| 1. |
|
|
| 2. |
- Fornasier, S., et al.
(författare)
-
Spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from the OSIRIS instrument onboard the ROSETTA spacecraft
- 2015
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 583
-
Tidskriftsartikel (refereegranskat)abstract
- Context. The Rosetta mission of the European Space Agency has been orbiting the comet 67P/Churyumov-Gerasimenko (67P) since August 2014 and is now in its escort phase. A large complement of scientific experiments designed to complete the most detailed study of a comet ever attempted are onboard Rosetta. Aims. We present results for the photometric and spectrophotometric properties of the nucleus of 67P derived from the OSIRIS imaging system, which consists of a Wide Angle Camera (WAC) and a Narrow Angle Camera (NAC). The observations presented here were performed during July and the beginning of August 2014, during the approach phase, when OSIRIS was mapping the surface of the comet with several filters at different phase angles (1.3 degrees-54 degrees). The resolution reached up to 2.1 m/px. Methods. The OSIRIS images were processed with the OSIRIS standard pipeline, then converted into I/F. radiance factors and corrected for the illumination conditions at each pixel using the Lommel-Seeliger disk law. Color cubes of the surface were produced by stacking registered and illumination-corrected images. Furthermore, photometric analysis was performed both on disk-averaged photometry in several filters and on disk-resolved images acquired with the NAC orange filter, centered at 649 ran, using Hapke modeling. Results. The disk-averaged phase function of the nucleus of 67P shows a strong opposition surge with a G parameter value of -0.13 +/- 0.01 in the HG system formalism and an absolute magnitude H-v(1, 1, 0) = 15.74 +/- 0.02 mag. The integrated spectrophotometry in 20 filters covering the 250-1000 nm wavelength range shows a red spectral behavior, without clear absorption bands except for a potential absorption centered at similar to 290 rim that is possibly due to SO2 ice. The nucleus shows strong phase reddening, with disk-averaged spectral slopes increasing from 11%/( 100 nm) to 16%/(100 nm) in the 1.3 degrees-54 degrees phase angle range. The geometric albedo of the comet is 6.5 +/- 0.2% at 649 nm, with local variations of up to similar to 16% in the Hapi region. From the disk-resolved images we computed the spectral slope together with local spectrophotometry and identified three distinct groups of regions (blue, moderately red, and red). The Hapi region is the brightest, the bluest in term of spectral slope, and the most active surface on the comet. Local spectrophotometry shows an enhancement of the flux in the 700-750 nm that is associated with coma emissions.
|
|
| 3. |
- Preusker, F., et al.
(författare)
-
Shape model, reference system definition, and cartographic mapping standards for comet 67P/Churyumov-Gerasimenko Stereo-photogrammetric analysis of Rosetta/OSIRIS image data
- 2015
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 583
-
Tidskriftsartikel (refereegranskat)abstract
- We analyzed more than 200 OSIRIS NAC images with a pixel scale of 0.9-2.4 m/pixel of comet 67P/Churyumov-Gerasimenko (67P) that have been acquired from onboard the Rosetta spacecraft in August and September 2014 using stereo-photogrammetric methods (SPG). We derived improved spacecraft position and pointing data for the OSIRIS images and a high-resolution shape model that consists of about 16 million facets (2 m horizontal sampling) and a typical vertical accuracy at the decimeter scale. From this model, we derive a volume for the northern hemisphere of 9.35 km(3) +/- 0.1 km(3). With the assumption of a homogeneous density distribution and taking into account the current uncertainty of the position of the comet's center-of-mass, we extrapolated this value to an overall volume of 18.7 km(3) +/- 1.2 km(3), and, with a current best estimate of 1.0 X 10(13) kg for the mass, we derive a bulk density of 535 kg/m(3) +/- 35 kg/m(3). Furthermore, we used SPG methods to analyze the rotational elements of 67P. The rotational period for August and September 2014 was determined to be 12.4041 +/- 0.0004 h. For the orientation of the rotational axis (z-axis of the body-fixed reference frame) we derived a precession model with a half-cone angle of 0.14 degrees, a cone center position at 69.54 degrees/64.11 degrees (RA/Dec J2000 equatorial coordinates), and a precession period of 10.7 days. For the definition of zero longitude (x-axis orientation), we finally selected the boulder-like Cheops feature on the big lobe of 67P and fixed its spherical coordinates to 142.35 degrees right-hand-rule eastern longitude and -0.28 degrees latitude. This completes the definition of the new Cheops reference frame for 67P. Finally, we defined cartographic mapping standards for common use and combined analyses of scientific results that have been obtained not only within the OSIRIS team, but also within other groups of the Rosetta mission.
|
|
| 4. |
- Preusker, F., et al.
