701 research outputs found

    A Careful Examination of the Live Nation-Ticketmaster Merger

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    As great admirers of The Boss and as fans of live entertainment, we share in the popular dismay over rising ticket prices for live performances. But we have been asked as antitrust scholars to examine the proposed merger of Live Nation and Ticketmaster, and we do so with the objectivity and honesty called for by The Boss’s quotes above. The proposed merger has been the target of aggressive attacks from several industry commentators and popular figures, but the legal and policy question is whether the transaction is at odds with the nation’s antitrust laws. One primary source of concern to critics is that Ticketmaster and Live Nation are two leading providers of ticket distribution services, and these critics argue that the merged entity would have a combined market share that is presumptively anticompetitive. We observe, however, that this transaction is taking place within a rapidly changing industry. The spread of Internet technologies has transformed the entertainment industry, and along with it the ticket distribution business such that a reliance on market shares based on historical sales is misleading. A growing number of venues, aided by a competitive bidding process that creates moments of focused competition, can now acquire the requisite capabilities to distribute tickets to their own events and can thus easily forgo reliance upon providers of outsourced distribution services. If self-distribution is an available and attractive option for venues, as it appears to be, then it is unlikely that even a monopolist provider of fully outsourced ticketing services could exercise market power. Ultimately, a proper assessment of the horizontal effects of this merger would have to weigh heavily the emerging role of Internet technologies in this dynamic business and the industry-wide trend towards self-distribution. The second category of arguments by critics opposing the merger rests on claims that vertical aspects of the transaction would produce anticompetitive effects. Indeed, Ticketmaster’s and Live Nation’s core businesses are in successive markets, and thus the proposed transaction is primarily a vertical merger, but there is broad agreement among economists and antitrust authorities that vertical mergers rarely introduce competitive concerns and are usually driven by efficiency motivations. This wealth of academic scholarship, which is reflected in current antitrust law, has not - from our vantage point - been properly incorporated into the public dialogue concerning the proposed merger. To the contrary, critics articulate concerns, including the fears that the merger would lead to the leveraging of market power and the foreclosure of downstream competition, that are refuted by accepted scholarship. Moreover, there are a number of specific efficiencies that, consistent with economic and organizational theory, are likely to emerge from a Live Nation-Ticketmaster merger and would be unlikely but for the companies’ integration. For these reasons, we submit this analysis in an effort to inform the debate with current economic and legal scholarship

    A 110,000-year History of Change in Continental Biogenic Emissions and Related Atmospheric Circulation Inferred from the Greenland Ice Sheet Project Ice Core

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    The 110,000-year record of ammonium concentrations from the Greenland Ice Sheet Project 2 (GISP2) ice core provides the basis for an analysis of terrestrial biological production and atmospheric circulation patterns involved in the transport of biologically produced ammonium to the Greenland atmosphere. The directly measured concentration series was selected for analysis, rather than that of estimated ammonium flux, after a detailed analysis of the relationship among ice core glaciochemical concentrations and a high-resolution simultaneous record of snow accumulation from the GISP2 core. Analysis of the ammonium concentration series shows that maxima in background levels of ammonium in the Greenland atmosphere are strongly related to and synchronous with summer forcing associated with the precessional cycle of insolation. Minima in background levels, on the other hand, are delayed relative to minima in summer insolation at those times when ice volume is significant. The duration of these delays are similar in magnitude (≈6000 years) to other paleoclimatic responses to changes in ice volume. Decadal and centennial scale variation about background levels of ammonium concentration exhibit two modes of behavior when compared to a record of polar atmospheric circulation intensity. During warmer periods ammonium transport to Greenland is similar to present patterns. Under coldest conditions the low levels of ammonium transported to Greenland are the result of extreme southerly excursions of the predominantly zonal polar circulation. The rapid transitions (≈200 years) between these two climatic conditions appear to be associated with a critical volume or extent of the continental ice sheets

    Grid-texture mechanisms in human vision:contrast detection of regular sparse micro-patterns requires specialist templates

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    Previous work has shown that human vision performs spatial integration of luminance contrast energy, where signals are squared and summed (with internal noise) over area at detection threshold. We tested that model here in an experiment using arrays of micro-pattern textures that varied in overall stimulus area and sparseness of their target elements, where the contrast of each element was normalised for sensitivity across the visual field. We found a power-law improvement in performance with stimulus area, and a decrease in sensitivity with sparseness. While the contrast integrator model performed well when target elements constituted 50–100% of the target area (replicating previous results), observers outperformed the model when texture elements were sparser than this. This result required the inclusion of further templates in our model, selective for grids of various regular texture densities. By assuming a MAX operation across these noisy mechanisms the model also accounted for the increase in the slope of the psychometric function that occurred as texture density decreased. Thus, for the first time, mechanisms that are selective for texture density have been revealed at contrast detection threshold. We suggest that these mechanisms have a role to play in the perception of visual textures

    The Retail FX Trader: Random Trading and the Negative Sum Game

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    With the internet boom of early 2000 making access to trading the Foreign Exchange (FX) market far simpler for members of the general public, the growth of 'retail' FX trading continues, with daily transaction volumes as high as $200 billion. Potential new entrants to the retail FX trading world may come from the recent UK pension deregulations, further increasing the volumes. The attraction of FX trading is that it offers high returns and whilst it has been understood that it is high-risk in nature, the rewards are seen as being commensurately high for the 'skilled and knowledgeable' trader who has an edge over other market participants. This paper analyses a number of independent sources of data and previous research, to examine the profitability of the Retail FX trader and compares the results with that of a simulated random trading models. This paper finds evidence to suggest that whilst approximately 20% of traders can expect to end up with a profitable account, around 40% might expect their account to be subject to a margin call. This paper finds a strong correlation between the overall profitability of traders and impact of the cost of the bid-ask spread, whilst finding little if any evidence that retail FX traders, when viewed as a group, are achieving results better than that from random trading

