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| 2. |
- Faatz, B., et al.
(författare)
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Simultaneous operation of two soft x-ray free-electron lasers driven by one linear accelerator
- 2016
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Extreme-ultraviolet to x-ray free-electron lasers (FELs) in operation for scientific applications are up to now single-user facilities. While most FELs generate around 100 photon pulses per second, FLASH at DESY can deliver almost two orders of magnitude more pulses in this time span due to its superconducting accelerator technology. This makes the facility a prime candidate to realize the next step in FELs-dividing the electron pulse trains into several FEL lines and delivering photon pulses to several users at the same time. Hence, FLASH has been extended with a second undulator line and self-amplified spontaneous emission (SASE) is demonstrated in both FELs simultaneously. FLASH can now deliver MHz pulse trains to two user experiments in parallel with individually selected photon beam characteristics. First results of the capabilities of this extension are shown with emphasis on independent variation of wavelength, repetition rate, and photon pulse length.
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| 3. |
- Aoyama, T., et al.
(författare)
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The anomalous magnetic moment of the muon in the Standard Model
- 2020
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Ingår i: Physics reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 887, s. 1-166
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Forskningsöversikt (refereegranskat)abstract
- We review the present status of the Standard Model calculation of the anomalous magnetic moment of the muon. This is performed in a perturbative expansion in the fine-structure constant α and is broken down into pure QED, electroweak, and hadronic contributions. The pure QED contribution is by far the largest and has been evaluated up to and including O(α5) with negligible numerical uncertainty. The electroweak contribution is suppressed by (mμ/MW)2 and only shows up at the level of the seventh significant digit. It has been evaluated up to two loops and is known to better than one percent. Hadronic contributions are the most difficult to calculate and are responsible for almost all of the theoretical uncertainty. The leading hadronic contribution appears at O(α2) and is due to hadronic vacuum polarization, whereas at O(α3) the hadronic light-by-light scattering contribution appears. Given the low characteristic scale of this observable, these contributions have to be calculated with nonperturbative methods, in particular, dispersion relations and the lattice approach to QCD. The largest part of this review is dedicated to a detailed account of recent efforts to improve the calculation of these two contributions with either a data-driven, dispersive approach, or a first-principle, lattice-QCD approach. The final result reads aμSM = 116 591 810(43) x 10-11 and is smaller than the Brookhaven measurement by 3.7 σ. The experimental uncertainty will soon be reduced by up to a factor four by the new experiment currently running at Fermilab, and also by the future J-PARC experiment. This and the prospects to further reduce the theoretical uncertainty in the near future - which are also discussed here - make this quantity one of the most promising places to look for evidence of new physics.
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| 5. |
- Dubernet, M. L., et al.
(författare)
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The virtual atomic and molecular data centre (VAMDC) consortium
- 2016
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 49:7
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Tidskriftsartikel (refereegranskat)abstract
- The Virtual Atomic and Molecular Data Centre (VAMDC) Consortium is a worldwide consortium which federates atomic and molecular databases through an e-science infrastructure and an organisation to support this activity. About 90% of the inter-connected databases handle data that are used for the interpretation of astronomical spectra and for modelling in many fields of astrophysics. Recently the VAMDC Consortium has connected databases from the radiation damage and the plasma communities, as well as promoting the publication of data from Indian institutes. This paper describes how the VAMDC Consortium is organised for the optimal distribution of atomic and molecular data for scientific research. It is noted that the VAMDC Consortium strongly advocates that authors of research papers using data cite the original experimental and theoretical papers as well as the relevant databases.
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| 6. |
- Tomić, I., et al.
(författare)
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Shake-table testing of a stone masonry building aggregate : overview of blind prediction study
- 2023
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Ingår i: Bulletin of Earthquake Engineering. - : Springer Science and Business Media LLC. - 1570-761X .- 1573-1456.
