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| 4. |
- Algaba, Juan-Carlos, et al.
(författare)
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Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign
- 2021
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 911:1
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Forskningsöversikt (refereegranskat)abstract
- In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M o˙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87's spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded.
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| 5. |
- Abe, H., et al.
(författare)
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Gamma-ray observations of MAXI J1820+070 during the 2018 outburst
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press. - 0035-8711 .- 1365-2966. ; 517:4, s. 4736-4751
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Tidskriftsartikel (refereegranskat)abstract
- MAXIJ1820+070 is a low-mass X-ray binary with a black hole (BH) as a compact object. This binary underwent an exceptionally bright X-ray outburst from 2018 March to October, showing evidence of a non-thermal particle population through its radio emission during this whole period. The combined results of 59.5 h of observations of the MAXI J1820+070 outburst with the H.E.S.S., MAGIC and VERITAS experiments at energies above 200 GeV are presented, together with Fermi-LAT data between 0.1 and 500 GeV, and multiwavelength observations from radio to X-rays. Gamma-ray emission is not detected from MAXI J1820+070, but the obtained upper limits and the multiwavelength data allow us to put meaningful constraints on the source properties under reasonable assumptions regarding the non-thermal particle population and the jet synchrotron spectrum. In particular, it is possible to show that, if a high-energy (HE) gamma-ray emitting region is present during the hard state of the source, its predicted flux should be at most a factor of 20 below the obtained Fermi-LAT upper limits, and closer to them for magnetic fields significantly below equipartition. During the state transitions, under the plausible assumption that electrons are accelerated up to similar to 500 GeV, the multiwavelength data and the gamma-ray upper limits lead consistently to the conclusion that a potential HE and very-HE gamma-ray emitting region should be located at a distance from the BH ranging between 10(11) and 10(13) cm. Similar outbursts from low-mass X-ray binaries might be detectable in the near future with upcoming instruments such as CTA.
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| 6. |
- Acharyya, A., et al.
(författare)
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Multiwavelength Observations of the Blazar PKS 0735+178 in Spatial and Temporal Coincidence with an Astrophysical Neutrino Candidate IceCube-211208A
- 2023
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Ingår i: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 954:1
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Tidskriftsartikel (refereegranskat)abstract
- We report on multiwavelength target-of-opportunity observations of the blazar PKS 0735+178, located 2 degrees .2 away from the best -fit position of the IceCube neutrino event IceCube-211208A detected on 2021 December 8. The source was in a high -flux state in the optical, ultraviolet, X-ray, and GeV ?-ray bands around the time of the neutrino event, exhibiting daily variability in the soft X-ray flux. The X-ray data from Swift-XRT and NuSTAR characterize the transition between the low-energy and high-energy components of the broadband spectral energy distribution (SED), and the ?-ray data from Fermi-LAT, VERITAS, and H.E.S.S. require a spectral cutoff near 100 GeV. Both the X-ray and ?-ray measurements provide strong constraints on the leptonic and hadronic models. We analytically explore a synchrotron self-Compton model, an external Compton model, and a lepto-hadronic model. Models that are entirely based on internal photon fields face serious difficulties in matching the observed SED. The existence of an external photon field in the source would instead explain the observed ?-ray spectral cutoff in both the leptonic and lepto-hadronic models and allow a proton jet power that marginally agrees with the Eddington limit in the lepto-hadronic model. We show a numerical lepto-hadronic model with external target photons that reproduces the observed SED and is reasonably consistent with the neutrino event despite requiring a high jet power.
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| 8. |
- Baker, Laura, et al.
