| 1. |
- Lindehammer, Sabina, et al.
(författare)
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Temporal trends of HLA genotype frequencies of type 1 diabetes patients in Sweden from 1986 to 2005 suggest altered risk
- 2008
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Ingår i: Acta Diabetologica. - : Springer Science and Business Media LLC. - 0940-5429 .- 1432-5233. ; 45:4, s. 231-5
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to compare the frequency of human leukocyte antigen (HLA) genotypes in 1-18-year-old patients with type 1 diabetes newly diagnosed in 1986-1987 (n = 430), 1996-2000 (n = 342) and in 2003-2005 (n = 171). We tested the hypothesis that the HLA DQ genotype distribution changes over time. Swedish type 1 diabetes patients and controls were typed for HLA using polymerase chain reaction amplification and allele specific probes for DQ A1* and B1* alleles. The most common type 1 diabetes HLA DQA1*-B1*genotype 0501-0201/0301-0302 was 36% (153/430) in 1986-1987 and 37% (127/342) in 1996-2000, but decreased to 19% (33/171) in 2003-2005 (P \ 0.0001). The 0501-0201/0501-0201 genotype increased from 1% in 1986-1987 to 7% in 1996-2000 (P = 0.0047) and to 5% in 2003-2005 (P > 0.05). This study in 1-18-year-old Swedish type 1 diabetes patients supports the notion that there is a temporal change in HLA risk.
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| 2. |
- Gyllenberg, A, et al.
(författare)
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Variability in the CIITA gene interacts with HLA in multiple sclerosis.
- 2014
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Ingår i: Genes and immunity. - Stockholm : Springer Science and Business Media LLC. - 1476-5470 .- 1466-4879. ; 15, s. 162-167
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Tidskriftsartikel (refereegranskat)abstract
- The human leukocyte antigen (HLA) is the main genetic determinant of multiple sclerosis (MS) risk. Within the HLA, the class II HLA-DRB1*15:01 allele exerts a disease-promoting effect, whereas the class I HLA-A*02 allele is protective. The CIITA gene is crucial for expression of class II HLA molecules and has previously been found to associate with several autoimmune diseases, including MS and type 1 diabetes. We here performed association analyses with CIITA in 2000 MS cases and up to 6900 controls as well as interaction analysis with HLA. We find that the previously investigated single-nucleotide polymorphism rs4774 is associated with MS risk in cases carrying the HLA-DRB1*15 allele (P=0.01, odds ratio (OR): 1.21, 95% confidence interval (CI): 1.04-1.40) or the HLA-A*02 allele (P=0.01, OR: 1.33, 95% CI: 1.07-1.64) and that these associations are independent of the adjacent confirmed MS susceptibility gene CLEC16A. We also confirm interaction between rs4774 and HLA-DRB1*15:01 such that individuals carrying the risk allele for rs4774 and HLA-DRB1*15:01 have a higher than expected risk for MS. In conclusion, our findings support previous data that variability in the CIITA gene affects MS risk, but also that the effect is modulated by MS-associated HLA haplotypes. These findings further underscore the biological importance of HLA for MS risk.Genes and Immunity advance online publication, 16 January 2014; doi:10.1038/gene.2013.71.
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| 3. |
- Marcaide, J. M., et al.
(författare)
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The quasars 1038+528 A and B
- 1985
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 142:1, s. 71-84
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Tidskriftsartikel (refereegranskat)abstract
- The results of VLBI observations of the quasars 1038 + 528 A and B at 2.8, 3.6, 13, and 18 cm at various times between November 1979 and March 1981 are reported. The observations and data calibration are described, as are the mapping and astrometric techniques applied in the study. Both quasars are found to have 'core-jet' morphologies. The core of the A quasar dominates its morphology at centrimetric wavelengths with the brightness temperature of its 400 pc long jet being about 1/100 that of the core. By contrast, the 'jet' in the B quasar is very short (about 70 pc); the tail of this jet has the steepest spectral index found to date in extragalactic compact sources, indicating that high electron losses are responsible for the shortness of the jet. No evidence for appreciable morphological change in the B quasar was found over the time span of the study, whereas a new feature may be emerging from the A quasar core at superluminal speed.
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| 4. |
- Tateyama, Claudio E., et al.
(författare)
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Global 3- and 7-mm VLBI Observations of OJ 287
- 1996
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Ingår i: Nippon Tenmon Gakkai obun kenkyu hokoku. - Japan : Astronomical Society of Japan. - 0004-6264. ; 48:1, s. 37-44
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Tidskriftsartikel (refereegranskat)abstract
- We present new results from global VLBI observations of the highly active blazar OJ287 at 7 and 3 mm wavelengths. We show the first map of the mas to sub-mas structure of OJ287 at 43 GHz and discuss this image in the context with models of the source structure seen at 100 GHz.
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| 5. |
- Bartel, N., et al.
(författare)
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The Compact Radio Source 2021+614 : Simultaneous 2.3 and 8.3 GHz Mark III VLBI Observations
- 1984
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Ingår i: Astrophysical Journal. - Philadelphia, PA : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 279:1, s. 116-121
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Tidskriftsartikel (refereegranskat)abstract
- Second-epoch VLBI observations of the flat-spectrum radio source 2021+614 made simultaneously at 2.3 and 8.3 GHz with the Mark III system are reported. The maps derived from these observations reveal a complex, frequency-dependent radio structure on the milliarcsecond scale. The object has four nearly collinear components oriented at a position angle of about 35 degrees and embedded in an extended region. Two of these are optically thin, one has a flat spectrum, and the other appears to be synchrotron self-absorbed in the frequency range 2.3-8.3 GHz. No significant structural variation is found at either frequency between epochs separated by about three years. The formal estimate of the transverse velocity between two components, one with a flat and the other with an inverted spectrum, is v/c = 0.7 + or - 2.3. Remarkable similarities between 2021+614 and the unusual source 0316+413 are discussed.
