| 1. |
- Akiyama, Kazunori, et al.
(författare)
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First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multiwavelength Observations, Data Processing, and Calibration
- 2022
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2
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Tidskriftsartikel (refereegranskat)abstract
- We present Event Horizon Telescope (EHT) 1.3 mm measurements of the radio source located at the position of the supermassive black hole Sagittarius A* (Sgr A*), collected during the 2017 April 5-11 campaign. The observations were carried out with eight facilities at six locations across the globe. Novel calibration methods are employed to account for Sgr A*'s flux variability. The majority of the 1.3 mm emission arises from horizon scales, where intrinsic structural source variability is detected on timescales of minutes to hours. The effects of interstellar scattering on the image and its variability are found to be subdominant to intrinsic source structure. The calibrated visibility amplitudes, particularly the locations of the visibility minima, are broadly consistent with a blurred ring with a diameter of similar to 50 mu as, as determined in later works in this series. Contemporaneous multiwavelength monitoring of Sgr A* was performed at 22, 43, and 86 GHz and at near-infrared and X-ray wavelengths. Several X-ray flares from Sgr A* are detected by Chandra, one at low significance jointly with Swift on 2017 April 7 and the other at higher significance jointly with NuSTAR on 2017 April 11. The brighter April 11 flare is not observed simultaneously by the EHT but is followed by a significant increase in millimeter flux variability immediately after the X-ray outburst, indicating a likely connection in the emission physics near the event horizon. We compare Sgr A*'s broadband flux during the EHT campaign to its historical spectral energy distribution and find that both the quiescent emission and flare emission are consistent with its long-term behavior.
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| 2. |
- Akiyama, Kazunori, et al.
(författare)
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The persistent shadow of the supermassive black hole of M 87: I. Observations, calibration, imaging, and analysis*
- 2024
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 681
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Tidskriftsartikel (refereegranskat)abstract
- In April 2019, the Event Horizon Telescope (EHT) Collaboration reported the first-ever event-horizon-scale images of a black hole, resolving the central compact radio source in the giant elliptical galaxy M 87. These images reveal a ring with a southerly brightness distribution and a diameter of ∼42 μas, consistent with the predicted size and shape of a shadow produced by the gravitationally lensed emission around a supermassive black hole. These results were obtained as part of the April 2017 EHT observation campaign, using a global very long baseline interferometric radio array operating at a wavelength of 1.3 mm. Here, we present results based on the second EHT observing campaign, taking place in April 2018 with an improved array, wider frequency coverage, and increased bandwidth. In particular, the additional baselines provided by the Greenland telescope improved the coverage of the array. Multiyear EHT observations provide independent snapshots of the horizon-scale emission, allowing us to confirm the persistence, size, and shape of the black hole shadow, and constrain the intrinsic structural variability of the accretion flow. We have confirmed the presence of an asymmetric ring structure, brighter in the southwest, with a median diameter of 43.3-3.1+1.5 μas. The diameter of the 2018 ring is remarkably consistent with the diameter obtained from the previous 2017 observations. On the other hand, the position angle of the brightness asymmetry in 2018 is shifted by about 30 relative to 2017. The perennial persistence of the ring and its diameter robustly support the interpretation that the ring is formed by lensed emission surrounding a Kerr black hole with a mass ∼6.5× 109M. The significant change in the ring brightness asymmetry implies a spin axis that is more consistent with the position angle of the large-scale jet.
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| 3. |
- Hudson, Lawrence N, et al.
(författare)
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The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project
- 2017
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Ingår i: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 7:1, s. 145-188
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Tidskriftsartikel (refereegranskat)abstract
- The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.
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| 4. |
- Kim, Jae-Young, et al.
