81,925 research outputs found

    Competition between noise and coupling in the induction of synchronisation.

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    We apply a Fokker-Planck analysis to investigate the relative influences of coupling strength and noise on the synchronisation of two phase oscillators. We go beyond earlier studies of noise-induced synchronisation (without couplings) and coupling-induced synchronisation (without common noise) to consider both effects together, and we obtain a result that is very different from a straightforward superposition of the effects of each agent acting alone: two regimes are possible depending on which agent is inducing the synchronisation. In each regime, one agent induces and the other hinders the synchronisation. In particular we show that, counterintuitively, coupling can sometimes inhibit synchronisation

    Verification of Shared-Reading Synchronisers

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    Synchronisation classes are an important building block for shared memory concurrent programs. Thus to reason about such programs, it is important to be able to verify the implementation of these synchronisation classes, considering atomic operations as the synchronisation primitives on which the implementations are built. For synchronisation classes controlling exclusive access to a shared resource, such as locks, a technique has been proposed to reason about their behaviour. This paper proposes a technique to verify implementations of both exclusive access and shared-reading synchronisers. We use permission-based Separation Logic to describe the behaviour of the main atomic operations, and the basis for our technique is formed by a specification for class AtomicInteger, which is commonly used to implement synchronisation classes in java.util.concurrent. To demonstrate the applicability of our approach, we mechanically verify the implementation of various synchronisation classes like Semaphore, CountDownLatch and Lock.Comment: In Proceedings MeTRiD 2018, arXiv:1806.0933

    Staggering and Synchronisation of Prices in a Low Inflation Environment: Evidence from German Food Stores

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    Only a few studies have analysed staggering and synchronisation in pricing behaviour of multi-product firms. These studies used low-frequency data in an environment of high rates of inflation. This paper investigates staggering and synchronisation of weekly prices for ten food products in 131 grocery stores in Germany over the period from May 1995 to December 2000 (296 weeks). Different forms of staggering and synchronisation (across-store synchronisation, within type-of-store synchronisation, within retailer synchronisation or across-product synchronisation) have been analysed. None of these forms of synchronisation is supported empirically however. In contrast, perfect staggering can only be rejected in very few cases indicating that fixed or firm specific menu costs are not major causes for price stickiness. --Food Retail Market,Germany,Pricing Behaviour,Menu Costs

    A power-law distribution of phase-locking intervals does not imply critical interaction

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    Neural synchronisation plays a critical role in information processing, storage and transmission. Characterising the pattern of synchronisation is therefore of great interest. It has recently been suggested that the brain displays broadband criticality based on two measures of synchronisation - phase locking intervals and global lability of synchronisation - showing power law statistics at the critical threshold in a classical model of synchronisation. In this paper, we provide evidence that, within the limits of the model selection approach used to ascertain the presence of power law statistics, the pooling of pairwise phase-locking intervals from a non-critically interacting system can produce a distribution that is similarly assessed as being power law. In contrast, the global lability of synchronisation measure is shown to better discriminate critical from non critical interaction.Comment: (v3) Fixed error in Figure 1; (v2) Added references. Minor edits throughout. Clarified relationship between theoretical critical coupling for infinite size system and 'effective' critical coupling system for finite size system. Improved presentation and discussion of results; results unchanged. Revised Figure 1 to include error bars on r and N; results unchanged; (v1) 11 pages, 7 figure

    A fresh look at business cycle synchronisation in the euro area

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    This paper revisits the issue of business cycle synchronisation in the euro area looking back on more than eight years of EMU experience. The dispersion of output gaps across Member States has reached historically low levels since around 2002. Yet, this observation seems to reflect a general decrease in the amplitude of cyclical fluctuations rather than a continued increase in business cycle synchronisation. Using cross-country correlations, the mean level of synchronisation of national cycles within the currency union since 1999 is found to be overall high, though not higher than in the first half of the nineties. Around 2003, the level of cross-country synchronisation experienced a quite abrupt decrease. This picture is shared between several measures of the business cycle. A rebound and partial recovery of cross-country synchronisation is indicated from around 2004 onwards. The observed dip in synchronisation thus appears to be a transitory phenomenon, partly rooted in a recurrent pattern of falling business cycle synchronisation in early recovery phases.Business cycles, synchronisation, convergence, EMUBusiness cycles, synchronisation, convergence, EMU, Gayer

    A dynamic model for real-time tracking of hands in bimanual movements

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    The problem of hand tracking in the presence of occlusion is addressed. In bimanual movements the hands tend to be synchronised effortlessly. Different aspects of this synchronisation are the basis of our research to track the hands. The spatial synchronisation in bimanual movements is modelled by the position and the temporal synchronisation by the velocity and acceleration of each hand. Based on a dynamic model, we introduce algorithms for occlusion detection and hand tracking