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Sökning: WFRF:(Gudmundsson M.T.)

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1.
  • Lind, Lars, et al. (författare)
  • Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight NCD Risk Factor Collaboration (NCD-RisC)
  • 2021
  • Ingår i: eLife. - : eLife Sciences Publications Ltd. - 2050-084X. ; 10
  • Tidskriftsartikel (refereegranskat)abstract
    • From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMI distribution was left behind as the distribution shifted. There is a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions.
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2.
  • Bixby, H., et al. (författare)
  • Rising rural body-mass index is the main driver of the global obesity epidemic in adults
  • 2019
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 569:7755, s. 260-4
  • Tidskriftsartikel (refereegranskat)abstract
    • Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities(.)(1,2) This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity(3-6). Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55% of the global rise in mean BMI from 1985 to 2017-and more than 80% in some low- and middle-income regions-was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing-and in some countries reversal-of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories.
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3.
  • Sigmundsson, F., et al. (författare)
  • Segmented lateral dyke growth in a rifting event at Bardarbunga volcanic system, Iceland
  • 2015
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 517:7533
  • Tidskriftsartikel (refereegranskat)abstract
    • Crust at many divergent plate boundaries forms primarily by the injection of vertical sheet-like dykes, some tens of kilometres long(1). Previous models of rifting events indicate either lateral dyke growth away from a feeding source, with propagation rates decreasing as the dyke lengthens(2-4), or magma flowing vertically into dykes from an underlying source(5,6), with the role of topography on the evolution of lateral dykes not clear. Here we show how a recent segmented dyke intrusion in the Bardarbunga volcanic system grew laterally for more than 45 kilometres at a variable rate, with topography influencing the direction of propagation. Barriers at the ends of each segment were overcome by the build-up of pressure in the dyke end; then a new segment formed and dyke lengthening temporarily peaked. The dyke evolution, which occurred primarily over 14 days, was revealed by propagating seismicity, ground deformation mapped by Global Positioning System(GPS), interferometric analysis of satellite radar images (InSAR), and graben formation. The strike of the dyke segments varies from an initially radial direction away from the Bardarbunga caldera, towards alignment with that expected from regional stress at the distal end. A model minimizing the combined strain and gravitational potential energy explains the propagation path. Dyke opening and seismicity focused at the most distal segment at any given time, and were simultaneous with magma source deflation and slow collapse at the Bardarbunga caldera, accompanied by a series of magnitude M > 5 earthquakes. Dyke growth was slowed down by an effusive fissure eruption near the end of the dyke. Lateral dyke growth with segment barrier breaking by pressure build-up in the dyke distal end explains how focused upwelling of magma under central volcanoes is effectively redistributed over long distances to create new upper crust at divergent plate boundaries.
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4.
  • Gislason, S.R., et al. (författare)
  • Environmental pressure from the 2014–15 eruption of Bárðarbunga volcano, Iceland
  • 2015
  • Ingår i: Geochemical Perspectives Letters. - : European Association of Geochemistry. - 2410-3403 .- 2410-339X. ; 1:2015, s. 84 - 93
  • Tidskriftsartikel (refereegranskat)abstract
    • The effusive six months long 2014-2015 Bárðarbunga eruption (31 August-27 February) was the largest in Iceland for more than 200 years, producing 1.6 ± 0.3 km3 of lava. The total SO2 emission was 11 ± 5 Mt, more than the amount emitted from Europe in 2011. The ground level concentration of SO2 exceeded the 350 μg m−3 hourly average health limit over much of Iceland for days to weeks. Anomalously high SO2 concentrations were also measured at several locations in Europe in September. The lowest pH of fresh snowmelt at the eruption site was 3.3, and 3.2 in precipitation 105 km away from the source. Elevated dissolved H2SO4, HCl, HF, and metal concentrations were measured in snow and precipitation. Environmental pressures from the eruption and impacts on populated areas were reduced by its remoteness, timing, and the weather. The anticipated primary environmental pressure is on the surfacewaters, soils, and vegetation of Iceland.
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5.
  • Hreinsdottir, S., et al. (författare)
  • Volcanic plume height correlated with magma-pressure change at Grimsvotn Volcano, Iceland
  • 2014
  • Ingår i: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 7:3, s. 214-218
  • Tidskriftsartikel (refereegranskat)abstract
    • Magma flow during volcanic eruptions causes surface deformation that can be used to constrain the location, geometry and internal pressure evolution of the underlying magmatic source(1). The height of the volcanic plumes during explosive eruptions also varies with magma flow rate, in a nonlinear way(2,3). In May 2011, an explosive eruption at Grimsvotn Volcano, Iceland, erupted about 0.27 km(3) dense-rock equivalent of basaltic magma in an eruption plume that was about 20 km high. Here we use Global Positioning System (GPS) and tilt data, measured before and during the eruption at Grimsvotn Volcano, to show that the rate of pressure change in an underlying magma chamber correlates with the height of the volcanic plume over the course of the eruption. We interpret ground deformation of the volcano, measured by geodesy, to result from a pressure drop within a magma chamber at about 1.7 km depth. We estimate the rate of magma discharge and the associated evolution of the plume height by differentiating the co-eruptive pressure drop with time. The time from the initiation of the pressure drop to the onset of the eruption was about 60 min, with about 25% of the total pressure change preceding the eruption. Near-real-time geodetic observations can thus be useful for both timely eruption warnings and for constraining the evolution of volcanic plumes.
