| 1. |
- Pulit, S. L., et al.
(författare)
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Atrial fibrillation genetic risk differentiates cardioembolic stroke from other stroke subtypes
- 2018
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Ingår i: Neurology-Genetics. - : Ovid Technologies (Wolters Kluwer Health). - 2376-7839. ; 4:6
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Tidskriftsartikel (refereegranskat)abstract
- Objective We sought to assess whether genetic risk factors for atrial fibrillation (AF) can explain cardioembolic stroke risk. We evaluated genetic correlations between a previous genetic study of AF and AF in the presence of cardioembolic stroke using genome-wide genotypes from the Stroke Genetics Network (N = 3,190 AF cases, 3,000 cardioembolic stroke cases, and 28,026 referents). We tested whether a previously validated AF polygenic risk score (PRS) associated with cardioembolic and other stroke subtypes after accounting for AF clinical risk factors. We observed a strong correlation between previously reported genetic risk for AF, AF in the presence of stroke, and cardioembolic stroke (Pearson r = 0.77 and 0.76, respectively, across SNPs with p < 4.4 x 10(-4) in the previous AF meta-analysis). An AF PRS, adjusted for clinical AF risk factors, was associated with cardioembolic stroke (odds ratio [OR] per SD = 1.40, p = 1.45 x 10(-48)), explaining similar to 20% of the heritable component of cardioembolic stroke risk. The AF PRS was also associated with stroke of undetermined cause (OR per SD = 1.07,p = 0.004), but no other primary stroke subtypes (all p > 0.1). Genetic risk of AF is associated with cardioembolic stroke, independent of clinical risk factors. Studies are warranted to determine whether AF genetic risk can serve as a biomarker for strokes caused by AF.
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| 2. |
- Marini, S., et al.
(författare)
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Association of Apolipoprotein E With Intracerebral Hemorrhage Risk by Race/Ethnicity A Meta-analysis
- 2019
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Ingår i: Jama Neurology. - : American Medical Association (AMA). - 2168-6149 .- 2168-6157. ; 76:4, s. 480-491
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE Genetic studies of intracerebral hemorrhage (ICH) have focused mainly on white participants, but genetic risk may vary or could be concealed by differing nongenetic coexposures in nonwhite populations. Transethnic analysis of risk may clarify the role of genetics in ICH risk across populations. OBJECTIVE To evaluate associations between established differences in ICH risk by race/ethnicity and the variability in the risks of apolipoprotein E (APOE) epsilon 4 alleles, the most potent genetic risk factor for ICH. DESIGN, SETTING, AND PARTICIPANTS This case-control study of primary ICH meta-analyzed the association of APOE allele status on ICH risk, applying a 2-stage clustering approach based on race/ethnicity and stratified by a contributing study. A propensity score analysis was used to model the association of APOE with the burden of hypertension across race/ethnic groups. Primary ICH cases and controls were collected from 3 hospital- and population-based studies in the United States and 8 in European sites in the International Stroke Genetic Consortium. Participants were enrolled from January 1, 1999, to December 31, 2017. Participants with secondary causes of ICH were excluded from enrollment. Controls were regionally matched within each participating study. MAIN OUTCOMES AND MEASURES Clinical variables were systematically obtained from structured interviews within each site. APOE genotype was centrally determined for all studies. RESULTS In total, 13 124 participants (7153 [54.5%] male with a median [interquartile range] age of 66 [56-76] years) were included. In white participants, APOE epsilon 2 (odds ratio [OR], 1.49; 95% CI, 1.24-1.80; P < .001) and APOE epsilon 4 (OR, 1.51; 95% CI, 1.23-1.85; P < .001) were associated with lobar ICH risk; however, within self-identified Hispanic and black participants, no associations were found. After propensity score matching for hypertension burden, APOE epsilon 4 was associated with lobar ICH risk among Hispanic (OR, 1.14; 95% CI, 1.03-1.28; P = .01) but not in black (OR, 1.02; 95% CI, 0.98-1.07; P = .25) participants. APOE epsilon 2 and epsilon 4 did not show an association with nonlobar ICH risk in any race/ethnicity. CONCLUSIONS AND RELEVANCE APOE epsilon 4 and epsilon 2 alleles appear to affect lobar ICH risk variably by race/ethnicity, associations that are confirmed in white individuals but can be shown in Hispanic individuals only when the excess burden of hypertension is propensity score-matched; further studies are needed to explore the interactions between APOE alleles and environmental exposures that vary by race/ethnicity in representative populations at risk for ICH.