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| 6. |
- Bååth, L.B. 1948-, et al.
(författare)
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The microarcsecond structure of 3C 273 at 3 MM
- 1991
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 241:1, s. L1-L4
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Tidskriftsartikel (refereegranskat)abstract
- Recent improvements in data analysis and receiver techniques have allowed us to produce a map of the 100GHz emission from the compact radio source 3C273 with the unsurpassed resolution of 50-mu-as (microarcseconds). Our map shows that the structure within 300-mu-as (approximately 1.5.10(18).h-1 cm) has a position angle significantly different from the position angle of the jet observed at lower frequencies. There are also indications in our map that the inner structure has a more pronounced wiggling structure than has been observed on larger scales. The observations were made about 60 days from the start of the outburst of 1988. Most of the flux from the outburst is concentrated in a component which is elongated approximately (56 x 5).10(16).h-1 cm perpendicular to the overall jet-axis. The distance between this component and the core is approximately 128-mu-as, which corresponds to the distance expected from an apparent velocity of approximately 800-mu-as year-1.
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| 7. |
- Bååth, L.B. 1948-, et al.
(författare)
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Time-Dependent Radio Fine Structure of the Compact Sources NRAO 150 and 4C 39.25
- 1980
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 86:3, s. 364-372
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Tidskriftsartikel (refereegranskat)abstract
- Very long baseline interferometer observations at 7.85 GHz have been used to probe the milliarcsecond structure of the unidentified, very compact radio source NRAO 150 and QSO 4 C 39.25. NRAO 150 exhibited no structural variations from 1972 to the end of 1974. A model with two circular Gaussian components fits the data well. NRAO 150 had a flux density of 7.6 plus or minus 0.5 Jy in the compact component; 4 C 39.25 showed a two-component structure, the components having a separation of (2.02 plus or minus 0.05 arc sec) x 10 to the -3rd power. The upper bound on the speed of transverse separation is 0.0001 arc sec per year or less than 2.7 c. From the spectrum there are also indications of a third, larger component.
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| 8. |
- Bååth, L.B. 1948-, et al.
(författare)
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VLBI observations of active galactic nuclei at 3 MM
- 1992
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 257:1, s. 31-46
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Tidskriftsartikel (refereegranskat)abstract
- Recent improvements in data analysis and receiver techniques have allowed us to produce maps of the 100 GHz emission from the compact cores of active galactic nuclei with the unsurpassed resolution of 50-mu-as (microarcseconds). We present here hybrid maps of a set of compact radio sources observed at two epochs with a global VLBI array. The high resolution enables us to show details of active galactic nuclei on size scales of 10(16)-10(17) cm. Jets are shown to be more curved in these inner parts than further out in the areas mapped with VLBI at lower frequencies. Our maps of the quasar 3C345 show that the curvature seen with lower resolution instruments continues very close to the core. New components are seen separating from the cores of 3C84 and BL Lac. We observe a component in 3C84 separating from the core with an apparent speed approximately 21000 km sec-1. The radio source OJ287 is still unresolved with our array, having a core size of less-than-or-similar-to 10(17) cm. There is no indication of any compact component in 3C279 which would be associated with the outburst in integrated flux density which happened some months before our observation. The flux density of the most compact component we observe in 3C279 agrees well with that of the quiet core as extrapolated from its radio spectrum at lower frequencies. The inner part of the radio jet of the giant elliptical galaxy M87 also shows a continuation of the structure on a larger size scale, with a structure we interpret as parts of a helical pattern. No fringes were found for 4C39.25 or Sgr A.
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| 9. |
- Lerner, M.S., et al.
(författare)
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A 100 GHZ map of 3C 446
- 1993
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 280:1, s. 117-120
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Tidskriftsartikel (refereegranskat)abstract
- The first map made from 100 GHz VLBI observations of the quasar/BL Lac object 3C446 is presented. This map represents a 25-fold increase in resolution compared to earlier maps. Our main conclusions are that the core of 3C 446 is still almost unresolved (less than or similar to 30 muas) at this frequency and that a jet extends several hundred microarcseconds at position angle almost-equal-to -142-degrees. A comparison is also made with observations at other size scales.
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| 10. |
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| 11. |
- Marcaide, J. M., et al.
(författare)
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Discovery of shell-like radio-structure in SN1993J
- 1995
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Ingår i: Nature. - London : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 373:6509, s. 44-45
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Tidskriftsartikel (refereegranskat)abstract
- SUPERNOVA explosions are poorly understood, partly because of difficulties in modelling them theoretically(1), and partly because there have been no supernovae observed in our Galaxy since the invention of the telescope. But the recent discovery(2) of supernova SN1993J in the nearby galaxy M81 offers an opportunity to investigate the evolution of the remnant, and its interaction with the surrounding interstellar medium, at high resolution. Here we present radio observations of SN1993J, made using very-long-baseline interferometry, which show the development of a shell structure. This 8-month-old radio shell is the youngest ever discovered in a supernova. The data suggest that the supernova explosion and the expanding shell of the remnant have nearly spherical symmetry, with small deviations where some parts of the shell are brighter than others. If these deviations arise because of variations in the density of the shell, this may reconcile earlier reports of symmetric radio emission(3) with the observed optical asymmetry(4,5), as the density variations could easily cause the latter. We infer that the radio emission is generated at the interface(6-9), where the surrounding gas is shocked by the ejecta.