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6.
  • Kaptoge, S., et al. (författare)
  • World Health Organization cardiovascular disease risk charts: revised models to estimate risk in 21 global regions
  • 2019
  • Ingår i: Lancet Global Health. - : Elsevier BV. - 2214-109X. ; 7:10
  • Tidskriftsartikel (refereegranskat)abstract
    • Background To help adapt cardiovascular disease risk prediction approaches to low-income and middle-income countries, WHO has convened an effort to develop, evaluate, and illustrate revised risk models. Here, we report the derivation, validation, and illustration of the revised WHO cardiovascular disease risk prediction charts that have been adapted to the circumstances of 21 global regions. Methods In this model revision initiative, we derived 10-year risk prediction models for fatal and non-fatal cardiovascular disease (ie, myocardial infarction and stroke) using individual participant data from the Emerging Risk Factors Collaboration. Models included information on age, smoking status, systolic blood pressure, history of diabetes, and total cholesterol. For derivation, we included participants aged 40-80 years without a known baseline history of cardiovascular disease, who were followed up until the first myocardial infarction, fatal coronary heart disease, or stroke event. We recalibrated models using age-specific and sex-specific incidences and risk factor values available from 21 global regions. For external validation, we analysed individual participant data from studies distinct from those used in model derivation. We illustrated models by analysing data on a further 123 743 individuals from surveys in 79 countries collected with the WHO STEPwise Approach to Surveillance. Findings Our risk model derivation involved 376 177 individuals from 85 cohorts, and 19 333 incident cardiovascular events recorded during 10 years of follow-up. The derived risk prediction models discriminated well in external validation cohorts (19 cohorts, 1 096 061 individuals, 25 950 cardiovascular disease events), with Harrell's C indices ranging from 0.685 (95% CI 0 . 629-0 741) to 0.833 (0 . 783-0- 882). For a given risk factor profile, we found substantial variation across global regions in the estimated 10-year predicted risk. For example, estimated cardiovascular disease risk for a 60-year-old male smoker without diabetes and with systolic blood pressure of 140 mm Hg and total cholesterol of 5 mmol/L ranged from 11% in Andean Latin America to 30% in central Asia. When applied to data from 79 countries (mostly low-income and middle-income countries), the proportion of individuals aged 40-64 years estimated to be at greater than 20% risk ranged from less than 1% in Uganda to more than 16% in Egypt. Interpretation We have derived, calibrated, and validated new WHO risk prediction models to estimate cardiovascular disease risk in 21 Global Burden of Disease regions. The widespread use of these models could enhance the accuracy, practicability, and sustainability of efforts to reduce the burden of cardiovascular disease worldwide. Copyright (C) 2019 The Author(s). Published by Elsevier Ltd.
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7.
  • Magnusson, E., et al. (författare)
  • Development of a subglacial lake monitored with radio-echo sounding: case study from the eastern Skafta cauldron in the Vatnajokull ice cap, Iceland
  • 2021
  • Ingår i: Cryosphere. - : Copernicus GmbH. - 1994-0416. ; 15:8, s. 3731-3749
  • Tidskriftsartikel (refereegranskat)abstract
    • We present repeated radio-echo sounding (RES, 5 MHz) on a profile grid over the eastern Skafta cauldron (ESC) in Vatnajokull ice cap, Iceland. The ESC is a similar to 3 km wide and 50-150 m deep ice cauldron created and maintained by subglacial geothermal activity of similar to 1GW. Beneath the cauldron and 200-400 m thick ice, water accumulates in a subglacial lake and is released semi-regularly in jokulhlaups. The RES record consists of annual surveys conducted at the beginning of every summer during the period 2014-2020. Comparison of the RES surveys reveals variable lake area (0.5-4.1 km(2)) and enables traced reflections from the lake roof to be distinguished from bedrock reflections. This allows construction of a digital elevation model (DEM) of the bedrock in the area, further constrained by two borehole measurements at the cauldron centre. It also allows creation of lake thickness maps and an estimate of lake volume at the time of each survey, which we compare with lowering patterns and released water volumes obtained from pre- and post-jokulhlaup surface DEMs. The estimated lake volume was 250 GL (gigalitres = 10(6) m(3)) in June 2015, but 320 +/- 20 GL drained from the ESC in October 2015. In June 2018, RES profiles revealed a lake volume of 185 GL, while 220 +/- 30 GL were released in a jokulhlaup in August 2018. Considering the water accumulation over the periods between RES surveys and jokulhlaups, this indicates 10 %-20% uncertainty in the RES-derived volumes at times when significant jokulhlaups may be expected.
