130 research outputs found

    Monitoring Foraging Behavior in Ruminants in a Diverse Pasture

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    Symposium mini revie

    Collective Phase Sensitivity

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    The collective phase response to a macroscopic external perturbation of a population of interacting nonlinear elements exhibiting collective oscillations is formulated for the case of globally-coupled oscillators. The macroscopic phase sensitivity is derived from the microscopic phase sensitivity of the constituent oscillators by a two-step phase reduction. We apply this result to quantify the stability of the macroscopic common-noise induced synchronization of two uncoupled populations of oscillators undergoing coherent collective oscillations.Comment: 6 pages, 3 figure

    Noise-Induced Synchronization and Clustering in Ensembles of Uncoupled Limit-Cycle Oscillators

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    We study synchronization properties of general uncoupled limit-cycle oscillators driven by common and independent Gaussian white noises. Using phase reduction and averaging methods, we analytically derive the stationary distribution of the phase difference between oscillators for weak noise intensity. We demonstrate that in addition to synchronization, clustering, or more generally coherence, always results from arbitrary initial conditions, irrespective of the details of the oscillators.Comment: 6 pages, 2 figure

    Spectral detection of grazing degradation in the Xilingol Steppe, Inner Mongolia

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    In order to detect the grazing degradation of steppe vegetation, spectral reflectance was measured using a portable spectral radiometer in the Xilingol steppe, Inner Mongolia. There is only one main drinking place for animals, which is supplied by a water tank at the center of Branch No.4 site-00. In addition to the measurement of surface reflectance, vegetation surveys were carried out involving floristic composition and plant growth parameters as a function of the distance from site-00 at every 1-km interval until the 5-km point. It becomes clear that the effects of grazing on vegetation and soil mitigated according to the distance from site-00. Negative plant indicators of grazing intensity such as Stipa grandis and Filifolium sibiricum increased in dominance with distance from site-00, whereas positive indicators of grazing intensity, such as Cleistogenens squarrosa and Agropyron cristatum, decreased in dominance. Changes in growth parameters along the environmental gradients were reflected on NDVI (Normalized Difference Vegetation Index), in which NDVI was positively correlated with the aboveground biomass (r=0.77, P<0.001), plant height (r=0.69, P<0.001) and coverage (r=0.89, P<0.001), respectively. These results suggested that a spectral vegetation index is effective in the detection of the degradation of grazing grassland in a non-destruction way.Original Pape

    Bayesian Modeling for Estimating Cattle’s Dung position in Pasture

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    Livestock excrement is one of the major sources of greenhouse gas (GHG) emission in pasture. As a first step in evaluating its contribution to overall GHG emissions, an understanding of excretion distribution patterns in pastures is required. Betteridge et al. (2010) describe a urine sensor that detects and logs each urination event of female sheep and cattle. The urine sensor records time and ambient temperature at one-second intervals however, patters of dung distribution are not specified. The objective of this study was to predict spatial distribution of cattle dung. The knowledge of livestock excrement position may be useful for farmers to minimize overall GHG emissions

    Transvenous embolisation via an occluded inferior petrosal sinus for cavernous sinus dural arteriovenous fistulas

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    Aim of the study: We retrospectively searched for cases of transvenous embolisation for cavernous sinus dural arteriovenous fistulas.Materials and methods: Twenty-five cases underwent transvenous embolisation via the inferior petrosal sinus (IPS). IPS was probed using a standard 0.035-inch guidewire for microcatheter navigation, which was successful in all cases.Results: IPS was occluded in 17 cases (68%). Only one case experienced a complication, where the approach was changed to the contralateral side because of internal jugular vein injury. The relationship between the external auditory canal and the IPS route was reviewed in 18 cases using digital angiography (lateral view). The guidewire passed across, above, or below the external auditory canal in 10 (56%), six (33%), and two (11%) cases, respectively.Clinical implications: No previous reports have analysed the relationship between the external auditory canal and the IPS route. We present a safe and successful technique for approaching the cavernous sinus via the IPS

    Collective dynamical response of coupled oscillators with any network structure

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    We formulate a reduction theory that describes the response of an oscillator network as a whole to external forcing applied nonuniformly to its constituent oscillators. The phase description of multiple oscillator networks coupled weakly is also developed. General formulae for the collective phase sensitivity and the effective phase coupling between the oscillator networks are found. Our theory is applicable to a wide variety of oscillator networks undergoing frequency synchronization. Any network structure can systematically be treated. A few examples are given to illustrate our theory.Comment: 4 pages, 2 figure

    Phase synchronization between collective rhythms of globally coupled oscillator groups: noisy identical case

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    We theoretically investigate collective phase synchronization between interacting groups of globally coupled noisy identical phase oscillators exhibiting macroscopic rhythms. Using the phase reduction method, we derive coupled collective phase equations describing the macroscopic rhythms of the groups from microscopic Langevin phase equations of the individual oscillators via nonlinear Fokker-Planck equations. For sinusoidal microscopic coupling, we determine the type of the collective phase coupling function, i.e., whether the groups exhibit in-phase or anti-phase synchronization. We show that the macroscopic rhythms can exhibit effective anti-phase synchronization even if the microscopic phase coupling between the groups is in-phase, and vice versa. Moreover, near the onset of collective oscillations, we analytically obtain the collective phase coupling function using center-manifold and phase reductions of the nonlinear Fokker-Planck equations.Comment: 15 pages, 7 figure
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