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- Aikio, A T, et al.
(författare)
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On the origin of the high-altitude electric field fluctuations in the auroral zone
- 1996
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 101:A12, s. 27157-27170
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Tidskriftsartikel (refereegranskat)abstract
- Intense fluctuations in the electric field at high altitudes in the auroral zone are frequently measured by the Viking satellite. We have made an analysis of the origin of electric and magnetic fluctuations in the frequency range of 0.1 - 1 Hz by assuming four different sources for the signals: (I) spatial structures, (2) spatial structures with a parallel potential drop below the satellite, (3) traveling; shear Alfven waves, and (4) interfering shear Alfven waves. We will shaw that these different sources of the signals may produce similar amplitude ratios and phase differences between the perpendicular electric and magnetic fields. Since the different sources have different frequency dependencies, this can be used as an additional test if the signals are broadband. In other cases, additional information is needed, for example, satellite particle measurements or ground; magnetic measurements. The ideas presented in the theory were tested for one Viking eveningside pass over Scandinavia, where ground-based magnetometer and EISCAT radar measurements were available. The magnetic conditions were active during this pass and several interfering shear Alfven waves were found. Also, a spatial structure with a parallel potential drop below the satellite was identified. The magnitude of the 10-km-wide potential drop was at least 2 kV and the upward field-aligned current 26 mu A m(-2) (value mapped to the ionospheric level). The held-aligned conductance was estimated as 1.3 - 2.2x10(-8) S m(-2).
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- Danielides, M. A., et al.
(författare)
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Measurement of Auroral characteristics by Auroral Turbulence II sounding rocket
- 1999
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Ingår i: Geophysica. - 0367-4231 .- 2324-0741. ; 35:1-2, s. 33-44
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Tidskriftsartikel (refereegranskat)abstract
- The Auroral Turbulence II sounding rocket was launched into a moderately active night-side aurora from the Poker Flat Research Range, Alaska, US. This unique three payload rocket experiment contained both electric and magnetic field, and particle instruments, which provided three point measurements over a wide range of scales. The payloads passed through several auroral arcs providing details of the auroral fine structure and the three point measurements allowed the distinction of spatial and temporal variations. The rocket data are compared with optical observations with special emphasis on a large quiet arc traversed in the middle of the flight. The observed features and field-aligned current densities are found to agree with earlier studies.
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- Eliasson, L, et al.
(författare)
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Observations of electron conics by the Viking satellite
- 1996
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - : AMER GEOPHYSICAL UNION. - 0148-0227. ; 101:A6, s. 13225-13238
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Electron angular distributions peaked at oblique angles to the magnetic field, electron conics, are frequently found in the Viking data at all magnetic local times, but with a maximum in the dusk sector. Several types of electron conics have been observed
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- Lanne, B, et al.
(författare)
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Glycoconjugate receptors for P-fimbriated Escherichia coli in the mouse. An animal model of urinary tract infection.
- 1995
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Ingår i: The Journal of biological chemistry. - 0021-9258. ; 270:15, s. 9017-25
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Tidskriftsartikel (refereegranskat)abstract
- Glycosphingolipids were isolated from kidneys, urethers, and bladders (including urethrae) of C3H/HeN mice. Binding was studied of a clinical isolate and recombinant strains of uropathogenic P-fimbriated Escherichia coli to these glycolipids. A series of receptor-active glycolipids with Gal alpha 4Gal in common, previously shown to be recognized by these bacteria, was identified by use of specific monoclonal antibodies, fast-atom bombardment and electron-impact mass spectrometry, and proton nuclear magnetic resonance spectroscopy: galabiosylceramide (Gal alpha 4Gal beta Cer), globotriaosylceramide (Gal alpha 4Gal beta 4Glc beta Cer), globoside (GalNAc beta 3Gal alpha 4Gal beta 4Glc beta Cer), the Forssman glycolipid (GalNAc alpha 3GalNAc beta 3Gal alpha 4Gal beta 4Glc beta Cer), Gal beta 4GlcNAc beta 6(Gal beta 3)GalNAc beta 3Gal alpha 4Gal beta 4Glc beta Cer, and Gal beta 4(Fuc alpha 3)GlcNAc beta 6(Gal beta 3)GalNAc beta 3Gal alpha 4Gal beta 4Glc beta Cer. The binding pattern for mouse kidney glycolipids differed from that for kidney glycolipids of man and monkey. In particular, the dominant 8-sugar glycolipid in the mouse was not detected in the primates. A second difference was found in the binding of E. coli to kidney glycoproteins on blots after electrophoresis; the mouse showed distinct receptor-active bands while human and monkey did not. These differences may be of relevance when using the mouse as a model for clinical urinary tract infection of man.