(författare)
-
The global meter-level shape model of comet 67P/Churyumov-Gerasimenko
- 2017
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 607
-
Tidskriftsartikel (refereegranskat)abstract
- We performed a stereo-photogrammetric (SPG) analysis of more than 1500 Rosetta/OSIRIS NAC images of comet 67P/ChuryumovGerasimenko (67P). The images with pixel scales in the range 0.2-3.0 m/pixel were acquired between August 2014 and February 2016. We finally derived a global high-resolution 3D description of 67P's surface, the SPG SHAP7 shape model. It consists of about 44 million facets (1-1.5 m horizontal sampling) and a typical vertical accuracy at the decimeter scale. Although some images were taken after perihelion, the SPG SHAP7 shape model can be considered a pre-perihelion description and replaces the previous SPG SHAP4S shape model. From the new shape model, some measures for 67P with very low 3 sigma uncertainties can be retrieved: 18.56 km(3) +/- 0 : 02 km(3) for the volume and 537.8 kg/m(3) +/- 0.7 kg/m(3) for the mean density assuming a mass value of 9 : 982 +/- 10(12) kg.
|
|
| 5. |
- Urlep, Z, et al.
(författare)
-
Disrupting Hepatocyte Cyp51 from Cholesterol Synthesis Leads to Progressive Liver Injury in the Developing Mouse and Decreases RORC Signalling
- 2017
-
Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7, s. 40775-
-
Tidskriftsartikel (refereegranskat)abstract
- Development of mice with hepatocyte knockout of lanosterol 14α-demethylase (HCyp51−/−) from cholesterol synthesis is characterized by the progressive onset of liver injury with ductular reaction and fibrosis. These changes begin during puberty and are generally more aggravated in the knockout females. However, a subgroup of (pre)pubertal knockout mice (runts) exhibits a pronounced male prevalent liver dysfunction characterized by downregulated amino acid metabolism and elevated Casp12. RORC transcriptional activity is diminished in livers of all runt mice, in correlation with the depletion of potential RORC ligands subsequent to CYP51 disruption. Further evidence for this comes from the global analysis that identified a crucial overlap between hepatic Cyp51−/− and Rorc−/− expression profiles. Additionally, the reduction in RORA and RORC transcriptional activity was greater in adult HCyp51−/− females than males, which correlates well with their downregulated amino and fatty acid metabolism. Overall, we identify a global and sex-dependent transcriptional de-regulation due to the block in cholesterol synthesis during development of the Cyp51 knockout mice and provide in vivo evidence that sterol intermediates downstream of lanosterol may regulate the hepatic RORC activity.
|
|
| 6. |
- Andersson, A, et al.
(författare)
-
The Foiling Optimist
- 2017
-
Ingår i: The Proceedings of the 4th International Conference on Innovation in High Performance Sailing Yachts, Lorient, France, 28-30 June 2017.. ; , s. 19-30
-
Konferensbidrag (refereegranskat)
|
|
| 7. |
|
|
| 8. |
- Lassmann-Klee, Paul, et al.
(författare)
-
Differences of FENO in adult general populations of Nordic regions
- 2019
-
Ingår i: European Respiratory Journal. - : European Respiratory Society. - 0903-1936 .- 1399-3003. ; 54:Suppl. 63
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: Eventual differences of expiratory nitric oxide (FENO) levels in general populations of Nordic countries may reflect differences in eosinophilic inflammation at population level.Aim: To study the differences in FENO of Nordic regions and their epidemiological associations.Methods: From 1997 to 2003 we measured FENO (ppb) and conducted skin prick-tests for a random sample of adults (n=1498), aged 20-60 years from Finland (Helsinki), Sweden (Stockholm and Örebro) and Estonia (Narva and Saaremaa). We compared differences between regions by estimating odds ratios (OR) and 95% confidence intervals (CIs) for high FENO (>25 ppb) using logistic regression adjusted for gender, smoking and allergy. Finally, we estimated crude ORs and 95% CIs for high FENO and for asthma, rhinitis, current asthma symptoms and asthma medication.Results: The mean and standard deviation (SD) for FENO was 19(14) in Finland, 18(12) in Sweden and 16(15) in Estonia (p<0.001). Estonia had a lower mean FENO than other countries, with no differences between Finland and Sweden. Compared to Helsinki, the adjusted OR (95%CI) for high FENO was 0.42(0.21-0.81) in Stockholm, 0.65(0.43-0.98) in Örebro, 0.53(0.32-0.84) in Narva and 0.45(0.28-0.71) in Saaremaa. In Estonia, high FENO was associated with asthma, allergy, rhinitis, current asthma, and asthma medication; in Finland with rhinitis and use of short acting β-agonist; in Sweden with asthma and asthma medication. Smoking was associated with low FENO. Mean FENO in asthmatics was 24(19) in Finland, 20(12) in Sweden, and 43(49) in Estonia (p=0.07).Conclusions: We observed a higher mean FENO in Finland and Sweden compared to Estonia, and found no overall differences of FENO levels in asthmatics.
|
|
