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211.
Nakhilnitskaya ZN Klimovskaya LD Kuzmina ZF Mastryukova VM Smirnova NP Strzhizhovsky AD Cherkasov GV 《Acta Astronautica》1983,10(3):159-161
Animal adaptation to a strong magnetic field was investigated. Mice were exposed to 30-day total-body continuous effects of a constant magnetic field (CMF) of 1.6T, and their physiological responses were assessed. Analysis of the data obtained showed that different parameters varied in a dissimilar manner. Red blood changes returned to normal in the course of the experiment. Leucocytosis and increased content of catecholamines and corticosterone of blood and adrenals persisted throughout the exposure. Changes in the spermatogenic epithelium were most distinct after the exposure. The recovery of certain parameters during the CMF exposure is indicative of adaptation of some physiological systems. The adaptation is, however, incomplete as suggested by the long persisting stress manifestation. Reticulocytopenia and spermatogenetic abnormalities found after exposure are of particular importance. 相似文献
212.
Z.K. Smith W.J. Murtagh 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009,44(7):775-788
Predicting the occurrence of large geomagnetic storms more than an hour in advance is an important, yet difficult task. Energetic ion data show enhancements in flux that herald the approach of interplanetary shocks, usually for many hours before the shock arrival. We present a technique for predicting large geomagnetic storms (Kp 7) following the arrival of interplanetary shocks at 1 AU, using low-energy energetic ions (47–65 keV) and solar wind data measured at the L1 libration point. It is based on a study of the relationship between energetic ion enhancements (EIEs) and large geomagnetic storms by Smith et al. [Smith, Z., Murtagh, W., Smithtro, C. Relationship between solar wind low-energy energetic ion enhancements and large geomagnetic storms. J. Geophys. Res. 109, A01110, 2004. doi:10.1029/ 2003JA010044] using data in the rise and maximum of solar cycle 23 (February 1998–December 2000). An excellent correlation was found between storms with Kp 7 and the peak flux of large energetic ion enhancements that almost always (93% of time in our time period) accompany the arrival of interplanetary shocks at L1. However, as there are many more large EIEs than large geomagnetic storms, other characteristics were investigated to help determine which EIEs are likely to be followed by large storms. An additional parameter, the magnitude of the post-shock total magnetic field at the L1 Lagrangian point, is introduced here. This improves the identification of the EIEs that are likely to be followed by large storms. A forecasting technique is developed and tested on the time period of the original study (the training data set). The lead times, defined as the times from the arrival of the shock to the start of the 3-h interval of maximum Kp, are also presented. They range from minutes to more than a day; the average for large storms is 7 h. These times do not include the extra warning time given when the EI flux cross the high thresholds ahead of the shock. Because the data-stream used in the original study is no longer available, we extended the original study (1998–2000) to 2001, in order to: (a) investigate EIEs in 2001; (b) present a validation of the technique on an independent data set; (c) compare the results based on the original (P1) energy channel to those of the replacement (P1′) and (d), determine new EIE thresholds for forecasting geomagnetic storms using P1′ data. The verification of this P1′ training data set is also presented, together with lead times. 相似文献
213.
John Z. Kiss Prem Kumar Katherine D.L. Millar Richard E. Edelmann Melanie J. Correll 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
Plants will be an important component in bioregenerative systems for long-term missions to the Moon and Mars. Since gravity is reduced both on the Moon and Mars, studies that identify the basic mechanisms of plant growth and development in altered gravity are required to ensure successful plant production on these space colonization missions. To address these issues, we have developed a project on the International Space Station (ISS) to study the interaction between gravitropism and phototropism in Arabidopsis thaliana. These experiments were termed TROPI (for tropisms) and were performed on the European Modular Cultivation System (EMCS) in 2006. In this paper, we provide an operational summary of TROPI and preliminary results on studies of tropistic curvature of seedlings grown in space. Seed germination in TROPI was lower compared to previous space experiments, and this was likely due to extended storage in hardware for up to 8 months. Video downlinks provided an important quality check on the automated experimental time line that also was monitored with telemetry. Good quality images of seedlings were obtained, but the use of analog video tapes resulted in delays in image processing and analysis procedures. Seedlings that germinated exhibited robust phototropic curvature. Frozen plant samples were returned on three space shuttle missions, and improvements in cold stowage and handing procedures in the second and third missions resulted in quality RNA extracted from the seedlings that was used in subsequent microarray analyses. While the TROPI experiment had technical and logistical difficulties, most of the procedures worked well due to refinement during the project. 相似文献
214.
