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- Yamauchi, M, et al.
(author)
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Dynamic response of the cusp morphology to the solar wind : A case study during passage of the solar wind plasma cloud on February 21, 1994
- 1996
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In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 101:A11, s. 24675-24687
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Journal article (peer-reviewed)abstract
- On February 21, 1994, both Geotail and LMP 8 satellites detected an interplanetary plasma cloud with intense interplanetary magnetic field (IMF>50 nT) and high dynamic pressure (> 50 nPa). During this interval the Freja satellite detected intense cusp-like plasma injections in four out of six dayside traversals. The first two traversals are carefully studied, During the first traversal the overall morphology of the ion injection is characterized by a ''multiple-injection'' signature over a wide magnetic local time (MLT) range, whereas it is characterized by a ''single-injection'' signature with narrow injection region at 8 MLT in the second traversal, The solar wind conditions were also quite different between these two periods: while both dynamic and magnetic pressures stayed high during entire period, the dynamic beta was much higher during the first Freja traversal than during the second traversal. Between these two traversals, the cusp plasma injection is detected by the Sondre Stromfjord radar. The radar signature of the plasma injection is identified using the satellite particle data when the satellite and the radar were conjugate (the satellite's footprint was in the radar's field of view.) The cusp position and dynamics observed by the Sondre Stromfjord radar again show a very good correlation to the solar wind condition, especially to the dynamic pressure. The result indicates the following. (1) During southward IMF the cusp morphology differs for conditions of high or low solar wind dynamic pressure. High dynamic pressure widens the cusp (with multiple injections), whereas high magnetic pressure narrows it (with single injection), The effect of the IMF on the cusp locations and morphology becomes dominant only when the dynamic pressure is not very high, (2) Such a morphological difference reflects dynamic pressure more than dynamic beta during southward IMF at least during times of high solar wind dynamic pressure. (3) The cusp morphology responds very quickly to the changes in the solar wind conditions.
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| 2. |
- Funakoshi, H, et al.
(author)
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Targeted expression of a multifunctional chimeric neurotrophin in the lesioned sciatic nerve accelerates regeneration of sensory and motor axons
- 1998
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 95:9, s. 5269-5274
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Journal article (peer-reviewed)abstract
- Peripheral nerve injury markedly regulates expression of neurotrophins and their receptors in the lesioned nerve. However, the role of endogenously produced neurotrophins in the process of nerve regeneration is unclear. Expression of a multifunctional neurotrophin, pan-neurotrophin-1 (PNT-1), was targeted to the peripheral nerves of transgenic mice by using a gene promoter that is specifically activated after nerve lesion but that is otherwise silent in all other tissues and during development. PNT-1 is a chimeric neurotrophin that combines the active sites of the neurotrophins nerve growth factor, brain-derived neurotrophic factor, and neurotrophin-3 and binds and activates all known neurotrophin receptors. In adult transgenic mice, PNT-1 was highly expressed in transected but not in intact sciatic nerve. Morphometric analyses at the electron microscopy level showed increased and accelerated recovery of axon diameter of myelinated fibers in crushed peripheral nerves of transgenic mice compared with wild type. Examination of nerve bundles in target tissues indicated accelerated reinnervation of foot pad dermis and flexor plantaris muscle in transgenic mice. Moreover, transected sensory and motor axons of transgenic mice showed faster and increased return of neurophysiological responses, suggesting an accelerated rate of axonal elongation. Importantly, transgenic mice also showed a markedly ameliorated loss of skeletal muscle weight, indicating functional regeneration of motor axons. Together, these data provide evidence, at both the anatomical and functional levels, that neurotrophins endogenously produced by the lesioned nerve are capable of significantly accelerating the regeneration of both sensory and motor axons after peripheral nerve damage. In addition, our results indicate that exogenous PNT-1 administration may be an effective therapeutic treatment of peripheral nerve injuries.
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| 5. |
- Saito, A, et al.
(author)
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Conjugate observations of the mid-latitude electric field fluctuations with the MU radar and the Freja satellite
- 1998
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In: Journal of Atmospheric and Solar-Terrestrial Physics. - 1364-6826 .- 1879-1824. ; 60:1, s. 129-140
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Journal article (peer-reviewed)abstract
- Conjugate Freja satellite and MU radar observations were conducted from 1993 to 1995 to clarify the generation mechanism of mid-latitude electric field fluctuations (MEFs) which were found from DE-2 satellite observations. The detection of MEFs at higher altitudes than 1000 km by the Freja satellite confirms that the MEFs are transmitted along the geomagnetic held line without any significant damping. On one night of such conjugate observations, MEFs were observed in a traveling ionospheric disturbance (TID). On the other nights when the MEFs were observed by Freja, large scale density structures in the ionosphere were observed with the MU radar. Spread-F phenomena were also observed by ionosondes associated with these structures. The large scale modulation of the ionosphere, such as TIDs, might cause small scale modulations which grow through ionospheric instabilities. The linear growth rate is evaluated using a set of equations describing the growth of the mid-latitude ionospheric irregularities. The growth rate is shown to be too small under average conditions; however, when the neutral wind in TIDs is included, it is large enough to generate MEFs. (C) 1998 Elsevier Science Ltd. All rights reserved.
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| 7. |
- Yamaoka, H, et al.
(author)
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A thin superconducting solenoid magnet for the WASA detector
- 1996
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In: IEEE TRANSACTIONS ON MAGNETICS. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9464. ; 32:4, s. 2151-2154
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Journal article (other academic/artistic)abstract
- A thin superconducting solenoid magnet has been developed for the WASA detector, The magnet consists of a pair of coils and it provides a central magnetic field of 1.3T at 900A in a cylindrical volume of 0.65 m in diameter and 0.555 m in length, The featu
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