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| 12. |
- Rantakyrö, F.T., et al.
(författare)
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50 μas resolution VLBI images of AGN’s at λ3 mm
- 1998
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Ingår i: Astronomy and Astrophysics. - Berlin : Springer-Verlag. - 0004-6361 .- 1432-0746. ; 131, s. 451-467
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Tidskriftsartikel (refereegranskat)abstract
- We present 15 images from the global mm-VLBI sessions in 1990 April at 100 GHz and 1993 April at 86 GHz. These observations probe the central engines of the 16 observed AGN's with up to 50 mu as resolution. Among other sources previously observed with lambda 3 mm VLBI we present the first lambda 3 mm maps of 0735+178, 0748+126, 1055+018, 2145+067, and CTA102, in total we have been able to image 13 out of the 16 observed sources. 6 out of the 13 imaged sources observed exhibit curvature and rapid structural changes, although the low dynamic range in two thirds of the maps limits the detection of weak features. Most of the sources have unresolved cores even at this high resolution. There is substantial evidence that the observed sources can be grouped into two general groups: A misaligned population with parsec scale jets in the form of low pitch helices and an aligned population with straight jets with small changes in PA due to intrinsic bends.
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| 13. |
- Sanjeevi, Carani B., et al.
(författare)
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The risk conferred by HLA-DR and DQ for type 1 diabetes in 0-35-year age group are different in different regions of Sweden
- 2008
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Ingår i: Annals of the New York Academy of Sciences. - : Wiley. - 0077-8923 .- 1749-6632. - 9781573317337 ; 1150, s. 106-11
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Tidskriftsartikel (refereegranskat)abstract
- HLA DR4-DQ8 and DR3-DQ2 haplotypes account for 89% of newly diagnosed cases of type 1 diabetes (T1D) in Sweden. The presence of a single copy of DQ6 confers protection. The aim of the present study is to evaluate whether the risk conferred by high risk HLA DR and DQ to T1D is similar in all regions of Sweden and see whether there are any significant regional differences. The subjects comprised 799 consecutively diagnosed T1D patients and 585 age-, sex-, and geography-matched healthy controls in the age group 0-35 years. HLA typing for high-risk haplotypes was previously performed using PCR-SSOP and RFLP. The results showed that HLA DR3-DR4 gave an odds ratio of 8.14 for the whole of Sweden. However, when the study group was divided into six geographical regions, subjects from Stockholm had the highest OR, followed by those from Lund, Linköping, Gothenburg, Umeå, and Uppsala. Absolute protection was conferred by the presence of DQ6 in subjects from the Linköping region, but varied in the other regions. The frequency of DR3 and DQ2, DR4 and DQ8, DR15, and DQ6 in patients showed high linkage for each region, but were different between regions. In conclusion: The risk conferred by high-risk HLA varies in different regions for a homogenous population in Sweden. The results highlight the important role played by the various environmental factors in the precipitation of T1D.
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| 14. |
- Alberdi, A., et al.
(författare)
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The high-frequency compact radio structure of the peculiar quasar 4C 39.25
- 1997
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Ingår i: Astronomy and Astrophysics. - : Springer-Verlag. - 0004-6361 .- 1432-0746. ; 327:2, s. 513-521
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Tidskriftsartikel (refereegranskat)abstract
- We present new high angular resolution images of the compact non-thermal radio source 4C 39.25 obtained from VLBI observations at λ1.3cm, λ7mm, and λ3mm wavelengths. These maps and Gaussian model-fits show that the milli-arcsecond to sub-milliarcsecond structure of 4C 39.25 consists of a complex bent core-jet structure with embedded moving and stationary VLBI components. Facilitated by the small observing beams and high angular resolutions obtained at mm-wavelengths, we measured the relative positions of the jet components with an accuracy of a few hundred micro-arcseconds. This allows the detailed followup of the ongoing merging process of a westward superluminally moving component (b_) with a stationary component a_, located at ~2.9 mas east of the putative core d_. In contrast to the other components of the structure with steeper spectra, the westernmost component d_ exhibits an inverted spectrum peaking between λ7mm and λ3mm, thus further supporting its identification as the VLBI core, self-absorbed at longer wavelengths. From two VLBI maps obtained nearly simultaneously at λ7mm and λ1.3cm, we made the first spectral index map of 4C 39.25 in this wavelength regime. The main characteristics of the spectral index distribution of the jet are pronounced changes of the spectral index between orientations parallel and transverse to the jet axis. Near the merging components a_ and b_ the spectral index steepens with increasing separation from d_. However, in the bridge of emission c_, which connects d_ with a_ and b_, the spectral index gradient has a direction transverse to the jet axis, suggesting a frequency dependent jet curvature and edge-brightening. A brief discussion of this behaviour within current jet models is presented.
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| 15. |
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| 16. |
- Doeleman, S., et al.
(författare)
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86 GHz Global VLBI Progress Report
- 1993
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Ingår i: VLBI Technology. - Tokyo : Terrapub. - 4887041128 ; , s. 89-92
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Bokkapitel (refereegranskat)
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| 17. |
- Giuffrida, T.S., et al.