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| 3. |
- Abdo, A. A., et al.
(författare)
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Fermi Observations of High-Energy Gamma-Ray Emission from GRB 080916C
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 323:5922, s. 1688-1693
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Tidskriftsartikel (refereegranskat)abstract
- Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades of gamma-ray energy. In September 2008, Fermi observed the exceptionally luminous GRB 080916C, with the largest apparent energy release yet measured. The high-energy gamma rays are observed to start later and persist longer than the lower energy photons. A simple spectral form fits the entire GRB spectrum, providing strong constraints on emission models. The known distance of the burst enables placing lower limits on the bulk Lorentz factor of the outflow and on the quantum gravity mass.
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| 4. |
- Ally, M., et al.
(författare)
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Cross-sectional and longitudinal evaluation of plasma glial fibrillary acidic protein to detect and predict clinical syndromes of Alzheimer's disease
- 2023
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Ingår i: Alzheimer's and Dementia: Diagnosis, Assessment and Disease Monitoring. - 2352-8729. ; 15:4
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: This study examined plasma glial fibrillary acidic protein (GFAP) as a biomarker of cognitive impairment due to Alzheimer's disease (AD) with and against plasma neurofilament light chain (NfL), and phosphorylated tau (p-tau)181+231.Methods: Plasma samples were analyzed using Simoa platform for 567 participants spanning the AD continuum. Cognitive diagnosis, neuropsychological testing, and dementia severity were examined for cross-sectional and longitudinal outcomes.Results: Plasma GFAP discriminated AD dementia from normal cognition (adjusted mean difference = 0.90 standard deviation [SD]) and mild cognitive impairment (adjusted mean difference = 0.72 SD), and demonstrated superior discrimination compared to alternative plasma biomarkers. Higher GFAP was associated with worse dementia severity and worse performance on 11 of 12 neuropsychological tests. Longitudinally, GFAP predicted decline in memory, but did not predict conversion to mild cognitive impairment or dementia.Discussion: Plasma GFAP was associated with clinical outcomes related to suspected AD and could be of assistance in a plasma biomarker panel to detect in vivo AD.
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| 5. |
- Case, L. K., et al.
(författare)
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Ab-CT Affective Touch: Touch Pleasantness Ratings for Gentle Stroking and Deep Pressure Exhibit Dependence on A-Fibers
- 2023
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Ingår i: Eneuro. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- Gentle stroking of the skin is a common social touch behavior with positive affective consequences. A prefer-ence for slow versus fast stroking of hairy skin has been closely linked to the firing of unmyelinated C-tactile (CT) somatosensory afferents. Because the firing of CT afferents strongly correlates with touch pleasantness, the CT pathway has been considered a social-affective sensory pathway. Recently, ablation of the spinotha-lamic pathway-thought to convey all C-fiber sensations-in patients with cancer pain impaired pain, tempera-ture, and itch, but not ratings of pleasant touch. This suggested integration of afferent A and CT fiber input in the spinal cord, or mechanoreceptive A-fiber contributions to computations of touch pleasantness in the brain. However, contribution of mechanoreceptive A-fibers to touch pleasantness, in humans without pain, remains unknown. In the current, single-blinded study, we performed two types of peripheral nerve blocks in healthy adults to temporarily eliminate the contribution of A-fibers to touch perception. Our findings show that when mechanoreceptive A-fiber function is greatly diminished, the perceived intensity and pleasantness of both gen-tle stroking and deep pressure are nearly abolished. These findings demonstrate that explicit perception of the pleasantness of CT-targeted brushing and pressure both critically depend on afferent A-fibers.
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| 6. |
- Hwang, K. -J, et al.
(författare)
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Electron Vorticity Indicative of the Electron Diffusion Region of Magnetic Reconnection
- 2019
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Ingår i: Geophysical Research Letters. - : AMER GEOPHYSICAL UNION. - 0094-8276 .- 1944-8007. ; 46:12, s. 6287-6296
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Tidskriftsartikel (refereegranskat)abstract
- While vorticity defined as the curl of the velocity has been broadly used in fluid and plasma physics, this quantity has been underutilized in space physics due to low time resolution observations. We report Magnetospheric Multiscale (MMS) observations of enhanced electron vorticity in the vicinity of the electron diffusion region of magnetic reconnection. On 11 July 2017 MMS traversed the magnetotail current sheet, observing tailward-to-earthward outflow reversal, current-carrying electron jets in the direction along the electron meandering motion or out-of-plane direction, agyrotropic electron distribution functions, and dissipative signatures. At the edge of the electron jets, the electron vorticity increased with magnitudes greater than the electron gyrofrequency. The out-of-plane velocity shear along distance from the current sheet leads to the enhanced vorticity. This, in turn, contributes to the magnetic field perturbations observed by MMS. These observations indicate that electron vorticity can act as a proxy for delineating the electron diffusion region of magnetic reconnection.
