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Sökning: WFRF:(Wedemeyer S.)

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  • Bruggmann, P., et al. (författare)
  • Historical epidemiology of hepatitis C virus (HCV) in selected countries
  • 2014
  • Ingår i: Journal of Viral Hepatitis. - Hoboken : Wiley-Blackwell. - 1352-0504 .- 1365-2893. ; 21, s. 5-33
  • Tidskriftsartikel (refereegranskat)abstract
    • Chronic infection with hepatitis C virus (HCV) is a leading indicator for liver disease. New treatment options are becoming available, and there is a need to characterize the epidemiology and disease burden of HCV. Data for prevalence, viremia, genotype, diagnosis and treatment were obtained through literature searches and expert consensus for 16 countries. For some countries, data from centralized registries were used to estimate diagnosis and treatment rates. Data for the number of liver transplants and the proportion attributable to HCV were obtained from centralized databases. Viremic prevalence estimates varied widely between countries, ranging from 0.3% in Austria, England and Germany to 8.5% in Egypt. The largest viremic populations were in Egypt, with 6358000 cases in 2008 and Brazil with 2106000 cases in 2007. The age distribution of cases differed between countries. In most countries, prevalence rates were higher among males, reflecting higher rates of injection drug use. Diagnosis, treatment and transplant levels also differed considerably between countries. Reliable estimates characterizing HCV-infected populations are critical for addressing HCV-related morbidity and mortality. There is a need to quantify the burden of chronic HCV infection at the national level.
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  • Razavi, H., et al. (författare)
  • The present and future disease burden of hepatitis C virus (HCV) infection with today's treatment paradigm
  • 2014
  • Ingår i: Journal of Viral Hepatitis. - Hoboken : Wiley-Blackwell. - 1352-0504 .- 1365-2893. ; 21:Suppl. 1, s. 34-59
  • Tidskriftsartikel (refereegranskat)abstract
    • The disease burden of hepatitis C virus (HCV) is expected to increase as the infected population ages. A modelling approach was used to estimate the total number of viremic infections, diagnosed, treated and new infections in 2013. In addition, the model was used to estimate the change in the total number of HCV infections, the disease progression and mortality in 2013-2030. Finally, expert panel consensus was used to capture current treatment practices in each country. Using today's treatment paradigm, the total number of HCV infections is projected to decline or remain flat in all countries studied. However, in the same time period, the number of individuals with late-stage liver disease is projected to increase. This study concluded that the current treatment rate and efficacy are not sufficient to manage the disease burden of HCV. Thus, alternative strategies are required to keep the number of HCV individuals with advanced liver disease and liver-related deaths from increasing.
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  • Wedemeyer, H., et al. (författare)
  • Strategies to manage hepatitis C virus (HCV) disease burden
  • 2014
  • Ingår i: Journal of Viral Hepatitis. - Hoboken : Wiley-Blackwell. - 1352-0504 .- 1365-2893. ; 21, s. 60-89
  • Tidskriftsartikel (refereegranskat)abstract
    • The number of hepatitis C virus (HCV) infections is projected to decline while those with advanced liver disease will increase. A modeling approach was used to forecast two treatment scenarios: (i) the impact of increased treatment efficacy while keeping the number of treated patients constant and (ii) increasing efficacy and treatment rate. This analysis suggests that successful diagnosis and treatment of a small proportion of patients can contribute significantly to the reduction of disease burden in the countries studied. The largest reduction in HCV-related morbidity and mortality occurs when increased treatment is combined with higher efficacy therapies, generally in combination with increased diagnosis. With a treatment rate of approximately 10%, this analysis suggests it is possible to achieve elimination of HCV (defined as a >90% decline in total infections by 2030). However, for most countries presented, this will require a 3-5 fold increase in diagnosis and/or treatment. Thus, building the public health and clinical provider capacity for improved diagnosis and treatment will be critical.