(författare)
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VLBI Studies of the W3OH Water Maser
- 1977
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Ingår i: Bulletin of the American Astronomical Society. - New York, NY : American Institute of Physics (AIP). - 0002-7537 .- 2330-9458. ; 9, s. 576-576
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Tidskriftsartikel (refereegranskat)
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| 18. |
- Standke, K. J., et al.
(författare)
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High Sensitivity VLBI at 86 GHz : First Fringes with the 100 m Radio Telescope at Effelsberg
- 1993
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Ingår i: VLBI Technology. - Tokyo : Terra Scientific. - 4887041128 ; , s. 75-85
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Bokkapitel (refereegranskat)abstract
- Inclusion of large and sensitive antennas is of essential importance to further improve the imaging capabilities of VLBI at 3.5 mm wavelength. The combination of the 100 m radio telescope at Effelsberg (illuminated diameter ~60 m at lambda = 3.5 mm) with the 30 m radio telescope at Pico Veleta presently allows the detection of compact flux down to a level of 0.2 Jy (for τ=360 seconds integration time). Fringes have been found for 23 radio sources many of them not observed previously with VLBI at 86 GHz. On European baselines to Effelsberg the SNR typically was 10 to 30 (and ranged up to 107 for 3C279), facilitating model fitting for the brightest sources. Even in spite of chaning weather conditions during the observations (coherence times ranged between 10 to 100 seconds) and a still non-optimum pointing model for the 100 m antenna for observations at high frequencies, these results demonstrate that the 100 m radio telescope can be successfully incorporated in global VLBI experiments at 3.5 mm wavelength.
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| 19. |
- Sun, Chengjun, et al.
(författare)
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CRYAB-650 C>G (rs2234702) affects susceptibility to type 1 diabetes and IAA-positivity in Swedish population
- 2012
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Ingår i: Human Immunology. - : Elsevier. - 0198-8859 .- 1879-1166. ; 73:7, s. 759-766
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Single nucleotide polymorphisms (SNPs) in the promoter region of CRYAB gene have been associated with in multiple sclerosis. CRYAB gene, which encodes alpha B-crystallin (a member of small heat shock protein), was reported as a potential autoimmune target. In this study we investigated whether SNPs in the promoter region of CRYAB gene were also important in the etiology of Type 1 diabetes (T1D).METHODS: Genotyping of SNPs in the promoter region of CRYAB gene was performed in a Swedish cohort containing 444 T1D patients and 350 healthy controls. Three SNPs were included in this study: CRYAB-652 A>G (rs762550), -650 C>G (rs2234702) and -249 C > G (rs14133). Two SNPs (CRYAB-652 and -650) were not included in previous genome wide association studies.RESULTS: CRYAB-650 (rs2234702)*C allele was significantly more frequent in patients than in controls (OR = 1.48, Pc = 0.03). CRYAB-650*C allele was associated with IAA positivity (OR = 8.17, Pc < 0.0001) and IA-2A positivity (OR = 2.14, Pc = 0.005) in T1D patients. This association with IAA was amplified by high-risk HLA carrier state (OR = 10.6, P < 0.0001). No association was found between CRYAB-650 and other autoantibody positivity (GADA and ICA). CRYAB haplotypes were also associated with IAA and IA-2A positivity (highest OR = 2.07 and 2.11, respectively), these associations remain in high HLA-risk T1D patients.CONCLUSIONS: CRYAB-650 was associated with T1D in the Swedish cohort we studied. CRYAB-650*C allele might confers susceptibility to the development of T1D. CRYAB-650 was also associated with the development of IAA-positivity in T1D patients, especially in those carrying T1D high-risk HLA haplotypes.
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| 20. |
- Akujor, Chidi E., et al.
(författare)
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Combined-Array Imaging of Extra-Galactic Radio Sources
- 1994
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Ingår i: Astronomy with Millimeter and Submillimeter Wave Interferometry. - San Francisco : Astronomical Society of the Pacific. - 0937707783 ; , s. 123-124
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Konferensbidrag (refereegranskat)
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| 21. |
- Barreiro, A., et al.
(författare)
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Bacterial and fungal growth in burnt acid soils amended with different high C/N mulch materials
- 2016
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Ingår i: Soil Biology & Biochemistry. - : Elsevier BV. - 0038-0717. ; 97, s. 102-111
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Tidskriftsartikel (refereegranskat)abstract
- Wildfire has become a major disturbance agent in Mediterranean area, with Galicia in the north-west of Spain having the most frequent fires. In order to combat soil erosion, different post-fire stabilization treatments can be applied, like adding different mulch materials. In a laboratory experiment we evaluated the effect of adding plant residues, commonly used in post-fire rehabilitation (wheat straw, coconut fibre, Eucalyptus bark and wood chips), at two different rates on the microbial response (respiration, bacterial and fungal growth, using leucine and acetate-in-ergosterol incorporation, and biomass and community structure by means of phospholipids fatty acid analysis) in an acid forest soil affected by a high intensity wildfire. We expected fungal growth to be favoured compared to bacterial growth after adding plant material with high C/N content, especially at the higher rate. Compared to unburnt soil, burnt soil had higher pH (increasing from 4.4 to 5.8) and more extractable (available) C, resulting in a relatively higher increase in bacterial compared to fungal growth. Adding Eucalyptus residues to burnt soil, especially wood chips, favoured fungal growth, especially at the higher rate. Straw addition favoured both fungal and bacterial growth and was the substrate most available for decomposition, as indicated by the higher soil respiration rates. Coconut fibre contained less available C. Adding Eucalyptus residue, at both rates, and coconut fibres at the high rate, initially inhibited bacterial growth, resulting in at most a 14 day lag period. Aiming at high fungal to bacterial growth in order to maximize stabilization of soils through fungi suggest Eucalyptus residues to the prime choice for further studies on effective mulching agents, although coconut fibres, with low degradation rates, may also be a suitable choice. Nevertheless, besides aspects related to soil quality, additional information concerning the efficiency of these materials to control post-fire soil erosion should also be considered before their implementation under field conditions.