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- Marklund, S, et al.
(författare)
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Molecular basis for the dominant white phenotype in the domestic pig.
- 1998
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Ingår i: Genome research. - 1088-9051. ; 8:8, s. 826-33
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Tidskriftsartikel (refereegranskat)abstract
- The change of phenotypic traits in domestic animals and crops as a response to selective breeding mimics the much slower evolutionary change in natural populations. Here, we describe that the dominant white phenotype in domestic pigs is caused by two mutations in the KIT gene encoding the mast/stem cell growth factor receptor (MGF), one gene duplication associated with a partially dominant phenotype and a splice mutation in one of the copies leading to the fully dominant allele. The splice mutation is a G to A substitution in the first nucleotide of intron 17 and leads to skipping of exon 17. The duplication is most likely a regulatory mutation affecting KIT expression, whereas the splice mutation is expected to cause a receptor with impaired or absent tyrosine kinase activity. Immunocytochemistry showed that this variant form is expressed in 17- to 19-day-old pig embryos. Hundreds of millions of white pigs around the world are assumed to be heterozygous or homozygous for the two mutations. [The EMBL accession numbers for porcine KIT1*0101, KIT1*0202, KIT2*0202, and KIT2*0101 are AJ223228-AJ223231, respectively.]
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- Mishin, V M, et al.
(författare)
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A study of the CDAW 9C substorm of May 3, 1986, using magnetogram inversion technique 2, and a substorm scenario with two active phases
- 1997
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - 0148-0227. ; 102:A9, s. 19845-19859
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Tidskriftsartikel (refereegranskat)abstract
- One of the CDAW 9C substorms is investigated in this paper using the database reported by Hones et al. and supplemented with magnetogram inversion technique (MIT) 2 data. These latter have provided information about the dynamics of the open tail magnetic Aux, current systems in the ionosphere, and the size and dynamics of the current wedge. We have identified the growth: expansion, and recovery phases of this substorm, with characteristics expected from a generally accepted scenario. However, specific signatures were observed in the interval (0919-0935) UTI i.e., between the growth and expansion phases, indicating the concurrent development of the substorm onset and corresponding instabilities in the innermost current sheet, and small-scale cross-tail current disruptions without the open tail reconnection. In addition to signatures of small-scale dipolarization, an increase of the open tail magnetic flux, and a current system of the type close to DP 2 were observed at (0919-0935) UT, which is more likely to suggest predominance of the tail-stretching process than magnetic collapse, This fact was interpreted in tel ms of a relevant simple model as a signature of the growth of the energy input from the solar wind which ensures the observable disturbance power. Hence the disturbance st (0919-0935) UT was more likely a driven one than an unloading one. The aforementioned signatures make it possible to identify the interval (0919-0935) UT as the ''phase of multiple onsets'' or: (equivalently) the ''first active phase,'' which was previously defined by Mishin [1991., and references therein] as one of the four standard phases of a typical substorm (in addition to the expansion phase). Thus the case study supports the substorm scenario with two active phases and, accordingly, with two different kinds of physics, This case study illustrates also the informativity of MIT 2 data and their ability to effectively complement the database traditionally used in substorm studies.
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