| 1. |
- Ciuculete, Diana-Maria, et al.
(författare)
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A methylome-wide mQTL analysis reveals associations of methylation sites with GAD1 and HDAC3 SNPs and a general psychiatric risk score
- 2017
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Ingår i: Translational Psychiatry. - : NATURE PUBLISHING GROUP. - 2158-3188. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association studies have identified a number of single-nucleotide polymorphisms (SNPs) that are associated with psychiatric diseases. Increasing body of evidence suggests a complex connection of SNPs and the transcriptional and epigenetic regulation of gene expression, which is poorly understood. In the current study, we investigated the interplay between genetic risk variants, shifts in methylation and mRNA levels in whole blood from 223 adolescents distinguished by a risk for developing psychiatric disorders. We analyzed 37 SNPs previously associated with psychiatric diseases in relation to genome-wide DNA methylation levels using linear models, with Bonferroni correction and adjusting for cell-type composition. Associations between DNA methylation, mRNA levels and psychiatric disease risk evaluated by the Development and Well-Being Assessment (DAWBA) score were identified by robust linear models, Pearson's correlations and binary regression models. We detected five SNPs (in HCRTR1, GAD1, HADC3 and FKBP5) that were associated with eight CpG sites, validating five of these SNP-CpG pairs. Three of these CpG sites, that is, cg01089319 (GAD1), cg01089249 (GAD1) and cg24137543 (DIAPH1), manifest in significant gene expression changes and overlap with active regulatory regions in chromatin states of brain tissues. Importantly, methylation levels at cg01089319 were associated with the DAWBA score in the discovery group. These results show how distinct SNPs linked with psychiatric diseases are associated with epigenetic shifts with relevance for gene expression. Our findings give a novel insight on how genetic variants may modulate risks for the development of psychiatric diseases.
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| 2. |
- Berg, Frenk van den, et al.
(författare)
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Results of the European collaborative project "Product Uniformity Control" to improve the inline sensing of mechanical properties and microstructure of automotive steels
- 2018
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Ingår i: e-Journal of Nondestructive Testing (eJNDT). - 1435-4934. ; 23:8
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Tidskriftsartikel (refereegranskat)abstract
- A European consortium consisting of four major steel manufacturers and ten academic technology institutes has conducted a research and development project, called “Product Uniformity Control“ (PUC) in the period 2013 to 2017. This project aimed to develop and improve non-destructive (inline) measurement techniques to characterise the (uniformity of the) microstructure of steel strip products. In this project, a multitude of strip steel samples from various stages of production have been collected from the four participating steel manufacturers. The samples have been characterised in various ways, namely on their (1) non-destructive measurement parameters using different techniques suited for inline evaluation, (2) fundamental ultrasonic and electromagnetic properties (wave speed, ultrasonic attenuation, magnetisation loops, coercive field), (3) tensile properties (stress-strain curves) and (4) microstructure (by optical micrographs and EBSD images). The correlations between these different characterisations will be addressed. Besides the experimental characterisation, a strong accent has been on modelling activities: during the project, fundamental models have been developed to describe, starting from 2D and 3D microstructures, the ultrasonic and magnetic properties, which are next used as input to sensor models that predict the output of the inline measurement systems. This contribution presents the recent results of experimental work, which underlines the importance of associated modelling studies for the interpretation of the measurement data for the benefit of inline characterisation of the mechanical properties complementary to traditional destructive tensile testing.
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| 3. |
- Boström, Adrian, et al.
(författare)
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A MIR4646 associated methylation locus is hypomethylated in adolescent depression
- 2017
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Ingår i: Journal of Affective Disorders. - : Elsevier BV. - 0165-0327 .- 1573-2517. ; 220, s. 117-128
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Tidskriftsartikel (refereegranskat)abstract
- Background: Studies of epigenetics and transcriptional activity in adolescents may provide knowledge about possible preventive strategies of depression. Methods: We present a methylome-wide association study (MWAS) and cohort validation analysis of depression in adolescents, in two separate cohorts: discovery (n = 93) and validation data set 1 (n = 78). The genome-wide methylation pattern was measured from whole blood using the Illumina 450K array. A second validation cohort, validation data set 2, consists of post-mortem brain biopsies from depressed adults (n = 58). We performed a MWAS by robust multiple linear regressions of methylation to a modified risk-score assessment of depression. Methylation levels of candidate CpG sites were correlated with expression levels of the associated gene in an independent cohort of 11 healthy volunteers. Results: The methylation state of two CpG sites reliably predicted ratings of depression in adolescents (cg13227623 and cg04102384) (p < 10E-06). Cohort validation analysis confirmed cg04102384 - located in the promoter region of microRNA 4646 (MIR4646) - to be hypomethylated in both validation data set 1 and validation data set 2 (p < 0.05). Cg04102384 was inversely correlated to expression levels of MIR4646-3p in healthy controls (p < 0.05). Limitations: MIR4646 was not differentially expressed in a subset of samples with adolescent depression measured by qRT-PCR measurements. Conclusion: We identify a specific MIR4646 associated epigenetic risk site to be associated with depression in adolescents. Cg04102384 putatively regulates gene expression of MIR4646-3p. Target gene prediction and gene set overrepresentation analysis revealed involvement of this miRNA in fatty acid elongation, a process related to omega-3 fatty acids, previously associated with depression.
