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- Marklund, G.T., Ivchenko, N., Karlsson, T., Fazakerley, A., Dunlop, M., Lindqvist, P.A., Buchert, S., Owen, C., Taylor, M., Vaivalds, A., Carter, P., Andre, M. and Balogh, A.
(författare)
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Temporal evolution of the electric field accelerating electrons away from the auroral ionosphere.
- 2001
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Ingår i: Nature. ; 414:6865, s. 724-727
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Tidskriftsartikel (refereegranskat)abstract
- The bright night-time aurorae that are visible to the unaided eye are caused by electrons accelerated towards Earth by an upward-pointing electric field(1-3). On adjacent geomagnetic field lines the reverse process occurs: a downward-pointing electric fie
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- Marklund, Göran T., et al.
(författare)
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Temporal evolution of the electric field accelerating electrons away from the auroral ionosphere
- 2001
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 414:6865, s. 724-727
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Tidskriftsartikel (refereegranskat)abstract
- The bright night-time aurorae that are visible to the unaided eye are caused by electrons accelerated towards Earth by an upward-pointing electric field(1-3). On adjacent geomagnetic field lines the reverse process occurs: a downward-pointing electric field accelerates electrons away from Earth(4-11). Such magnetic-field-aligned electric fields in the collisionless plasma above the auroral ionosphere have been predicted(12), but how they could be maintained is still a matter for debate(13). The spatial and temporal behaviour of the electric fields-a knowledge of which is crucial to an understanding of their nature-cannot be resolved uniquely by single satellite measurements. Here we report on the first observations by a formation of identically instrumented satellites crossing a beam of upward-accelerated electrons. The structure of the electric potential accelerating the beam grew in magnitude and width for about 200 s, accompanied by a widening of the downward-current sheet, with the total current remaining constant. The 200-s timescale suggests that the evacuation of the electrons from the ionosphere contributes to the formation of the downward-pointing magnetic-field-aligned electric fields. This evolution implies a growing load in the downward leg of the current circuit, which may affect the visible discrete aurorae.
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- Szita, S., Fazakerley, A.N., Carter, P.J., James, A.M., Travnicek, P., Watson, G., André, M., Ericsson, A. and Torkar, K.
(författare)
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Cluster PEACE observations of electrons of spacecraft.
- 2001
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Ingår i: Annales Geophysicae. ; 19, s. 1721-1730
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Tidskriftsartikel (refereegranskat)abstract
- The two PEACE (Plasma Electron And Current Experiment) sensors onboard each Cluster spacecraft sample the electron velocity distribution across the full 4 ¡ solid angle and the energy range 0.7eV to 26keV with a time resolution of 4 sec-onds. We present h
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- Carter, N, et al.
(författare)
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EUROQUEST - A questionnaire for solvent related symptoms: Factor structure, item analysis and predictive validity
- 2002
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Ingår i: NeuroToxicology. - 1872-9711 .- 0161-813X. ; 23:6, s. 711-717
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Tidskriftsartikel (refereegranskat)abstract
- The study evaluates the factor structure and predictive validity of the symptom questionnaire EUROQUEST (EQ) that had been developed with the goal of simplifying the evaluation of health effects associated with long-term solvent exposure. The EQ was added to the normal evaluation procedures for 118 male patients with suspected solvent-induced toxic encephalopathy (TE) referred to seven Swedish clinics of occupational medicine during an 18-month period. EQ was also completed by 239 males from a random sample of 400 Swedish males aged 25-64 years selected from the general population and a sample of 559 occupationally active male spray painters aged 25-64 years. Factor and item analyses of EQ responses were performed. Ordinary least square regression analysis was used to evaluate sensitivity and correlation to evaluate the specificity of EQ and the separate components. Questions concerning memory and concentration symptoms alone showed better sensitivity than the other five EQ dimensions singly or combined for the entire EQ and for a subset of questions approximating Q16, a widely used organic solvent symptom screening questionnaire. However, the diagnosis of TE required information in addition to exposure and responses to EQ and Q16-like questions. The results indicate that the subset of EQ questions concerning memory and concentration might replace the more cumbersome EQ and less sensitive Q16 in screening for TE, although none of the screening instruments alone replaces current clinical diagnostic procedures. (C) 2002 Elsevier Science Inc. All rights reserved.
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