975 research outputs found

    An Empirical Investigation of the Mergers Decision Process in Australia

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    In this paper we examine a database assembled from an Australian public register of 553 merger decisions taken between March 2004 and July 2008. Mergers may be accepted without public assessment, accepted in conjunction with publication of a Public Competition Assessment, or rejected. We estimate an ordered probit model, using these three possible outcomes, with the objective of gaining better insight into the regulator’s decision-making process. Our two major findings are: (i) the existence of entry barriers and the existence of undertakings are highly correlated with the regulator’s decision to closely scrutinise a merger proposal; and (ii) if we compare two decisions, one which does not mention entry barriers (or import competition) with a decision that does mention entry barriers (or import competition), then the latter is significantly more likely to be opposed than the former.

    Testing Regulatory Consistency

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    We undertake an analysis of regulatory consistency using a database of publicly available regulatory decisions in Australia. We propose a simple exploratory model which allows us to test for regulatory consistency across jurisdictions and industries without detailed knowledge of the regulatory process. We compare two measures using our approach--the weighted average cost of capital and the proportion of firms’ revenue requirement claims disallowed by the regulator. We advocate use of the second measure, but our empirical results may be interpreted as indicating that a range of measures ought to be considered when assessing regulatory consistency.

    Thermal Conductivity and Specific Heat of the Spin-Ice Compound Dy2_2Ti2_2O7_7: Experimental Evidence for Monopole Heat Transport

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    Elementary excitations in the spin-ice compound Dy2_2Ti2_2O7_7 can be described as magnetic monopoles propagating independently within the pyrochlore lattice formed by magnetic Dy ions. We studied the magnetic-field dependence of the thermal conductivity {\kappa}(B) for B || [001] and observe clear evidence for magnetic heat transport originating from the monopole excitations. The magnetic contribution {\kappa}_{mag} is strongly field-dependent and correlates with the magnetization M(B). The diffusion coefficient obtained from the ratio of {\kappa}_{mag} and the magnetic specific heat is strongly enhanced below 1 K indicating a high mobility of the monopole excitations in the spin-ice state.Comment: 5 pages, 4 figure

    Substitution effects on the temperature vs. magnetic-field phase diagrams of the quasi-1D effective Ising spin-1/2 chain system BaCo2_2V2_2O8_8

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    BaCo2_2V2_2O8_8 is a one-dimensional antiferromagnetic spin-1/2 chain system with pronounced Ising anisotropy of the magnetic exchange. Due to finite interchain interactions long-range antiferromagnetic order develops below TN5.5T_{\rm N} \simeq 5.5 K, which is accompanied by a structural distortion in order to lift magnetic frustration effects. The corresponding temperature vs.vs. magnetic-field phase diagram is highly anisotropic with respect to the magnetic-field direction and various details are still under vivid discussion. Here, we report the influence of several substitutions on the magnetic properties and the phase diagrams of BaCo2_2V2_2O8_8. We investigate the substitution series Ba1-x_{\text{1-x}}Srx_{\text{x}}Co2_{\text{2}}V2_{\text{2}}O8_{\text{8}} over the full range 0x10\le x \le 1 as well as the influence of a partial substitution of the magnetic Co2+^{2+} by small amounts of other magnetic transition metals or by non-magnetic magnesium. In all cases, the phase diagrams were obtained on single crystals from magnetization data and/or high-resolution studies of the thermal expansion and magnetostriction.Comment: 10 pages, 10 figure

    Efficient Spatio-Temporal Modelling to Enable Topological Analysis

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    Low-temperature ordered phases of the spin-12\frac{1}{2} XXZ chain system Cs2_2CoCl4_4

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    In this study the magnetic order of the spin-1/2 XXZ chain system Cs2_2CoCl4_4 in a temperature range from 50 mK to 0.5 K and in applied magnetic fields up to 3.5 T is investigated by high-resolution measurements of the thermal expansion and the specific heat. Applying magnetic fields along a or c suppresses TNT_\textrm{N} completely at about 2.1 T. In addition, we find an adjacent intermediate phase before the magnetization saturates close to 2.5 T. For magnetic fields applied along b, a surprisingly rich phase diagram arises. Two additional transitions are observed at critical fields μ0HSF10.25\mu_0 H_{SF1}\simeq 0.25 T and μ0HSF20.7\mu_0 H_{SF2}\simeq 0.7 T, which we propose to arise from a two-stage spin-flop transition.Comment: 10 pages, 10 figure

    Topologically Consistent Models for Efficient Big Geo-Spatio-Temporal Data Distribution

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    Geo-spatio-temporal topology models are likely to become a key concept to check the consistency of 3D (spatial space) and 4D (spatial + temporal space) models for emerging GIS applications such as subsurface reservoir modelling or the simulation of energy and water supply of mega or smart cities. Furthermore, the data management for complex models consisting of big geo-spatial data is a challenge for GIS and geo-database research. General challenges, concepts, and techniques of big geo-spatial data management are presented. In this paper we introduce a sound mathematical approach for a topologically consistent geo-spatio-temporal model based on the concept of the incidence graph. We redesign DB4GeO, our service-based geo-spatio-temporal database architecture, on the way to the parallel management of massive geo-spatial data. Approaches for a new geo-spatio-temporal and object model of DB4GeO meeting the requirements of big geo-spatial data are discussed in detail. Finally, a conclusion and outlook on our future research are given on the way to support the processing of geo-analytics and -simulations in a parallel and distributed system environment

    Towards intelligent geo-database support for earth system observation: Improving the preparation and analysis of big spatio-temporal raster data

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    The European COPERNICUS program provides an unprecedented breakthrough in the broad use and application of satellite remote sensing data. Maintained on a sustainable basis, the COPERNICUS system is operated on a free-and-open data policy. Its guaranteed availability in the long term attracts a broader community to remote sensing applications. In general, the increasing amount of satellite remote sensing data opens the door to the diverse and advanced analysis of this data for earth system science. However, the preparation of the data for dedicated processing is still inefficient as it requires time-consuming operator interaction based on advanced technical skills. Thus, the involved scientists have to spend significant parts of the available project budget rather on data preparation than on science. In addition, the analysis of the rich content of the remote sensing data requires new concepts for better extraction of promising structures and signals as an effective basis for further analysis. In this paper we propose approaches to improve the preparation of satellite remote sensing data by a geo-database. Thus the time needed and the errors possibly introduced by human interaction are minimized. In addition, it is recommended to improve data quality and the analysis of the data by incorporating Artificial Intelligence methods. A use case for data preparation and analysis is presented for earth surface deformation analysis in the Upper Rhine Valley, Germany, based on Persistent Scatterer Interferometric Synthetic Aperture Radar data. Finally, we give an outlook on our future research
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