| 1. |
- Carlsson Almlöf, Jonas, et al.
(författare)
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Novel risk genes for systemic lupus erythematosus predicted by random forest classification
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association studies have identified risk loci for SLE, but a large proportion of the genetic contribution to SLE still remains unexplained. To detect novel risk genes, and to predict an individual's SLE risk we designed a random forest classifier using SNP genotype data generated on the "Immunochip" from 1,160 patients with SLE and 2,711 controls. Using gene importance scores defined by the random forest classifier, we identified 15 potential novel risk genes for SLE. Of them 12 are associated with other autoimmune diseases than SLE, whereas three genes (ZNF804A, CDK1, and MANF) have not previously been associated with autoimmunity. Random forest classification also allowed prediction of patients at risk for lupus nephritis with an area under the curve of 0.94. By allele-specific gene expression analysis we detected cis-regulatory SNPs that affect the expression levels of six of the top 40 genes designed by the random forest analysis, indicating a regulatory role for the identified risk variants. The 40 top genes from the prediction were overrepresented for differential expression in B and T cells according to RNA-sequencing of samples from five healthy donors, with more frequent over-expression in B cells compared to T cells.
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| 2. |
- Gunnarsson, Christofer, et al.
(författare)
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Corrections for gravitational lensing of supernovae : better than average?
- 2006
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Ingår i: Astrophysical Journal. - : The American Astronomical Society. - 0004-637X .- 1538-4357. ; 640, s. 417-427
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the possibility of correcting for magnification due to gravitational lensing of standard candlesources, such as Type Ia supernovae. Our method uses the observed properties of the foreground galaxies along thelines of sight to each source, and the accuracy of the lensing correction depends on the quality and depth of theseobservations as well as the uncertainties in translating the observed luminosities to the matter distribution in thelensing galaxies. The current work is limited to cases in which the matter density is dominated by the individualgalaxy halos. However, it is straightforward to generalize the method to also include gravitational lensing fromcluster scale halos.We show that the dispersion due to lensing for a standard candle source at z ¼1:5 can be reducedfrom about 7% toP3%; i.e., the magnification correction is useful in reducing the scatter in the Type Ia Hubble diagram,especially at high redshifts where the required long exposure times make it hard to reach large statistics andthe dispersion due to lensing becomes comparable to the intrinsic Type Ia scatter.
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| 4. |
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| 5. |
- Gunnarsson, Christofer, 1976-
(författare)
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Supernovae under the gravitational lens
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With general relativity as its foundation, the Standard Model of Cosmology has been developed, a model in which all matter is homogeneously and isotropically distributed throughout the Universe. We know for sure that this is not true since inhomogeneous structures such as galaxies, planets and synthesizers, are known to exist on small cosmological scales. However, on large scales the approximation of homogeneity is very good. Despite this, inhomogeneities such as galaxies or clusters of galaxies, will affect the propagation of light in the Universe by bending the paths of light-rays according to the laws of general relativity. The phenomenon is known as gravitational lensing. The bending of light-rays is similar to what happens in an optical lens, where an image of an object may be distorted or (de-)magnified depending on the shape of the lens.Using the magnifying power of a gravitational lens it is possible to see further out in the Universe, it is used as a natural gravitational telescope. Under the right circumstances this can be something very useful. By studying light from supernovae, exploding stars, it is to some extent possible to gather information on the constituents of our universe. If for some reason this light is affected on its way to us, e.g. by gravitational lensing, we are mislead into drawing erroneous conclusions unless the lensing effects are under control and corrected for. Trying to control this and other systematic uncertainties is a big challenge in supernova cosmology and is also becoming more and more important as statistical errors are being beaten down to very low levels.
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| 7. |
- Jönsson, Jakob, et al.
(författare)
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Lensing magnification of supernovae in the GOODS-fields
- 2006
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 639:2, s. 991-998
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Tidskriftsartikel (refereegranskat)abstract
- Gravitational lensing of high-redshift supernovae is potentially an important source of uncertainty when cosmological parameters are being derived from the measured brightness of Type Ia supernovae, especially in deep surveys with scarce statistics. Photometric and spectroscopic measurements of foreground galaxies along the lines of sight of 33 supernovae discovered with the Hubble Space Telescope, both core-collapse and Type Ia, are used to model the magnification probability distributions of the sources. Modelling galaxy halos with SIS or NFW profiles and using M/L scaling laws provided by the Faber-Jackson and Tully-Fisher relations, we find clear evidence for supernovae with lensing (de)magnification. However, the magnification distribution of the Type Ia supernovae used to determine cosmological distances matches very well the expectations for an unbiased sample; i.e., their mean magnification factor is consistent with unity. Our results show that the lensing distortions of the supernova brightness can be well understood for the GOODS sample and that correcting for this effect has a negligible impact on the derived cosmological parameters.
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