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81.
B. Gurevich 《Pure and Applied Geophysics》2000,157(5):811-827
82.
A simple geometric model is proposed to explain the recently reported effect of the prolateness of the solar chromosphere. We assume that a specific dynamical part of the solar atmosphere above the 2 Mm level, being a mixture of moving up and down jets of chromospheric matter with the coronal plasma between them, is responsible for the solar prolateness. Due to the dynamic nature of this layer, the magnetic field is considered to play a very important role in the density distribution with the height, guiding the mass flows along the field lines. The difference of the magnetic field topology in the polar and the equatorial regions leads to different heights of the chromospheric limb. Calculations show a satisfactory coincidence with observations when the mean separation between opposite polarity concentrations is about 9 Mm. The possible observational signature of this network in low photospheric and chromospheric layers is discussed. 相似文献
83.
C. R. DeVore N. R. Sheeley Jr. J. P. Boris T. R. Young Jr. K. L. Harvey 《Solar physics》1985,102(1-2):41-49
We simulate the evolution of several observed solar active regions by solving a transport equation for magnetic flux at the photosphere. The rates of rotation, meridional flow, and diffusion of the flux are determined self-consistently in the calculations. Our findings are in good quantitative agreement with previous measures of the rotation rate and diffusion constant associated with photospheric magnetic fields. Although our meridional velocities are consistent in direction and magnitude with recently reported poleward flows, relatively large uncertainties in our velocity determinations make this result inconclusive.Laboratory for Computational Physics.E. O. Hulburt Center for Space Research. 相似文献
84.
A consistent theory of excitation, stabilization, and propagation of electromagnetic oscillations in a relativistic one-dimensional electron-positron plasma flowing along curved magnetic field lines is presented. It is shown that in such a medium which is typical of the magnetosphere of a neutron star there exist unstable natural modes of oscillations. Nonlinear saturation of the instability leads to an effective energy conversion into transverse oscillations capable of leaving the magnetosphere of a pulsar. The polarization spectrum and the directivity pattern of generated radiation are determined. A comparison with observations has shown that the theory makes it possible to explain practically all the basic characteristics of observed pulsar radio emission. 相似文献
85.
Boris Garfinkel 《Celestial Mechanics and Dynamical Astronomy》1985,36(1):19-45
E.W. Brown conjectured (1911) that the family of the long-periodic orbits in the Troian case of the restricted problem of three bodies terminates in an asymptotic orbit passing through the Lagrangian point L3 at t=±∞. In 1977 the author showed that such an orbit deviates from L3 by the epicyclic term mg (±∞). It is shown here that $$g\left( { \pm \infty } \right) = 0,$$ so that the Brown conjecture regarding L3 is false. Contrary to what Brown believed, there is an entire family ofhomoclinic orbits, doubly asymptotic to short-periodic orbits around L3. In the complex z-plane of the Poincaré eccentric variables, the latter orbits are circles of radius mR, with R bounded away from zero. The kinematics of the homoclinic family is investigated here in some detail. 相似文献
86.
Boris Kolesov 《Physics and Chemistry of Minerals》2008,35(5):271-278
Single-crystal polarized Raman spectra (3,000–4,000 cm−1 at 3 ≤ T ≤ 300 K) were measured for synthetic alkali-free and natural beryl, Be2Al3Si6O18·xH2O, to determine the behavior of H2O molecules of both Type I and Type II in the cavities. At low temperature, the H2O molecules of Type I displace from the center of cavity and give rise to very weak hydrogen bonding with the host lattice.
The H2O Type I translational motion is characterized by substantial anharmonicity and looks like a motion of “a particle in the
box” with a frequency of 6.3 cm−1. Water Type II is characterized by a free rotation with respect to the C
2 molecule axis, and it makes possible the water nuclear isomers (i.e. ortho- and para-) to be observed at low temperature.
相似文献
Boris KolesovEmail: |
87.
88.
Bérénice Preller Julia Affolderbach Christian Schulz Sebastian Fastenrath Boris Braun 《The Professional geographer》2017,69(2):214-224
Knowledge coproduction between practitioners and scientists offers promising opportunities for the emerging research field of the geography of sustainability transitions. Drawing on experiences from an international research project on urban green building transitions, this article explores the potentials and challenges of interactive and collaborative knowledge generation methods in understanding sustainability transitions. Our results show that ongoing engagement with local experts and practitioners through interactive World Café workshops and follow-up exchanges allows for a better understanding of the research context and knowledge exchange to all participants involved in the research process. 相似文献
89.
Abstract. In this paper we present a one-year investigation on the fluorescence characteristics of released products of selected Adriatic seaweeds. The technique chosen was UV-fluorescence spectroscopy with the synchronous mode, which involves the stepping of the excitation and emission monochromators. The five species, of representative macrophytes, Cystoseira compressa, Dictyopreris polypodioides, Gracilaria bursapastoris, Pterocladia capillacea, and Ulva rigida, were chosen on the basis of their dominance in the plant communities typical for the area near Split - Central Adriatic. Our results suggest that macroalgal-related dissolved fluorescent matter can be categorized into two distinct groups of fluorescing compounds with the following excitation wavelengths: one from 320–360 nm, probably for compounds with 2 fused aromatic rings, and another from 360–420 nm, corresponding with 3 & 4 fused rings. The contribution of aromatics with 2 and with 3 & 4 rings was very similar in the brown algae Cysroseira compressa and Dictyopteris polypodioides, while in the red algae Gracilaria bursapastoris and Pterocludia capillacea as well in the green alga Ulva rigida the group with 2 rings dominated. 相似文献
90.
Reversed-phase liquid chromatography/mass spectrometry (LC/MS) is introduced as a new molecular fingerprinting technique for tracing terrigenous dissolved organic matter (DOM) and its photochemical decay in the ocean. DOM along a transect from the mangrove-fringed coast in Northern Brazil to the shelf edge was compared with mangrove-derived porewater DOM exposed to natural sunlight for 2–10 days in a photodegradation experiment. DOM was isolated from all samples via solid-phase extraction (C18) for LC/MS analysis. DOM in the estuary and ocean showed a bimodal mass distribution with two distinct maxima in the lower m/z range from 400 to 1000 Da (intensity-weighted average of 895 Da). Terrigenous porewater DOM from the mangroves was characterized by a broad molecular mass distribution over the detected range from 150 to 2000 Da (intensity-weighted average of 1130 Da). Polar compounds, i.e., those that eluted early in the reversed-phase chromatography, absorbed more UV light and had on average smaller molecular masses than the more apolar compounds. 相似文献