| 1. |
- Viñas Boström, Florinda, et al.
(författare)
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Magnon-mediated topological superconductivity in a quantum wire
- 2024
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Ingår i: Physical Review Research. - 2643-1564. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- Many emergent phases of matter stem from the intertwined dynamics of quasiparticles. Here we show that a topological superconducting phase emerges as the result of interactions between electrons and magnons in a quantum wire and a helical magnet. The magnon-mediated interaction favors triplet superconductivity over a large magnetic phase space region, and stabilizes topological superconductivity over an extended region of chemical potentials. The superconducting gap depends exponentially on the spin-electron coupling, allowing it to be enhanced through material engineering techniques.
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| 2. |
- Östberg, Emil, et al.
(författare)
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Microscopic theory of current-induced skyrmion transport and its application in disordered spin textures
- 2023
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Ingår i: Frontiers in Physics. - 2296-424X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Magnetic skyrmions hold great promise for realizing compact and stable memory devices that can be manipulated at very low energy costs via electronic current densities. Methods: In this work, we extend a recently introduced method to describe classical skyrmion textures coupled to dynamical itinerant electrons. In this scheme, the electron dynamics is described via nonequilibrium Green’s function (NEGF) within the generalized Kadanoff–Baym ansatz, and the classical spins are treated via the Landau–Lifshitz–Gilbert equation. Here, the framework is extended to open systems by the introduction of a non-interacting approximation to the collision integral of NEGFs. This, in turn, allows us to perform computations of the real-time response of skyrmions to electronic currents in large quantum systems coupled to electronic reservoirs, which exhibit linear scaling in the number of time steps. We use this approach to investigate how electronic spin currents and dilute spin disorder affect skyrmion transport and the skyrmion Hall drift. Results: Our results show that the skyrmion dynamics is sensitive to a specific form of the spin disorder, such that different disorder configurations lead to qualitatively different skyrmion trajectories for the same applied bias. Discussion: This sensitivity arises from the local spin dynamics around the magnetic impurities, a feature that is expected not to be well-captured by phenomenological or spin-only descriptions. At the same time, our findings illustrate the potential of engineering microscopic impurity patterns to steer skyrmion trajectories.
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| 3. |
- Andersson, Tobias, 1976, et al.
(författare)
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The effect of statins on mortality and cardiovascular disease in primary care hypertensive patients without other cardiovascular disease or diabetes.
- 2023
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Ingår i: European journal of preventive cardiology. - 2047-4881. ; 30:17, s. 1883-1894
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Tidskriftsartikel (refereegranskat)abstract
- Studies in primary health care (PHC) assessing the effect of primary prevention with statins on mortality and cardiovascular disease (CVD) are scarce. This study aimed to estimate the effect of statins on all-cause mortality, cardiovascular mortality, myocardial infarction (MI) and stroke in individuals in PHC with hypertension without CVD or diabetes.Using the Swedish PHC quality assurance register QregPV, the study included 13 193 individuals with hypertension without CVD or diabetes, who had filled a first statin prescription between 2010 and 2016, and 13 193 matched controls without a filled statin prescription at index date. Controls were matched on sex and propensity score using clinical data and data from national registers on co-morbidities, prescriptions, and socioeconomic status. The effect of statins was estimated in Cox regression models.During a median of 4.2 years of follow-up, 395 individuals in the statin group versus 475 in the control group died, 197 versus 232 died of cardiovascular disease, 171 versus 191 had a MI, and 161 versus 181 had a stroke. The treatment effect of statins was significant for all-cause mortality (HR 0.83, 95% confidence interval [CI] 0.74-0.93) and cardiovascular mortality (HR 0.85, 95% CI 0.72-0.998). Overall, no significant treatment effect of statins was seen for MI (HR 0.89, 95% CI 0.74-1.07), but there was a significant interaction with sex (p=0.008) with decreased risk of MI for women but not for men (HR 0.66, 95% CI 0.49-0.88 versus HR 1.09, 95% CI 0.86-1.38).Primary prevention with statins in PHC was associated with reduced risk of all-cause mortality, cardiovascular mortality, and in women, lower risk of MI.
