| 1. |
- Beerten, Jef, et al.
(author)
-
Influence of DC voltage droop settings on AC system stability
- 2012
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In: Proceedings on 10th International Conference on AC and DC Power Transmission. - : Institution of Engineering and Technology. - 9781849197007
-
Conference paper (peer-reviewed)abstract
- This paper presents a methodology to study the impact of different DC voltage droop settings on the AC system stability. When several Voltage Source Converters (VSC) in a DC system jointly control the DC voltage by means of droop control, an outage of one converter results in an abrupt change of the active power set-points of several other converters. This relative power change is related to the relative droop settings of the other converters. In this paper, the influence of the power sharing on the AC system stability is discussed by means of a singular value decomposition.
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| 2. |
- Ceynowa, Dylan J., et al.
(author)
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Morning Glory Disc Anomaly in childhood - a population-based study
- 2015
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In: Acta Ophthalmologica. - : Wiley. - 1755-375X .- 1755-3768. ; 93:7, s. 626-634
-
Journal article (peer-reviewed)abstract
- Purpose: To report prevalence, ocular characteristics and coexisting neurological, behavioural, somatic and neuroradiological abnormalities in children and adolescents with morning glory disc anomaly (MGDA).Methods: In a cross-sectional population-based study, 12 patients with MGDA, aged 2-20years, were identified. All 12 agreed to ophthalmological assessments including visual functions, refraction, fundus photography, optical coherence tomography (OCT) and ocular motor score (OMS). Neurological examinations and behavioural/developmental screening were carried out. Data from previous or new neuroradiological investigations were collected.Results: The prevalence of MGDA was 2.6/100000. MGDA was unilateral in 11/12 patients with a best-corrected visual acuity (BCVA) in the MGDA eye ranging from hand motion to 0.65 (median 0.06). Severe microphthalmus prevented unilaterality to be determined in one adolescent. All patients had a binocular BCVA of 0.5. OMS showed abnormalities in pupil response, vestibulo-ocular reflex, stereo visual acuity, strabismus and convergence. OCT revealed peripapillary or macular oedema in 5/8 patients and foveal aplasia in 3/8 patients. Three patients had extensive capillary hemangiomas, of which one had PHACES syndrome and one had additional cerebrovascular anomalies and corpus callosum agenesis. Neuroradiology showed craniovascular anomalies in two patients. Neurology was mostly normal. Behavioural/developmental screening showed attention deficit hyperactivity disorder in one patient.Conclusions: The prevalence data, previously not reported, of morning glory disc anomaly was 2.6/100 000. Coexisting retinal peripapillary or macular oedema was common, as were cerebral abnormalities and/or cutaneous vascular malformations. The associated findings may not be discovered through routine ophthalmological examination why OCT and neuroimaging are called for.
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| 3. |
- Coleman, V. A., et al.
(author)
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Defect Formation In Graphene Nanosheets By Acid Treatment : An X-Ray Absorption Spectroscopy And Density Functional Theory Study
- 2008
-
In: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 41:6, s. 062001-4
-
Journal article (peer-reviewed)abstract
- In-plane defects have been introduced into graphene nanosheets by treatment with hydrochloric acid. Acid treatment induces bond cleavage in the C–C network via electrophilic attack. These resultant vacancy sites will then undergo further reactions with the surrounding ambient to produce C–O and C–H bonds. A σ* resonance at 287 eV in the carbon K-edge x-ray absorption spectra is observed with acid treatment and is assigned to C–O states. Theoretical modelling of a di-vacancy in a graphene bilayer reproduces all essential features of this resonance and in addition predicts a metallic conductivity of states around this vacancy. The possibility of engineering the properties of graphene via the routes explored here is an important step towards establishing strategies for building devices based on this material.
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| 4. |
- Eklöf, Johan S., 1978-, et al.
(author)
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Effects of seasonal spawning closures on pike (Esox lucius L.) and perch (Perca fluviatilis L.) catches and coastal food webs in the western Baltic Sea
- 2023
-
In: Fisheries Research. - : Elsevier BV. - 0165-7836 .- 1872-6763. ; 263
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Journal article (peer-reviewed)abstract
- Marine protected areas have become one of the main tools in the battle to curb marine biodiversity loss and habitat degradation. Yet, implementation of permanent fishery closures has often generated resource user conflicts that ultimately undermine conservation goals. Here we assessed the influence of an alternative and often more accepted measure – seasonal fish spawning closures – on large predatory fish and coastal food webs in the western Baltic Sea (Sweden). In spring 2017, we conducted a multivariable field survey in 11 seasonal closures and 11 paired references areas open to fishing. In each area, pike was sampled through angling, and perch and mesopredators through gillnet surveys. To assess trophic cascades, we measured zooplankton abundance and loss of tethered gammarids from predation. Catches per unit effort of northern pike (Esox lucius) – the main target species in recreational fisheries – were ca. 2.5 times higher per unit effort in closures than reference areas; an effect that may be caused by higher abundance and/or higher catchability of pike in the absence of fishing. Catch and weight per unit effort of the more common predator European perch (Perca fluviatilus), and the mesopredators roach (Rutilus rutilus) and three-spined stickleback (Gasterosteus aculeatus) in survey nets were, however, unaffected by closures. Moreover, a previously hypothesized trophic cascade from perch to zooplankton via three-spined stickleback was supported by the analyses, but appeared independent of closures. Yet, predation risk for tethered gammarid amphipods (a prey of stickleback and an important grazer on macroalgae) was three times higher in fished areas than in closures; a cascading closure effect that may potentially be caused by small predatory fish being less active in protected areas to avoid pike predation. Overall, our results suggest that spawning closures impact pike abundance and/or behavior and could help limit the effects of fishing, but that more research is needed to disentangle i) what mechanism(s) that underlie the protection effect on pike catches, ii) the apparently weaker closure impacts on other fish species, as well as iii) the potential for cascading effects on lower trophic levels. Therefore, new seasonal spawning closures should be implemented in addition to (and not instead of) much-needed permanent closures, which have well-known effects on the wider ecosystem.