(författare)
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Resting heart rate and the development of antisocial behavior from age 9 to 14 : genetic and environmental influences
- 2009
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Ingår i: Development and psychopathology (Print). - 0954-5794 .- 1469-2198. ; 21:3, s. 939-960
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Tidskriftsartikel (refereegranskat)abstract
- The genetic and environmental basis of a well-replicated association between antisocial behavior (ASB) and resting heart rate was investigated in a longitudinal twin study, based on two measurements between the ages of 9 and 14 years. ASB was defined as a broad continuum of externalizing behavior problems, assessed at each occasion through a composite measure based on parent ratings of trait aggression, delinquent behaviors, and psychopathic traits in their children. Parent ratings of ASB significantly decreased across age from childhood to early adolescence, although latent growth models indicated significant variation and twin similarity in the growth patterns, which were explained almost entirely by genetic influences. Resting heart rate at age 9-10 years old was inversely related to levels of ASB but not change patterns of ASB across age or occasions. Biometrical analyses indicated significant genetic influences on heart rate during childhood, as well as ASB throughout development from age 9 to 14. Both level and slope variation were significantly influenced by genetic factors. Of importance, the low resting heart rate and ASB association was significantly and entirely explained by their genetic covariation, although the heritable component of heart rate explained only a small portion (1-4%) of the substantial genetic variance in ASB. Although the effect size is small, children with low resting heart rate appear to be genetically predisposed toward externalizing behavior problems as early as age 9 years old.
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| 9. |
- Bannon, Brittany L., et al.
(författare)
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Confirmatory factor analysis of illness behavior in the Swedish Adoption/Twin Study of Aging (SATSA)
- 2017
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Ingår i: Annals of Behavioral Medicine. - : Springer. - 0883-6612 .- 1532-4796. ; 51:Suppl. 1, s. S2654-S2655
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Tidskriftsartikel (refereegranskat)abstract
- Background: Illness behaviors—or affective, cognitive, and behavioral responses to symptoms of illness—predict patient outcomes, including symptom exacerbation and functional recovery, and they account for a large proportion of U.S. healthcare costs. Although priorcross-sectional work has examined illness behaviors like symptom reporting in isolation, the measurement of illness behavior using a longitudinal, multi-indicator approach has yet to be explored.Aim: We evaluated illness behavior as a latent, developmental construct in the Swedish Adoption/Twin Study of Aging (SATSA).Method: Participants were up to 1,886 individuals (from 1,223 twin pairs) ages 29 to 102 years (Mage baseline = 62.32 years; SD =13.69; 59% Female). Illness behavior indicators included somatic complaints, non-prescription medication use, pain-related disability and perceived illness complications. The psychomotor retardation subscale of the CES-D was used to index somatic complaints, and medication use was a simple composite of 9 dichotomous items on participants’ use of non-prescription medications, such as over-the-counter analgesics, in the previous month. Pain-related disability included a simple composite of three dichotomous items on the presence of neck,back, or shoulder pain that prevented participants from performing daily tasks or activities. Perceived illness disability was a composite of difference scores, calculated from subtracting a physician panel’s objective ratings of disability for each of 35 medical conditions (on a 3-pointscale; 1= Little or no disability; 3= Severe disability) from participants’ self-ratings of how much each of the same endorsed medical conditions interfered with their daily lives (on the same 3-point scale; 1= Not at all; 3= A lot). Positive composite scores reflected higher perceived disability relative to what was expected from the objective ratings, whereas a composite score of zero reflected “accuracy” or agreement in perceived illness complications. Confirmatory Factor Analysis (CFA) was used to evaluate invariance in the loadings of these four indicatorson a latent illness behavior factor across four questionnaire waves (1987-2004).Findings: Confirmatory factor analyses revealed moderate factor loadings of the four indicators (standardized loadings ranged from .49 to .52, all ps < .0001). Also, practical fit indices from the nested model comparisons suggested strong factorial invariance in the loadings across time (CFI = .96; TLI = .95, RMSEA= .03, 90% CI: [.026, .035]).Conclusion: Illness behavior as a latent, multi-indicator construct represents a promising focus for longitudinal work on behavior change and maintenance.
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| 11. |
- Beam, Christopher R., et al.
