50,461 research outputs found

    Consequences of using nonlinear particle trajectories to compute spatial diffusion coefficients

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    The propagation of charged particles through interstellar and interplanetary space has often been described as a random process in which the particles are scattered by ambient electromagnetic turbulence. In general, this changes both the magnitude and direction of the particles' momentum. Some situations for which scattering in direction (pitch angle) is of primary interest were studied. A perturbed orbit, resonant scattering theory for pitch-angle diffusion in magnetostatic turbulence was slightly generalized and then utilized to compute the diffusion coefficient for spatial propagation parallel to the mean magnetic field, Kappa. All divergences inherent in the quasilinear formalism when the power spectrum of the fluctuation field falls off as K to the minus Q power (Q less than 2) were removed. Various methods of computing Kappa were compared and limits on the validity of the theory discussed. For Q less than 1 or 2, the various methods give roughly comparable values of Kappa, but use of perturbed orbits systematically results in a somewhat smaller Kappa than can be obtained from quasilinear theory

    Einstein's Equations and a Cosmology with Finite Matter

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    We discuss various space-time metrics which are compatible with Einstein's equations and a previously suggested cosmology with a finite total mass. In this alternative cosmology the matter density was postulated to be a spatial delta function at the time of the big bang thereafter diffusing outward with constant total mass. This proposal explores a departure from standard assumptions that the big bang occurred everywhere at once or was just one of an infinite number of previous and later transitions.Comment: 14 pages, one figure, two typographical correction

    Damping of high frequency waves in the solar wind

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    Cyclotron damping by suprathermal fluxes of protons and electrons in the interplanetary medium will greatly attenuate high frequency Alfven waves and whistler waves within distances 1 AU of the sun. Electrons with energies between 50 eV to 2 KeV are heated as a result of damping interplanetary whistler waves with frequencies 2 omega meson/2 pion 30 Hz in the frame of the solar wind. This heating may account, in part, for the observed suprathermal tail of solar wind electrons. Protons with energies approximately 50 KeV damp Alfven waves with frequencies .001 omega meson/2 pion .01 Hz. This damping mechanism may explain several features of a scatter free solar electron events and high intensity, anisotropic solar proton streams

    Magnetohydrodynamic turbulence in the solar wind

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    Recent work in describing the solar wind as an MHD turbulent fluid has shown that the magnetic fluctuations are adequately described as time stationary and to some extent as spatially homogeneous. Spectra of the three rugged invariants of incompressible MHD are the principal quantities used to characterize the velocity and magnetic field fluctuations. Unresolved issues concerning the existence of actively developing turbulence are discussed

    Experimental investigation of the interaction between the electron gas and the excited atoms in a plasma by means of a xenon laser

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    Xenon laser effect on interaction between electron gas and excited atoms in plasm

    Negotiate or Litigate? Effects of WTO Judicial Delegation on U.S. Trade Politics

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    Goldstein and Steinberg argue that the World Trade Organization Appellate Body has been able to use its authority to engage in judicial lawmaking to reduce trade barriers in ways that would not otherwise have been possible through negotiation. This lawmaking authority was not the result of a purposeful delegation; rather, it was an unintended byproduct of the creation of an underspecified set of rules and procedures. There is nevertheless a high rate of compliance with Appellate Body decisions because decentralized enforcement can induce domestic importers to lobby for trade liberalization. In the US, this judicial lawmaking may also allow the President to achieve trade policies that are more liberal than those desired by Congress, if compliance can be achieved by a regulatory change or by sole Executive action

    Remark on the (Non)convergence of Ensemble Densities in Dynamical Systems

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    We consider a dynamical system with state space MM, a smooth, compact subset of some Rn{\Bbb R}^n, and evolution given by TtT_t, xt=Ttxx_t = T_t x, xMx \in M; TtT_t is invertible and the time tt may be discrete, tZt \in {\Bbb Z}, Tt=TtT_t = T^t, or continuous, tRt \in {\Bbb R}. Here we show that starting with a continuous positive initial probability density ρ(x,0)>0\rho(x,0) > 0, with respect to dxdx, the smooth volume measure induced on MM by Lebesgue measure on Rn{\Bbb R}^n, the expectation value of logρ(x,t)\log \rho(x,t), with respect to any stationary (i.e. time invariant) measure ν(dx)\nu(dx), is linear in tt, ν(logρ(x,t))=ν(logρ(x,0))+Kt\nu(\log \rho(x,t)) = \nu(\log \rho(x,0)) + Kt. KK depends only on ν\nu and vanishes when ν\nu is absolutely continuous wrt dxdx.Comment: 7 pages, plain TeX; [email protected], [email protected], [email protected], to appear in Chaos: An Interdisciplinary Journal of Nonlinear Science, Volume 8, Issue

    The formation of arcs in the dynamic spectra of Jovian decameter bursts

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    A model is presented that can account for several features of the dynamic spectral arcs observed at decameter wavelengths by the planetary radio astronomy experiment on Voyagers 1 and 2. It is shown that refraction of an extraordinary mode wave initially excited nearly orthogonal to the local magnetic field is significantly influenced by the local plasma density, being greater the higher the density. It is assumed that the source of the decameter radiation lies along the L = 6 flux tube and that the highest frequencies are produced at the lowest altitudes, where both the plasma density and magnetic field gradients are largest. It is further assumed that the decameter radiation is emitted into a thin conical sheet, consistent with both observation and theory. In the model the emission cone angle of the sheet is chosen to vary with frequency so that it is relatively small at both high and low frequencies, but approximately 80 deg at intermediate frequencies. The resulting emission pattern as seen by a distant observer is shown to resemble the observed arc pattern. The model is compared and contrasted with examples of Voyager radio data

    Basic processes occurring in gaseous plasmas in various charge density and energy states Final report

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    Sensitive laser diagnostic procedures and properties of gaseous plasmas at various charge densities and energy state
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