(författare)
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Event Horizon Telescope imaging of the archetypal blazar 3C 279 at an extreme 20 microarcsecond resolution
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 640
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Tidskriftsartikel (refereegranskat)abstract
- 3C 279 is an archetypal blazar with a prominent radio jet that show broadband flux density variability across the entire electromagnetic spectrum. We use an ultra-high angular resolution technique - global Very Long Baseline Interferometry (VLBI) at 1.3mm (230 GHz) - to resolve the innermost jet of 3C 279 in order to study its fine-scale morphology close to the jet base where highly variable-ray emission is thought to originate, according to various models. The source was observed during four days in April 2017 with the Event Horizon Telescope at 230 GHz, including the phased Atacama Large Millimeter/submillimeter Array, at an angular resolution of ∼20 μas (at a redshift of z = 0:536 this corresponds to ∼0:13 pc ∼ 1700 Schwarzschild radii with a black hole mass MBH = 8 × 108 M⊙). Imaging and model-fitting techniques were applied to the data to parameterize the fine-scale source structure and its variation.We find a multicomponent inner jet morphology with the northernmost component elongated perpendicular to the direction of the jet, as imaged at longer wavelengths. The elongated nuclear structure is consistent on all four observing days and across diffierent imaging methods and model-fitting techniques, and therefore appears robust. Owing to its compactness and brightness, we associate the northern nuclear structure as the VLBI "core". This morphology can be interpreted as either a broad resolved jet base or a spatially bent jet.We also find significant day-to-day variations in the closure phases, which appear most pronounced on the triangles with the longest baselines. Our analysis shows that this variation is related to a systematic change of the source structure. Two inner jet components move non-radially at apparent speeds of ∼15 c and ∼20 c (∼1:3 and ∼1:7 μas day-1, respectively), which more strongly supports the scenario of traveling shocks or instabilities in a bent, possibly rotating jet. The observed apparent speeds are also coincident with the 3C 279 large-scale jet kinematics observed at longer (cm) wavelengths, suggesting no significant jet acceleration between the 1.3mm core and the outer jet. The intrinsic brightness temperature of the jet components are ≤1010 K, a magnitude or more lower than typical values seen at ≥7mm wavelengths. The low brightness temperature and morphological complexity suggest that the core region of 3C 279 becomes optically thin at short (mm) wavelengths.
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| 5. |
- Menzies, Scott W, et al.
(författare)
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Dermoscopic Evaluation of Nodular Melanoma.
- 2013
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Ingår i: JAMA dermatology (Chicago, Ill.). - : American Medical Association (AMA). - 2168-6084 .- 2168-6068. ; 149:6, s. 699-709
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE Nodular melanoma (NM) is a rapidly progressing potentially lethal skin tumor for which early diagnosis is critical. OBJECTIVE To determine the dermoscopy features of NM. DESIGN Eighty-three cases of NM, 134 of invasive non-NM, 115 of nodular benign melanocytic tumors, and 135 of nodular nonmelanocytic tumors were scored for dermoscopy features using modified and previously described methods. Lesions were separated into amelanotic/hypomelanotic or pigmented to assess outcomes. SETTING Predominantly hospital-based clinics from 5 continents. MAIN OUTCOME MEASURES Sensitivity, specificity, and odds ratios for features/models for the diagnosis of melanoma. RESULTS Nodular melanoma occurred more frequently as amelanotic/hypomelanotic (37.3%) than did invasive non-NM (7.5%). Pigmented NM had a more frequent (compared with invasive non-NM; in descending order of odds ratio) symmetrical pigmentation pattern (5.8% vs 0.8%), large-diameter vessels, areas of homogeneous blue pigmentation, symmetrical shape, predominant peripheral vessels, blue-white veil, pink color, black color, and milky red/pink areas. Pigmented NM less frequently displayed an atypical broadened network, pigment network or pseudonetwork, multiple blue-gray dots, scarlike depigmentation, irregularly distributed and sized brown dots and globules, tan color, irregularly shaped depigmentation, and irregularly distributed and sized dots and globules of any color. The most important positive correlating features of pigmented NM vs nodular nonmelanoma were peripheral black dots/globules, multiple brown dots, irregular black dots/globules, blue-white veil, homogeneous blue pigmentation, 5 to 6 colors, and black color. A model to classify a lesion as melanocytic gave a high sensitivity (>98.0%) for both nodular pigmented and nonnodular pigmented melanoma but a lower sensitivity for amelanotic/hypomelanotic NM (84%). A method for diagnosing amelanotic/hypomelanotic malignant lesions (including basal cell carcinoma) gave a 93% sensitivity and 70% specificity for NM. CONCLUSIONS AND RELEVANCE When a progressively growing, symmetrically patterned melanocytic nodule is identified, NM needs to be excluded.
