1,584 research outputs found

    Two-dimensional structures in the quintic Ginzburg-Landau equation

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    By using ZEUS cluster at Embry-Riddle Aeronautical University we perform extensive numerical simulations based on a two-dimensional Fourier spectral method Fourier spatial discretization and an explicit scheme for time differencing) to find the range of existence of the spatiotemporal solitons of the two-dimensional complex Ginzburg-Landau equation with cubic and quintic nonlinearities. We start from the parameters used by Akhmediev {\it et. al.} and slowly vary them one by one to determine the regimes where solitons exist as stable/unstable structures. We present eight classes of dissipative solitons from which six are known (stationary, pulsating, vortex spinning, filament, exploding, creeping) and two are novel (creeping-vortex propellers and spinning "bean-shaped" solitons). By running lengthy simulations for the different parameters of the equation, we find ranges of existence of stable structures (stationary, pulsating, circular vortex spinning, organized exploding), and unstable structures (elliptic vortex spinning that leads to filament, disorganized exploding, creeping). Moreover, by varying even the two initial conditions together with vorticity, we find a richer behavior in the form of creeping-vortex propellers, and spinning "bean-shaped" solitons. Each class differentiates from the other by distinctive features of their energy evolution, shape of initial conditions, as well as domain of existence of parameters.Comment: 19 pages, 19 figures, 8 tables, updated text and reference

    Separation of random telegraph signals from 1/f noise in MOSFETs under constant and switched bias conditions

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    The low-frequency noise power spectrum of small dimension MOSFETs is dominated by Lorentzians arising from random telegraph signals (RTS). The low-frequency noise is observed to decrease when the devices are periodically switched 'off'. The technique of determining the statistical lifetimes and amplitudes of the RTS by fitting the signal level histogram of the time-domain record to two-Gaussian histograms has been reported in the literature. This procedure is then used for analysing the 'noisy' RTS along with the device background noise, which turned out to be 1/f noise. The 1/f noise of the device can then be separated from the RTS using this procedure. In this work, RTS observed in MOSFETs, under both constant and switched biased conditions, have been investigated in the time domain, Further, the 1/f noise in both the constant and the switched biased conditions is investigated

    2D Novel Structures Along an Opitcal Fiber

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    By using spectral methods, we present seven classes of stable and unstable structures that occur in a dissipative media. By varying parameters and initial conditions we find ranges of existence of stable structures (spinning elliptic, pulsating, stationary, organized exploding), and unstable structures (filament, disorganized exploding, creeping). By varying initial conditions, vorticity, and parameters of the equation, we find a reacher behavior of solutions in the form of creeping-vortex (propellers), spinning rings and spinning “bean-shape” solitons. Each class differentiates from the other by distinctive features of their shape and energy evolution, as well as domain of existence

    Biodiversity defrosted : unveiling non-compliant fish trade in ethnic food stores

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    Out of nearly 30,000 teleosts dwelling in our planet’s water bodies, only hundreds of them are commercially exploited and prevail on the global food market. Yet, our estimates of the species actually underpinning global trade is severely hampered by inaccuracy and non-compliance in labelling and reporting. Here, we target ethnic food stores in two British cities (Liverpool and Manchester metropolitan areas), whose numbers are increasing throughout Europe, to examine accuracy of traceability information available to consumers. Despite the existence of thorough EU labelling regulations, we unveil a high level of non-compliance, with a diverse range of poorly-known fish species, often sold without any label, or with erroneous information, as demonstrated by DNA barcoding. Results indicate that about 41% of the samples were mislabelled, in stark contrast with a recent study that, in 2015, found less than 5% mislabelling in EU supermarkets and fishmongers. These results highlight that inspectors and governments might not be fully aware of the wide diversity of fish species traded, indicating the need for a stronger enforcement of the EU labelling legislations. Compliance with regulations is required not only to protect consumers, but also fish stocks, as for many of the species identified in this survey, population assessment is poor or lacking altogether

    PCR detection of Burkholderia multivorans in water and soil samples

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    Background: Although semi-selective growth media have been developed for the isolation of Burkholderia cepacia complex bacteria from the environment, thus far Burkholderia multivorans has rarely been isolated from such samples. Because environmental B. multivorans isolates mainly originate from water samples, we hypothesized that water rather than soil is its most likely environmental niche. The aim of the present study was to assess the occurrence of B. multivorans in water samples from Flanders (Belgium) using a fast, culture-independent PCR assay. Results: A nested PCR approach was used to achieve high sensitivity, and specificity was confirmed by sequencing the resulting amplicons. B. multivorans was detected in 11 % of the water samples (n = 112) and 92 % of the soil samples (n = 25) tested. The percentage of false positives was higher for water samples compared to soil samples, showing that the presently available B. multivorans recA primers lack specificity when applied to the analysis of water samples. Conclusions: The results of the present study demonstrate that B. multivorans DNA is commonly present in soil samples and to a lesser extent in water samples in Flanders (Belgium)

    Linguistics

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    Contains reports on four research projects.U. S. Air Force (Electronics Systems Division) under Contract AF 19(628)-2487Joint Services Electronics Programs (U.S. Army, U.S. Navy, and U.S. Air Force) under Contract DA 28-043-AMC-02536(E)National Science Foundation (Grant GK-835)National Institutes of Health (Grant 2 PO1 MH-04737-06)National Aeronautics and Space Administration (Grant NsG-496

    Linguistics

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    Contains reports on four research projects.National Institutes of Health (Grant MH-13390-01U. S. Air Force (Electronic Systems Division) under Contract AF 19(628)-248
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