| 1. |
- Szymanski, J. J., et al.
(författare)
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MEGA : A search for the decay mu –> e gamma
- 1994
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Ingår i: Intersections between particle and nuclear physics. Proceedings, 5th Conference, St. Petersburg, USA, May 31-June 6, 1994. ; , s. 789-792
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Konferensbidrag (refereegranskat)
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| 2. |
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| 3. |
- Zhang, Yong-Yuan, et al.
(författare)
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Antibodies to hepatitis C virus and hepatitis C virus RNA in Chinese blood donors determined by ELISA, recombinant immunoblot assay and polymerase chain reaction
- 1993
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Ingår i: Chinese Medical Journal. - 0366-6999. ; 106:3, s. 171-174
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Tidskriftsartikel (refereegranskat)abstract
- Antibodies to hepatitis C virus (anti-HCV) were determined in Chinese blood donors from the city of Wuhan by ELISA screening tests and confirmatory recombinant immunoblot assay (RIBA). 281 and 222 sera were sampled under similar conditions in 1989 and 1990, respectively. The first collection of sera was sent to Sweden in lyophilized form, the second directly as fresh, unfrozen sera. A high proportion (22%) of the lyophilized sera were positive in the screening assay but only 6 (2.10%) were positive by RIBA with antibodies against both the C100-3 and 5-1-1 peptides. HCV RNA could be detected by polymerase chain reaction (PCR) analysis in 3 of the 6 sera and in one reacting with C100-3 only. In the second material of fresh sera only 3 were positive in the screening anti-HCV ELISA, but none was RIBA or PCR positive. Thus, the overall prevalence of anti-HCV among the 503 Chinese blood donors as identified by RIBA was 1.2%, and that of HCV RNA by PCR was 0.8%. The confirmed antibody prevalence is higher than that reported in the western literature.
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| 4. |
- Bååth, L.B. 1948-, et al.
(författare)
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0735+178 : The cosmic conspiracy
- 1991
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 250:1, s. 50-56
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses a radio outburst in the BL Lac-object 0735+178 which started in early 1988, ended during 1990 and was succeeded by a new outburst which is still in progress. Our image obtained with a global VLBI network shows the source to mainly consist of a core-jet like structure ending in diffuse emission region of low surface brightness located to the east of the core. We identify two new components as having been produced during the late 1980's. They are moving out with apparent superluminal motion in a viewing angle of greater-than-or-similar-to 10-degrees at a distance of less-than-or-similar-to 2 mas from the core. The core includes another new component, but our resolution is just sufficient to resolve out this component from the core at our epoch of observation. We suggest that the weak emission region is caused by an older component reaching the point at which the Doppler boosting is at its maximum and that the long time scale flux variation are due to successive events when evolved components reach that point.
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| 5. |
- Bååth, L.B. 1948-, et al.
(författare)
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IMAGES OF THE BL LACERTAE OBJECT 1749+701 AT 5 GHZ
- 1992
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Ingår i: Astronomy and Astrophysics. - Les Ulis, France : EDP Sciences. - 0004-6361 .- 1432-0746. ; 262:1, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents images of 1749+701 from data obtained between 1980 and 1983 as a part of our VLBI programme to monitor a subsample of BL Lac objects at 5GHz. Our images show that this source has a complex structure with a jet pointing towards the north-west at a position angle of about -65-degrees. The brightest component is growing in extension along this position angle. We suggest this to be the core and that the growing extension was caused by a shock generated during an outburst and moving out along the jet. From the extension rate, we obtain an angular separation speed of 0.18 mas yr-1, which corresponds to an apparent transverse speed of 5c. The distances and position angles of two outer components seem remarkably constant. The phenomenon can be understood through a model in which a relativistic jet bends such that its axis is very close to the line of sight in two points. We also deduce that the Lorentz factor must be 4.5 less-than-or-equal-to gamma less-than-or-equal-to 6.5 and that the viewing angle must be 5-degrees less-than-or-equal-to theta less-than-or-equal-to 10-degrees. In this paper, we also present two images obtained from 5GHz MERLIN and combined MERLIN-VLBI data respectively. These maps show that there is a weak component located at a distance of 0.42 arcsec from the core at p.a -155-degrees.
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| 6. |
- Bååth, L.B. 1948-, et al.