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| 7. |
- Klassen, A. F., et al.
(författare)
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FACE-Q craniofacial module: Part 2 Psychometric properties of newly developed scales for children and young adults with facial conditions
- 2021
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Ingår i: Journal of Plastic, Reconstructive and Aesthetic Surgery. - : Elsevier BV. - 1748-6815. ; 74:9, s. 2330-2340
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Tidskriftsartikel (refereegranskat)abstract
- Background: The FACE-Q Craniofacial Module is a patient-reported outcome measure designed for patients aged 8 to 29 years with conditions associated with a facial difference. In part 1, we describe the psychometric findings for the original CLEFT-Q scales tested in patients with cleft and noncleft facial conditions. The aim of this study was to examine psychometric performance of new FACE-Q Craniofacial Module scales. Methods: Data were collected between December 2016 and December 2019 from patients aged 8 to 29 years with conditions associated with a visible or functional facial difference. Rasch measurement theory (RMT) analysis was used to examine psychometric properties of each scale. Scores were transformed from 0 (worst) to 100 (best) for tests of construct validity. Results: 1495 participants were recruited with a broad range of conditions (e.g., birthmarks, facial paralysis, craniosynostosis, craniofacial microsomia, etc.) RMT analysis resulted in the refinement of 7 appearance scales (Birthmark, Cheeks, Chin, Eyes, Forehead, Head Shape, Smile), two function scales (Breathing, Facial), and an Appearance Distress scale. Person separation index and Cronbach alpha values met criteria. Three checklists were also formed (Eye Function, and Eye and Face Adverse Effects). Significantly lower scores on eight of nine scales were reported by participants whose appearance or functional difference was rated as a major rather than minor or no difference. Higher appearance distress correlated with lower appearance scale scores. Conclusion: The FACE-Q Craniofacial Module scales can be used to collect and compare patient reported outcomes data in children and young adults with a facial condition. © 2021
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| 8. |
- Lapenta, G., et al.
(författare)
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On the origin of the crescent-shaped distributions observed by MMS at the magnetopause
- 2017
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Ingår i: Journal of Geophysical Research - Space Physics. - 2169-9380 .- 2169-9402. ; 122:2, s. 2024-2039
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Tidskriftsartikel (refereegranskat)abstract
- MMS observations recently confirmed that crescent-shaped electron velocity distributions in the plane perpendicular to the magnetic field occur in the electron diffusion region near reconnection sites at Earth's magnetopause. In this paper, we reexamine the origin of the crescent-shaped distributions in the light of our new finding that ions and electrons are drifting in opposite directions when displayed in magnetopause boundary-normal coordinates. Therefore, E x B drifts cannot cause the crescent shapes. We performed a high-resolution multiscale simulation capturing subelectron skin-depth scales. The results suggest that the crescent-shaped distributions are caused by meandering orbits without necessarily requiring any additional processes found at the magnetopause such as the highly asymmetric magnetopause ambipolar electric field. We use an adiabatic Hamiltonian model of particle motion to confirm that conservation of canonical momentum in the presence of magnetic field gradients causes the formation of crescent shapes without invoking asymmetries or the presence of an E x B drift. An important consequence of this finding is that we expect crescent-shaped distributions also to be observed in the magnetotail, a prediction that MMS will soon be able to test.
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| 9. |
- Morrison, M. S., et al.