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| 4. |
- Bager, Johan-Emil, et al.
(författare)
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Blood pressure levels and risk of haemorrhagic stroke in patients with atrial fibrillation and oral anticoagulants: results from The Swedish Primary Care Cardiovascular Database of Skaraborg.
- 2021
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Ingår i: Journal of hypertension. - 1473-5598. ; 39:8, s. 1670-1677
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Tidskriftsartikel (refereegranskat)abstract
- To assess the risk of haemorrhagic stroke at different baseline SBP levels in a primary care population with hypertension, atrial fibrillation and newly initiated oral anticoagulants (OACs).We identified 3972 patients with hypertension, atrial fibrillation and newly initiated OAC in The Swedish Primary Care Cardiovascular Database of Skaraborg. Patients were followed from 1 January 2006 until a first event of haemorrhagic stroke, death, cessation of OAC or 31 December 2016. We analysed the association between continuous SBP and haemorrhagic stroke with a multivariable Cox regression model and plotted the hazard ratio as a function of SBP with a restricted cubic spline with 130mmHg as reference.There were 40 cases of haemorrhagic stroke during follow-up. Baseline SBP in the 145-180mmHg range was associated with a more than doubled risk of haemorrhagic stroke, compared with a SBP of 130mmHg.In this cohort of primary care patients with hypertension and atrial fibrillation, we found that baseline SBP in the 145-180mmHg range, prior to initiation of OAC, was associated with a more than doubled risk of haemorrhagic stroke, as compared with an SBP of 130mmHg. This suggests that lowering SBP to below 145mmHg, prior to initiation of OAC, may decrease the risk of haemorrhagic stroke in patients with hypertension and atrial fibrillation.
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| 5. |
- Bager, Johan-Emil, et al.
(författare)
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Hypertension: sex-related differences in drug treatment, prevalence and blood pressure control in primary care.
- 2023
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Ingår i: Journal of human hypertension. - : Springer Science and Business Media LLC. - 1476-5527. ; 37, s. 662-670
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Forskningsöversikt (refereegranskat)abstract
- Antihypertensive treatment is equally beneficial for reducing cardiovascular risk in both men and women. Despite this, the drug treatment, prevalence and control of hypertension differ between men and women. Men and women respond differently, particularly with respect to the risk of adverse events, to many antihypertensive drugs. Certain antihypertensive drugs may also be especially beneficial in the setting of certain comorbidities - of both cardiovascular and extracardiac nature - which also differ between men and women. Furthermore, hypertension in pregnancy can pose a considerable therapeutic challenge for women and their physicians in primary care. In addition, data from population-based studies and from real-world data are inconsistent regarding whether men or women attain hypertension-related goals to a higher degree. In population-based studies, women with hypertension have higher rates of treatment and controlled blood pressure than men, whereas real-world, primary-care data instead show better blood pressure control in men. Men and women are also treated with different antihypertensive drugs: women use more thiazide diuretics and men use more angiotensin-enzyme inhibitors and calcium-channel blockers. This narrative review explores these sex-related differences with guidance from current literature. It also features original data from a large, Swedish primary-care register, which showed that blood pressure control was better in women than men until they reached their late sixties, after which the situation was reversed. This age-related decrease in blood pressure control in women was not, however, accompanied by a proportional increase in use of antihypertensive drugs and female sex was a significant predictor of less intensive antihypertensive treatment.
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| 6. |
- Bijnens, Johan, et al.
(författare)
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Two-loop sunset integrals at finite volume
- 2014
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :1
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Tidskriftsartikel (refereegranskat)abstract
- We show how to compute the two-loop sunset integrals at finite volume, for non-degenerate masses and non-zero momentum. We present results for all integrals that appear in the Chiral Perturbation Theory (chi PT) calculation of the pseudoscalar meson masses and decay constants at next-to-next-to-leading order, including the case of Partially Quenched chi PT. We also provide numerical implementations of the finite-volume sunset integrals, and review the results for one-loop integrals at finite volume.