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  • Wedemeyer, S., et al. (författare)
  • Solar Science with the Atacama Large Millimeter/Submillimeter Array-A New View of Our Sun
  • 2016
  • Ingår i: Space Science Reviews. - : Springer Science and Business Media LLC. - 0038-6308 .- 1572-9672. ; 200:1-4, s. 1-73
  • Forskningsöversikt (refereegranskat)abstract
    • The Atacama Large Millimeter/submillimeter Array (ALMA) is a new powerful tool for observing the Sun at high spatial, temporal, and spectral resolution. These capabilities can address a broad range of fundamental scientific questions in solar physics. The radiation observed by ALMA originates mostly from the chromosphere-a complex and dynamic region between the photosphere and corona, which plays a crucial role in the transport of energy and matter and, ultimately, the heating of the outer layers of the solar atmosphere. Based on first solar test observations, strategies for regular solar campaigns are currently being developed. State-of-the-art numerical simulations of the solar atmosphere and modeling of instrumental effects can help constrain and optimize future observing modes for ALMA. Here we present a short technical description of ALMA and an overview of past efforts and future possibilities for solar observations at submillimeter and millimeter wavelengths. In addition, selected numerical simulations and observations at other wavelengths demonstrate ALMA's scientific potential for studying the Sun for a large range of science cases.
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  • Kamal, H., et al. (författare)
  • Long-Term Study of Hepatitis Delta Virus Infection at Secondary Care Centers: The Impact of Viremia on Liver-Related Outcomes
  • 2020
  • Ingår i: Hepatology. - : Ovid Technologies (Wolters Kluwer Health). - 0270-9139 .- 1527-3350. ; 72:4, s. 1177-1190
  • Tidskriftsartikel (refereegranskat)abstract
    • Background and Aims Hepatitis delta virus (HDV) infection is associated with fast progression to liver cirrhosis and liver complications. Previous studies have, however, been mainly from tertiary care centers, with risk for referral bias toward patients with worse outcomes. Furthermore, the impact of HDV viremiaper seon liver-related outcomes is not really known outside the human immunodeficiency virus co-infection setting. We have therefore evaluated the long-term impact of HDV viremia on liver-related outcomes in a nationwide cohort of patients with hepatitis B and D co-infection, cared for at secondary care centers in Sweden. Approach and Results In total, 337 patients with anti-HDV positivity, including 233 patients with HDV RNA viremia and 91 without HDV viremia at baseline, were retrospectively studied, with a mean follow-up of 6.5 years (range, 0.5-33.1). The long-term risks for liver-related events (i.e., hepatocellular carcinoma [HCC], hepatic decompensation, or liver-related death/transplantation) were assessed, using Cox regression analysis. The risk for liver-related events and HCC was 3.8-fold and 2.6-fold higher, respectively, in patients with HDV viremia compared with those without viremia, although the latter was not statistically significant. Among patients with HDV viremia with no baseline cirrhosis, the cumulative risk of being free of liver cirrhosis or liver-related events was 81.9% and 64.0% after 5 and 10 years of follow-up, respectively. This corresponds to an incidence rate of 0.04 cases per person-year. Conclusions HDV RNA viremia is associated with a 3.8-fold higher risk for liver-related outcomes. The prognosis was rather poor for patients with HDV viremia without cirrhosis at baseline, but it was nevertheless more benign than previous estimates from tertiary centers. Our findings may be of importance when making decisions about treatment and evaluating potential outcomes of upcoming antivirals against HDV.