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| 6. |
- Hayden, Kathleen M, et al.
(författare)
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Effects of family history and apolipoprotein E epsilon4 status on cognitive decline in the absence of Alzheimer dementia: the Cache County Study.
- 2009
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Ingår i: Archives of neurology. - : American Medical Association (AMA). - 1538-3687 .- 0003-9942. ; 66:11, s. 1378-83
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate the influences of a family history of Alzheimer dementia (FHxAD) and the apolipoprotein E epsilon4 genotype (APOE epsilon4) on cognitive decline. DESIGN, SETTING, AND PARTICIPANTS: Residents of Cache County, Utah, aged 65 years or older, were invited to participate. At baseline, 2957 participants provided DNA for genotyping of APOE and a detailed FHxAD. They also completed the Modified Mini-Mental State Examination. Cognitive status was reexamined after 3 and 7 years. We used mixed-effects models to examine the association among FHxAD, APOE epsilon4, and cognitive trajectories. MAIN OUTCOME MEASURE: Modified Mini-Mental State Examination score trajectories over time. RESULTS: Compared with participants who did not have APOE epsilon4 or an FHxAD, those with APOE epsilon4 scored lower on the Modified Mini-Mental State Examination at baseline (-0.70 points; 95% confidence interval [CI], -1.15 to -0.24). Participants with an FHxAD and APOE epsilon4 differed less, if at all, in baseline score (-0.46 points; 95% CI, -1.09 to 0.16) but declined faster during the 7-year study (-9.75 points [95% CI, -10.82 to -8.67] vs -2.91 points [95% CI, -3.37 to -2.44]). After exclusion of participants who developed prodromal AD or incident dementia, the group with an FHxAD and APOE epsilon4 declined much less during the 7-year study (-1.54; 95% CI, -2.59 to -0.50). CONCLUSIONS: Much of the association among FHxAD, APOE epsilon4, and cognitive decline may be attributed to undetected incipient (latent) disease. In the absence of latent disease, the 2 factors do not appear individually to be associated with cognitive decline, although they may be additive.
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| 7. |
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| 8. |
- Liljedahl, Leena, et al.
(författare)
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Effects of insulin and the glucagon-like peptide 1 receptor agonist liraglutide on the kidney proteome in db/db mice.
- 2017
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Ingår i: Physiological Reports. - : Wiley. - 2051-817X. ; 5:6
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Tidskriftsartikel (refereegranskat)abstract
- Diabetes mellitus (DM) is a worldwide disease that affects 9% of the adult world population and type 2 DM accounts for 90% of those. A common consequence of DM is kidney complications, which could lead to kidney failure. We studied the potential effects of treatment with insulin and the glucagon-like peptide 1 receptor (GLP-1R) agonist liraglutide on the diabetic kidney proteome through the use of the db/db mouse model system and mass spectrometry (MS). Multivariate analyses revealed distinct effects of insulin and liraglutide on the db/db kidney proteome, which was seen on the protein levels of, for example, pterin-4 α-carbinolamine dehydratase/dimerization cofactor of hepatocyte nuclear factor-1α (PCBD1), neural precursor cell expressed developmentally down-regulated-8 (NEDD8), transcription elongation factor-B polypeptide-1 (ELOC) and hepcidin (HEPC). Furthermore, the separation of the insulin, liraglutide and vehicle db/db mouse groups in multivariate analyses was not mainly related to the albumin excretion rate (AER) or the level of glycated hemoglobin A1c (HbA1c%) in the mice. In summary, we show that insulin and liraglutide give rise to separate protein profiles in the db/db mouse kidney.
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| 9. |
- Norton, Alexander J., et al.