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| 5. |
- Elhanoty, Mohamed F., et al.
(author)
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Different fingerprints for the OISTR mechanism in the magnetic alloys experiments
- 2022
-
In: ADVANCES IN ULTRAFAST CONDENSED PHASE PHYSICS III. - : SPIE - The International Society for Optics and Photonics. - 9781510651418 - 9781510651401
-
Conference paper (peer-reviewed)abstract
- The interplay between various degrees of freedom in laser induced ultrafast magnetization dynamics (LIUMD) of magnetic alloys is intricate due to the competition between different mechanisms and processes. In this work, we resolve the element specific magnetization dynamics of FePd alloy and further elucidate the dependency of the OISTR mechanism on the laser pulse parameters using ultrashort, short and relatively longer pulse duration with weak and strong fluence. Remarkably, our results illustrate potential discrepancies in experiments measuring the optical inter site spin transfer (OISTR) effect in magnetic alloys.
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| 6. |
- Elhanoty, Mohamed F., et al.
(author)
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Element-selective ultrafast magnetization dynamics of hybrid Stoner-Heisenberg magnets
- 2022
-
In: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 105:10
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Journal article (peer-reviewed)abstract
- Stoner and Heisenberg excitations in magnetic materials are inherently different. The first involves an effective reduction of the exchange splitting, whereas the second comprises excitation of spin waves. In this work, we test the impact of these two excitations in the hybrid Stoner-Heisenberg system of FePd. We present a microscopic picture of ultrafast demagnetization dynamics in this alloy, which represents both components of strong local exchange splitting in Fe and induced polarization in Pd. We identify the spin-orbit coupling (SOC) and the optical intersite spin transfer (OISTR) as the two dominant factors for demagnetization at ultrashort timescales. Remarkably, the drastic difference in the origin of the magnetic moment of the Fe and Pd species is not deciding the initial magnetization dynamics in this alloy. By tuning the external laser pulse, the extrinsic OISTR can be manipulated for site-selective demagnetization on femtosecond timescales providing the fastest way for optical and selective control of the magnetization dynamics in alloys. Saliently, our results signify why various experiments demonstrating OISTR might obtain conflicting results.
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| 7. |
- Eriksson, Olle, et al.
(author)
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Ordering in diluted magnetic semiconductors : A magnetic percolation phenomenon (invited)
- 2007
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 101:9, s. 09H114-
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Journal article (peer-reviewed)abstract
- We report on first principles calculations that describe the electronic structure, magnetic exchange interactions, and ordering temperatures of diluted magnetic semiconductors. The calculated interatomic exchange couplings are used in a Heisenberg Hamiltonian, and ordering temperatures are calculated with the use of Monte Carlo simulations. The accuracy of the method is analyzed by comparing observed and calculated ordering temperatures of several Mn and Cr doped III-V and II-VI semiconductors. The effect of magnetic percolation is discussed along with clustering phenomena and the effect of strong electron-electron interaction.
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| 8. |
- Eriksson-Trenter, Anna, 1972-
(author)
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Anspråk och argumentation : En studie av användning och uttolkning av lag vid naturresurskonflikter i nordvästra Hälsingland, ca 1830-1870
- 2002
-
Doctoral thesis (other academic/artistic)abstract
- This thesis is concerned with the use, interpretation and practice of law in a local community during a period of institutional, demographic and market change, c.1830-c.1870. The area studied is one of the forest regions of northern Sweden which experienced great changes during the 19th century. Besides the pressure of population growth and expanded demand for forest products such as timber, the state’s increased interest to control the natural resources in the northern provinces implied new challenges for the local peasantry. In order to study how state officials, peasants, colonisers and other actors claimed and protected their rights to resources, two case studies were carried out. The first concerns negotiations between the peasantry and the state during the so-called yngre avvittringar or late enclosures. The other deals with cases concerning natural resources that where resolved in the local court. The study implies that the claimants used the institutional framework, i.e. laws, norms and customs, creatively in order to legitimise their claims. Furthermore, the findings of this study stand in contrast to the common view of the avvittringar which sees the reform as part of a process of modernisation of property rights regarding forests.
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| 9. |
- Falk, Ronny, et al.
(author)
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Targeted protein pullout from human tissue samples using competitive elution
- 2011
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In: Biotechnology Journal. - : Wiley. - 1860-6768 .- 1860-7314. ; 6:1, s. 28-37
-
Journal article (peer-reviewed)abstract
- One commonly used strategy to gain information on the proteins in a cell is to isolate the proteins of interest by specific binders, often antibodies. Not only the specificity of the capturing antibodies but also the washing and elution conditions are crucial to avoid false-positive protein identifications. Eluting the target protein from the matrix, while avoiding the release of unrelated background proteins, should both provide more correct information on the target protein and its interaction partners, and minimize the effort to perform downstream analyses through the reduced number of eluted proteins. In this study, a novel approach for selective protein pullout is presented. Monospecific antibodies were used to selectively pullout target proteins from a complex biosample. Subsequently, the target proteins were competitively eluted from the affinity media with the recombinant antigen. To deplete the antigen from the eluted sample, I MAC spin columns were utilized to bind the N-terminal His-tag of the antigens. The competitive elution method was applied both to a model system, and for the extraction of a native human target protein. In the model system the recombinant target protein BBC7 was spiked into a protein extract of human liver, whereas an endogenously expressed target protein, cTAGE5, was extracted from the liver extract directly. SDS-PAGE analysis and mass spectrometry confirmed affinity isolation of expected target proteins. More selective elution was obtained using the competitive procedure as compared to elution at low pH. Competitive elution has thus been shown to offer an effective approach for wide-scale pullout experiments where proteins and their interaction partners are to be studied.