(författare)
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Ante-mortem plasma phosphorylated tau (181) predicts Alzheimer's disease neuropathology and regional tau at autopsy
- 2022
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Ingår i: Brain. - : Oxford University Press (OUP). - 0006-8950 .- 1460-2156. ; 145:10, s. 3546-3557
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Tidskriftsartikel (refereegranskat)abstract
- In one of the largest studies of its kind, Morrison et al. show that ante-mortem plasma phosphorylated-tau(181) concentrations accurately differentiate brain donors with and without autopsy-confirmed Alzheimer's disease. Blood tests could be a minimally invasive, cost-effective tool for the detection and monitoring of Alzheimer's disease. Blood-based biomarkers such as tau phosphorylated at threonine 181 (phosphorylated-tau(181)) represent an accessible, cost-effective and scalable approach for the in vivo detection of Alzheimer's disease pathophysiology. Plasma-pathological correlation studies are needed to validate plasma phosphorylated-tau(181) as an accurate and reliable biomarker of Alzheimer's disease neuropathological changes. This plasma-to-autopsy correlation study included participants from the Boston University Alzheimer's Disease Research Center who had a plasma sample analysed for phosphorylated-tau(181) between 2008 and 2018 and donated their brain for neuropathological examination. Plasma phosphorelated-tau(181) was measured with single molecule array technology. Of 103 participants, 62 (60.2%) had autopsy-confirmed Alzheimer's disease. Average time between blood draw and death was 5.6 years (standard deviation = 3.1 years). Multivariable analyses showed higher plasma phosphorylated-tau(181) concentrations were associated with increased odds for having autopsy-confirmed Alzheimer's disease [AUC = 0.82, OR = 1.07, 95% CI = 1.03-1.11, P < 0.01; phosphorylated-tau standardized (z-transformed): OR = 2.98, 95% CI = 1.50-5.93, P < 0.01]. Higher plasma phosphorylated-tau(181) levels were associated with increased odds for having a higher Braak stage (OR = 1.06, 95% CI = 1.02-1.09, P < 0.01) and more severe phosphorylated-tau across six cortical and subcortical brain regions (ORs = 1.03-1.06, P < 0.05). The association between plasma phosphorylated-tau(181) and Alzheimer's disease was strongest in those who were demented at time of blood draw (OR = 1.25, 95%CI = 1.02-1.53), but an effect existed among the non-demented (OR = 1.05, 95% CI = 1.01-1.10). There was higher discrimination accuracy for Alzheimer's disease when blood draw occurred in years closer to death; however, higher plasma phosphorylated-tau(181) levels were associated with Alzheimer's disease even when blood draw occurred >5 years from death. Ante-mortem plasma phosphorylated-tau(181) concentrations were associated with Alzheimer's disease neuropathology and accurately differentiated brain donors with and without autopsy-confirmed Alzheimer's disease. These findings support plasma phosphorylated-tau(181) as a scalable biomarker for the detection of Alzheimer's disease.
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| 10. |
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| 11. |
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| 12. |
- Sahraoui, F., et al.
(författare)
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Evidence of a Cascade and Dissipation of Solar-Wind Turbulence at the Electron Gyroscale
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:23, s. 231102-
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Tidskriftsartikel (refereegranskat)abstract
- We report the first direct determination of the dissipation range of magnetofluid turbulence in the solar wind at the electron scales. Combining high resolution magnetic and electric field data of the Cluster spacecraft, we computed the spectrum of turbulence and found two distinct breakpoints in the magnetic spectrum at 0.4 and 35 Hz, which correspond, respectively, to the Doppler-shifted proton and electron gyroscales, f(rho p) and f(rho e). Below f(rho p), the spectrum follows a Kolmogorov scaling f(-1.62), typical of spectra observed at 1 AU. Above f(rho p), a second inertial range is formed with a scaling f(-2.3) down to f(rho e). Above f(rho e), the spectrum has a steeper power law similar to f(-4.1) down to the noise level of the instrument. We interpret this as the dissipation range and show a remarkable agreement with theoretical predictions of a quasi-two-dimensional cascade into Kinetic Alfveacuten Waves (KAW).
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| 13. |
- Sugarman, M. A., et al.
(författare)
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A longitudinal examination of plasma neurofilament light and total tau for the clinical detection and monitoring of Alzheimer's disease
- 2020
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Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580. ; 94, s. 60-70
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Tidskriftsartikel (refereegranskat)abstract
- We examined baseline and longitudinal associations between plasma neurofilament light (NfL) and total tau (t-tau), and the clinical presentation of Alzheimer's disease (AD). A total of 579 participants (238, normal cognition [NC]; 185, mild cognitive impairment [MCI]; 156, AD dementia) had baseline blood draws; 82% had follow-up evaluations. Plasma samples were analyzed for NfL and t-tau using Simoa technology. Baseline plasma NfL was higher in AD dementia than MCI (standardized mean difference = 0.55, 95% CI: 0.37–0.73) and NC (standardized mean difference = 0.68, 95% CI: 0.49–0.88), corresponded to Clinical Dementia Rating scores (OR = 1.94, 95% CI: 1.35–2.79]), and correlated with all neuropsychological tests (r's = 0.13–0.42). Longitudinally, NfL did not predict diagnostic conversion but predicted decline on 3/10 neuropsychological tests. Baseline plasma t-tau was higher in AD dementia than NC with a small effect (standardized mean difference = 0.33, 95% CI: 0.10–0.57) but not MCI. t-tau did not statistically significant predict any longitudinal outcomes. Plasma NfL may be useful for the detection of AD dementia and monitoring of disease progression. In contrast, there was minimal evidence in support of plasma t-tau. © 2020 Elsevier Inc.