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  • Wedemeyer, S., et al. (författare)
  • SSALMON - The Solar Simulations for the Atacama Large Millimeter Observatory Network
  • 2015
  • Ingår i: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 56:12, s. 2679-2692
  • Tidskriftsartikel (refereegranskat)abstract
    • The Solar Simulations for the Atacama Large Millimeter Observatory Network (SSALMON) was initiated in 2014 in connection with two ALMA development studies. The Atacama Large Millimeter/submillimeter Array (ALMA) is a powerful new tool, which can also observe the Sun at high spatial, temporal, and spectral resolution. The international SSALMONetwork aims at co-ordinating the further development of solar observing modes for ALMA and at promoting scientific opportunities for solar physics with particular focus on numerical simulations, which can provide important constraints for the observing modes and can aid the interpretation of future observations. The radiation detected by ALMA originates mostly in the solar chromosphere - a complex and dynamic layer between the photosphere and corona, which plays an important role in the transport of energy and matter and the heating of the outer layers of the solar atmosphere. Potential targets include active regions, prominences, quiet Sun regions, flares. Here, we give a brief overview over the network and potential science cases for future solar observations with ALMA.
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  • Chintzoglou, Georgios, et al. (författare)
  • ALMA and IRIS Observations of the Solar Chromosphere. I. An On-disk Type II Spicule
  • 2021
  • Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 906:2
  • Tidskriftsartikel (refereegranskat)abstract
    • We present observations of the solar chromosphere obtained simultaneously with the Atacama Large Millimeter/submillimeter Array (ALMA) and the Interface Region Imaging Spectrograph. The observatories targeted a chromospheric plage region of which the spatial distribution (split between strongly and weakly magnetized regions) allowed the study of linear-like structures in isolation, free of contamination from background emission. Using these observations in conjunction with a radiative magnetohydrodynamic 2.5D model covering the upper convection zone all the way to the corona that considers nonequilibrium ionization effects, we report the detection of an on-disk chromospheric spicule with ALMA and confirm its multithermal nature.
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  • Chintzoglou, Georgios, et al. (författare)
  • ALMA and IRIS Observations of the Solar Chromosphere. II. Structure and Dynamics of Chromospheric Plages
  • 2021
  • Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 906:2
  • Tidskriftsartikel (refereegranskat)abstract
    • We propose and employ a novel empirical method for determining chromospheric plage regions, which seems to better isolate a plage from its surrounding regions than other methods commonly used. We caution that isolating a plage from its immediate surroundings must be done with care in order to successfully mitigate statistical biases that, for instance, can impact quantitative comparisons between different chromospheric observables. Using this methodology, our analysis suggests that lambda = 1.25 mm free-free emission in plage regions observed with the Atacama Large Millimeter/submillimeter Array (ALMA)/Band6 may not form in the low chromosphere as previously thought, but rather in the upper chromospheric parts of dynamic plage features (such as spicules and other bright structures), i.e., near geometric heights of transition-region temperatures. We investigate the high degree of similarity between chromospheric plage features observed in ALMA/Band6 (at 1.25 mm wavelengths) and the Interface Region Imaging Spectrograph (IRIS)/Si iv at 1393 angstrom. We also show that IRIS/Mg ii h and k are not as well correlated with ALMA/Band6 as was previously thought, and we discuss discrepancies with previous works. Lastly, we report indications of chromospheric heating due to propagating shocks supported by the ALMA/Band6 observations.