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| 10. |
- Felix, Janine F, et al.
(author)
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Genome-wide association analysis identifies three new susceptibility loci for childhood body mass index.
- 2016
-
In: Human molecular genetics. - : Oxford University Press (OUP). - 1460-2083 .- 0964-6906. ; 25:2, s. 389-403
-
Journal article (peer-reviewed)abstract
- A large number of genetic loci are associated with adult body mass index. However, the genetics of childhood body mass index are largely unknown. We performed a meta-analysis of genome-wide association studies of childhood body mass index, using sex- and age-adjusted standard deviation scores. We included 35 668 children from 20 studies in the discovery phase and 11 873 children from 13 studies in the replication phase. In total, 15 loci reached genome-wide significance (P-value < 5 × 10(-8)) in the joint discovery and replication analysis, of which 12 are previously identified loci in or close to ADCY3, GNPDA2, TMEM18, SEC16B, FAIM2, FTO, TFAP2B, TNNI3K, MC4R, GPR61, LMX1B and OLFM4 associated with adult body mass index or childhood obesity. We identified three novel loci: rs13253111 near ELP3, rs8092503 near RAB27B and rs13387838 near ADAM23. Per additional risk allele, body mass index increased 0.04 Standard Deviation Score (SDS) [Standard Error (SE) 0.007], 0.05 SDS (SE 0.008) and 0.14 SDS (SE 0.025), for rs13253111, rs8092503 and rs13387838, respectively. A genetic risk score combining all 15 SNPs showed that each additional average risk allele was associated with a 0.073 SDS (SE 0.011, P-value = 3.12 × 10(-10)) increase in childhood body mass index in a population of 1955 children. This risk score explained 2% of the variance in childhood body mass index. This study highlights the shared genetic background between childhood and adult body mass index and adds three novel loci. These loci likely represent age-related differences in strength of the associations with body mass index.
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| 11. |
- Grånäs, Oscar, 1979-, et al.
(author)
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Ultrafast modification of the electronic structure of a correlated insulator
- 2022
-
In: Physical Review Research. - : American Physical Society. - 2643-1564. ; 4:3
-
Journal article (peer-reviewed)abstract
- A nontrivial balance between Coulomb repulsion and kinematic effects determines the electronic structure of correlated electron materials. The use of electromagnetic fields strong enough to rival these native microscopic interactions allows us to study the electronic response as well as the time scales and energies involved in using quantum effects for possible applications. We use element-specific transient x-ray absorption spectroscopy and high-harmonic generation to measure the response to ultrashort off-resonant optical fields in the prototypical correlated electron insulator NiO. Surprisingly, fields of up to 0.22 V/angstrom lead to no detectable changes in the correlated Ni 3d orbitals contrary to previous predictions. A transient directional charge transfer is uncovered, a behavior that is captured by first-principles theory. Our results highlight the importance of retardation effects in electronic screening and pinpoints a key challenge in functionalizing correlated materials for ultrafast device operation.
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| 12. |
- Iusan, Diana, et al.
(author)
-
Electronic structure and chemical and magnetic interactions in ZnO doped with Co and Al : Experiments and ab initio density-functional calculations
- 2008
-
In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 78:8, s. 085319-
-
Journal article (peer-reviewed)abstract
- We present results of electronic structure and magnetization measurements of Co:ZnO and Co:ZnO codoped with Al thin-film samples fabricated by solution-based methods together with ab initio electronic structure calculations. Electronic structure measurements indicate that the Co states lie close to the valence-band edge with pinning of the Fermi level primarily due to native defects yielding a heavily n-doped material. The findings in the electronic structure measurements are corroborated by results from theoretical calculations. We find that it is necessary to go beyond the local-density approximation to achieve agreement with experiments. Moreover, the theoretical calculations indicate a tendency for the formation of Co clusters, giving rise to an antiferromagnetic exchange interaction between the Co atoms. The magnetization measurements are well in line with the theoretical predictions, showing a dominating superparamagnetic behavior arising from small antiferromagnetic clusters containing uncompensated spins.
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| 13. |
- Jana, Somnath, et al.
(author)
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Analysis of the linear relationship between asymmetry and magnetic moment at the M edge of 3d transition metals
- 2020
-
In: Physical Review Research. - : American Physical Society. - 2643-1564. ; 2:1
-
Journal article (peer-reviewed)abstract
- The magneto-optical response of Fe and Ni during ultrafast demagnetization is studied experimentally and theoretically. We have performed pump-probe experiments in the transverse magneto-optical Kerr effect (T-MOKE) geometry using photon energies that cover the M absorption edges of Fe and Ni between 40 and 72 eV. The magnetic asymmetry was obtained by forming the difference of reflected intensities obtained for two opposite orientations of the sample magnetization. Density functional theory (DFT) was used to calculate the magneto-optical response of different magnetic configurations, representing different types of excitations: long wavelength magnons, short wavelength magnons, and Stoner excitations. In the case of Fe, we find that the calculated asymmetry is strongly dependent on the specific type of magnetic excitation. Our modeling also reveals that during remagnetization Fe is, to a reasonable approximation, described by magnons, even though small nonlinear contributions could indicate some degree of Stoner excitations as well. In contrast, we find that the calculated asymmetry in Ni is rather insensitive to the type of magnetic excitations. However, there is a weak nonlinearity in the relation between asymmetry and the off-diagonal component of the dielectric tensor, which does not originate from the modifications of the electronic structure. Our experimental and theoretical results thus emphasize the need to consider a coupling between asymmetry and magnetization that may be more complex than a simple linear relationship. This insight is crucial for the microscopic interpretation of ultrafast magnetization experiments.