    The Effect of Interocular Phase Difference on Perceived Contrast

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    Binocular vision is traditionally treated as two processes: the fusion of similar images, and the interocular suppression of dissimilar images (e.g. binocular rivalry). Recent work has demonstrated that interocular suppression is phase-insensitive, whereas binocular summation occurs only when stimuli are in phase. But how do these processes affect our perception of binocular contrast? We measured perceived contrast using a matching paradigm for a wide range of interocular phase offsets (0–180°) and matching contrasts (2–32%). Our results revealed a complex interaction between contrast and interocular phase. At low contrasts, perceived contrast reduced monotonically with increasing phase offset, by up to a factor of 1.6. At higher contrasts the pattern was non-monotonic: perceived contrast was veridical for in-phase and antiphase conditions, and monocular presentation, but increased a little at intermediate phase angles. These findings challenge a recent model in which contrast perception is phase-invariant. The results were predicted by a binocular contrast gain control model. The model involves monocular gain controls with interocular suppression from positive and negative phase channels, followed by summation across eyes and then across space. Importantly, this model—applied to conditions with vertical disparity—has only a single (zero) disparity channel and embodies both fusion and suppression processes within a single framework

    Stacking chairs:local sense and global nonsense

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    We report a confusing stimulus which demonstrates the power of local interpretation of threedimensional structure to disrupt a coherent global perception

    A New Technique for Firn Grain-Size Measurement Using SEM Image Analysis

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    Firn microstructure is accurately characterized using images obtained from scanning electron microscopy (SEM). Visibly etched grain boundaries within images are used to create a skeleton outline of the microstructure. A pixel-counting utility is applied to the outline to determine grain area. Firn grain sizes calculated using the technique described here are compared to those calculated using the techniques of Cow (1969) and Gay and Weiss (1999) on samples of the same material, and are found to be substantially smaller. The differences in grain size between the techniques are attributed to sampling deficiencies (e.g. the inclusion of pore filler in the grain area) in earlier methods. The new technique offers the advantages of greater accuracy and the ability to determine individual components of the microstructure (grain and pore), which have important applications in ice-core analyses. The new method is validated by calculating activation energies of grain boundary diffusion using predicted values based on the ratio of grain-size measurements between the new and existing techniques. The resulting activation energy falls within the range of values previously reported for firn/ice

    On the Nature of Memory and Rejuvenation in Glassy Systems

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    The memory effect in a single crystal spin glass (Cu0.92Mn0.08\mathrm{Cu}_{0.92}\mathrm{Mn}_{0.08}) has been measured using 1Hz1 \mathrm{Hz} ac susceptibility techniques over a reduced temperature range of 0.40.7Tg0.4 - 0.7 \, T_g and a model of the memory effect has been developed. A double-waiting-time protocol is carried out where the spin glass is first allowed to age at a temperature below TgT_g, followed by a second aging at a lower temperature after it has fully rejuvenated. The model is based on calculating typical coincidences between the growth of correlated regions at the two temperatures. It accounts for the absolute magnitude of the memory effect as a function of both waiting times and temperatures. The data can be explained by the memory loss being a function of the relative change in the correlated volume at the first waiting temperature because of the growth in the correlations at the second waiting temperature.Comment: 11 pages, 6 figure

    Joint modelling of multi-scale animal movement data using hierarchical hidden Markov models

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    1.Hidden Markov models are prevalent in animal movement modelling, where they are widely used to infer behavioural modes and their drivers from various types of telemetry data. To allow for meaningful inference, observations need to be equally spaced in time, or otherwise regularly sampled, where the corresponding temporal resolution strongly affects what kind of behaviours can be inferred from the data. 2.Recent advances in biologging technology have led to a variety of novel telemetry sensors which often collect data from the same individual simultaneously at different time scales, e.g. step lengths obtained from GPS tags every hour, dive depths obtained from time‐depth recorders once per dive, or accelerations obtained from accelerometers several times per second. However, to date, statistical machinery to address the corresponding complex multi‐stream and multi‐scale data is lacking. 3.We propose hierarchical hidden Markov models as a versatile statistical framework that naturally accounts for differing temporal resolutions across multiple variables. In these models, the observations are regarded as stemming from multiple, connected behavioural processes, each of which operates at the time scale at which the corresponding variables were observed. 4.By jointly modelling multiple data streams, collected at different temporal resolutions, corresponding models can be used to infer behavioural modes at multiple time scales, and in particular help to draw a much more comprehensive picture of an animal's movement patterns, e.g. with regard to long‐term vs. short‐term movement strategies. 5.The suggested approach is illustrated in two real‐data applications, where we jointly model i) coarse‐scale horizontal and fine‐scale vertical Atlantic cod (Gadus morhua) movements throughout the English Channel, and ii) coarse‐scale horizontal movements and corresponding fine‐scale accelerations of a horn shark (Heterodontus francisci) tagged off the Californian coast
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