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| 2. |
- Rettig, L., et al.
(författare)
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Disentangling transient charge order from structural dynamics contributions during coherent atomic motion studied by ultrafast resonant x-ray diffraction
- 2019
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Ingår i: Physical Review B. - 2469-9950. ; 99:13
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Tidskriftsartikel (refereegranskat)abstract
- We report on the ultrafast dynamics of charge order and structural response during the photoinduced suppression of charge and orbital order in a mixed-valence manganite. Employing femtosecond time-resolved resonant x-ray diffraction below and at the Mn K absorption edge, we present a method to disentangle the transient charge order and structural dynamics in thin films of Pr0.5Ca0.5MnO3. Based on the static resonant scattering spectra, we extract the dispersion correction of charge-ordered Mn3+ and Mn4+ ions, allowing us to separate the transient contributions of purely charge order from structural contributions to the scattering amplitude after optical excitation. Our finding of a coherent structural mode at around 2.3THz, which primarily modulates the lattice but does not strongly affect the charge order, supports the picture of the charge order being the driving force of the combined charge, orbital, and structural transition.
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| 3. |
- Mariager, S. O., et al.
(författare)
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Structural and magnetic dynamics in the magnetic shape-memory alloy Ni2MnGa
- 2014
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 90:16
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic shape-memory Heusler alloys are multiferroics stabilized by the correlations between electronic, magnetic, and structural order. To study these correlations we use time-resolved x-ray diffraction and magneto-optical Kerr effect experiments to measure the laser induced dynamics in a Heusler alloy Ni2MnGa film and reveal a set of time scales intrinsic to the system. We observe a coherent phonon which we identify as the amplitudon of the modulated structure and an ultrafast phase transition leading to a quenching of the incommensurate modulation within 300 fs with a recovery time of a few ps. The thermally driven martensitic transition to the high temperature cubic phase proceeds via nucleation within a few ps and domain growth limited by the speed of sound. The demagnetization time is 320 fs, which is comparable to the quenching of the structural modulation.
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| 4. |
- Carsin, Anne-Elie, et al.
(författare)
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Physical activity and incidence of restrictive spirometry pattern in adults
- 2018
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Ingår i: European Respiratory Journal. - : European Respiratory Society. - 0903-1936 .- 1399-3003. ; 52
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: A restrictive spirometry pattern is associated with high morbidity and mortality. Whether regular physical activity (PA) protects against this pattern has never been studied.Objective: To assess if PA is associated with the development of restrictive pattern.Methods: Lung function and PA were assessed in the second and third follow-up of the ECRHS (n=2757, 39-67 years) and SAPALDIA (n=2610, 36-82 y) cohorts. Subjects with restrictive or obstructive pattern at baseline were excluded. We assessed the association of being active at baseline (defined as exercising vigorously >2-3 times/wk for >1 h) and restrictive pattern at follow-up (defined as a post-bronchodilator FEV1/FVC≥LLN and FVC<80% pred.) using modified Poisson regression, adjusting for age, sex, smoking and asthma. We explored the impact of adjusting for baseline FVC. Additionally, models were repeated stratified by BMI.Results: After 10 years follow-up, 3.7% and 2.8% of participants developed a restrictive pattern, in ECRHS and SAPALDIA respectively. In both cohorts, being physically active was associated with lower risk of a restrictive pattern (meta-analysed RR 0.65, 95% CI 0.47-0.89). This association was stronger in overweight (0.41, 0.23-0.75) and obese (0.42, 0.17-1.05) than in normal weight subjects, but was attenuated when adjusting for baseline FVC (0.77, 0.58-1.04).Conclusion: In two large European studies, adults who reported more PA were at lower risk of developing a restrictive spirometry pattern. Lung function at baseline seemed to explain part of the observed association, stressing the need of adequate method to take into account both horse-racing and regression-to-the-means effects.
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| 5. |
- Carsin, A. E., et al.
(författare)
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Spirometric patterns in young and middle-aged adults: a 20-year European study
- 2024
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Ingår i: Thorax. - : BMJ Publishing Group Ltd. - 0040-6376 .- 1468-3296. ; 79:2, s. 153-162
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Tidskriftsartikel (refereegranskat)abstract
- Background Understanding the natural history of abnormal spirometric patterns at different stages of life is critical to identify and optimise preventive strategies. We aimed to describe characteristics and risk factors of restrictive and obstructive spirometric patterns occurring before 40 years (young onset) and between 40 and 61 years (mid-adult onset). Methods We used data from the population- based cohort of the European Community Respiratory Health Survey (ECRHS). Prebronchodilator forced expiratory volume in one second (FEV 1) and forced vital capacity (FVC) were assessed longitudinally at baseline (ECRHS1, 1993-1994) and again 20 years later ( ECRHS3, 2010-2013). Spirometry patterns were defined as: restrictive if FEV1/ FVC >= LLN and FVC<10th percentile, obstructive if FEV1/FVC
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| 6. |
- Harb, Maher, et al.
(författare)
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Picosecond dynamics of laser-induced strain in graphite
- 2011
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 84:4
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Tidskriftsartikel (refereegranskat)abstract
- We report on the use of grazing-incidence time-resolved x-ray diffraction to investigate the evolution of strain in natural graphite excited by femtosecond-laser pulses in the fluence range of 6-35 mJ/cm(2). Strains corresponding to up to similar to 2.8% c-axis expansion were observed. We show that the experimental data is in good agreement with calculations based on the Thomsen strain model in conjunction with dynamical diffraction theory. Furthermore we find no evidence of nonthermal lattice expansion as reported in recent ultrafast electron-diffraction studies of laser-excited graphite conducted under comparable excitation conditions.
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