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| 22. |
- Booth, R. S., et al.
(författare)
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High-resolution observations of quasars from the Parkes +/- 4 deg. sample
- 1979
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Ingår i: Monthly notices of the Royal Astronomical Society. - Oxford : Oxford University Press. - 0035-8711 .- 1365-2966. ; 188, s. 159-163
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Tidskriftsartikel (refereegranskat)abstract
- VLBI observations of 20 compact quasars have been made between Jodrell Bank and Onsala at a frequency of 1666 MHz. Twelve of the quasars have inverted or peaked spectra at centimetre wavelengths and these are all unresolved, having angular diameters of less than 0.015 arcsec. Two out of five quasars with overall flat spectra are partially resolved on this scale size, as are three steep-spectrum quasars.
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| 23. |
- Bååth, E., et al.
(författare)
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Growth of bacteria in the rhizoplane and the rhizosphere of rape seedlings
- 1988
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Ingår i: FEMS Microbiology Letters. - 0378-1097. ; 53:6, s. 355-360
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Tidskriftsartikel (refereegranskat)abstract
- The growth of 10 isolates of rhizosphere bacteria was compared in the rhizoplane (RP), rhizosphere (RS) and non-rhizosphere soil of a model system with rape seedlings growing in sterile sand. The colonization of the RP differed little among isolates. However, the bacterial isolates differed according to their degree of dependence on the root for growth, as judged by RS:RP and plant:non-plant ratios for CFU. These two ratios were correlated with changes in viability and 'physiological status' (as judged by γ values, Hattori, T. (1983) J. Gen. Appl. Microbiol. 29, 9-16).
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| 24. |
- Bååth, L.B. 1948-, et al.
(författare)
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High Resolution Observations of the QSO 3C 345 at 1.3 centimeters
- 1981
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Ingår i: Astrophysical Journal. - Philadelphia, PA : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 243, s. L123-L126
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution VLBI observations made at a frequency of 22.235 GHz of the quasar 3C 345 are discussed. Antennas located at the Crimean Astrophysical Observatory, USSR; Onsala, Sweden; Effelsberg, West Germany; and the Haystack Observatory, Massachusetts were employed at 4-min integration times to provide baselines ranging up to 5.5 x 10 to the 8th wavelengths. About 40% of the total flux density of 7.85 Jy, observed in November 1977, and 8.05 Jy, observed in October 1978, is found to originate in an unresolved component of the quasar core in a region less than 0.1 milliarcsec in diameter. The elongated jet-like component of the quasar is observed to contain several peaks of emission extending up to 6 milliarsec from the core which decreased in extent between the two observations.
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| 25. |
- 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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| 26. |
- Chu, H.S., et al.
(författare)
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Discovery of Helical Magnetic Fields in AGN and CME and Ejection of Large Scale Magnetic Fields from AGN
- 2003
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Ingår i: Symposium - International astronomical union. - : International Astronomical Union. - 0074-1809. ; 214, s. 303-310
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic Fields are the crucial and most important ingredient involved in the processes of various violent activities in Active Galactic Nuclei and other celestial bodies. The generally accepted 2-sided symmetric-jets model of active galactic nuclei (AGN) does not include the magnetic fields. We present here the first direct detection of helical magnetic field in AGN, and the first direct detection of ejection of large scale magnetic fields from AGN. (CME) 2. The annular (helical) magnetic field is responsible for the collimation of the jet (through Pinch Effect) and may be of crucial importance for extraction of black hole rotational energy. 3. The CMEs are responsible for sporadic ejection of jet components in AGN, while the general accepted 2-sided jets pertain to the quiescent Jets. 4.Observations show that the CME with Asymmetric Jets can explain many phenomena and much of the morphological diversities in AGN.
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| 27. |
- Fernández-Calviño, David, et al.
(författare)
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Isothiazolinone inhibition of soil microbial activity persists despite biocide dissipation
- 2023
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717. ; 178
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Tidskriftsartikel (refereegranskat)abstract
- Soil microbial growth and activity are generally assumed to recover rapidly after dissipation of organic toxicants. We studied the effects of four readily degradable isothiazolinone biocides (benzisothiazolinone, BIT; methylisothiazolinone, MIT; octylisothiazolinone, OIT; 4,5-dichloro-2-octyl-isothiazolinone, DCOIT) on bacterial growth, fungal growth, basal respiration, and substrate-induced respiration in controlled soil microcosm experiments. Bacterial growth followed by fungal growth were the two most sensitive endpoints during the first two days. Significant dissipation of biocides occurred within just 8 h and 94–100% had dissipated after 40 days except for DCOIT tested at a high concentration (50 mg kg−1, 54% remaining after 40 d). Despite biocide dissipation, all isothiazolinones inhibited bacterial growth for >7 days, whereas fungal growth and substrate-induced respiration were inhibited for up to 40 days. Bacterial growth recovery after 40 days was linked to development of bacterial community tolerance for DCOIT, but not for the other less persistent isothiazolinones. Our study is the first to report on toxic effects of isothiazolinones on soil microbial growth and demonstrates that inhibitory effects of isothiazolinones on soil microbial growth and activity (especially fungal growth and substrate-induced respiration) persisted even long after biocide dissipation, indicating “legacy effects” and retarded recovery of soil microbial functions. We propose that retarded recovery of fungal, relative to bacterial, growth may be a general phenomenon during the dissipation of toxicants in contaminated soils and that it may be explained by intrinsic differences between bacterial and fungal biology in soil and by competitive interactions between these two dominant groups of soil microbial decomposers.