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| 14. |
- Vaivads, Andris, et al.
(författare)
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Turbulence Heating ObserveR - satellite mission proposal
- 2016
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Ingår i: JOURNAL OF PLASMA PHYSICS. - 0022-3778. ; 82
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Tidskriftsartikel (refereegranskat)abstract
- The Universe is permeated by hot, turbulent, magnetized plasmas. Turbulent plasma is a major constituent of active galactic nuclei, supernova remnants, the intergalactic and interstellar medium, the solar corona, the solar wind and the Earth's magnetosphere, just to mention a few examples. Energy dissipation of turbulent fluctuations plays a key role in plasma heating and energization, yet we still do not understand the underlying physical mechanisms involved. THOR is a mission designed to answer the questions of how turbulent plasma is heated and particles accelerated, how the dissipated energy is partitioned and how dissipation operates in different regimes of turbulence. THOR is a single-spacecraft mission with an orbit tuned to maximize data return from regions in near-Earth space - magnetosheath, shock, foreshock and pristine solar wind - featuring different kinds of turbulence. Here we summarize the THOR proposal submitted on 15 January 2015 to the 'Call for a Medium-size mission opportunity in ESAs Science Programme for a launch in 2025 (M4)'. THOR has been selected by European Space Agency (ESA) for the study phase.
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| 15. |
- Weiner, D. J., et al.
(författare)
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Polygenic transmission disequilibrium confirms that common and rare variation act additively to create risk for autism spectrum disorders
- 2017
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 49:7
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Tidskriftsartikel (refereegranskat)abstract
- Autism spectrum disorder (ASD) risk is influenced by common polygenic and de novo variation. We aimed to clarify the influence of polygenic risk for ASD and to identify subgroups of ASD cases, including those with strongly acting de novo variants, in which polygenic risk is relevant. Using a novel approach called the polygenic transmission disequilibrium test and data from 6,454 families with a child with ASD, we show that polygenic risk for ASD, schizophrenia, and greater educational attainment is over-transmitted to children with ASD. These findings hold independent of proband IQ. We find that polygenic variation contributes additively to risk in ASD cases who carry a strongly acting de novo variant. Lastly, we show that elements of polygenic risk are independent and differ in their relationship with phenotype. These results confirm that the genetic influences on ASD are additive and suggest that they create risk through at least partially distinct etiologic pathways.
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| 16. |
- Witasse, O., et al.
(författare)
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Interplanetary coronal mass ejection observed at STEREO-A, Mars, comet 67P/Churyumov-Gerasimenko, Saturn, and New Horizons en route to Pluto : Comparison of its Forbush decreases at 1.4, 3.1, and 9.9 AU
- 2017
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Ingår i: Journal of Geophysical Research - Space Physics. - 2169-9380 .- 2169-9402. ; 122:8, s. 7865-7890
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Tidskriftsartikel (refereegranskat)abstract
- We discuss observations of the journey throughout the Solar System of a large interplanetary coronal mass ejection (ICME) that was ejected at the Sun on 14 October 2014. The ICME hit Mars on 17 October, as observed by the Mars Express, Mars Atmosphere and Volatile EvolutioN Mission (MAVEN), Mars Odyssey, and Mars Science Laboratory (MSL) missions, 44h before the encounter of the planet with the Siding-Spring comet, for which the space weather context is provided. It reached comet 67P/Churyumov-Gerasimenko, which was perfectly aligned with the Sun and Mars at 3.1 AU, as observed by Rosetta on 22 October. The ICME was also detected by STEREO-A on 16 October at 1 AU, and by Cassini in the solar wind around Saturn on the 12 November at 9.9AU. Fortuitously, the New Horizons spacecraft was also aligned with the direction of the ICME at 31.6 AU. We investigate whether this ICME has a nonambiguous signature at New Horizons. A potential detection of this ICME by Voyager 2 at 110-111 AU is also discussed. The multispacecraft observations allow the derivation of certain properties of the ICME, such as its large angular extension of at least 116 degrees, its speed as a function of distance, and its magnetic field structure at four locations from 1 to 10 AU. Observations of the speed data allow two different solar wind propagation models to be validated. Finally, we compare the Forbush decreases (transient decreases followed by gradual recoveries in the galactic cosmic ray intensity) due to the passage of this ICME at Mars, comet 67P, and Saturn.
