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991.
In 2003, geomagnetic activity was found to be considerably higher than in any other year of the current solar cycle. This was caused by the time coincidence of large low-latitude coronal holes and a significant burst of the flare and eruptive activity of the Sun. The features of recent intensification of the activity are discussed, and the long-period behavior of indices of the geomagnetic activity in the 23rd and previous cycles is compared. The large magnetic storms in October–November 2003 are analyzed in more detail.Translated from Kosmicheskie Issledovaniya, Vol. 42, No. 6, 2004, pp. 563–573.Original Russian Text Copyright © 2004 by Belov, Gaidash, Ivanov, Kanonidi. 相似文献
992.
S Philosoph-Hadas H Friedman S Meir R Berkovitz-SimanTov I Rosenberger A H Halevy P B Kaufman P Balk E J Woltering 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2001,27(5):921-932
The negative gravitropic response of cut flower stalks is a complex multistep process that requires the participation of various cellular components acting in succession or in parallel. The process was particularly characterized in snapdragon (Antirrhinum majus L.) spikes with regard to (1) gravity stimulus perception associated with amyloplast reorientation; (2) stimulus transduction mediated through differential changes in the level, action and related genes of auxin and ethylene and their possible interaction; (3) stimulus response associated with differential growth leading to stalk curvature; (4) involvement of cytosolic calcium and actin cytoskeleton. Results show that the gravity-induced amyloplast reorientation, differential over-expression of two early auxin responsive genes and asymmetrical distribution of free IAA are early events in the bending process. These precede the asymmetrical ethylene production and differential stem growth, which was derived from initial shrinkage of the upper stem side and a subsequent elongation of the lower stem side. Results obtained with various calcium- and cytoskeleton-related agents indicate that cytosolic calcium and actin filaments may play essential roles in gravitropism-related processes of cut flower stalks. Therefore, modulators of these two physiological mediators may serve as means for controlling any undesired gravitropic bending. 相似文献
993.
Extended PGA for range migration algorithms 总被引:2,自引:0,他引:2
Van Rossum W.L. Otten M.P.G. Van Bree R.J.P. 《IEEE transactions on aerospace and electronic systems》2006,42(2):478-488
The phase gradient autofocus (PGA) algorithm is extended to work for synthetic aperture radar (SAR) spotlight images processed with range migration (w-k) algorithms. Several pre-processing steps are proposed for aligning the range-compressed phase-history data needed for successful autofocusing of the data. The proposed algorithm gave good results for both data with large point targets and data without point targets. 相似文献
994.
995.
V. P. Shabansky 《Space Science Reviews》1968,8(3):366-454
In this paper we consider those processes mainly related to the behaviour of the low-energetic magnetospheric plasma, which nevertheless contains the main mass and the predominant part of the thermal energy. Our attention has been concentrated on those processes which, from our point of view, determine geomagnetic phenomena on the surface of the earth. Because of the scope of the project, we had to exclude the processes of acceleration of high-energetic particles in the tail of the magnetosphere, their diffusion deep within, and the formation of the radiation belts. These problems are of independent interest and may be considered separately.When describing various phenomena we tried to stress the principal side of a question without regard to the details of one theory or other, though we did not keep to this principle throughout. Together with the results which are dealt with in the literature, we took the risk of including those considerations which are not as yet published. It mainly concerns Sections 2.3, 2.4, 3.4, 3.6, 3.7, and 4. where, together with other problems, three new hypotheses of the main phase of a storm and of Sq-variations are discussed. We prefer the mechanism connected with the current induction in the ionosphere (Section 4.4). For this purpose some aspects of magnetohydrodynamics were examined (Section 4.3). 相似文献
996.
