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81.
Maxim Lyutikov 《Monthly notices of the Royal Astronomical Society》1998,298(4):1198-1206
It is shown that induced Raman scattering of electromagnetic waves in the strongly magnetized electron–positron plasma of pulsar magnetospheres may be important for wave propagation and as an effective saturation mechanism for electromagnetic instabilities. The frequencies at which strong Raman scattering occurs in the outer parts of a magnetosphere fall into the observed radio band. The typical threshold intensities for the strong Raman scattering are of the order of the observed intensities, implying that pulsar magnetospheres may be optically thick to Raman scattering of electromagnetic waves. 相似文献
82.
鲅鱼(Spanish mackerel)加工后的废弃物富含蛋白质,为了提高蛋白质的利用率并减少环境污染,可以采用微生物发酵的方法酶解这部分蛋白质制取抗氧化活性肽。本实验室已经筛选出一株芽孢杆菌(Bacillus subtilis)Hy-2,以其发酵水产加工废弃物得到了具有较高抗氧化性的产物。为了进一步提高产物的抗氧化性,作者以该株产蛋白酶芽孢杆菌Hy-2为出发菌,采用常压室温等离子体(ARTP)诱变的方法筛选出1株突变菌Hy-23,以鲅鱼加工后的废弃物为原料,接种该突变菌株进行发酵,得到了具有一定抗氧化活性的发酵产物,酶解物总抗氧化活性提高了12.4%。经遗传稳定性测定,该芽孢杆菌突变株在传代8次之后其遗传稳定性仍然良好。 相似文献
83.
84.
The propagation of highly relativistic electron beams in dense matter induces a cascade of secondary particles that spreads in the environment redistributing efficiently the beam energy in the medium. Such a highly relativistic beams are expected to be produced in the magnetic reconnection events associated with the flaring activity of the magnetized accretion disks of the AGNs. This contribution presents a quantitative analysis of the possible role of these beams in the excitation of the Fe Kα line. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
85.
86.
The plasma flow in the vicinity of the heliopause stagnation point in the presence of the H atom flow is studied. The plasma at both sides of the heliopause is considered to be a single fluid. The back reaction of the plasma flow on the H atom flow is neglected, and the density, temperature and velocity of the H atom flow are taken to be constant. The solution describing the plasma flow is obtained in the form of power series expansions with respect to the radial distance from the symmetry axis. The main conclusion made on the basis of the obtained solution is that the heliopause is not the surface of discontinuity anymore. Rather, it is the surface separating the flows of the solar wind and interstellar medium with all plasma parameters continuous at this surface. 相似文献
87.
Stephen L. Redman Geoffrey A. E. Wright Joanna M. Rankin 《Monthly notices of the Royal Astronomical Society》2005,357(3):859-872
Analyses of multiple pulse sequences of the pulsar PSR B2303+30 reveal two distinct emission modes. One mode (B) follows a steady even–odd pattern and is more intense. The second mode (Q) is characteristically weak, but has intermittent drift bands with a periodicity of approximately 3 P 1 /cycle, and nulls much more frequently than the B mode. Both modes occur with roughly equal frequency, and their profiles have a similar single-humped form with a slight asymmetry. Our observations and analyses strongly suggest that the subpulse drift rates in both modes are linked in a series of cycles, which can be modelled as relaxing oscillations in the underlying circulation rate. 相似文献
88.
Tian-Xi Zhang Jing-Xiu Wang Chi-Jie Xiao National Astronomical Observatories Chinese Academy of Sciences Beijing Center for Space Plasma Aeronomic Research The University of Alabama in Huntsville Huntsville AL USA 《中国天文和天体物理学报》2005,(3)
Resonant heating of H, O+5, and Mg+9 by parallel propagating ion cyclotron Alfven waves in solar coronal holes at a heliocentric distance is studied using the heating rate derived from the quasilinear theory. It is shown that the particle-AlfVen-wave interaction is a significant microscopic process. The temperatures of the ions are rapidly increased up to the observed order in only microseconds, which implies that simply inserting the quasilinear heating rate into the fluid/MHD energy equation to calculate the radial dependence of ion temperatures may cause errors as the time scales do not match. Different species ions are heated by Alfven waves with a power law spectrum in approximately a mass order. To heat O+5 over Mg+9 as measured by the Ultraviolet Coronagraph Spectrometer (UVCS) in the solar coronal hole at a region ≥1.9.R, the energy density of Alfven waves with a frequency close to the O+5-cyclotron frequency must be at least double of that at the Mg+9-cyclotron frequency. With an appropriate wa 相似文献
89.
As laser–plasma interactions access ever-increasing ranges of plasma temperatures and densities, it is interesting to consider
whether they will some day shed light on questions concerning nuclear synthesis. One such open question is the process of
endothermic nuclear synthesis for elements with A > 60, thought to have taken place at a point in time during the big bang, or currently in supernovae. We present an explanation
based on a Boltzmann equilibrium condition, in combination with the change of the Fermi-statistics from the relativistic branch
for hadrons from higher than nuclear densities to the lower density subrelativistic branch. The Debye length confinement of
nuclei breaks down at the relativistic change, thus leading to the impossibility of nucleation of the quark-gluon state at
higher than nuclear densities. Taking the increment for the proton number Z as Z′ = 10 of the measured standard abundance distribution (SAD) of the elements for a Boltzmann probability for heavy element
synthesis, a sequence 3
n
was found with the exponent n for the sequence of the magic numbers. The jump between the magic numbers 20 and 28 does not need then the usual spin-orbit
explanation. 相似文献
90.
We study the properties of density perturbations of a two-component plasma with a temperature difference on a homogeneous and isotropic background. For this purpose, we extend the general relativistic gauge-invariant and covariant (GIC) perturbation theory to include a multifluid with a particular equation of state (ideal gas) and imperfect fluid terms due to the relative energy flux between the two species. We derive closed sets of GIC vector and subsequently scalar evolution equations. We then investigate solutions in different regimes of interest. In particular, we study long-wavelength and arbitrary-wavelength Langmuir and ion-acoustic perturbations. The harmonic oscillations are superposed on a Jeans-type instability. We find a generalized Jeans criterion for collapse in a two-temperature plasma, which states that the species with the largest sound velocity determines the Jeans wavelength. Furthermore, we find that within the limit for gravitational collapse, initial perturbations in either the total density or charge density lead to a growth in the initial temperature difference. These results are relevant for the basic understanding of the evolution of inhomogeneities in cosmological models. 相似文献