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| 28. |
- Fernández-Calviño, David, et al.
(författare)
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Short-term toxicity assessment of a triazine herbicide (terbutryn) underestimates the sensitivity of soil microorganisms
- 2021
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717. ; 154
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the impacts of persistent triazine herbicides and biocides on soil microorganisms. Terbutryn toxicity in soil microorganisms was studied using bacterial and fungal growth, substrate induced respiration (SIR) and basal respiration as ecotoxicological end-points. In the short-term (0–7 days), increasing concentrations of terbutryn (0–800 mg kg−1) progressively inhibited bacterial and fungal growth by up to 33–36% (4 h) and 49–55% (7 days), whereas SIR and basal soil respiration remained unaffected. Following long-term (40 days) exposure to terbutryn, both bacterial and fungal growth were inhibited by up to 76–78%, and SIR was inhibited by up to 53%. Hence, our results unexpectedly demonstrate time-cumulative microbial growth inhibition over extended time periods in soil and indicate that current ecotoxicological guidelines may underestimate risks posed by chemicals to soil microorganisms.
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| 29. |
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| 30. |
- Frostegård, Å, et al.
(författare)
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Changes in microbial community structure during long-term incubation in two soils experimentally contaminated with metals
- 1996
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Ingår i: Soil Biology and Biochemistry. - 0038-0717. ; 28:1, s. 55-63
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Tidskriftsartikel (refereegranskat)abstract
- The effects of Zn contamination on the microbial community structure of a forest humus and an arable soil, as estimated by phospholipid fatty acid (PLFA) analysis, were followed during 18 months. The soils were contaminated at 10 different metal concentrations and incubated in plastic jars at 22°C. In both soils effects of heavy metal contamination could be detected after 2 weeks. Qualitatively similar changes in the PLFA pattern were found at the later sampling occasions, although the changes became more pronounced with prolonged incubation. In the forest soil the double-unsaturated 18:2ω6, indicating fungi, increased proportionally due to the metal amendment, while there was a strong negative effect of incubation on the fungal biomass in all samples of this soil type. In the arable soil 18:2ω6 showed a strong increase in response to the Zn pollution. As in the forest soil, incubation decreased the mol% of 18:2ω6, although the effect was less pronounced than in the forest soil. The proportions of several individual bacterial PLFAs changed in both soils due to the treatments, indicating shifts within the bacterial community in the soils, but these shifts could not be interpreted in terms of changes in the proportional abundance of specific taxonomic groups of bacteria. The ratio of 16:1ω7t-to-16:1ω7c, which has been proposed as a starvation index, increased in the forest soil due to Zn contamination. In the high-metal samples this ratio decreased during incubation, while it remained unchanged in the uncontaminated control. In the arable soil no clear effect was found on the trans-to-cis ratio either in response to metal contamination or to incubation. The ATP content decreased during incubation. Little or no effect was found on the total amount of PLFAs or on the lipid phosphate content, except after 18 months when these biomass measurements decreased.
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| 31. |
- Frostegård, Å, et al.
(författare)
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Microbial biomass measured as total lipid phosphate in soils of different organic content
- 1991
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Ingår i: Journal of Microbiological Methods. - 0167-7012. ; 14:3, s. 151-163
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Tidskriftsartikel (refereegranskat)abstract
- The use of total lipid phosphate as a measure of biomass was evaluated in soils with different organic matter content. Lipids were extracted with a one-phase mixture of chloroform, methanol, and a buffer, and digested with either persulfate or perchloric acid to liberate lipid-bound phosphate. This procedure was evaluated by varying the extraction buffer, the extraction and digestion times, the amount of soil extracted, and the amount of lipid material digested. An extraction period of 2 h was sufficient to yield maximum lipid phosphate. Neither sonication, vigorous mixing, nor longer extraction periods increased the amount of lipid phosphate extracted. However, the amount of lipid phosphate recovered was dependent on the choice of buffer. When organic soil was used, citrate buffer in the extraction mixture gave higher amounts of lipid phosphate than acetate buffer, Tris, H2O or phosphate buffer. In a sandy loam with low organic matter content, citrate or phosphate buffers performed equally well. When 13 soils of different organic matter content were examined, the two digestion methods showed a good linear correlation (r2 = 0.991). Substrate-induced respiration (SIR) and ATP contents of the different soils correlated well with the total lipid phosphate. Based on these measurements, a conversion factor of 500 μmol lipid phosphate·g-1 biomass-C (perchloric acid digestion) was calculated.
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| 32. |
- Grosso, F., et al.