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| 17. |
- Zhou, M., et al.
(författare)
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Coalescence of Macroscopic Flux Ropes at the Subsolar Magnetopause : Magnetospheric Multiscale Observations
- 2017
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 119:5
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Tidskriftsartikel (refereegranskat)abstract
- We report unambiguous in situ observation of the coalescence of macroscopic flux ropes by the magnetospheric multiscale (MMS) mission. Two coalescing flux ropes with sizes of similar to 1 R-E were identified at the subsolar magnetopause by the occurrence of an asymmetric quadrupolar signature in the normal component of the magnetic field measured by the MMS spacecraft. An electron diffusion region (EDR) with a width of four local electron inertial lengths was embedded within the merging current sheet. The EDR was characterized by an intense parallel electric field, significant energy dissipation, and suprathermal electrons. Although the electrons were organized by a large guide field, the small observed electron pressure nongyrotropy may be sufficient to support a significant fraction of the parallel electric field within the EDR. Since the flux ropes are observed in the exhaust region, we suggest that secondary EDRs are formed further downstream of the primary reconnection line between the magnetosheath and magnetospheric fields.
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| 18. |
- Zhou, M., et al.
(författare)
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Magnetospheric Multiscale Observations of an Ion Diffusion Region With Large Guide Field at the Magnetopause : Current System, Electron Heating, and Plasma Waves
- 2018
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Ingår i: Journal of Geophysical Research - Space Physics. - : American Geophysical Union (AGU). - 2169-9380 .- 2169-9402. ; 123:3, s. 1834-1852
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Tidskriftsartikel (refereegranskat)abstract
- We report Magnetospheric Multiscale (MMS) observations of a reconnecting current sheet in the presence of a weak density asymmetry with large guide field at the dayside magnetopause. An ion diffusion region (IDR) was detected associated with this current sheet. Parallel current dominated over the perpendicular current in the IDR, as found in previous studies of component reconnection. Electrons were preferentially heated parallel to the magnetic field within the IDR. The heating was manifested as a flattop distribution below 400eV. Two types of electromagnetic electron whistler waves were observed within the regions where electrons were heated. One type of whistler wave was associated with nonlinear structures in E-|| with amplitudes up to 20mV/m. The other type was not associated with any structures in E-||. Poynting fluxes of these two types of whistler waves were directed away from the X-line. We suggest that the nonlinear evolution of the oblique whistler waves gave rise to the solitary structures in E-||. There was a perpendicular super-Alfvenic outflow jet that was carried by magnetized electrons. Intense electrostatic lower hybrid drift waves were localized in the current sheet center and were probably driven by the super-Alfvenic electron jet, the velocity of which was approximately equal to the diamagnetic drift of demagnetized ions. Our observations suggest that the guide field significantly modified the structures (Hall electromagnetic fields and current system) and wave properties in the IDR.
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| 19. |
- Zhou, M., et al.
(författare)
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Observation of high-frequency electrostatic waves in the vicinity of the reconnection ion diffusion region by the spacecraft of the Magnetospheric Multiscale (MMS) mission
- 2016
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 43:10, s. 4808-4815
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Tidskriftsartikel (refereegranskat)abstract
- We report Magnetospheric Multiscale observations of high-frequency electrostatic waves in the vicinity of the reconnection ion diffusion region on the dayside magnetopause. The ion diffusion region is identified during two magnetopause crossings by the Hall electromagnetic fields, the slippage of ions with respect to the magnetic field, and magnetic energy dissipation. In addition to electron beam modes that have been previously detected at the separatrix on the magnetospheric side of the magnetopause, we report, for the first time, the existence of electron cyclotron harmonic waves at the magnetosheath separatrix. Broadband waves between the electron cyclotron and electron plasma frequencies, which were probably generated by electron beams, were found within the magnetopause current sheet. Contributions by these high-frequency waves to the magnetic energy dissipation were negligible in the diffusion regions as compared to those of lower-frequency waves.
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