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Tidskriftsartikel (refereegranskat)abstract
- City centres of Europe are often composed of unreinforced masonry structural aggregates, whose seismic response is challenging to predict. To advance the state of the art on the seismic response of these aggregates, the Adjacent Interacting Masonry Structures (AIMS) subproject from Horizon 2020 project Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe (SERA) provides shake-table test data of a two-unit, double-leaf stone masonry aggregate subjected to two horizontal components of dynamic excitation. A blind prediction was organized with participants from academia and industry to test modelling approaches and assumptions and to learn about the extent of uncertainty in modelling for such masonry aggregates. The participants were provided with the full set of material and geometrical data, construction details and original seismic input and asked to predict prior to the test the expected seismic response in terms of damage mechanisms, base-shear forces, and roof displacements. The modelling approaches used differ significantly in the level of detail and the modelling assumptions. This paper provides an overview of the adopted modelling approaches and their subsequent predictions. It further discusses the range of assumptions made when modelling masonry walls, floors and connections, and aims at discovering how the common solutions regarding modelling masonry in general, and masonry aggregates in particular, affect the results. The results are evaluated both in terms of damage mechanisms, base shear forces, displacements and interface openings in both directions, and then compared with the experimental results. The modelling approaches featuring Discrete Element Method (DEM) led to the best predictions in terms of displacements, while a submission using rigid block limit analysis led to the best prediction in terms of damage mechanisms. Large coefficients of variation of predicted displacements and general underestimation of displacements in comparison with experimental results, except for DEM models, highlight the need for further consensus building on suitable modelling assumptions for such masonry aggregates.
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| 7. |
- Albert, Damien, et al.
(författare)
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A Decade with VAMDC : Results and Ambitions
- 2020
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 8:4
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an overview of the current status of the Virtual Atomic and Molecular Data Centre (VAMDC) e-infrastructure, including the current status of the VAMDC-connected (or to be connected) databases, updates on the latest technological development within the infrastructure and a presentation of some application tools that make use of the VAMDC e-infrastructure. We analyse the past 10 years of VAMDC development and operation, and assess their impact both on the field of atomic and molecular (A&M) physics itself and on heterogeneous data management in international cooperation. The highly sophisticated VAMDC infrastructure and the related databases developed over this long term make them a perfect resource of sustainable data for future applications in many fields of research. However, we also discuss the current limitations that prevent VAMDC from becoming the main publishing platform and the main source of A&M data for user communities, and present possible solutions under investigation by the consortium. Several user application examples are presented, illustrating the benefits of VAMDC in current research applications, which often need the A&M data from more than one database. Finally, we present our vision for the future of VAMDC.
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| 8. |
- Broman, J., et al.
(författare)
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Association of post-stroke-initiated antidepressants with long-term outcomes in young adults with ischaemic stroke
- 2022
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Ingår i: Annals of Medicine. - : Informa UK Limited. - 0785-3890 .- 1365-2060. ; 54:1, s. 1757-1766
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Tidskriftsartikel (refereegranskat)abstract
- Objective We examined the association between initiation of antidepressants within the first year after ischaemic stroke (IS) in young adults and long-term fatal and non-fatal cardiovascular events, as well as all-cause mortality. Patients and methods The Helsinki Young Stroke Registry (HYSR) includes patients aged 15-49 years with their first-ever IS occurring 1994-2007. From nationwide registers, we obtained data on prescriptions (1993-2011) and outcomes of interest (1994-2011). Time of initiating post-stroke antidepressants (PSADs) was defined as time of the first filled prescription for antidepressants within the first year from IS. To account for non-random assignment of PSADs, we performed propensity score matching and studied the relationship between PSAD initiation and outcomes using Cox regression models with time-varying coefficients. Results Of all patients (n = 888), 206 (23.2%) initiated PSADs within the first year, of which 203 (98.5%) could be matched to 406 non-initiators. In this matched sample of 609 patients, the median follow-up time was 8.1 (interquartile range [IQR] 5.0-12.6) years and 169 (28.9%) patients had any cardiovascular events, 95 (15.8%) had recurrent ischaemic or haemorrhagic strokes and 106 (17.4%) died. Adjusted for sociodemographics and cardiovascular comorbidities, PSAD initiation was associated with recurrent ischaemic or haemorrhagic stroke 5-10 years after IS (hazard ratio [HR] 3.07, 95% confidence interval [CI] 1.32-7.12). No association emerged between PSAD initiation and other outcomes. Conclusions In young adults, PSAD initiation within the first year after IS was associated with a heightened hazard of recurrent ischaemic or haemorrhagic stroke in the long term. Future studies are needed to verify the results and to further study the nature of this finding. KEY MESSAGES Initiation of post-stroke antidepressants (PSADs) within the first year after ischaemic stroke (IS) was associated with a heightened hazard of recurrent ischaemic or haemorrhagic stroke in the long term. Patients starting antidepressants after IS should be followed up more closely in case of recurrent events. Future studies are needed to verify the results and to further study the nature of this finding.