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| 14. |
- Jana, Somnath, et al.
(author)
-
Atom-specific magnon driven ultrafast spin dynamics in Fe1-xNix alloys
-
Other publication (other academic/artistic)abstract
- By employing element specific ultrafast spectroscopy in Fe1-xNix alloys alloys, we find a composition dependent effect in the demagnetization that we relate to changes in electron-magnon scattering. In all six measured alloys of different composition, the demagnetization of Ni compared to Fe exhibits a delay, an effect which we find is inherent in alloys but not in elemental Fe and Ni. Using a model based on electron-magnon scattering, we extract a spin-wave stiffness from all alloys that show excellent agreement with values obtained from other techniques. The result establishes the atom-specific sd-exchange induced magnon generation as an underlying mechanism during ultrafast demagnetization in Fe1-xNix alloys
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| 15. |
- Jana, Somnath, et al.
(author)
-
Atom-specific magnon-driven ultrafast spin dynamics in Fe1-xNix alloys
- 2023
-
In: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 107:18
-
Journal article (peer-reviewed)abstract
- By employing element-specific spectroscopy in the ultrafast time scale in Fe1-xNix alloys, we find a composition-dependent effect in the demagnetization that we relate to electron-magnon scattering and changes in the spin-wave stiffness. In all six measured alloys of different composition, the demagnetization of Ni compared to Fe exhibits a delay, an effect which we find is inherent in alloys but not in elemental Fe and Ni. Using a model based on electron-magnon scattering, we extract a spin-wave stiffness from all alloys that show excellent agreement with values obtained from other techniques.
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| 16. |
- Johannesson, Tomas, 1975-
(musician, creator_code:sds_t, creator_code:cre_t)
-
Norrbotten blues : CD-produktion av Ronny Eriksson och Ramblin' Minds
- 2019
-
Artistic workabstract
- CD-inspelning: Norrbotten blues - Ronny Eriksson & Ramblin' MindsLåtlista1. Norrbotten Blues2. Gråtvals3. På kanten av en grop4. Flyktingarna5. Då tänker jag på Syrien6. Låt mig gå, jag har inte tid att stanna7. Tröstvals8. Blues för ingen alls9. Brorsan10. Den officiella versionen11. Blues under fullmånenMusikerRonny Eriksson - sångMikael Bäckman - munspelLeo Holmberg - gitarr/körAnders Wedin - gitarrAnna Wedin - bas/körKatarina Pettersson - trummorMathias Lundqvist - piano/orgelTomas Johannesson - barytonsaxStefan Tjerngren - tenorsaxTomas Johannesson - Ljudtekniker (inspelning, redigering och mix)Stockholm Mastering - masteringRootsy Music - bolagInspelat på musikhögskolan i Piteå 7-9 september 2018.Publicerad 9 mars 2019.
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| 17. |
- Kammer, Ronny, et al.
(author)
-
Evaluation of a tape-stripping technique for measuring dermal exposure to pyrene and benzo(a)pyrene.
- 2011
-
In: Journal of Environmental Monitoring. - : Royal Society of Chemistry (RSC). - 1464-0325 .- 1464-0333. ; 13:8, s. 2165-2171
-
Journal article (peer-reviewed)abstract
- Epidemiological studies have shown an increased incidence of cancer among workers occupationally exposed to polycyclic aromatic hydrocarbons (PAHs). As the dermal route is considered important for exposure to PAHs in the workplace, the aim of this study was to develop and evaluate a tape-stripping technique for monitoring dermal exposure to pyrene and benzo(a)pyrene. The tape-stripping method was evaluated by applying different concentrations of pyrene and benzo(a)pyrene directly onto tape strips (spiked tapes), clean glass plates, and on the skin of five volunteers. The glass plates were stripped using a single strip of tape and the skin of the volunteers was stripped with five consecutive strips of tape after 0 and 30 minutes. The method was also tested on five chimney sweeps at three exposure sites. High-performance liquid chromatography with fluorescence detection was employed for the quantification of pyrene and benzo(a)pyrene. The mean recovery from the spiked tapes was 97% for pyrene and 93% for benzo(a)pyrene. The mean overall recovery from the glass plates was 88% and 76% for pyrene and 88 and 85% for benzo(a)pyrene. The recovery from human skin was 70% and 63% for pyrene and 60 and 54% for benzo(a)pyrene, after 0 and 30 minutes, respectively. A concentration gradient was clearly detected between the five consecutive strips. Detectable amounts of pyrene and benzo(a)pyrene were found on all chimney sweeps at all exposure sites. This method can thus be used to detect and quantify dermal exposure to pyrene and benzo(a)pyrene. The results also show that pyrene and benzo(a)pyrene may be taken up by the skin.
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| 18. |
- Locht, Inka L. M., 1986-, et al.