(författare)
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Bacterial and fungal growth on different plant litter in Mediterranean soils : Effects of C/N ratio and soil pH
- 2016
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393. ; 108, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Plant litter represents an important source of nutrients and energy for soil microorganisms, but will also selectively affect which organism group, fungi or bacteria, that will be favoured during decomposition. The balance of fungal to bacterial growth will furthermore be affected by soil chemistry like pH. A laboratory experiment was carried out using two different Mediterranean forest soils differing in pH, adding five types of litter varying in C/N ratio from 15 to 75, including the major litter type from the two soils. Growth of bacteria (using the leucine incorporation technique) and fungi (using the acetate into ergosterol incorporation technique) was then followed during 6 weeks. The balance of fungal to bacterial growth was positively affected by litter with increasing C/N ratio, while the C availability, as judged by evolved CO2, did not have any influence. Furthermore, low pH in the soil further favoured fungal growth, irrespective of the litter type. Despite differences in fungal to bacterial growth this appeared to have little influence on respiration rates from the added litter, suggesting functional redundancy. Our results highlight how both initial soil conditions (pH) and litter composition (C/N ratio) independently affects fungal and bacterial growth during decomposition.
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| 33. |
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| 34. |
- Mundy, Lee G., et al.
(författare)
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High-resolution images of the Orion molecular ridge in the CS J = 2-1 transition
- 1988
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Ingår i: Astrophysical Journal. - Philadelphia, PA : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 325:1, s. 382-388
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Tidskriftsartikel (refereegranskat)abstract
- The authors have constructed 7arcsec.5 resolution images of the CS J = 2-1 emission from a 3arcmin.5 section of the Orion molecular ridge using a maximum entropy algorithm to combine Owens Valley Millimeter-Wave Interferometer and Onsala Space Observatory 20 m data. The resulting images include all of the flux and have positional accuracy of 1arcsec-2arcsec on the small-scale features. The observed section of the ridge includes four condensations. The condensations have dimensions from 0.03 to 0.11 pc and virial massses from 30 to 80 M_sun;. Approximately 70% of the total mass within the 3arcmin region is contained in these condensations.
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| 35. |
- Nottingham, A. T., et al.
(författare)
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Annual to decadal temperature adaptation of the soil bacterial community after translocation across an elevation gradient in the Andes
- 2021
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717. ; 158
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Tidskriftsartikel (refereegranskat)abstract
- The response of soil microbial activity to climate warming has been predicted to have a large destabilising effect on the carbon cycle. However, the nature of this feedback remains poorly understood, especially in tropical ecosystems and across annual to decadal timescales. We studied the response of bacterial community growth to 2 and 11 years of altered temperature regimes, by translocating soil across an elevation gradient in the tropical Andes. Soil cores were reciprocally translocated among five sites across 3 km in elevation, where mean annual temperature (MAT) ranged from 26.4 to 6.5°C. The bacterial community growth response to temperature was estimated using a temperature Sensitivity Index (SI): the log-ratio of growth determined by leucine incorporation at 35°C: 4°C. Bacterial communities from soil translocated to their original site (controls) had a growth response assumed to be ‘adapted’ to the original MAT. Translocating soil downslope (warming) resulted in an increased SI relative to their original growth response, and vice versa under cooling, indicating community-level adaptation over the incubation period to the altered MAT. The average level of adaptation (i.e., the extent to which SI converged on the control values) was 77% after 2 years, and was complete after 11 years. The adaptive response was faster when soil was warmed rather than cooled: instances of complete adaptation of SI occurred in soils after 2 years when warmed, but only after 11 years when they were cooled. Taken together, our results show that the majority of the growth adaptation to warming by the bacterial community occurs rapidly, within 2 years, whilst growth adaptation to cooling occurs within a decade. Our analysis demonstrates rapid warm-adaptation of bacterial community growth, with potential consequences for the temperature sensitivity of soil carbon cycling in response to future climate warming.
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| 36. |
- Okopi, J. E., et al.
(författare)
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Wide field mapping of 5C12
- 1991
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Ingår i: Radio Interferometry. - San Francisco, USA : Astronomical Society of the Pacific. - 0937707384 - 9780937707388 ; , s. 253-256
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Konferensbidrag (refereegranskat)abstract
- A wide-field mapping technique aimed at resolving problems which occur in the radio mapping of very wide fields is described. The technique has been successfully applied to Merlin observations of the 5C12 region covering an area of 1800 arcsec x 180 arcsec.
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| 37. |
- Rantakyrö, Fredrik T., et al.
(författare)
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Multiband VLBI observations of CTA 102
- 1996
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 310:1, s. 66-74
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Tidskriftsartikel (refereegranskat)abstract
- The source CTA102, known to exhibit low frequency variability, has been observed at six epochs (three at λ32cm, two at λ18cm, and one at λ1.3cm) with intercontinental VLBI arrays. On the basis of the changes observed in the structure, we believe that the flux density variations at these wavelengths are due to intrinsic processes and not due to interstellar scintillation. This source exhibits behaviour suggestive of being expanding with a very high apparent transverse velocity.
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| 38. |
- Rantakyrö, F.T., et al.
(författare)
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Multifrequency interferometer and radio continuum monitoring observations of CTA 102
- 2003
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Ingår i: Astronomy and Astrophysics. - Berlin : Springer. - 0004-6361 .- 1432-0746. ; 42:5, s. 473-485
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Tidskriftsartikel (refereegranskat)abstract
- This paper represents the work of several years of observation of CTA 102 with both single dish telescopes andinterferometric arrays, covering wavelengths from 1.2 cm to 1.3 mm. The resolution of the maps covers an order of magnitudefrom 0.5 mas to 50 μas. The images presented demonstrate the rapid structural changes in this source. These rapid structuralchanges correlates with the outbursts seen in the total flux, turnover frequency and in the spectral index. We have calculated theBrightness Temperatures of the components (TB ) directly from the determined component sizes and also using the logarithmicvariability amplitudes and timescales to calculate the TB s. Both the methods yielded measurements of source frame T Bs nohigher than∼a few × 1012K. We find that the observed average proper motion is0.4 0.07 mas/yr, which corresponds to anapparent transverse velocity of 11± 2 c.