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| 9. |
- Broman, J., et al.
(författare)
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Initiation of antidepressants in young adults after ischemic stroke: a registry-based follow-up study
- 2022
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Ingår i: Journal of Neurology. - : Springer Science and Business Media LLC. - 0340-5354 .- 1432-1459. ; 269, s. 956-965
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Data on post-stroke use of antidepressants in young individuals are scarce. We examined pattern and factors associated with initiating post-stroke antidepressants (PSAD) after ischemic stroke (IS) in young adults. Methods: Helsinki Young Stroke Registry includes patients aged 15–49years with first-ever IS, 1994–2007. Data on prescriptions, hospitalizations and death came from nationwide registers. We defined time of initiating PSAD as time of the first filled prescription for antidepressants within 1year from IS. We assessed factors associated with initiating PSAD with multivariable Cox regression models, allowing for time-varying effects when appropriate. Results: We followed 888 patients, of which 206 (23.2%) initiated PSAD. Higher hazard of starting PSAD within the first 100days appeared among patients with mild versus no limb paresis 2.53 (95% confidence interval 1.48–4.31) and during later follow-up among those with silent infarcts (2.04; 1.27–3.28), prior use of antidepressants (2.09; 1.26–3.46) and moderate versus mild stroke (2.06; 1.18–3.58). The relative difference in the hazard rate for moderate–severe limb paresis persisted both within the first 100days (3.84, 2.12–6.97) and during later follow-up (4.54; 2.51–8.23). The hazard rate was higher throughout the follow-up among smokers (1.48; 1.11–1.97) as well as lower (1.78; 1.25–2.54) and upper white-collar workers (2.00; 1.24–3.23) compared to blue-collar workers. Conclusion: One-fourth of young adults started PSADs within 1year from IS. We identified several specific clinical characteristics associated with PSAD initiation, highlighting their utility in assessing the risk of post-stroke depression during follow-up. © 2021, The Author(s).
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| 10. |
- Lagerstedt, J. O., et al.
(författare)
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Anti-ApoA-I IgG antibodies are not associated with carotid artery disease progression and first-time cardiovascular events in middle-aged individuals
- 2019
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820. ; 285:1, s. 49-58
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Tidskriftsartikel (refereegranskat)abstract
- Objective: IgG antibodies against apolipoprotein A-I (ApoA-I) have been found to be elevated in subjects from the general population with clinically manifest cardiovascular disease and in myocardial infarction patients with an adverse prognosis. Here, we investigated whether these antibodies are prospectively associated with carotid artery disease progression and with the risk for first-time cardiovascular events in individuals with no previous history of cardiovascular disease. Approach and results: We selected 383 subjects from the cardiovascular cohort of Malmö Diet and Cancer study who suffered a coronary event during a median follow-up period of 15.4 (10.3–16.4) years and 395 age- and sex-matched controls. None of the study participants had a previous history of coronary artery disease or stroke. Anti-ApoA-I IgG were measured by ELISA in serum samples collected at baseline. Intima-media thickness (IMT) was measured in the common carotid artery and in the carotid bifurcation at baseline and after 15.9 (±1.5) years. We found no associations between anti-ApoA-I IgG and carotid artery IMT at baseline or with IMT progression during follow-up. In Cox proportional hazards analyses adjusted for traditional cardiovascular risk factors, the hazard ratio (HR 95%CI) for the primary outcome, incident coronary events, was 0.97 (0.75–1.25), P = 0.782, in subjects with anti-ApoA-I IgG within the highest tertile compared with the lowest tertile. Similarly, we did not find any associations with the secondary outcome, incident first-time stroke. Conclusions: Serum autoantibodies against ApoA-I do not correlate with disease progression and adverse events in cardiovascular disease-free individuals from the general population.
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