(author)
-
Magnetic asymmetry around the 3p absorption edge in Fe and Ni
-
Other publication (other academic/artistic)abstract
- This work is a joint theoretical and experimental study of the relation between the magneto- optical response of a material in the sub-picosecond timescale and its instantaneous magnetisation. We perform pump-probe experiments in the transverse magneto-optical Kerr effect (T-MOKE) geometry. We measure the magnetic asymmetry of elemental Fe and Ni before and after the laser pulse. The observed differences between the magnetic asymmetry curves for various photon energies suggest that the relation between asymmetry and sample magnetization is more complex than a simple proportionality. Further insight is obtained by means of theoretical simulations based on density-functional theory. Our calculations show that non-linear effects in the asymmetry are most prominent at energies corresponding to the absorption edge and that the proportionality is recovered outside of this region. In conclusion, our experimental and theoretical results emphasize the need of including the complex relation between asymmetry and magnetization in the interpretation of ultrafast magnetization experiments in terms of microscopic properties.
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| 19. |
- Malik, Rameez Saeed, 1987-, et al.
(author)
-
Ultrafast dynamics in Fe65Co35 alloys: Effect of Re doping
-
Other publication (pop. science, debate, etc.)abstract
- Soft magnetic FeCo alloys are of great interest due to their potential spintronics applications. The magnetic damping parameter plays a vital role in the performance of these spintronics devices. The Gilbert damping parameter increase in these alloys with doping of 5d elements. Here, we have investigated the effect of Re doping on the element-specific magnetization dynamics of Ru/Fe65Co35/Ru thin films using the time-resolved magneto-optical Kerr effect. When varying the concentration of Re from 0 to 12.6 %, no change of the demagnetization time constant is observed. However, a gradual change of the remagnetization time is observed with the increase of Re concentration. This remagnetization dynamics can be related to the Gilbert damping parameter of these films. An interesting time-resolved dynamics at the Ru-edge is observed. A significant increase (40%) of the asymmetry signal is observed for the undoped sample and drops down with the Re doping. This effect is possibly a super diffusive spin current going from the magnetic layer to the non magnetic capping layer.
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| 20. |
- Malik, Rameez Saeed, 1987-, et al.
(author)
-
Ultrafast magnetization dynamics in half-metallic Co2FeAl Heusler alloy
-
Other publication (pop. science, debate, etc.)abstract
- We report on optically induced, ultrafast magnetization dynamics in the Heusler alloy Co2FeAl,probed by time-resolved magneto-optical Kerr effect. Experimental results are compared to resultsfrom electronic structure theory and atomistic spin-dynamics simulations. Experimentally, we findthat the demagnetization time (τM) in films of Co2FeAl is almost independent of varying structuralorder, and that it is similar to that in elemental 3d ferromagnets. In contrast, the slower processof magnetization recovery, specified byτR, is found to occur on picosecond time scales, and isdemonstrated to correlate strongly with the Gilbert damping parameter (α). Our results showthat Co2FeAl is unique, in that it is the first material that clearly demonstrates the importance ofthe damping parameter in the remagnetization process. Based on these results we argue that for Co2FeAl the remagnetization process is dominated by magnon dynamics, something which mighthave general applicabilit
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| 21. |
- Malik, Rameez Saeed, 1987-, et al.
(author)
-
Ultrafast magnetization dynamics in magnetically frustrated NiFe2O4 ferrimagnet
-
Other publication (pop. science, debate, etc.)abstract
- NiFe2O4 shows complex dynamics between its elements after an ultrashort laser pulse excitation. The reflectivity shows oscillations, indicating either a reordering of the charge distribution several picoseconds after absorption of the laser pulse or a coherent phonon mode with a frequency of 0.5 THz. Also, the magnetic asymmetry exhibits oscillations that cannot be attributed to transverse magnetic excitations (magnons) but correspond to longitudinal excitations. The demagnetization shows different behavior depending on the excitation photon energy, for energies close to the band gap (1.55 eV) oscillations in the asymmetry are prominent, while for higher energies (3.1 eV) the demagnetization becomes dominant and the oscillations vanish. A fast demagnetization is observed when using 3.1 eV compared to 1.55 eV, while the electronic response remains similar, which indicates that the fast demagnetization dynamics is driven by holes created deeper in the valence band while the dynamics of electrons excited to d-states in the conduction band provides a smaller contribution to the demagnetization.The oscillations in the asymmetry can be a consequence of the competing exchange interactions that are antiferromagnetic between all three sublattices, but where a ferromagnetic alignment between octahedral Ni and octahedral Fe is the ground state.
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| 22. |
- Malik, Rameez Saeed, 1987-, et al.
(author)
-
Ultrafast magnetization dynamics in the half-metallic Heusler alloy Co2FeAl
- 2021
-
In: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 104:10
-
Journal article (peer-reviewed)abstract
- We report on optically induced, ultrafast magnetization dynamics in the Heusler alloy Co2FeAl, probed by time-resolved magneto-optical Kerr effect. Experimental results are compared to results from electronic structure theory and atomistic spin-dynamics simulations. Experimentally, we find that the demagnetization time (tau(M)) in films of Co2FeAl is almost independent of varying structural order, and that it is similar to that in elemental 3d ferromagnets. In contrast, the slower process of magnetization recovery, specified by tau(R), is found to occur on picosecond time scales, and is demonstrated to correlate strongly with the Gilbert damping parameter (alpha). Based on these results we argue that for Co2FeAl the remagnetization process is dominated by magnon dynamics, something which might have general applicability.
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| 23. |
- Middeldorp, Christel M., et al.