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8.
  • Pinel, Virginie, et al. (författare)
  • Consequences of local surface load variations for volcanoes monitoring: Application to Katla subglacial volcano, Iceland
  • 2009
  • Ingår i: The VOLUME Project. VOLcanoes: Understanding subsurface mass moveMEnt. Edited by C.J. Bean, A.K. Braiden, I. Lokmer, F. Martini, G.S. O´Brien. - Dublin, Ireland. - 9781905254392 ; , s. 25-39
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
    • Surface load variations occur frequently in the vicinity of volcanoes inducing deformation and stress field perturbations that can be recorded by geophysical monitoring. It is thus necessary to discriminate these perturbations from those caused by shallow magma movement and to understand their potential influence on themagmatic plumbing system. Discrimination can be performed by modelling the deformation induced by surface load variations using integration of Green's function. This method was applied to the Katla volcano located beneath the Mýrdalsjökull ice cap, Iceland, where an annual cycle in ice load occurs as well as a gradual ice retreat. We also estimated pressure changes induced by the seasonal ice load variation within a magma reservoir, and calculated the deformation field and the Coulomb stress changes induced by the combined effect of the ice load variation and the magma pressure re-equilibration. Seismicity rate response to the seasonal perturbation strongly depends on the shape and state of the magma reservoir. Finally, introducing a rupture criterion, we conclude that, in the case of spherical or horizontally elongated reservoir and a slow magma inflow, eruptions at Katla volcano are more likely during the summer period, which is consistent with historical observations.
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9.
  • Slav, A., et al. (författare)
  • Influence of preparation conditions on structure and photosensing properties of GeSi/TiO2 multilayers
  • 2017
  • Ingår i: 2017 International Semiconductor Conference (CAS). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509039852 ; , s. 63-66
  • Konferensbidrag (refereegranskat)abstract
    • The photosensing properties related to the structure of GeSi/TiO2 multilayers prepared under different conditions are studied. TiO2 cap/(GeSi/TiO2)2 multilayers (ML) were deposited by magnetron sputtering (MS) and annealed by rapid thermal annealing. Trilayers of TiO2 cap/GeSi/TiO2 (TL) were also deposited using reactive high power impulse MS (HiPIMS) for TiO2 layers and dc MS for the GeSi layer. For TL samples a two-step annealing was employed, one before and the second after depositing TiO2 cap. Structure and morphology characterization (X-ray diffraction, scanning and transmission electron microscopy) was carried out and photocurrent measurements (voltage dependences, spectral curves) were performed. The annealed ML samples are formed of GeSi NCs with 5-10 nm sizes, while in the annealed TL samples, the GeSi NCs are larger (20-30 nm). These morphologies determine the multilayers photosensing properties in VIS-NIR of ML structures and in UV in TL ones, respectively.
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10.
  • Sturkell, Erik, 1962, et al. (författare)
  • Sveakratern 1919-Grimsvotn revisit 2019: The legacy of Erik Ygberg and Hakon Wadell
  • 2020
  • Ingår i: Jokull. - 0449-0576. ; 70, s. 129-138
  • Tidskriftsartikel (refereegranskat)abstract
    • The first recorded visit to Grimsvotn occurred on the 31st of August 1919. Two Swedish geology students, Hakon Wadell and Erik Ygberg, stood on the edge of a hitherto unknown large caldera. This discovery was the most significant finding in the first west-to-east transect across Vatnajokull, starting at SOujokull on the 27th of August. This was an expedition into the unknown, but a principal aim was nevertheless to find the source of the large jokulhlaups on Skeioararsandur. They named the ice-filled caldera "Sviagigur". Studies of written sources in the 1930s revealed that this place was indeed Grimsvotn, well known in the 17th and 18th centuries but the name and location had been forgotten in the 19th century. From Sviagigur they continued eastwards, descending down the crevassed Heinabergsjokull, reaching civilization in the morning the 6th. They announced the news that a huge volcano existed under Vatnajokull and this was the source of the jokulhlaups emerging from Skeioarcirjokull. Upon their return to Stockholm., they received a hero's welcome, but soon it all changed into no one believing them, as prominent figures in Sweden at this time insisted that a volcano can't be active beneath a glacier! After they finished their studies, both left Sweden very disappointed. Hakon Wadell had a successful geological career in America presenting a doctoral thesis in 1932 from the University of Chicago. Erik Ygberg worked as an international prospector a few years before his bad health, a result of the hardships experienced at the end of the Vatnajokull expedition, forced him back to Sweden, where he had a career at the Swedish Geological Survey. The name Sviagigur has not been used but the two nunataks marking the highest points on Grim:flail are named in the honour of the two Swedes, Sviahzikur eystri and Sviahnakur vestri.
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