(författare)
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The radio fine structure of the BL Lacertae object 0735 + 178
- 1991
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 243:2, s. 328-332
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Tidskriftsartikel (refereegranskat)abstract
- The BL Lacertae object 0735 + 178 has been mapped with global VLBI arrays at four epochs from 1979 to 1983. The hybrid maps presented in this paper show a complex structure with a component separating from the core with an apparent transverse velocity of almost-equal-to 7.9 c. We suggest a model in which new components are born in the core during an outburst, initially move away towards northeast and then at a distance of almost-equal-to 4.2 mas turn towards the southeast. At this point, the component does not show any discernible motion away from the core. We suggest that the jet curls towards the south and towards the observer and at this point has its minimum viewing angle, with maximum boosting and minimum apparent velocity. We associate the outburst of 1989 with the event when a superluminally moving component reaches this point.
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| 7. |
- Chu, H.S., et al.
(författare)
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AO 0235+164 - A "Heretic" BL Lac
- 1994
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Ingår i: VLBI TECHNOLOGY. - Tokyo : Terra Scientific Publishing Company. ; , s. 146-155
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Bokkapitel (refereegranskat)
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| 8. |
- Hammar, M., et al.
(författare)
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Investigation of chemically vapour deposited tungsten and tungsten silicide as contacts to n+ and p+ silicon areas
- 1990
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 185:1, s. 9-19
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Tidskriftsartikel (refereegranskat)abstract
- Tungsten and WSi2 have been examined as contact barriers between aluminium and n+ - or p+ -Si. The specific contact resistivity and diode leakage current were evaluated after heat treatment at different temperatures. Rutherford backscattering spectrometry measurements, X-ray diffraction analysis, scanning electron microscopy and sheet resistance measurements were performed to study the thermal stabilities of the Al/W/Si and Al/WSi2/Si systems. The contact resistivities of chemically vapour deposited tungsten and WSi2 to n+ -Si with a surface concentration of 7.5 × 1019 cm-3 were 8 × 10-7 Ωcm2 and 9 × 10-7 Ωcm2 respectively. To p+ -Si with a surface concentration of 2.6 × 1019 cm-3, they were 5 × 10-6 and 1 × 10-6 Ωcm2. Diffusion of aluminium was revealed to occur above 475°C in the case of tungsten and at 475°C in the case of WSi2. The void formation in silicon substrates was observed after heat treatment at 500°C for the Al/WSi2/Si system. The increase in leakage current for the Al/W/Si and Al/WSi2/Si structures is related to the onset of Si-Al interpenetration. Alloy formation was observed at 500°C for tungsten contacts whereas W-Al or other alloys were not detected up to 600°C for the WSi2 contact.
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| 9. |
- Zhang, F. J., et al.
(författare)
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1404+286 : A non-ideal calibrator for VLBI observations
- 1994
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 281:3, s. 649-652
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Tidskriftsartikel (refereegranskat)abstract
- The radio source 1404+286 was observed with global VLBI arrays at 5 and 1.67 GHz in 1990.88 and 1991.45 respectively. High quality maps are presented in this paper, and show the source to be resolved at both frequencies with a core-jet like structure extending approximately 6 mas in position angle approximately -145-degrees. The jet direction is similar in both maps. 1404+286 has often been used in the past as a flux density calibrator or a phase referencing source. Our results show that this source is not an ideal calibrator on VLBI scales.
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| 10. |
- Zhang, F.J., et al.
(författare)
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Are there two engines at the center of 3C 286?
- 1994
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 287:1, s. 32-37
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents images of the compact steep-spectrum quasar 3C 286 obtained with global VLBI arrays at 4.99 and 1.66 GHz. The morphology appears to be intermediate between the core-jet types and grossly distorted objects. The central portion is resolved into two components of almost equal peak brightnesses and spectral indices. On the 1.66 GHz map, the jet extends in position angle approximately -136-degrees, up to a knot (W1) (approximately 75 mas from the component C2) from which it curves rapidly towards the west to form another knot (W2). It is possible that the VLBI jet bends further towards the secondary component separated from the core by approximately 2.6'' in p.a. -115-degrees seen in high dynamic range VLA or Merlin maps. The jet has a sinuous feature shown clearly on the 5 GHz map. There is a low brightness extension at the North (designated N1) shown on both the 1.66 and 5 GHz maps, which is connected to the component C1 and bends towards the east.
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