(author)
-
The Early Growth Genetics (EGG) and EArly Genetics and Lifecourse Epidemiology (EAGLE) consortia : design, results and future prospects
- 2019
-
In: European Journal of Epidemiology. - : Springer Science and Business Media LLC. - 0393-2990 .- 1573-7284. ; 34:3, s. 279-300
-
Journal article (peer-reviewed)abstract
- The impact of many unfavorable childhood traits or diseases, such as low birth weight and mental disorders, is not limited to childhood and adolescence, as they are also associated with poor outcomes in adulthood, such as cardiovascular disease. Insight into the genetic etiology of childhood and adolescent traits and disorders may therefore provide new perspectives, not only on how to improve wellbeing during childhood, but also how to prevent later adverse outcomes. To achieve the sample sizes required for genetic research, the Early Growth Genetics (EGG) and EArly Genetics and Lifecourse Epidemiology (EAGLE) consortia were established. The majority of the participating cohorts are longitudinal population-based samples, but other cohorts with data on early childhood phenotypes are also involved. Cohorts often have a broad focus and collect(ed) data on various somatic and psychiatric traits as well as environmental factors. Genetic variants have been successfully identified for multiple traits, for example, birth weight, atopic dermatitis, childhood BMI, allergic sensitization, and pubertal growth. Furthermore, the results have shown that genetic factors also partly underlie the association with adult traits. As sample sizes are still increasing, it is expected that future analyses will identify additional variants. This, in combination with the development of innovative statistical methods, will provide detailed insight on the mechanisms underlying the transition from childhood to adult disorders. Both consortia welcome new collaborations. Policies and contact details are available from the corresponding authors of this manuscript and/or the consortium websites.
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| 24. |
- Olin, Agnes B., et al.
(author)
-
Predation and spatial connectivity interact to shape ecosystem resilience to an ongoing regime shift
- 2024
-
In: Nature Communications. - 2041-1723. ; 15:1
-
Journal article (peer-reviewed)abstract
- Ecosystem regime shifts can have severe ecological and economic consequences, making it a top priority to understand how to make systems more resilient. Theory predicts that spatial connectivity and the local environment interact to shape resilience, but empirical studies are scarce. Here, we use >7000 fish samplings from the Baltic Sea coast to test this prediction in an ongoing, spatially propagating shift in dominance from predatory fish to an opportunistic mesopredator, with cascading effects throughout the food web. After controlling for the influence of other drivers (including increasing mesopredator densities), we find that predatory fish habitat connectivity increases resilience to the shift, but only when densities of fish-eating top predators (seals, cormorants) are low. Resilience also increases with temperature, likely through boosted predatory fish growth and recruitment. These findings confirm theoretical predictions that spatial connectivity and the local environment can together shape resilience to regime shifts.
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| 25. |
- Paul, Souvik, et al.
(author)
-
Investigation of the spectral properties and magnetism of BiFeO3 by dynamical mean-field theory
- 2018
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In: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 97:12
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Journal article (peer-reviewed)abstract
- Using the local density approximation plus dynamical mean-field theory (LDA+DMFT), we have computed the valence-band photoelectron spectra and magnetic excitation spectra of BiFeO3, one of the most studied multiferroics. Within the DMFT approach, the local impurity problem is tackled by the exact diagonalization solver. The solution of the impurity problem within the LDA+DMFT method for the paramagnetic and magnetically ordered phases produces result in agreement with the experimental data on electronic and magnetic structures. For comparison, we also present results obtained by the LDA+U approach which is commonly used to compute the physical properties of this compound. Our LDA+DMFT derived electronic spectra match adequately with the experimental hard x-ray photoelectron spectroscopy and resonant photoelectron spectroscopy for Fe 3d states, whereas the LDA+U method fails to capture the general features of the measured spectra. This indicates the importance of accurately incorporating the dynamical aspect of electronic correlation among Fe 3d orbitals to reproduce the experimental excitation spectra. Specifically, the LDA+DMFT derived density of states exhibits a significant amount of Fe 3d states at the position of Bi lone pairs, implying that the latter are not alone in the spectral scenario. This fact might modify our interpretation about the origin of ferroelectric polarization in this material. Our study demonstrates that the combination of orbital cross sections for the constituent elements and broadening schemes for the spectral functions are crucial to explain the detailed structures of the experimental electronic spectra. Our magnetic excitation spectra computed from the LDA+DMFT result conform well with the inelastic neutron scattering data.
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| 26. |
- Persson, K. I., et al.
(author)
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Motivators and barriers for HIV testing among men who have sex with men in Sweden
- 2016
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In: Journal of Clinical Nursing. - : Wiley. - 0962-1067 .- 1365-2702. ; 25:23-24, s. 3605-3618
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Journal article (peer-reviewed)abstract
- Aims and objectives: To explore motivators and barriers to HIV testing and to assess the factors associated with testing among men who have sex with men. Background: Previous research has considered fear, worries and structural barriers as hindrances to HIV testing among men who have sex with men. However, few studies have included assessments of actual HIV testing when exploring barriers or motivators for such testing. Design: The design of the study was a stratified cross-sectional online survey (n=2373). Method: Factor analysis was conducted to analyse the barriers and motivators for HIV testing. Logistic regression analysis was conducted to assess predictors for HIV testing. Results: Many men who have sex with men test for HIV regularly, and specific reasons for testing were having unprotected sex or starting/ending a relationship. A lack of awareness and a perception of being at low risk for exposure were common reasons for never being tested. Fear and anxiety as well as barriers related to the use of test services remain important hindrances for testing. Predictors associated with having been tested within the past 12months were: younger age (15–25years old compared with 47+); knowledge on where to take an HIV test on short notice as well as having talked with a counsellor, having received condoms for free, or having had unprotected anal intercourse with casual partners within the last 12months. Conclusion: Easily accessible test services offering testing and counselling on short notice should be available for all men who have sex with men. Outreach activities, distribution of free condoms and testing at venues where men who have sex with men meet are important prevention add-ons that can contribute to increased awareness about HIV and testing. Relevance to clinical practice: Test services must ensure confidentiality and health care professionals who meet men who have sex with men for testing need competency with regards to men who have sex with men sexual health needs. © 2016 John Wiley & Sons Ltd
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| 27. |
- Sanyal, Biplab, et al.