(författare)
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Estimating Likelihood of Dementia in the Absence of Diagnostic Data : A Latent Dementia Index in 10 Genetically Informed Studies
- 2022
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Ingår i: Journal of Alzheimer's Disease. - : IOS Press. - 1387-2877 .- 1875-8908. ; 90:3, s. 1187-1201
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Epidemiological research on dementia is hampered by differences across studies in how dementia is classified, especially where clinical diagnoses of dementia may not be available. OBJECTIVE: We apply structural equation modeling to estimate dementia likelihood across heterogeneous samples within a multi-study consortium and use the twin design of the sample to validate the results. METHODS: Using 10 twin studies, we implement a latent variable approach that aligns different tests available in each study to assess cognitive, memory, and functional ability. The model separates general cognitive ability from components indicative of dementia. We examine the validity of this continuous latent dementia index (LDI). We then identify cut-off points along the LDI distributions in each study and align them across studies to distinguish individuals with and without probable dementia. Finally, we validate the LDI by determining its heritability and estimating genetic and environmental correlations between the LDI and clinically diagnosed dementia where available. RESULTS: Results indicate that coordinated estimation of LDI across 10 studies has validity against clinically diagnosed dementia. The LDI can be fit to heterogeneous sets of memory, other cognitive, and functional ability variables to extract a score reflective of likelihood of dementia that can be interpreted similarly across studies despite diverse study designs and sampling characteristics. Finally, the same genetic sources of variance strongly contribute to both the LDI and clinical diagnosis. CONCLUSION: This latent dementia indicator approach may serve as a model for other research consortia confronted with similar data integration challenges.
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| 12. |
- Bennet, Anna M, et al.
(författare)
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Genetic association of sequence variants near AGER/NOTCH4 and dementia.
- 2011
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Ingår i: Journal of Alzheimer's disease : JAD. - 1875-8908. ; 24:3, s. 475-84
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Tidskriftsartikel (refereegranskat)abstract
- We performed a survey of sequence variation in a series of 20 genes involved in inflammation-related pathways for association with dementia risk in twin and unrelated case-control samples consisting in total of 1462 Swedish dementia casesand 1929 controls. For a total of 218 tested genetic markers, strong evidence was obtained implicating a region near AGER and NOTCH4 on chromosome 6p with replication across both samples and maximum combined significance at marker rs1800625 (OR = 1.37, 95% CI 1.19–1.56, p = 1.36×10(–6)). Imputation of the associated genomic interval provided an improved signal atrs8365, near the 3UTR of AGER (p = 7.34×10(–7)). The associated region extends 120 kb encompassing 11 candidate genes.While AGER encodes a key receptor for amyloid-β protein, an analysis of network context based upon genes now confirmed to contribute to dementia risk (AβPP, PSEN1, PSEN2, CR1, CLU, PICALM, and APOE) suggested strong functional coupling to NOTCH4, with no significant coupling to the remaining candidates. The implicated region occurs in the broad HLA locus on chromosome 6p, but associated markers were not in strong LD with known variants that regulate HLA gene function, suggesting that this may represent a signal distinct from immune-system pathways.
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| 13. |
- Bennet, Anna M, et al.
(författare)
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Pleiotropy in the Presence of Allelic Heterogeneity: Alternative Genetic Models for the Influence of APOE on Serum LDL, CSF Amyloid-β42, and Dementia.
- 2010
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Ingår i: Journal of Alzheimer's disease : JAD. - 1875-8908. ; 22:1, s. 129-134
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Tidskriftsartikel (refereegranskat)abstract
- The two genetic polymorphisms, rs7412 and rs429358, that collectively form the ε2, ε3, and ε4 alleles of apolipoprotein E (APOE) are among the most widely studied sequence variants in the genome. The predominant model for testing APOE involves the haplotype combinations of ε2, ε3, and ε4 and has been basis of associations with dementia, atherosclerosis, and serum lipid levels. Here, we demonstrate the functional independence of these two component sites, with rs7412 contributing to the majority of variance in serum LDL (p=10-20), whereas rs429358 alone influences variance in CSF amyloid-β42 (Aβ42) (p=10-17). This latter relationship is also reflected in the association of APOE with dementia, where rs429358 strongly influences disease (p=10-67), but rs7412 does not. Models based upon ε2, ε3, and ε4 explained less variance for both dementia risk and CSF Aβ42 than did rs429358 alone. When adjusted for CSF Aβ42, the association of rs429358 with dementia is greatly reduced but remains significant indicating that APOE polymorphism influences disease by additional mechanisms distinct from Aβ42 metabolism. We reach four principal conclusion from this study: 1) rs429358 alone is responsible for the association of APOE with dementia; 2) The association of APOE with dementia is substantially mediated by its effect on CNS Aβ42 levels; 3) The association of APOE with dementia is not mediated by its impact on peripheral lipid metabolism; and 4) The dichotomy of effects of rs429358 and rs7412 represents one of the best examples of genetic pleiotropy for complex traits known and illustrates the importance of allelic heterogeneity in APOE.
