12,873 research outputs found

    THREE-DIMENSIONAL STRUCTURE OF SOLAR WIND TURBULENCE

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    We present a measurement of the scale-dependent, three-dimensional structure of the magnetic field fluctuations in inertial range solar wind turbulence with respect to a local, physically motivated coordinate system. The Alfvenic fluctuations are three-dimensionally anisotropic, with the sense of this anisotropy varying from large to small scales. At the outer scale, the magnetic field correlations are longest in the local fluctuation direction, consistent with Alfven waves. At the proton gyroscale, they are longest along the local mean field direction and shortest in the direction perpendicular to the local mean field and the local field fluctuation. The compressive fluctuations are highly elongated along the local mean field direction, although axially symmetric perpendicular to it. Their large anisotropy may explain why they are not heavily damped in the solar wind

    Linking the network centrality measures closeness and degree

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    We propose a non-linear relationship between two of the most important measures of centrality in a network: degree and closeness. Based on a shortest-path tree approximation, we give an analytic derivation that shows the inverse of closeness is linearly dependent on the logarithm of degree. We show that our hypothesis works well for a range of networks produced from stochastic network models including the Erdos-Reyni and Barabasi-Albert models. We then test our relation on networks derived from a wide range of real-world data including social networks, communication networks, citation networks, co-author networks, and hyperlink networks. We find our relationship holds true within a few percent in most, but not all, cases. We suggest some ways that this relationship can be used to enhance network analysis

    Deranged calcium signaling and neurodegeneration in spinocerebellar ataxia type 3

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    Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease (MJD), is an autosomal-dominant neurodegenerative disorder caused by a polyglutamine expansion in ataxin-3 (SCA3, MJD1) protein. In biochemical experiments we demonstrate that mutant SCA3exp specifically associated with the type 1 inositol 1,4,5-trisphosphate receptor (InsP3R1), an intracellular calcium (Ca2+) release channel. In electrophysiological and Ca2+ imaging experiments we show that InsP3R1 are sensitized to activation by InsP3 in the presence of mutant SCA3exp. We found that feeding SCA3-YAC-84Q transgenic mice with dantrolene, a clinically relevant stabilizer of intracellular Ca2+ signaling, improved their motor performance and prevented neuronal cells loss in pontine nuclei and substantia nigra regions. Our results indicate that deranged Ca2+ signaling may play an important role in SCA3 pathology and that Ca2+ signaling stabilizers such as dantrolene may be considered as potential therapeutic drugs for treatment of SCA3 patients

    Fast adaptive blind beamforming technique for cyclostationary signals

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    Castedo et al. (1995) have present a blind beamforming criterion based on the property of cyclostationary signals. A stochastic gradient-based algorithm, which needs to choose the step size suitably, was derived to compute the optimum weight vector. In this paper a fast adaptive algorithm is proposed. We show that the recursive least square techniques can be applied to solve this problem successfully by making an appropriate approximation. Simulation results demonstrate the effect of the theoretic analysis.published_or_final_versio

    Experimental determination of whistler wave dispersion relation in the solar wind

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    The origins and properties of large-amplitude whistler wavepackets in the solar wind are still unclear. In this Letter, we utilize single spacecraft electric and magnetic field waveform measurements from the ARTEMIS mission to calculate the plasma frame frequency and wavevector of individual wavepackets over multiple intervals. This allows direct comparison of experimental measurements with theoretical dispersion relations to identify the observed waves as whistler waves. The whistlers are right-hand circularly polarized, travel anti-sunward, and are aligned with the background magnetic field. Their dispersion is strongly affected by the local electron parallel beta in agreement with linear theory. The properties measured are consistent with the electron heat flux instability acting in the solar wind to generate these waves

    NOMA Enhanced 5G Distributed Vehicle to Vehicle Communication for Connected Autonomous Vehicles

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    Connected autonomous vehicles (CAV) holds great potentials of improving road safety and efficiency. However ultra reliability and low latency vehicle to everything (V2X) communication service is required to fully unleash the potentials of CAV. In this paper we investigate distributed vehicle to vehicle (V2V) for CAV, which supports not only broadcast but also multicast/unicast communications. Power domain non-orthogonal multiple access (NOMA) is applied to deal with the CAV traffic patterns, which are different from those in the traditional connected vehicle applications. With NOMA the signals for long range broadcast with major power and signals for short range neighbors with small power can be superposed in one transmission. With the application of NOMA the channel load can be reduced and communication reliability and latency will be improved. The framework and operation of NOMA enhanced distributed V2V system are designed. Qualitative and quantitative benefits of the proposed scheme are analyzed. Simulation results show that the proposed scheme can achieve a gain of more than 80% on network capacity under the investigated scenarios, with large performance improvement in terms of communication throughput and reliability

    The Efficacy of Triamcinolone Acetonide in Keloid Treatment: A Systematic Review and Meta-analysis

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    A 2000 BPS LPC vocoder based on multiband excitation

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    This paper presents an improved mixed LPC vocoder at 2000 bps using Multi-Band Excitation analysis by a synthesis algorithm. The new vocoder determines the voiced/unvoiced characteristics harmonic by harmonic in a frame, and finds the first voiced/unvoiced transition as the cut-off frequency, which is more accurate and efficient than traditional cut-off frequency detection. The synthetic speech below the cut-off frequency is excited by a series of voiced harmonics, while the signal above the cut-off frequency is simulated by a noise source. The final output speech is the sum of these two outputs. To increase the naturalness and clearness of the synthesized speech, this model applies phase prediction and spectral enhancement in the synthesizer. It is also possible to reduce the bit rate to 1200 bps. Informal listening tests indicate that the output speech possesses higher intelligibility and quality than that of the 2.4 kbps LPC-10e standard, and is comparable with the 4.8 kbps FS1016 CELP vocoder.published_or_final_versio

    Influence of compressibility on scaling regimes of strongly anisotropic fully developed turbulence

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    Statistical model of strongly anisotropic fully developed turbulence of the weakly compressible fluid is considered by means of the field theoretic renormalization group. The corrections due to compressibility to the infrared form of the kinetic energy spectrum have been calculated in the leading order in Mach number expansion. Furthermore, in this approximation the validity of the Kolmogorov hypothesis on the independence of dissipation length of velocity correlation functions in the inertial range has been proved.Comment: REVTEX file with EPS figure

    BEX3 contributes to cisplatin chemoresistance in nasopharyngeal carcinoma

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