(author)
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Electronic structure of Co doped ZnO : Theory and experiment
- 2008
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 103:7, s. 07D130-
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Journal article (peer-reviewed)abstract
- We have studied the electronic structure of Co doped ZnO by theory and experiment. Photoelectron and x-ray absorption spectroscopy experiments were performed on 5% Co doped ZnO thin films. The results show that Co-3d states lie in the valence band and hybridize considerably with O-2p states. These results compare qualitatively with our density functional calculations combined with a Hubbard approach to include strong electron correlations within the Co-3d state.
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| 28. |
- Sanyal, Biplab, et al.
(author)
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Inhomogeneity in Co Doped ZnO Diluted Magnetic Semiconductor
- 2008
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 103:7, s. 07D131-
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Journal article (peer-reviewed)abstract
- Here, we have studied the chemical and magnetic interactions in Co doped ZnO diluted magnetic semiconductor by ab initio density functional calculations. The calculated chemical pair interaction parameters suggest a strong tendency of clustering between Co atoms. Both chemical and magnetic pair interaction parameters are short ranged with a large first neighbor interaction. Monte Carlo simulations show that the Curie temperature for a homogeneous sample is low, whereas allowing for an inhomogeneous growth results in very high Curie temperatures. It is argued that these inhomogeneities may be the reason for the observation of high Curie temperatures in Co doped ZnO. It is also demonstrated that the electronic structure is modified significantly in presence of Co clusters.
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| 29. |
- Shaw, Justin M., et al.
(author)
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Quantifying Spin-Mixed States in Ferromagnets
- 2021
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In: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 127:20
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Journal article (peer-reviewed)abstract
- We quantify the presence of spin-mixed states in ferromagnetic 3D transition metals by precise measurement of the orbital moment. While central to phenomena such as Elliot-Yafet scattering, quantification of the spin-mixing parameter has hitherto been confined to theoretical calculations. We demonstrate that this information is also available by experimental means. Comparison of ferromagnetic resonance spectroscopy with x-ray magnetic circular dichroism results show that Kittel's original derivation of the spectroscopic g factor requires modification, to include spin mixing of valence band states. Our results are supported by ab initio relativistic electronic structure theory.
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| 30. |
- Smith, Jennifer A, et al.
(author)
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Genome-wide association study identifies 74 loci associated with educational attainment
- 2016
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In: Nature (London). - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 533:7604, s. 539-542
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Journal article (peer-reviewed)abstract
- Educational attainment is strongly influenced by social and other environmental factors, but genetic factors are estimated to account for at least 20% of the variation across individuals. Here we report the results of a genome-wide association study (GWAS) for educational attainment that extends our earlier discovery sample of 101,069 individuals to 293,723 individuals, and a replication study in an independent sample of 111,349 individuals from the UK Biobank. We identify 74 genome-wide significant loci associated with the number of years of schooling completed. Single-nucleotide polymorphisms associated with educational attainment are disproportionately found in genomic regions regulating gene expression in the fetal brain. Candidate genes are preferentially expressed in neural tissue, especially during the prenatal period, and enriched for biological pathways involved in neural development. Our findings demonstrate that, even for a behavioural phenotype that is mostly environmentally determined, a well-powered GWAS identifies replicable associated genetic variants that suggest biologically relevant pathways. Because educational attainment is measured in large numbers of individuals, it will continue to be useful as a proxy phenotype in efforts to characterize the genetic influences of related phenotypes, including cognition and neuropsychiatric diseases.
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| 31. |
- Steen, Stig, et al.
(author)
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First human transplantation of a nonacceptable donor lung after reconditioning ex vivo.
- 2007
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In: Annals of Thoracic Surgery. - : Elsevier BV. - 1552-6259 .- 0003-4975. ; 83:6, s. 2191-2195
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Journal article (peer-reviewed)abstract
- Purpose. This article describes an ex vivo method to recondition and transplant rejected donor lungs. Description. A 19-year-old man was brain dead after a traffic accident. A roentgenogram showed bilateral lung contusion. He had ongoing intratracheal bleeding. After optimizing ventilator treatment and suctioning the airways, PaO2 was 9 kPa (67.5 mm Hg) on FiO(2) = 0.7. The lungs were rejected by all transplantation centers in the Nordic countries. We harvested the lungs for research. The right lung was severely injured. The left lung was edematous with bleeding spots in the lower lobe, and the mediobasal segment was atelectatic. The left lung was reconditioned ex vivo and kept in topical extracorporeal membrane oxygenation until it was transplanted into a 70-year-old man with chronic obstructive pulmonary disease 17 hours later. Evaluation. The transplanted lung functioned very well, and the patient recovered uneventfully. At 3 months control, a computed tomographic thoracic scan and transbronchial biopsies showed a normal left lung, and the patient was in very good clinical condition, only to succumb to death from unrelated events 11 months after the transplantation. Conclusions. Rejected donor lungs may be successfully transplanted after being reconditioned ex vivo.
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| 32. |
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| 33. |
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| 34. |
- Uhlén, Mathias, et al.