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| 15. |
- Blomqvist, Mia E-L, et al.
(författare)
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Towards compendia of negative genetic association studies: an example for Alzheimer disease.
- 2006
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Ingår i: Human genetics. - : Springer Science and Business Media LLC. - 0340-6717 .- 1432-1203. ; 119:1-2, s. 29-37
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Tidskriftsartikel (refereegranskat)abstract
- Most genetic sequence variants that contribute to variability in complex human traits will have small effects that are not readily detectable with population samples typically used in genetic association studies. A potentially valuable tool in the gene discovery process is meta-analysis of the accumulated published data, but in order to be valid these require a sample of studies representative of the true genetic effect and thus hypothetically should include some positive and an abundance of negative reports. A survey of the literature on association studies for Alzheimer disease (AD) from January 2004-April 2005, identified 138 studies, 86 of which reported positive findings other than for apolipoprotein E (APOE), strongly indicative of publication bias. We report here an analysis of 62 genetic markers, tested for association with AD risk as well as for possible effects upon quantitative indices of AD severity (mini-mental state examination scores, age-at-onset, and cerebrospinal fluid (CSF) beta-amyloid (Abeta) and CSF tau proteins). Within this set, only modest signals were present that, with the exception of APOE are easily lost when corrections for multiple hypotheses are applied. In isolation, results are thus broadly negative. Genes studied encompass both novel candidates as well as several recently claimed to be associated with AD (e.g. urokinase plasminogen activator (PLAU) and acetyl-coenzyme A acetyltransferase 1 (ACAT1)). By reporting these data we hope to encourage the publication of gene compendia to guide further studies and aid future meta-analyses aimed at resolving the involvement of genes in complex human traits.
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| 16. |
- Bombarda, F., et al.
(författare)
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Runaway electron beam control
- 2019
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 1361-6587 .- 0741-3335. ; 61:1
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Tidskriftsartikel (refereegranskat)
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| 19. |
- Dahl, Anna, 1975-, et al.
(författare)
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Accuracy of Recalled Body Weight-A Study with 20-years of Follow-Up
- 2013
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Ingår i: Obesity. - : John Wiley & Sons. - 1930-7381 .- 1930-739X. ; 21:6, s. 1293-1298
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Tidskriftsartikel (refereegranskat)abstract
- Objective:Weight changes may bean important indicator of an ongoing pathological process.Retrospective self-report might be the only possibility to capture prior weight. The objective of the study was to evaluate the accuracy of retrospective recallof body weight in old age and factors that might predict accuracy.Design and Methods:In 2007, 646 participants (mean age, 71.6 years) of the Swedish Adoption/Twin Study of Aging (SATSA)answered questions about their present weight and how much they weighed 20-years ago. Of these, 436 had self-reported their weighttwenty years earlier and among these 134 had also had their weight assessed at this time point.Results:Twenty yearretrospectively recalled weight underestimated the prior assessed weight by -1.89 ± 5.9 kg and underestimatedprior self-reported weight by -0.55 ±5.2 kg.Moreover, 82.4% of the sample were accurate within 10%, and 45.8% were accurate within 5% of their prior assessed weights;similarly, 84.2% and 58.0 %were accurate within 10% and 5% respectively, forprior self-reported weight. Current higher body mass index and preferences of reporting weights ending with zero or five was associated with an underestimation of prior weight, while greater weight change over 20 year, and low Mini-Mental State Scores (MMSE) (<25) led to an overestimation of prior weight.Conclusions:Recalled weight comes close to the assessed population mean, but at the individual level there is a large variation. The accuracy is affected by current BMI, changes in weight, end-digit preferences, and current cognitive ability. Recalled weight should be used with caution.
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| 20. |
- Dahl, Anna, et al.
(författare)
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Being overweight in midlife is associated with lower cognitive ability and steeper cognitive decline in late life.