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| 7. |
- Boström, Emil, et al.
(författare)
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Time-resolved spectroscopy at surfaces and adsorbate dynamics : Insights from a model-system approach
- 2016
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 93:19
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a model description of femtosecond laser induced desorption at surfaces. The substrate part of the system is taken into account as a (possibly semi-infinite) linear chain. Here, being especially interested in the early stages of dissociation, we consider a finite-size implementation of the model (i.e., a finite substrate), for which an exact numerical solution is possible. By time-evolving the many-body wave function, and also using results from a time-dependent density functional theory description for electron-nuclear systems, we analyze the competition between several surface-response mechanisms and electronic correlations in the transient and longer time dynamics under the influence of dipole-coupled fields. Our model allows us to explore how coherent multiple-pulse protocols can impact desorption in a variety of prototypical experiments.
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| 8. |
- Boström, Emil Viñas, et al.
(författare)
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Charge Separation in Donor-C60 Complexes with Real-Time Green Functions : The Importance of Nonlocal Correlations
- 2018
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 18:2, s. 785-792
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Tidskriftsartikel (refereegranskat)abstract
- We use the nonequilibrium Green function (NEGF) method to perform real-time simulations of the ultrafast electron dynamics of photoexcited donor-C60 complexes modeled by a Pariser-Parr-Pople Hamiltonian. The NEGF results are compared to mean-field Hartree-Fock (HF) calculations to disentangle the role of correlations. Initial benchmarking against numerically highly accurate time-dependent density matrix renormalization group calculations verifies the accuracy of NEGF. We then find that charge-transfer (CT) excitons partially decay into charge separated (CS) states if dynamical nonlocal correlation corrections are included. This CS process occurs in ∼10 fs after photoexcitation. In contrast, the probability of exciton recombination is almost 100% in HF simulations. These results are largely unaffected by nuclear vibrations; the latter become however essential whenever level misalignment hinders the CT process. The robust nature of our findings indicates that ultrafast CS driven by correlation-induced decoherence may occur in many organic nanoscale systems, but it will only be correctly predicted by theoretical treatments that include time-nonlocal correlations.
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| 9. |
- Gopalakrishna, Megha, et al.
(författare)
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Photon pumping, photodissociation and dissipation at interplay for the fluorescence of a molecule in a cavity
- 2023
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Ingår i: SciPost Physics. - 2542-4653. ; 15:4
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a model description of a diatomic molecule in an optical cavity, with pump and fluorescent fields, and electron and nuclear motion are treated on equal footing and exactly. The model accounts for several optical response temporal scenarios: A Mollow spectrum hindered by electron correlations, a competition of harmonic generation and molecular dissociation, a dependence of fluorescence on photon pumping rate and dissipation. It is thus a general and flexible template for insight into experiments where quantum photon confinement, leakage, nuclear motion and electronic correlations are at interplay.
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| 10. |
- Mårsell, Erik, et al.
(författare)
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Spatial Control of Multiphoton Electron Excitations in InAs Nanowires by Varying Crystal Phase and Light Polarization
- 2018
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 18:2, s. 907-915
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the control of multiphoton electron excitations in InAs nanowires (NWs) by altering the crystal structure and the light polarization. Using few-cycle, near-infrared laser pulses from an optical parametric chirped-pulse amplification system, we induce multiphoton electron excitations in InAs nanowires with controlled wurtzite (WZ) and zincblende (ZB) segments. With a photoemission electron microscope, we show that we can selectively induce multiphoton electron emission from WZ or ZB segments of the same wire by varying the light polarization. Developing ab initio GW calculations of first to third order multiphoton excitations and using finite-difference time-domain simulations, we explain the experimental findings: While the electric-field enhancement due to the semiconductor/vacuum interface has a similar effect for all NW segments, the second and third order multiphoton transitions in the band structure of WZ InAs are highly anisotropic in contrast to ZB InAs. As the crystal phase of NWs can be precisely and reliably tailored, our findings open up for new semiconductor optoelectronics with controllable nanoscale emission of electrons through vacuum or dielectric barriers.
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