The link between phase coherence and non-Gaussian statistics is investigated using magnetic field data observed in the solar wind turbulence near the Earth's bow shock. The phase coherence index C , which characterizes the degree of phase correlation ͑i.e., nonlinear wave-wave interactions͒ among scales, displays a behavior similar to kurtosis and reflects a departure from Gaussianity in the probability density functions of magnetic field fluctuations. This demonstrates that nonlinear interactions among scales are the origin of intermittency in the magnetic field turbulence. Solar wind is a good laboratory for the study of collisionless magnetohydrodynamic ͑MHD͒ turbulence ͑see, e.g., ͓1͔ and references therein͒. In particular, the intermittent nature of turbulence is one of the fundamental problems for understanding the complex behavior of fluids ͓2,3͔ and other dynamical systems ͓4͔. Solar wind intermittency can be characterized by the probability density functions ͑PDFs͒ of velocity ͑or magnetic͒ field fluctuations over a range of scales. For large scales the PDFs are approximately Gaussian. As the scale decreases, the tails of the distribution gradually become fatter ͓5͔.Since MHD turbulence is governed by nonlinear MHD equations, the turbulent fields may display non-Gaussian fluctuations where the phases among scales ͑e.g., phases of the Fourier modes͒ are not random. In some previous studies of MHD turbulence the so-called random-phase approximation has been adopted to describe random-phase mixing among scales ͓6͔. However, in solar wind turbulence coherent structures such as solitonlike waves are often observed, especially near the planetary bow shock ͓7͔. Therefore, in real situations, the description of MHD turbulence as a superposition of random-phase fluctuations may not be valid and a finite-phase correlation among scales is to be expected due to nonlinear wave-wave interactions. This paper investigates the link between non-Gaussianity ͑intermittency͒ and phase correlation ͑nonlinear interactions͒ among scales in solar wind turbulence. Previous works have revealed the nonGaussianity of PDFs in the solar wind as a signature of intermittency, but whether this departure from Gaussianity is due to nonlinear wave-wave interactions or not has not been clearly demonstrated yet. In analytic modeling and numerical simulations of intermittent turbulence based on a set of deterministic equations, it is naturally expected that the departure from Gaussianity is due to nonlinear interactions ͓2͔. In contrast, the observational data from solar wind are an admixture of deterministic signal and stochastic noise. In such a case, the demonstration of finite phase coherence is required to ascertain the nonlinear origin of non-Gaussian fluctuations. In the present work, we quantify the degree of nonlinear interactions in solar wind data using a phase coherence index and demonstrate its relation with kurtosis ͑flatness͒ in the structure function.A central assumption of the Kolmogorov 1941 ͑hereafter K41͒ theory is the sel...

A thorough investigation has enabled the optimization of the synthesis of 1,4-dihydro-pyrrolo[3,2- b ]pyrroles. Although salts of such metals as vanadium, niobium, cerium, and manganese were found to facilitate the formation of 1,4-dihydro-pyrrolo[3,2- b ]pyrroles from amines, aldehydes, and diacetyl, we confirmed that iron salts are the most efficient catalysts. The conditions identified (first step: toluene/AcOH = 1:1, 1 h, 50 °C; second step: toluene/AcOH = 1:1, Fe(ClO 4 ) 3 ·H 2 O, 16 h, 50 °C) resulted in the formation of tetraarylpyrrolo[3,2- b ]pyrroles in a 6–69% yield. For the first time, very electron-rich substituents (4-Me 2 NC 6 H 4 , 3-(OH)C 6 H 4 , pyrrol-2-yl) originating from aldehydes and sterically hindered substituents (2-ClC 6 H 4 , 2-BrC 6 H 4 , 2-CNC 6 H 4 , 2-(CO 2 Me)C 6 H 4 , 2-(TMS-C≡C)C 6 H 4 ) present on anilines can be appended to the pyrrolo[3,2- b ]pyrrole core. It is now also possible to prepare 1,4-dihydropyrrolo[3,2- b ]pyrroles bearing an ordered arrangement of N -substituents and C -substituents ranging from coumarin, quinoline, phthalimide to truxene. These advances in scope enable independent regulations of many desired photophysical properties, including the Stokes shift value and emission color ranging from violet-blue through deep blue, green, yellow to red. Simultaneously, the optimized conditions have finally allowed the synthesis of these extremely promising heterocycles in amounts of more than 10 g per run without a concomitant decrease in yield or product contamination. Empowered with better functional group compatibility, novel derivatization strategies were developed.

Magnetopause shadowing and wave‐particle interactions are recognized as the two primary mechanisms for losses of electrons from the outer radiation belt. We investigate these mechanisms, using satellite observations both in interplanetary space and within the magnetosphere and particle drift modeling. Two interplanetary shocks/sheaths impinged upon the magnetopause causing a relativistic electron flux dropout. The magnetic cloud (MC) and interplanetary structure sunward of the MC had primarily northward magnetic field, perhaps leading to a concomitant lack of substorm activity and a 10 daylong quiescent period. The arrival of two shocks caused an unusual electron flux dropout. Test‐particle simulations have shown ∼ 2 to 5 MeV energy, equatorially mirroring electrons with initial values of L≥5.5 can be lost to the magnetosheath via magnetopause shadowing alone. For electron losses at lower L‐shells, coherent chorus wave‐driven pitch angle scattering and ULF wave‐driven radial transport have been shown to be viable mechanisms.

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