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| 4. |
- Boström, Adrian E., et al.
(författare)
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Longitudinal genome-wide methylation study of Roux-en-Y gastric bypass patients reveals novel CpG sites associated with essential hypertension
- 2016
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Ingår i: BMC Medical Genomics. - : Springer Science and Business Media LLC. - 1755-8794. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Background: Essential hypertension is a significant risk factor for cardiovascular diseases. Emerging research suggests a role of DNA methylation in blood pressure physiology. We aimed to investigate epigenetic associations of promoter related CpG sites to essential hypertension in a genome-wide methylation approach. Methods: The genome-wide methylation pattern in whole blood was measured in 11 obese patients before and six months after Roux-en-Y gastric bypass surgery using the Illumina 450 k beadchip. CpG sites located within 1500 bp of the transcriptional start site of adjacent genes were included in our study, resulting in 124 199 probes investigated in the subsequent analysis. Percent changes in methylation states and SBP measured before and six months after surgery were calculated. These parameters were correlated to each other using the Spearman's rank correlation method (Edgeworth series approximation). To further investigate the detected relationship between candidate CpG sites and systolic blood pressure levels, binary logistic regression analyses were performed in a larger and independent cohort of 539 individuals aged 19-101 years to elucidate a relationship between EH and the methylation state in candidate CpG sites. Results: We identified 24 promoter associated CpG sites that correlated with change in SBP after RYGB surgery (p < 10-16). Two of these CpG loci (cg00875989, cg09134341) were significantly hypomethylated in dependency of EH (p < 10-03). These results were independent of age, BMI, ethnicity and sex. Conclusions: The identification of these novel CpG sites may contribute to a further understanding of the epigenetic regulatory mechanisms underlying the development of essential hypertension.
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| 5. |
- Boström, Anders E, 1951
(författare)
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Scattering by an anisotropic circle
- 2015
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Ingår i: Wave Motion. - : Elsevier BV. - 0165-2125. ; 57, s. 239-244
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Tidskriftsartikel (refereegranskat)abstract
- The scattering by a circle is considered when the outside medium is isotropic and the inside medium is anisotropic (orthotropic). The problem is a scalar one and is phrased as a scattering problem for elastic waves with polarization out of the plane of the circle (SH wave), but the solution is with minor modifications valid also for scattering of electromagnetic waves. The equation inside the circle is first transformed to polar coordinates and it then explicitly contains the azimuthal angle through trigonometric functions. Making an expansion in a trigonometric series in the azimuthal coordinate then gives a coupled system of ordinary differential equations in the radial coordinate that is solved by power series expansions. With the solution inside the circle complete the scattering problem is solved essentially as in the classical case. Some numerical examples are given showing the influence of anisotropy, and it is noted that the effects of anisotropy are generally strong except at low frequencies where the dominating scattering only depends on the mean stiffness and not on the degree of anisotropy.
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| 6. |
- Boström, Anders E, 1951
(författare)
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Scattering of In-plane Elastic Waves by an Anisotropic Circle
- 2018
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Ingår i: Quarterly Journal of Mechanics and Applied Mathematics. - : Oxford University Press (OUP). - 0033-5614 .- 1464-3855. ; 71:2, s. 139-155
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Tidskriftsartikel (refereegranskat)abstract
- The 2D scattering of in-plane elastic waves by a circle is considered when the surrounding medium is isotropic and the medium inside the circle is anisotropic (orthotropic). The equations inside the circle are transformed to polar coordinates and then depend explicitly on the azimuthal angle through trigonometric functions. Making expansions in trigonometric series in the azimuthal coordinate give a coupled system of ordinary differential equations in the radial coordinate that is solved by power series expansions. With the solution inside the circle complete the scattering problem is solved essentially as in the classical case. The elements of the transition (T) matrix of the circle are given explicitly for low frequencies (long wavelengths). For low frequencies some numerical examples are given showing the strong influence of anisotropy.