- 2010
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Ingår i: The journals of gerontology. Series A, Biological sciences and medical sciences. - : Oxford University Press (OUP). - 1758-535X .- 1079-5006. ; 65:1, s. 57-62
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Although an increasing body of evidence links being overweight in midlife with an increased risk for dementia in late life, no studies have examined the association between being overweight in midlife and cognitive ability in late life. Our aim was to examine the association between being overweight in midlife as measured by body mass index (BMI) and cognitive ability assessed over time. METHODS: Participants in the Swedish Adoption/Twin Study Aging were derived from a population-based sample. The participants completed baseline surveys in 1963 or 1973 (mean age 41.6 years, range 25-63 years). The surveys included questions about height, weight, diseases, and lifestyle factors. Beginning in 1986, the same individuals were assessed on neuropsychological tests every 3 years (except in 1995) until 2002. During the study period, 781 individuals who were 50 years and older (60% women) had at least one complete neuropsychological assessment. A composite score of general cognitive ability was derived from the cognitive test battery for each measurement occasion. RESULTS: Latent growth curve models adjusted for twinness showed that persons with higher midlife BMI scores had significantly lower general cognitive ability and significantly steeper longitudinal decline than their thinner counterparts. The association did not change substantially when persons who developed dementia during the study period were excluded from the analysis. CONCLUSIONS: Higher midlife BMI scores precede lower general cognitive ability and steeper cognitive decline in both men and women. The association does not seem to be mediated by an increased risk for dementia.
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| 21. |
- Dahl, Anna, 1975-, et al.
(författare)
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Being overweight in midlife is associated with lower cognitive ability and steeper cognitive decline in late life
- 2010
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Ingår i: The journals of gerontology. Series A, Biological sciences and medical sciences. - : Oxford University Press. - 1079-5006 .- 1758-535X. ; 65A:1, s. 57-62
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Although an increasing body of evidence links being overweight in midlife with an increased risk for dementia in late life, no studies have examined the association between being overweight in midlife and cognitive ability in late life. Our aim was to examine the association between being overweight in midlife as measured by body mass index (BMI) and cognitive ability assessed over time. METHODS: Participants in the Swedish Adoption/Twin Study Aging were derived from a population-based sample. The participants completed baseline surveys in 1963 or 1973 (mean age 41.6 years, range 25-63 years). The surveys included questions about height, weight, diseases, and lifestyle factors. Beginning in 1986, the same individuals were assessed on neuropsychological tests every 3 years (except in 1995) until 2002. During the study period, 781 individuals who were 50 years and older (60% women) had at least one complete neuropsychological assessment. A composite score of general cognitive ability was derived from the cognitive test battery for each measurement occasion. RESULTS: Latent growth curve models adjusted for twinness showed that persons with higher midlife BMI scores had significantly lower general cognitive ability and significantly steeper longitudinal decline than their thinner counterparts. The association did not change substantially when persons who developed dementia during the study period were excluded from the analysis. CONCLUSIONS: Higher midlife BMI scores precede lower general cognitive ability and steeper cognitive decline in both men and women. The association does not seem to be mediated by an increased risk for dementia
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| 22. |
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| 23. |
- Dahl, Anna, et al.
(författare)
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Body mass index across midlife and cognitive change in late life
- 2013
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Ingår i: International Journal of Obesity. - : Springer Science and Business Media LLC. - 0307-0565 .- 1476-5497. ; 37, s. 296-302
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: High midlife body mass index (BMI) has been linked to a greater risk of dementia in late life, but few have studied the effect of BMI across midlife on cognitive abilities and cognitive change in a dementia-free sample. METHODS: We investigated the association between BMI, measured twice across midlife (mean age 40 and 61 years, respectively), and cognitive change in four domains across two decades in the Swedish Adoption/Twin Study of Aging. RESULTS: Latent growth curve models fitted to data from 657 non-demented participants showed that persons who were overweight/obese in early midlife had significantly lower cognitive performance across domains in late life and significantly steeper decline in perceptual speed, adjusting for cardio-metabolic factors. Both underweight and overweight/obesity in late midlife were associated with lower cognitive abilities in late life. However, the association between underweight and low cognitive abilities did not remain significant when weight decline between early and late midlife was controlled for. CONCLUSION: There is a negative effect on cognitive abilities later in life related to being overweight/obese across midlife. Moreover, weight decline across midlife rather than low weight in late midlife per se was associated with low cognitive abilities. Weight patterns across midlife may be prodromal markers of late life cognitive health.
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