X. Zou Z. Deng M. Ge G. Dick W. Jiang J. Liu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
In order to obtain crustal deformations of higher spatial resolution, existing GPS networks must be densified. This densification can be carried out using single-frequency receivers at moderate costs. However, ionospheric delay handling is required in the data processing. We adapt the Satellite-specific Epoch-differenced Ionospheric Delay model (SEID) for GPS networks with mixed single- and dual-frequency receivers. The SEID model is modified to utilize the observations from the three nearest dual-frequency reference stations in order to avoid contaminations from more remote stations. As data of only three stations are used, an efficient missing data constructing approach with polynomial fitting is implemented to minimize data losses. Data from large scale reference networks extended with single-frequency receivers can now be processed, based on the adapted SEID model. A new data processing scheme is developed in order to make use of existing GPS data processing software packages without any modifications. This processing scheme is evaluated using a sub-network of the German SAPOS network. The results verify that the new scheme provides an efficient way to densify existing GPS networks with single-frequency receivers. 相似文献
215.
A. Nathues H. Boehnhardt A.W. Harris C. Jentsch S. Schaeff F. Weischede A. Wiegand N. Schmitz W. Goetz Z. Kachri 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
ASTEX (ASTeroid EXplorer) is a concept study of an in situ exploration mission to two Near-Earth-Asteroids (NEAs), which consists of an orbiting element and two individual lander units. The target candidates have different mineralogical compositions, i.e. one asteroid is chosen to be of “primitive’’ nature, the other to be a fragment of a differentiated asteroid. The main scientific goals of the ASTEX mission are the exploration of the physical, geological, and mineralogical nature of the NEAs. The higher level goal is the provision of information and constraints on the formation and evolution of our planetary system. The study identified realistic mission scenarios, defined the strawman payload as well as the requirements and options for the spacecraft bus including the propulsion system, the landers, the launcher, and assessed and defined the requirements for the mission’s operational ground segment. 相似文献
216.
L.H. Deng Z.Q. Qu T. Liu W.J. Huang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
We investigate the north–south (N–S) asynchrony of the polar faculae and compare it with the hemispheric asynchrony of solar activity at low latitudes. We find that, (1) both the solar activity at high and low latitudes do not synchronously occur in the northern and southern hemispheres, there is phase shifts between the two hemispheres; (2) the N–S asynchrony of the polar faculae is a function of latitudes, implying that the asynchrony of the polar faculae between the two hemispheres is related to the hemispheric asymmetry and latitudinal distribution of the polar faculae. 相似文献
217.
Prediction of Boundary Layer Transition Based on Modeling of Laminar Fluctuations Using RANS Approach 总被引:1,自引:0,他引:1
This article presents a linear eddy-viscosity turbulence model for predicting bypass and natural transition in boundary layers by using Reynolds-averaged Navier-Stokes (RANS) equations. The model includes three transport equations, separately, to compute laminar kinetic energy, turbulent kinetic energy, and dissipation rate in a flow field. It needs neither correlations of intermittency factors nor knowledge of the transition onset. Two transition tests are carried out: flat plate boundary layer under zero ... 相似文献
218.