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| 39. |
- Stannard, D., et al.
(författare)
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VLBI Observations of 3C345 at 1.67 GHz
- 1980
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Ingår i: Monthly notices of the Royal Astronomical Society. - Oxford : Oxford University Press. - 0035-8711 .- 1365-2966. ; 192:4, s. 555-560
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Tidskriftsartikel (refereegranskat)abstract
- VLBI observations of the quasar 3C 345 suggest that the milliarcsec subcomponents in the core have approximately equal intensities at 1.67 GHz. A new compact feature is detected in the inner jet structure at a distance of ∼ 12 m.arcsec from the core. © 1980 Royal Astronomical Society. Provided by the NASA Astrophysics Data System
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| 40. |
- Sving, E., et al.
(författare)
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The experiences of operating room teams working with real-time feedback of interface pressure to prevent pressure injuries : A feasibility study
- 2020
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Ingår i: Perioperative Care and Operating Room Management. - : Elsevier BV. - 2405-6030. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- Background: Surgical patients have an increased risk of sustaining a pressure induced injury. Novel technology has made it possible to objectively measure and visualize the interface pressure between the patient's tissue and the support surface in real time. The aim of this study was to describe operating room team members’ experiences of working with a pressure mapping system as a means to prevent intraoperative and postoperative recovery unit pressure injuries, and to describe the interface pressures and the incidence of observed pressure injuries. Methods: We used a descriptive design with a qualitative approach to investigate the operating room team members’ experiences of working with real-time feedback of interface pressure, and a quantitative approach to investigate the interface pressures and the incidence of observed pressure injuries. The technology was used during 49 surgeries. Results: The system increased clinician awareness and was considered beneficial in pressure injury prevention activities. There were wide variations in the interface pressures that measured from < 50 to 255 mmHg. Eight patients developed blanchable erythema during surgery and five other patients developed category 1 pressure injuries two hours postoperatively. Conclusions: This study shows that the new technology could play an important role in preventing pressure injuries during surgery in the future.
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| 41. |
- Witter, E, et al.
(författare)
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A study of the structure and metal tolerance of the soil microbial community six years after cessation of sewage sludge applications
- 2000
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Ingår i: Environmental Toxicology and Chemistry. - 0730-7268. ; 19:8, s. 1983-1991
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Tidskriftsartikel (refereegranskat)abstract
- Changes in soil microbial community structure and development of metal tolerance as a result of past applications of unamended sewage sludge and metal-amended sewage sludge were found in soils of a long-term field experiment at Braunschweig, Germany. Both the rate of sewage sludge application and metal amendment affected the size and activity of the microbial biomass and had caused changes in microbial community structure as seen by differences in phospholipid fatty acid (PLFA) profiles. Past sewage sludge additions and metal amendment had an effect on the microbial respiratory response to 15 different C substrates, but both the magnitude and the direction of this response were substrate dependent. Differences between the soils in the respiratory response to the substrates were therefore probably largely determined by differences in the composition of the microbial consortia utilizing the substrates. The level of metal tolerance of the soil bacterial community determined by the thymidine incorporation technique and that of the microbial consortium growing on glucose in situ (determined from respiration measurements) increased with the level of metal contamination of the soil. Metal tolerance measurements could identify the metal with the largest toxicity effect in this experiment with multiple metal-polluted sewage sludge.
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| 42. |
- 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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| 43. |
- 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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| 44. |
- Zornoza, R., et al.
(författare)
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Microbial growth and community structure in acid mine soils after addition of different amendments for soil reclamation
- 2016
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Ingår i: Geoderma. - : Elsevier BV. - 0016-7061. ; 272, s. 64-72
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Tidskriftsartikel (refereegranskat)abstract
- The extreme soil conditions in metalliferous mine soils have a negative influence on soil biological activity. Therefore, amendments are often used to improve soil quality and activate microbial communities. In order to elucidate some of the factors controlling microbial growth and community structure after application of amendments in acid mine soils, we performed an incubation experiment with four amendments: pig slurry (PS), pig manure (PM) and pyrogenic carbonaceous material (PCM), applied with and without marble waste (MW; CaCO3). Results showed that PM and PCM (alone or together with MW) contributed to an important increase in recalcitrant organic C, C/N ratio and aggregate stability. All the treatments, except PS without MW increased soil pH above six resulting in the partial immobilization of the metals. Bacterial and fungal growths were highly dependent on pH and labile organic C. Pig slurry supported the highest microbial growth: applied alone stimulated fungal growth, whereas applied with MW stimulated bacterial growth. Pyrogenic carbonaceous material provoked the lowest microbial growth, especially for fungi, with no significant increase in fungal biomass. MW + PCM increased bacterial growth up to values similar to PM and MW + PM, suggesting that, at least in the short term, part of the PCM was degraded, and mainly by bacteria rather than fungi. PM, MW + PS and MW + PM supported the highest microbial biomass and a similar community structure, related with the presence of high organic C concentrations and high pH, with immobilization of metals and increased soil quality. PCM contributed to improved soil structure, increased recalcitrant organic C, and decreased metal mobility, with low stimulation of microbial growth. Thus, in order to activate microbial populations in reclaimed mine soils, a source of labile organic compounds should be included in the management plan of the area.
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