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| 7. |
- Boström, Anders E, 1951, et al.
(författare)
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Ultrasonic Attenuation in Polycrystalline Materials in 2D
- 2019
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Ingår i: Journal of Nondestructive Evaluation. - : Springer Science and Business Media LLC. - 1573-4862 .- 0195-9298. ; 38:2
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Tidskriftsartikel (refereegranskat)abstract
- Grains in a polycrystalline material, typically a metal, act as scatterers of ultrasonic waves and thus give rise to attenuation of the waves. Grains have anisotropic stiffness properties, typically orthotropic or cubic. A new approach is proposed to calculate attenuation in a 2D setting starting from the scattering by an anisotropic circle in an isotropic surrounding. This problem has recently been solved, giving explicit, simple expressions for the elements of the transition (T) matrix (which gives the relation between the the incoming and scattered fields) when the circle is small compared to the ultrasonic wavelengths. The T matrix can be used to calculate the total scattering cross section, which in turn can be used to estimate the attenuation in the material. Explicit expressions for the attenuation coefficient for longitudinal and transverse waves are obtained for a cubic material, and contrary to results in the literature these expressions are valid also for strong anisotropy. For the longitudinal attenuation coefficient a comparison with recent FEM results for Inconel 600 gives excellent agreement.
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| 8. |
- Boström, Anders E, 1951
(författare)
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Ultrasonic damping in polycrystalline materials
- 2018
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Ingår i: 12th European Conference on Non-Destructive Testing (ECNDT 2018), Gothenburg 2018, June 11-15 (ECNDT 2018).
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Konferensbidrag (refereegranskat)abstract
- The grains in a polycrystalline material, typically metals, act as scatterers of ultrasonic waves and thus give rise to attenuation of the waves. The grains have anisotropic stiffness properties, typically orthotropic or cubic. A new approach is proposed to calculate damping in a 2D setting starting from the scattering by an anisotropic circle in an isotropic surrounding. This problem has recently been solved, giving explicit, simple expressions for the elements of the transition (T) matrix (which gives the relation between the the incoming and scattered fields) when the circle is small compared to the ultrasonic wavelengths. The T matrix can be used to calculate the total scattering cross section, which in turn can be used to estimate the damping in the material. Explicit expressions for the damping coefficient for longitudinal and transverse waves are obtained in this way.
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| 9. |
- Boström, E. Viñas, et al.
(författare)
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Time-Stretched Spectroscopy by the Quantum Zeno Effect : The Case of Auger Decay
- 2018
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Ingår i: Physical Review Letters. - 0031-9007. ; 121:23
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Tidskriftsartikel (refereegranskat)abstract
- A tenet of time-resolved spectroscopy is "faster laser pulses for shorter timescales". Here, we suggest turning this paradigm around, and slowing down the system dynamics via repeated measurements, to do spectroscopy on longer timescales. This is the principle of the quantum Zeno effect. We exemplify our approach with the Auger process, and find that repeated measurements increase the core-hole lifetime, redistribute the kinetic energy of Auger electrons, and alter entanglement formation. We further provide an explicit experimental protocol for atomic Li, to make our proposal concrete.
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| 10. |
- Boström, Jannika E., et al.
(författare)
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The flicker fusion frequency of budgerigars (Melopsittacus undulatus) revisited
- 2017
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Ingår i: Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology. - : SPRINGER. - 0340-7594 .- 1432-1351. ; 203:1, s. 15-22
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Tidskriftsartikel (refereegranskat)abstract
- While color vision and spatial resolution have been studied in many bird species, less is known about the temporal aspects of bird vision. High temporal resolution has been described in three species of passerines but it is unknown whether this is specific to passerines, to small actively flying birds, to insectivores or to birds living in bright habitats. Temporal resolution of vision is commonly tested by determining the flicker fusion frequency (FFF), at which the eye can no longer distinguish a flickering light from a constant light of equal intensity at different luminances. Using a food reward, we trained the birds to discriminate a constant light from a flickering light, at four different luminances between 750 and 7500 cd/m(2). The highest FFF found in one bird at 3500 cd/m(2) was 93 Hz. Three birds had higher FFF (82 Hz) at 7500 cd/m(2) than at 3500 cd/m(2). Six human subjects had lower FFF than the birds at 1500 but similar FFF at 750 cd/m(2). These results indicate that high temporal resolution is not a common trait for all small and active birds living in bright light habitats. Whether it is typical for passerines or for insectivorous birds remains to be tested.
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