(author)
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A human protein atlas for normal and cancer tissues based on antibody proteomics
- 2005
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In: Molecular & Cellular Proteomics. - 1535-9476 .- 1535-9484. ; 4:12, s. 1920-1932
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Journal article (peer-reviewed)abstract
- Antibody-based proteomics provides a powerful approach for the functional study of the human proteome involving the systematic generation of protein-specific affinity reagents. We used this strategy to construct a comprehensive, antibody-based protein atlas for expression and localization profiles in 48 normal human tissues and 20 different cancers. Here we report a new publicly available database containing, in the first version, similar to 400,000 high resolution images corresponding to more than 700 antibodies toward human proteins. Each image has been annotated by a certified pathologist to provide a knowledge base for functional studies and to allow queries about protein profiles in normal and disease tissues. Our results suggest it should be possible to extend this analysis to the majority of all human proteins thus providing a valuable tool for medical and biological research.
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| 35. |
- van der Valk, Ralf J P, et al.
(author)
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A novel common variant in DCST2 is associated with length in early life and height in adulthood.
- 2015
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In: Human molecular genetics. - : Oxford University Press (OUP). - 1460-2083 .- 0964-6906. ; 24:4, s. 1155-68
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Journal article (peer-reviewed)abstract
- Common genetic variants have been identified for adult height, but not much is known about the genetics of skeletal growth in early life. To identify common genetic variants that influence fetal skeletal growth, we meta-analyzed 22 genome-wide association studies (Stage 1; N = 28 459). We identified seven independent top single nucleotide polymorphisms (SNPs) (P < 1 × 10(-6)) for birth length, of which three were novel and four were in or near loci known to be associated with adult height (LCORL, PTCH1, GPR126 and HMGA2). The three novel SNPs were followed-up in nine replication studies (Stage 2; N = 11 995), with rs905938 in DC-STAMP domain containing 2 (DCST2) genome-wide significantly associated with birth length in a joint analysis (Stages 1 + 2; β = 0.046, SE = 0.008, P = 2.46 × 10(-8), explained variance = 0.05%). Rs905938 was also associated with infant length (N = 28 228; P = 5.54 × 10(-4)) and adult height (N = 127 513; P = 1.45 × 10(-5)). DCST2 is a DC-STAMP-like protein family member and DC-STAMP is an osteoclast cell-fusion regulator. Polygenic scores based on 180 SNPs previously associated with human adult stature explained 0.13% of variance in birth length. The same SNPs explained 2.95% of the variance of infant length. Of the 180 known adult height loci, 11 were genome-wide significantly associated with infant length (SF3B4, LCORL, SPAG17, C6orf173, PTCH1, GDF5, ZNFX1, HHIP, ACAN, HLA locus and HMGA2). This study highlights that common variation in DCST2 influences variation in early growth and adult height.
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| 36. |
- Wang, Xiaocui, et al.
(author)
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Ultrafast manipulation of the NiO antiferromagnetic order via sub-gap optical excitation
- 2022
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In: Faraday discussions. - : Royal Society of Chemistry (RSC). - 1359-6640 .- 1364-5498. ; 237:0, s. 300-316
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Journal article (peer-reviewed)abstract
- Wide-band-gap insulators such as NiO offer the exciting prospect of coherently manipulating electronic correlations with strong optical fields. Contrary to metals where rapid dephasing of optical excitation via electronic processes occurs, the sub-gap excitation in charge-transfer insulators has been shown to couple to low-energy bosonic excitations. However, it is currently unknown if the bosonic dressing field is composed of phonons or magnons. Here we use the prototypical charge-transfer insulator NiO to demonstrate that 1.5 eV sub-gap optical excitation leads to a renormalised NiO band-gap in combination with a significant reduction of the antiferromagnetic order. We employ element-specific X-ray reflectivity at the FLASH free-electron laser to demonstrate the reduction of the upper band-edge at the O 1s-2p core-valence resonance (K-edge) whereas the antiferromagnetic order is probed via X-ray magnetic linear dichroism (XMLD) at the Ni 2p-3d resonance (L-2-edge). Comparing the transient XMLD spectral line shape to ground-state measurements allows us to extract a spin temperature rise of 65 +/- 5 K for time delays longer than 400 fs while at earlier times a non-equilibrium spin state is formed. We identify transient mid-gap states being formed during the first 200 fs accompanied by a band-gap reduction lasting at least up to the maximum measured time delay of 2.4 ps. Electronic structure calculations indicate that magnon excitations significantly contribute to the reduction of the NiO band gap.
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| 37. |
- Wikberg, J Magnus, et al.
(author)
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Magnetocrystalline anisotropy and uniaxiality of MnAs/GaAs(100) films
- 2011
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 83:2, s. 024417-
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Journal article (peer-reviewed)abstract
- We present an investigation of the magnetic behavior of epitaxial MnAs films grown on GaAs(100). We address the dependence of the magnetic moment, ferromagnetic transition temperature (Tc), and magnetocrystalline anisotropy constants on epitaxial conditions. From thorough structural and magnetic investigations, our findings indicate a more complex relationship between strain and magnetic properties in MnAs films than a simple stretch/compression of the unit cell axes. While a small increase is seen in the anisotropy constants, the enhancement of the magnetic moment at saturation is significant. Results of x-ray magnetic circular dichroism show a behavior of the spin and orbital moment that is consistent with a structural transition at Tc. In particular, we find that the ratio of the orbital to the spin moment shows a marked increase in the coexistence region of the ferromagnetic α- and paramagnetic β-phases a result that is well in accord with the observed increase in the c/a ratio in the same temperature region. The ab initio density functional calculations reveal that the magnetic properties are more sensitive towards change in the ab-plane compared to change in the c-axis which is explained by the analysis of band structures. The effects of electron correlation in MnAs using ab initio dynamical mean field theory are also presented.
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