(författare)
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Assimilating solar-induced chlorophyll fluorescence into the terrestrial biosphere model BETHY-SCOPE v1.0 : Model description and information content
- 2018
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Ingår i: Geoscientific Model Development. - : Copernicus GmbH. - 1991-959X .- 1991-9603. ; 11:4, s. 1517-1536
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of model and observational information using data assimilation can improve our understanding of the terrestrial carbon cycle, a key component of the Earth's climate-carbon system. Here we provide a data assimilation framework for combining observations of solar-induced chlorophyll fluorescence (SIF) and a process-based model to improve estimates of terrestrial carbon uptake or gross primary production (GPP). We then quantify and assess the constraint SIF provides on the uncertainty in global GPP through model process parameters in an error propagation study. By incorporating 1 year of SIF observations from the GOSAT satellite, we find that the parametric uncertainty in global annual GPP is reduced by 73ĝ€% from ±19.0 to ±5.2ĝ€Pgĝ€†Cĝ€†yrĝ-1. This improvement is achieved through strong constraint of leaf growth processes and weak to moderate constraint of physiological parameters. We also find that the inclusion of uncertainty in shortwave down-radiation forcing has a net-zero effect on uncertainty in GPP when incorporated into the SIF assimilation framework. This study demonstrates the powerful capacity of SIF to reduce uncertainties in process-based model estimates of GPP and the potential for improving our predictive capability of this uncertain carbon flux.
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| 10. |
- Norton, Alexander J., et al.
(författare)
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Estimating global gross primary productivity using chlorophyll fluorescence and a data assimilation system with the BETHY-SCOPE model
- 2019
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 16:15, s. 3069-3093
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the assimilation of solar-induced chlorophyll fluorescence (SIF) into a terrestrial biosphere model to estimate the gross uptake of carbon through photosynthesis (GPP). We use the BETHY-SCOPE model to simulate both GPP and SIF using a process-based formulation, going beyond a simple linear scaling between the two. We then use satellite SIF data from the Orbiting Carbon Observatory-2 (OCO-2) for 2015 in the data assimilation system to constrain model biophysical parameters and GPP. The assimilation results in considerable improvement in the fit between model and observed SIF, despite a limited capability to fit regions with large seasonal variability in SIF. The SIF assimilation increases global GPP by 31% to 167±5 PgCyr-1 and shows an improvement in the global distribution of productivity relative to independent estimates, but a large difference in magnitude. This change in global GPP is driven by an overall increase in photosynthetic lightuse efficiency across almost all biomes and more minor, regionally distinct changes in APAR. This process-based data assimilation opens up new pathways to the effective utilization of satellite SIF data to improve our understanding of the global carbon cycle.
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| 11. |
- Norton, Maria C, et al.
(författare)
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Church attendance and new episodes of major depression in a community study of older adults: the Cache County Study.
- 2008
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Ingår i: The journals of gerontology. Series B, Psychological sciences and social sciences. - 1079-5014. ; 63:3
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Tidskriftsartikel (refereegranskat)abstract
- We examined the relation between church attendance, membership in the Church of Jesus Christ of Latter-Day Saints (LDS), and major depressive episode, in a population-based study of aging and dementia in Cache County, Utah. Participants included 2,989 nondemented individuals aged between 65 and 100 years who were interviewed initially in 1995 to 1996 and again in 1998 to 1999. LDS church members reported twice the rate of major depression that non-LDS members did (odds ratio = 2.56, 95% confidence interval = 1.07-6.08). Individuals attending church weekly or more often had a significantly lower risk for major depression. After controlling for demographic and health variables and the strongest predictor of future episodes of depression, a prior depression history, we found that church attendance more often than weekly remained a significant protectant (odds ratio = 0.51, 95% confidence interval = 0.28-0.92). Results suggest that there may be a threshold of church attendance that is necessary for a person to garner long-term protection from depression. We discuss sociological factors relevant to LDS culture.
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| 12. |
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| 13. |
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| 15. |
- Norton, Maria C, et al.
(författare)
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Three-year incidence of first-onset depressive syndrome in a population sample of older adults: the Cache County study.
