| 1. |
- Meech, K. J., et al.
(författare)
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EPOXI: Comet 103P/Hartley 2 Observations from a Worldwide Campaign
- 2011
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Ingår i: Astrophysical Journal Letters. - London : IOP. - 2041-8213 .- 2041-8205. ; 734:L1, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Earth- and space-based observations provide synergistic information for space mission encounters by providing data over longer timescales, at different wavelengths and using techniques that are impossible with an in situ flyby. We report here such observations in support of the EPOXI spacecraft flyby of comet 103P/Hartley 2. The nucleus is small and dark, and exhibited a very rapidly changing rotation period. Prior to the onset of activity, the period was ~16.4?hr. Starting in 2010 August the period changed from 16.6?hr to near 19?hr in December. With respect to dust composition, most volatiles and carbon and nitrogen isotope ratios, the comet is similar to other Jupiter-family comets. What is unusual is the dominance of CO 2 -driven activity near perihelion, which likely persists out to aphelion. Near perihelion the comet nucleus was surrounded by a large halo of water-ice grains that contributed significantly to the total water production.
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| 2. |
- Grun, E., et al.
(författare)
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The 2016 Feb 19 outburst of comet 67P/CG : an ESA Rosetta multi-instrument study
- 2016
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 462, s. S220-S234
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Tidskriftsartikel (refereegranskat)abstract
- On 2016 Feb 19, nine Rosetta instruments serendipitously observed an outburst of gas and dust from the nucleus of comet 67P/Churyumov-Gerasimenko. Among these instruments were cameras and spectrometers ranging from UV over visible to microwave wavelengths, in situ gas, dust and plasma instruments, and one dust collector. At 09: 40 a dust cloud developed at the edge of an image in the shadowed region of the nucleus. Over the next two hours the instruments recorded a signature of the outburst that significantly exceeded the background. The enhancement ranged from 50 per cent of the neutral gas density at Rosetta to factors > 100 of the brightness of the coma near the nucleus. Dust related phenomena (dust counts or brightness due to illuminated dust) showed the strongest enhancements (factors > 10). However, even the electron density at Rosetta increased by a factor 3 and consequently the spacecraft potential changed from similar to-16 V to -20 V during the outburst. A clear sequence of events was observed at the distance of Rosetta ( 34 km from the nucleus): within 15 min the Star Tracker camera detected fast particles (similar to 25 m s(-1)) while 100 mu m radius particles were detected by the GIADA dust instrument similar to 1 h later at a speed of 6 m s(-1). The slowest were individual mm to cm sized grains observed by the OSIRIS cameras. Although the outburst originated just outside the FOV of the instruments, the source region and the magnitude of the outburst could be determined.
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| 3. |
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| 4. |
- Minkevich, N. I., et al.
(författare)
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Formation of amyloid-like fibrillar structures and destruction of fibroblasts of the Tenon's capsule in progressive myopia due to resistance of the pigment epithelium-derived factor to restricted proteolysis
- 2012
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Ingår i: Russian journal of bioorganic chemistry. - 1068-1620 .- 1608-330X. ; 38:6, s. 605-612
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Tidskriftsartikel (refereegranskat)abstract
- We have previously shown that, normally, two forms of the pigment epithelium-derived factor (PEDF) with molecular weights of 50 and 45 kDa are present in the Tenon's capsule in equal amounts. These forms represent the full-length protein and a product of restricted proteolysis of PEDF. In persons with myopia, the full-length uncleaved factor was predominantly detected, which correlated with the disturbance of collagen fiber formation. An immunohistochemical study of the Tenon's capsule using polyclonal antibodies to PEDF showed that, in the control group, the factor is localized solely inside fibroblasts, whereas in patients with myopia, PEDF is distributed outside the cell as a halo around destroyed fibroblasts. It was shown in the present work using atomic force microscopy and immunodot assay with antibodies specific to amyloid fibrils that only the full-length PEDF is capable of forming amyloid-like fibrillar structures. The accumulation of fibrils leads to the destruction of fibroblasts and is a cause of changes in the biochemical composition and morphological structure of the Tenon's capsule in myopia.
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