W.J. Heikkila T. Chen Z.X. Liu Z.Y. Pu R.J. Pellinen T.I. Pulkkinen 《Space Science Reviews》2001,95(1-2):399-414
We propose that the appropriate instability to trigger a substorm is a tailward meander (in the equatorial plane) of the strong current filament that develops during the growth phase. From this single assumption follows the entire sequence of events for a substorm. The main particle acceleration mechanism in the plasma sheet is curvature drift with a dawn-dusk electric field, leading to the production of auroral arcs. Eventually the curvature becomes so high that the ions cannot negotiate the sharp turn at the field-reversal region, locally, at a certain time. The particle motion becomes chaotic, causing a local outward meander of the cross-tail current. An induction electric field is produced by Lenz's law, E
ind=–A/t. An outward meander with B
z>0 will cause E×B flow everywhere out from the disturbance; this reaction is a macroscopic instability which we designate the electromotive instability. The response of the plasma is through charge separation and a scalar potential, E
es=–. Both types of electric fields have components parallel to B in a realistic magnetic field. For MHD theory to hold the net E
must be small; this usually seems to happen (because MHD often does hold), but not always. Part of the response is the formation of field-aligned currents producing the well-known substorm current diversion. This is a direct result of a strong E
ind (the cause) needed to overcome the mirror force of the current carriers; this enables charge separation to produce an opposing electrostatic field E
es (the effect). Satellite data confirm the reality of a strong E
in the plasma sheet by counter-streaming of electrons and ions, and by the inverse ion time dispersion, up to several 100 keV. The electron precipitation is associated with the westward traveling surge (WTS) and the ion with omega () bands, respectively. However, with zero curl, E
es cannot modify the emf =Edl=–dM/dt of the inductive electric field E
ind (a property of vector fields); the charge separation that produces a reduction of E
must enhance the transverse component E
. The new plasma flow becomes a switch for access to the free energy of the stressed magnetotail. On the tailward side the dusk-dawn electric field with EJ<0 will cause tailward motion of the plasma and a plasmoid may be created; it will move in the direction of least magnetic pressure, tailward. On the earthward side the enhanced dawn-dusk induction electric field with EJ>0 will cause injection into the inner plasma sheet, repeatedly observed at moderate energies of 1–50 keV. This same electric field near the emerging X-line will accelerate particles non-adiabatically to moderate energies. With high magnetic moments in a weak magnetic field, electrons (ions) can benefit from gradient and curvature drift to attain high energies (by the ratio of the magnetic field magnitude) in seconds (minutes). 相似文献
219.
T.E. Gergely M.R. Kundu S.T. Wu M. Dryer Z. Smith R.T. Stewart 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(7):283-286
A large coronal transient took place on 8 May 1981. The transient was related to an M7.7/2B flare and was associated with at least two coronal type II bursts. The velocities of the type II bursts were in the range 1100–1800 kms?1, in excess of the transient velocity of 500–1000 kms?1. Two dimensional positions of the type II radio sources are available from both the Clark Lake and the Culgoora Radio Observatories. We carry out two dimensional MHD simulations of the event, taking into account the observed velocity, position, and size of the type II bursts. We simulate the multiple shocks observed during the event and their interaction, and discuss some results of the simulation. 相似文献
220.
S. Savin L. Zelenyi N. Maynard I. Sandahl H. Kawano C. T. Russell S. Romanov E. Amata L. Avanov J. Blecki J. Buechner G. Consolini G. Gustafsson S. Klimov F. Marcucci Z. Nemecek B. Nikutowski J. Pickett J. L. Rauch J. Safrankova A. Skalsky V. Smirnov K. Stasiewicz P. Song J. G. Trotignon Yu. Yermolaev 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2002,30(12):2821-2830
Multi-spacecraft tracing of the high latitude magnetopause (MP) and boundary layers and Interball-1 statistics indicate that:
- 1. (a) The turbulent boundary layer (TBL) is a persistent feature in the region of the cusp and ‘sash’, a noticeable part of the disturbances weakly depends on the interplanetary magnetic field By component; TBL is a major site for magnetosheath (MSH) plasma penetration inside the magnetosphere through percolation and local reconnection.
- 2. (b) The TBL disturbances are mainly inherent with the characteristic kinked double-slope spectra and, most probably, 3-wave cascading. The bi-spectral phase coupling indicates self-organization of the TBL as the entire region with features of the non-equilibrium multi-scale and multi-phase system in the near-critical state.
- 3. (c) We've found the different outer cusp topologies in summer/winter periods: the summer cusp throat is open for the decelerated MSH flows, the winter one is closed by the distant MP with a large-scale (several Re) diamagnetic ‘plasma ball’ inside the MP; the ‘ball’ is filled from MSH through patchy merging rather than large-scale reconnection.
