500 research outputs found

    Synchronization in Complex Systems Following the Decision Based Queuing Process: The Rhythmic Applause as a Test Case

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    Living communities can be considered as complex systems, thus a fertile ground for studies related to their statistics and dynamics. In this study we revisit the case of the rhythmic applause by utilizing the model proposed by V\'azquez et al. [A. V\'azquez et al., Phys. Rev. E 73, 036127 (2006)] augmented with two contradicted {\it driving forces}, namely: {\it Individuality} and {\it Companionship}. To that extend, after performing computer simulations with a large number of oscillators we propose an explanation on the following open questions (a) why synchronization occurs suddenly, and b) why synchronization is observed when the clapping period (TcT_c) is 1.5Ts<Tc<2.0Ts1.5 \cdot T_s < T_c < 2.0 \cdot T_s (TsT_s is the mean self period of the spectators) and is lost after a time. Moreover, based on the model, a weak preferential attachment principle is proposed which can produce complex networks obeying power law in the distribution of number edges per node with exponent greater than 3.Comment: 16 pages, 5 figure

    A Compact High Order Finite Volume Scheme for Advection-Diffusion-Reaction Equations

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    We present a new integral representation for the flux of the advection-diffusion-reaction equation, which is based on the solution of a local boundary value problem for the entire equation, including the source term. The flux therefore consists of two parts, corresponding to the homogeneous and particular solution of the boundary value problem. Applying Gauss-Legendre quadrature rules to the integral representation gives the high order finite volume complete flux scheme, which is fourth order accurate for both diffusion dominated and advection dominated flow

    Enhanced activation of the left inferior frontal gyrus in deaf and dyslexic adults during rhyming

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    Hearing developmental dyslexics and profoundly deaf individuals both have difficulties processing the internal structure of words (phonological processing) and learning to read. In hearing non-impaired readers, the development of phonological representations depends on audition. In hearing dyslexics, many argue, auditory processes may be impaired. In congenitally profoundly deaf individuals, auditory speech processing is essentially absent. Two separate literatures have previously reported enhanced activation in the left inferior frontal gyrus in both deaf and dyslexic adults when contrasted with hearing non-dyslexics during reading or phonological tasks. Here, we used a rhyme judgement task to compare adults from these two special populations to a hearing non-dyslexic control group. All groups were matched on non-verbal intelligence quotient, reading age and rhyme performance. Picture stimuli were used since this requires participants to generate their own phonological representations, rather than have them partially provided via text. By testing well-matched groups of participants on the same task, we aimed to establish whether previous literatures reporting differences between individuals with and without phonological processing difficulties have identified the same regions of differential activation in these two distinct populations. The data indicate greater activation in the deaf and dyslexic groups than in the hearing non-dyslexic group across a large portion of the left inferior frontal gyrus. This includes the pars triangularis, extending superiorly into the middle frontal gyrus and posteriorly to include the pars opercularis, and the junction with the ventral precentral gyrus. Within the left inferior frontal gyrus, there was variability between the two groups with phonological processing difficulties. The superior posterior tip of the left pars opercularis, extending into the precentral gyrus, was activated to a greater extent by deaf than dyslexic participants, whereas the superior posterior portion of the pars triangularis extending into the ventral pars opercularis, was activated to a greater extent by dyslexic than deaf participants. Whether these regions play differing roles in compensating for poor phonological processing is not clear. However, we argue that our main finding of greater inferior frontal gyrus activation in both groups with phonological processing difficulties in contrast to controls suggests greater reliance on the articulatory component of speech during phonological processing when auditory processes are absent (deaf group) or impaired (dyslexic group). Thus, the brain appears to develop a similar solution to a processing problem that has different antecedents in these two populations

    Transmission line method for the simulation of Fiber Bragg Gratings

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    A new method for the analysis and design of fiber Bragg gratings (FBGs) based on the theory of transmission lines has been developed and verified both theoretically and experimentally. The method is an extension of the coupled-mode theory and utilizes the equivalent transmission lines in order to simulate any type of grating, with an easy and direct implementation. The method provides the ability to analyze the optical devices without using full wave approaches, while also facilitating the incorporation of core materials with a complex or non-linear refractive index, non-uniform distributions of the grating&\#x2019;s refractive index, and tilted and phase-shifted gratings. The approach also allows the design of the grating for a given reflection spectra. Numerical results of the method&\#x2019;s application on a randomly varied inscription of the refractive index of a FBG have also been simulated and discussed. Using this method, the characteristics of an erbium-doped (ED)-FBG have been simulated and the predictions verified experimentally

    Novel 60 GHz CPW array antennas with beam-forming features for indoor wireless over fiber networks

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    In this study two types of coplanar waveguide (CPW) array antennas are designed and analyzed for use in a 60GHz Radio over Fiber indoor network. The first one is based on high permittivity Rogers 6010 and Indium Phosphide (InP) substrates incorporating slots as radiating elements. The second one utilizes stacked geometry based on the above substrates. Both arrays present more 1 GHz bandwidth and 10dBi gain. Furthermore they can provide beam-forming operation by properly adjusting the signal's amplitude and phase. A Least Mean Square (LMS) algorithm is generated for this purpose and the radiation pattern is steered accordingly. At last, a photodiode is simulated using equivalent circuit and is adopted with the proposed arrays, and an optical beam forming scenario is discussed. © 2013 SPIE
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