H. Klein H.U. Walter A. Bewersdorff J. Pöttschke 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(5):57-62
The evolution of a dispersion under the action of temperature gradients and solidification was followed optically in a transparent molten salt (CsCl) with inclusions of Pb-droplets and gas bubbles. This system is believed to model a solidifying metallic alloy. Rejection of Pb-particles by the solidification front was observed, while large gas bubbles were incorporated. Thermocapillary convection at the gas bubbles considerably distorted the temperature field and even caused local remelting. Marangoni migration of bubbles was not observed, contrary to expectations. 相似文献
997.
M.G. Tairbekov G.P. Parfyonov R.W. Platonova V.M. Abramova V.K. Golov A.V. Rostopshina V.Yu. Lyubchenko V.G. Chuchkin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(14):89-94
Experiments on insects, higher plants and lower fungi were carried out aboard the biological satellite Cosmos-1129, in Earth orbit, from 25 September to 14 October 1979. The main objective of these experiments was to gain more profound knowledge of the effect of weightlessness on living organisms and to study the mechanisms by which these various organisms with different life cycles can adjust and develop in weightlessness. Experiments on insects () were made with a view towards understanding gravitational preference in flies, the life cycle of which took place on board the biosatellite under conditions of artificial gravity. Experiments on higher plants () and lower fungi () were performed. 相似文献
998.
B. Schmieder P. Mein J.C. Vial E. Tandberg-Hanssen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(11):225-228
Simultaneous Hα (MSDP at Meudon) and C IV (UVSP aboard SMM) measurements of Active Region 2701 were made on October 2, 1980. Isodensity and velocity maps were derived for both lines and superposed. A good correlation was found between Hα and C IV velocities. A surge was observed for 10 minutes. The base was located in a bright point in CIV and Hα, and escaping matter followed the same channel (“absorbing” in Hα, “emitting” in C IV). The velocity along the surge was about 80 kms.-1 in Hα and 100 km s-1 in C IV. A loop appeared in C IV. We discuss the existing models and conclude that the vertical pressure gradient was capable of driving the surge. 相似文献
999.
P.M. Kintner M.C. Kelley 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(2):107-115
The Porcupine sounding rocket consisted of a central instrumented payload with 4 smaller payloads ejected in the radial direction. One of the smaller payloads contained a xenon ion gun which directed a 200eV Xe+ ion beam roughly perpendicular to the magnetic field. During the ion gun exercises a variety of plasma waves were observed by the δn/n experiment on the central spacecraft. For small separations betwen the ion gun and the plasma wave receivers, intense and very narrow band emissions were observed just above harmonics of the hydrogen gyrofrequency extending from n=1 to at least n=11 and perhaps to much higher harmonics. Additional structure at the helium gyrofrequency was also observed and the width of each spectral line was the order of the oxygen gyrofrequency. The fastest growing modes were at n=5 or 6. For larger separations between the ion gun and plasma wave receiver, band limited emissions were observed between the NO+ and O+ lower hybrid frequencies. The intense ion cyclotron harmonic waves observed for short separations are very similar to plasma waves observed at high altitudes in ion conics by the S3-3 satellite. In those examples, natural ion beams, which were nearly perpendicular to the magnetic field, produced plasma waves between harmonics of the hydrogen gyrofrequency and the most intense waves occurred between n=3 and n=7. Hence the ion beam experiment is directly applicable to understanding ion beams within the magnetosphere. 相似文献
1000.
F.J. Bonn P.J. Howarth 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(8):151-154
This report summarizes a major paper reviewing Canadian work using Landsat imagery for monitoring the environmental effects of the development of both renewable and non-renewable resources. Landsat has definite advantages for studying resources. In particular, the data are able to show changes in surface cover indicating in many cases development or the exploitation of resources. Monitoring of areas and rates of change over time is possible. Outlined in the paper are examples related to three aspects of resource development. First is the use of Landsat for updating topographic maps for areas where recent developments have taken place. The second aspect is forestry, and examples related to the detection and measurement of clear cuts and recording of areas affected by spruce budworm are reported. Finally, studies of landscape changes produced by mining activities are presented. 相似文献