- 4. (d) A mechanism for the energy release and mass inflow is the local TBL reconnection, which operates at the larger scales for the average anti-parallel fields and at the smaller scales for the nonlinear fluctuating fields; the latter is operative throughout the TBL. The remote from TBL anti-parallel reconnection seems to happen independently.
References
Chen, J., Fritz, T.A., Sheldon, R.B., Spencer, H.E., Spjeldvik, W.N. et al., 1997. Temporary confined population in the polar cap during the August 27, 1996 geomagnetic field distortion period. Geophys. Res. Lett. 24, p. 1447. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (51)
Chen, J. and Fritz, T.A., 1998. Correlation of cusp MeV helium with turbulent ULF power spectra and its implications. Geophys. Res. Lett. 25, p. 4113. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (34)
Consolini, G. and Lui, A.T., 2000. Symmetry breaking and nonlinear wave-wave interaction in current disruption: possible evidence for a phase transition. In: Magnetospheric Current SystemsGeophysical Monograph 118, American Geophysical Union, Washington D.C., pp. 395–401.
Dubinin, E., Skalsky, A., Song, P., Savin, S., Kozyra, J. et al., 2001. Polar-Interball coordinated observations of plasma characteristics in the region of the northern and southern distant cusps. J. Geophys. Res. accepted .
Fedorov, A., Dubinin, E., Song, P., Budnick, E., Larson, P. and Sauvaud, J.A., 2000. Characteristics of the exterior cusp for steady southward IMF: Interball observations. J. Geophys. Res. 105, pp. 15,945–15,957.
Fritz, T.A., Chen, J. and Sheldon, R.B., 2000. The role of the cusp as a source for magnetospheric particles: a new paradigm?. Adv. Space Res. 25, pp. 1445–1457. Article | PDF (871 K)
| View Record in Scopus | Cited By in Scopus (18)
Haerendel, G. and Paschmann, G., 1975. Entry of solar wind plasma into the magnetosphere. In: Hultqvist, B. and Stenflo, L., Editors, 1975. Physics of the Hot Plasma in the Magnetosphere, Plenum, NY, p. 23.
Haerendel, G., 1978. Microscopic plasma processes related to reconnection. J. Atmos. Terr. Phys. 40, pp. 343–353. Abstract | PDF (1141 K)
| View Record in Scopus | Cited By in Scopus (27)
Klimov, S. et al., 1997. ASPI Experiment: Measurements of Fields and Waves Onboard the INTERBALL-1 Spacecraft. Ann. Geophys. 15, pp. 514–527. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (88)
Kuznetsova, M.M. and Zelenyi, L.M., 1990. The theory of FTE: Stochastic percolation model. In: Russell, C.T., Priest, E.R. and Lee, L.C., Editors, 1990. Physics of Magnetic Flux RopesAmerican Geophysical Union, pp. 473–488.
La Belle-Hamer, A.L., Otto, A. and Lee, L.C., 1995. Magnetic reconnection in the presence of sheared flow and density asymmetry: application to the Earth's magnetopause. J. Geophys. Res. 100, pp. 11,875–11,889.
Lagoutte, D., Lefeuvre, F. and Hanasz, J., 1989. Application of bi-coherence analysis in study of wave interactions in space plasma. J. Geophys. Res. 94, p. 435. Full Text via CrossRef
Maynard, N.C., Savin, S., Erickson, G.A., Kawano, H. et al., 2001. Observations of fluxes of magnetosheath origin by Polar and Interball at high latitudes behind the terminator-relationships to the magnetospheric “sash”. J. Geophys. Res. 104, pp. 6097–6122. Full Text via CrossRef
Merka, J., Safrankova, J., Nemecek, Z., Fedorov, A., Borodkova, N., Savin, S. and Skalsky, A., 2000. High altitude cusp: Interball observations. Adv. Space Res. 25, pp. 1425–1434. Article | PDF (915 K)
| View Record in Scopus | Cited By in Scopus (22)
Onsager, T.G., Scudder, J., Lockwood, M. and Russell, C.T., 2001. Reconnection at the high latitude magnetopause during northward IMF conditions. J. Geophys. Res. 106, pp. 25,467–25,488.
