at these higher temperatures, supplies a flux of Cu atoms that results in the heterogeneous nucleation of the θ′ (Al2Cu) phase

Context-dependent and epistemic uses of attention for perceptual-demonstrative identification

Object identification via a perceptual-demonstrative mode of presentation has been studied in cognitive science as a particularly direct and context-dependent means of identifying objects. Several recent works in cognitive science have attempted to clarify the relation between attention, demonstrative identification and context exploration. Assuming a distinction between ‘(language-based) demonstrative reference’ and ‘perceptual demonstrative identification’, this article aims at specifying the role of attention in the latter and in the linking of conceptual and non conceptual contents while exploring a spatial context. First, the analysis presents an argument to the effect that selection by overt and covert attention is needed for perceptual demonstrative identification since overt/covert selective attention is required for the situated cognitive access to the target object. Second, it describes a hypothesis that makes explicit some of the roles of attention: the hypothesis of identification by epistemic attention via the control of perceptual routines.13 page(s