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  • da Silva Santos, Joäo Manuel, et al. (författare)
  • The multi-thermal chromosphere Inversions of ALMA and IRIS data
  • 2020
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 634
  • Tidskriftsartikel (refereegranskat)abstract
    • Context. Numerical simulations of the solar chromosphere predict a diverse thermal structure with both hot and cool regions. Observations of plage regions in particular typically feature broader and brighter chromospheric lines, which suggests that they are formed in hotter and denser conditions than in the quiet Sun, but also implies a nonthermal component whose source is unclear. Aims. We revisit the problem of the stratification of temperature and microturbulence in plage and the quiet Sun, now adding millimeter (mm) continuum observations provided by the Atacama Large Millimiter Array (ALMA) to inversions of near-ultraviolet Interface Region Imaging Spectrograph (IRIS) spectra as a powerful new diagnostic to disentangle the two parameters. We fit cool chromospheric holes and track the fast evolution of compact mm brightenings in the plage region. Methods. We use the STiC nonlocal thermodynamic equilibrium (NLTE) inversion code to simultaneously fit real ultraviolet and mm spectra in order to infer the thermodynamic parameters of the plasma. Results. We confirm the anticipated constraining potential of ALMA in NLTE inversions of the solar chromosphere. We find significant differences between the inversion results of IRIS data alone compared to the results of a combination with the mm data: the IRIS+ALMA inversions have increased contrast and temperature range, and tend to favor lower values of microturbulence (similar to 3-6 km s(-1) in plage compared to similar to 4-7 km s(-1) from IRIS alone) in the chromosphere. The average brightness temperature of the plage region at 1.25 mm is 8500 K, but the ALMA maps also show much cooler (similar to 3000 K) and hotter (similar to 11000 K) evolving features partially seen in other diagnostics. To explain the former, the inversions require the existence of localized low-temperature regions in the chromosphere where molecules such as CO could form. The hot features could sustain such high temperatures due to non-equilibrium hydrogen ionization effects in a shocked chromosphere - a scenario that is supported by low-frequency shock wave patterns found in the MgII lines probed by IRIS.
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  • Duberg, Ann-Sofi, Docent, 1957-, et al. (författare)
  • The incidence of hepatocellular carcinoma in hepatitis B virus infected persons of different origins, living in Sweden
  • 2018
  • Ingår i: Journal of Hepatology. - : Elsevier. - 0168-8278 .- 1600-0641. ; 68:Suppl. 1, s. S488-S488
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Background and Aims: Chronic hepatitis B (CHB) is associated with an increased risk of hepatocellular carcinoma (HCC) in both cirrhotic and non-cirrhotic persons. CHB patients with high risk for HCC are therefore recommended to undergo surveillance for HCC, with an estimated cut-off for surveillance in non-cirrhotic patients at incidence rate (IR) of 0.2% per year. People originating from Asia and men from Africa are estimated to have particularly high risks, but the IR for HCC when living in the Western world has not been fully estimated. Therefore, our aim was to study the incidence of HCC by age and origin in persons with CHB who are living in Sweden.Method: In this national population-based study all persons diagnosed with CHB in Sweden during 1990–2015, their country of birth, co-infections, antiviral therapy, liver cancer or death/emigration were identified retrospectively, using the national HBV-surveil-lance register and other national registers. Those co-infected with hepatitis C were excluded. Observation time started at date of reported CHB diagnosis. The IR was calculated for different age groups and by region of birth.Results: In total 16,410 persons (47% women) with CHB were studied. The number of persons and observation time (person-years) by origin were: Western Europe 2,316 (25,415); Eastern Europe 2,349 (26,237); Middle East/North Africa 4,402 (47,320); Sub-Saharan Africa 3,677 (30,565), Asia 3,537 (35,358) and other 129 (1,277). Those from Sub-Saharan Africa were youngest and had the shortest mean time in Sweden, 11.6 years. There were in total 232 diagnosed HCCs (82% in men); 23, 54 and 58 in people from Sub-Saharan Africa ,Asia and Middle East/North Africa, respectively. The corresponding mean ages at HCC diagnoses were 45, 51 and 59 years, respectively. The IRexceeded 0.2% for men from Asia from age-group≥40–49 years (IR 0.63, 95%CI 0.39–1.00), and for men of all other origins from age-group≥50–59 years. Among African men aged <40 yearstherewere 7 HCC, with incidence rate 0.05 and 0.11 in age groups 20–29 and 30–39 years, respectively. In women, HCC was rare but exceeded 0.2% among those aged≥60 years with origins from East Europe, Asia and Middle East/North Africa.Conclusion: In this study only men of Asian origin exceeded the cut-off for HCC surveillance by ages 40–49 years. African men had a few HCCs at youngerages, but did not exceed the cut-off before age 50–59 years. This study confirms the high risk for HCC in especially Asian men living in the Western world, but questions the benefit of surveillance at younger ages for men with African origin who live in a Northern European country
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