Romanov, V., Savin, S., Klimov, S., Romanov, S., Yermolaev, Yu., Blecki, J. and Wronowski, R., 1999. Magnetic turbulence at the magnetopause: plasma penetration. J. Tech. Phys. (Poland) 40 1, pp. 329–332.
Safrankova, J., Nemecek, Z., Prech, L., Sauvaud, J.-A. and Wing, S., 2001. The structure of the magnetopause layers at magnetospheric flanks. In: Proceedings of COSPAR/ESA, Colloquium.
Sagdeev, R.Z. and Galeev, A.A., 1969. Nonlinear plasma theory. In: , Benjamin, White Plains, N.Y., p. 6.
Sandahl, I., Popielavska, B., Budnick, E.Yu., Fedorov, A., Savin, S., Safrankova, J. and Nemecek, Z., 2000. The cusp as seen from Interball. In: Proceedings of Cluster II Workshop. Multiscale/Multipoint Plasma MeasurementsESA/SP-499, Imperial College, London, pp. 39–45.
Savin, S.P., Romanov, S.A., Fedorov, A.O., Zelenyi, L., Klimov, S.I. et al., 1998. The cusp/magnetosheath interface on May 29, 1996: Interball-1 and Polar observations. Geoph. Res. Lett. 25, pp. 2963–2966. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (23)
Savin, S.P., Borodkova, N.L., Budnik, E.Yu., Fedorov, A.O., Klimov, S.I. et al., 1998. Interball tail probe measurements in outer cusp and boundary layers. In: Horwitz, J.L., Gallagher, D.L. and Peterson, W.K., Editors, 1998. Geospace Mass and Energy Flow: Results from the International Solar-Terrestrial Physics ProgramGeophysical Monograph 104, American Geophysical Union, Washington, D.C., pp. 25–44.
Savin, S., Zelenyi, L., Budnik, L., Borodkova, N., Fedorov, A. et al., 1998. Manifestations of Boundary Layer Dynamics in Substrom Activity. Multi Spacecraft Study. In: Kokubun, S. and Kamide, Y., Editors, 1998. SUBSTORM-4, ‘Conf. on Substorms-4’Lake Hamana, Japan: March 9–13, 1998, , Terra Scientific Publ. Co., Tokyo, pp. 125–130.
Savin, S., Budnik, E., Nozdrachev, M., Romanov, V. et al., 1999. On the plasma turbulence and transport at the polar cusp outer border. Chekhoslovak J. Phys. 49 4a, pp. 679–693. View Record in Scopus | Cited By in Scopus (15)
Savin, S., Skalsky, A., Romanov, S., Budnick, E., Borodkova, N., Zelenyi, L. et al., 2000. Outer cusp boundary layer: summer/winter assymetry. In: Proceedings of Symposium ‘From solar corona through interplanetary space into magnetosphere and ionosphere’, Kyiv University, Kyiv, pp. 229–232.
Savin, S., Blecki, J., Pissarenko, N., Lutsenko, V., Kirpichev, I. et al., 2002. Accelerated particles from turbulent boundary layer. In: Proc. of Interball/COSPAR Colloquium ‘Acceleration And Heating In The Magnetosphere’ in press .
Savin, S., Maynard, N., Sandahl, I., Kawano, H., Russell, C.T., Romanov, S., Zelenyi, L. et al., 2002. Magnetosheath/Cusp Interface. Ann. Geophys. submitted .
Siscoe, G.L., Erickson, G.M., Sonnerup, B.U.Ö., Maynard, N.C., Siebert, K.D., Weimer, D.R. and White, W.W., 2001. Magnetospheric sash dependence on IMF direction. Geophys. Res. Lett. in press .
Spreiter, J.R. and Briggs, B.R., 1962. Theoretical determination of the form of the boundary of the solar corpuscular stream produced by interaction with the magnetic dipole field of the Earth. J. Geophys. Res. 67, pp. 37–51. Full Text via CrossRef
Zelenyi, L.M. and Milovanov, A.V., 1998. Multiscale magnetic structure of the distant tail: self-consistent fractal approach. In: New Perspectives on the Earth MagnetotailGeophys. Monograph 105, AGU, Washington DC, pp. 321–338.
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