- 2006
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Ingår i: Am J Geriatr Psychiatry. - 1064-7481. ; 14:3, s. 237-45
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Estimates of incidence of late-life depression vary greatly with few studies excluding demented cases through in-depth evaluation and most studies failing to control for the effect of mortality and interval treatment. In a large population-based study, the authors examined the effect on incidence of first-onset depressive syndrome to determine whether any gender or age differences in incidence are attenuated with inclusion of these additional measures. METHOD: Incidence rates of depressive syndrome per 1,000 person-years are presented for 2,877 nondemented elderly (ages 65 to 100 years) residents of Cache County, Utah. Cases are identified by direct interview methods, by inference from prescription antidepressant medicine use, and by postmortem informant interview for decedents. RESULTS: In-person interviews yielded incidence rates of first-onset depressive disorder (any type) of 13.09 for men and 19.44 for women. Inclusion of antidepressant users increased these figures to 15.55 for men and 23.30 for women. Addition of postmortem interview data yielded rates of 20.66 for men and 26.29 for women. Individuals with no history of depression had rates for major depression of 7.88 for men and 8.75 for women; minor depression rates were 19.23 for men and 24.46 for women (p = 0.691; effect for minor depression p <0.0001). Age did not predict incidence. CONCLUSIONS: Incidence of first-onset major depression varies with data source and prior lifetime history of depression. Gender effects apparent in interview data are attenuated when postmortem information and pharmacotherapy were considered.
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| 16. |
- Pooley, Colin, et al.
(författare)
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Introduction: Historical perspectives on pedestrians and the city
- 2021
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Ingår i: Urban History. - : Cambridge University Press. - 0963-9268 .- 1469-8706. ; 48:2, s. 204-210
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Forskningsöversikt (refereegranskat)abstract
- Walking is a neglected topic in the history of transport and mobility in cities. The four articles in this special section demonstrate the importance of travel on foot in nineteenth- A nd twentieth-century cities in four different countries, and reveal the ways in which pedestrian mobility has persisted despite the development of a car-dominated society. Together they provide important new evidence on a neglected topic and hopefully pave the way for further research on this theme.
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| 17. |
- Wang, Li-San, et al.
(författare)
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Rarity of the Alzheimer Disease-Protective APP A673T Variant in the United States.
- 2015
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Ingår i: JAMA neurology. - : American Medical Association (AMA). - 2168-6157 .- 2168-6149. ; 72:2
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Tidskriftsartikel (refereegranskat)abstract
- Recently, a rare variant in the amyloid precursor protein gene (APP) was described in a population from Iceland. This variant, in which alanine is replaced by threonine at position 673 (A673T), appears to protect against late-onset Alzheimer disease (AD). We evaluated the frequency of this variant in AD cases and cognitively normal controls to determine whether this variant will significantly contribute to risk assessment in individuals in the United States.
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| 18. |
- Zandi, Peter P, et al.
(författare)
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Reduced risk of Alzheimer disease in users of antioxidant vitamin supplements: the Cache County Study.
- 2004
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Ingår i: Archives of neurology. - : American Medical Association (AMA). - 0003-9942. ; 61:1, s. 82-8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Antioxidants may protect the aging brain against oxidative damage associated with pathological changes of Alzheimer disease (AD). OBJECTIVE: To examine the relationship between antioxidant supplement use and risk of AD. DESIGN: Cross-sectional and prospective study of dementia. Elderly (65 years or older) county residents were assessed in 1995 to 1997 for prevalent dementia and AD, and again in 1998 to 2000 for incident illness. Supplement use was ascertained at the first contact. SETTING: Cache County, Utah. PARTICIPANTS: Among 4740 respondents (93%) with data sufficient to determine cognitive status at the initial assessment, we identified 200 prevalent cases of AD. Among 3227 survivors at risk, we identified 104 incident AD cases at follow-up. MAIN OUTCOME MEASURE: Diagnosis of AD by means of multistage assessment procedures. RESULTS: Analyses of prevalent and incident AD yielded similar results. Use of vitamin E and C (ascorbic acid) supplements in combination was associated with reduced AD prevalence (adjusted odds ratio, 0.22; 95% confidence interval, 0.05-0.60) and incidence (adjusted hazard ratio, 0.36; 95% confidence interval, 0.09-0.99). A trend toward lower AD risk was also evident in users of vitamin E and multivitamins containing vitamin C, but we saw no evidence of a protective effect with use of vitamin E or vitamin C supplements alone, with multivitamins alone, or with vitamin B-complex supplements. CONCLUSIONS: Use of vitamin E and vitamin C supplements in combination is associated with reduced prevalence and incidence of AD. Antioxidant supplements merit further study as agents for the primary prevention of AD.
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