| 1. |
- Marković, Rastko S., et al.
(författare)
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Aeolian dynamics at the northern edge of Deliblato (Banat) Sand Sea, Vojvodina, Serbia, at the time of the last deglaciation
- 2024
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Ingår i: Quaternary Research (United States). - 0033-5894.
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Tidskriftsartikel (refereegranskat)abstract
- The Deliblato (Banat) Sand Sea, which is one of the largest areas of aeolian sand in Europe, is located near the Iron Gate, which marks the crossing of the Danube River through the biggest gorge of this river. Here, Danubian alluvium has served as the sand source for the Banat Sand Sea, which was formed primarily through southeasterly (Košava) winds. Utilizing a multi-proxy approach, the objective of this study is to gain a better understanding of the environmental dynamics of the Banat Sand Sea. To achieve this goal, we conducted an analysis of an archive representing an approximately 20-m-thick dune formation on the northern edge of this dune field. Using optically stimulated luminescence (OSL) dating, we calculated aeolian sedimentation rates and dune ages. Sand was deposited here approximately between 17 ka and 13 ka. Magnetic susceptibility, grain size, and colorimetric analyses were interpreted in terms of local paleoenvironmental conditions. Calculated sedimentation rates (SR) indicate intensive aeolian deposition during the study period that range from 483 cm/ka to 502 cm/ka. We compared our data with regional and other European archives, as well as with climatic variations recorded in the Greenland ice core North Greenland Ice Core Project (NGRIP).
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| 2. |
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| 3. |
- Marković, Slobodan B., et al.
(författare)
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The relationship between the loess stratigraphy in the Vojvodina region of northern Serbia and the Saalian and Rissian Stage glaciations – a review
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Ingår i: Boreas. - 0300-9483.
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Tidskriftsartikel (refereegranskat)abstract
- The regional loess stratigraphy in the Vojvodina region, in the southeastern Carpathian Basin, has often been successfully correlated to the global palaeoclimate. This is a quasi-continuous sedimentary record that provides detailed environmental reconstruction during the last four glacial/interglacial cycles. In this study, we present a standardized loess stratigraphy and illustrate how it correlates with the marine oxygen isotope and Chinese loess stratigraphical records. We argue that the loess stratigraphy in Vojvodina region is an important link in the integration of European terrestrial stratigraphical schemes and the deep-sea stratigraphical model. We highlight how the loess record can better illustrate terrestrial environmental change through multiple glacial cycles than other records, such as glacial records. The investigated loess record enables direct links to be made between the loess sediments and their glacial sources. This reveals evidence of glaciations during every glacial cycle of the Saalian Stage complex, equivalent to Marine Isotope Stage (MIS) 10, 8 and 6. Therefore, Serbian loess has the potential to provide a direct link between terrestrial glaciations and wider records of global climate change, which is an enigma for many other continental records. These loess records display a strong relationship with the intensity of European glaciations during different glacial cycles. Loess sedimentation rates are highest in the most intensive European glaciation of the Saalian complex (MIS 6) and much lower during the weaker ‘missing’ glaciations equivalent to MIS 8 and 10. A key observation from the Vojvodina loess is the gradual increase in interglacial aridity through the late Middle Pleistocene. The explanation for the progressively increasing aridity in the investigated region at this time is still unclear. However, this trend is consistent with the idea of the Saalian complex as representing a 400 ka mega glacial cycle modulated by shorter classic 100 ka glacial cycles.
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| 4. |
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| 5. |
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| 6. |
- Biswas, Deepnarayan, et al.
(författare)
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Ultrafast Triggering of Insulator-Metal Transition in Two-Dimensional VSe2
- 2021
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 21:5, s. 1968-1975
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Tidskriftsartikel (refereegranskat)abstract
- The transition-metal dichalcogenide VSe2 exhibits an increased charge density wave transition temperature and an emerging insulating phase when thinned to a single layer. Here, we investigate the interplay of electronic and lattice degrees of freedom that underpin these phases in single-layer VSe2 using ultrafast pump-probe photoemission spectroscopy. In the insulating state, we observe a light-induced closure of the energy gap, which we disentangle from the ensuing hot carrier dynamics by fitting a model spectral function to the time-dependent photoemission intensity. This procedure leads to an estimated time scale of 480 fs for the closure of the gap, which suggests that the phase transition in single-layer VSe2 is driven by electron-lattice interactions rather than by Mott-like electronic effects. The ultrafast optical switching of these interactions in SL VSe2 demonstrates the potential for controlling phase transitions in 2D materials with light.
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| 7. |
- Bombarda, F., et al.
(författare)
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Runaway electron beam control
- 2019
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 1361-6587 .- 0741-3335. ; 61:1
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Tidskriftsartikel (refereegranskat)
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| 8. |
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| 9. |
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| 10. |
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| 11. |
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| 12. |
- Fiddaman, Steven R., et al.
(författare)
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Ancient chicken remains reveal the origins of virulence in Marek's disease virus
- 2023
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Ingår i: Science (New York, N.Y.). - 1095-9203. ; 382:6676, s. 1276-1281
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Tidskriftsartikel (refereegranskat)abstract
- The pronounced growth in livestock populations since the 1950s has altered the epidemiological and evolutionary trajectory of their associated pathogens. For example, Marek's disease virus (MDV), which causes lymphoid tumors in chickens, has experienced a marked increase in virulence over the past century. Today, MDV infections kill >90% of unvaccinated birds, and controlling it costs more than US$1 billion annually. By sequencing MDV genomes derived from archeological chickens, we demonstrate that it has been circulating for at least 1000 years. We functionally tested the Meq oncogene, one of 49 viral genes positively selected in modern strains, demonstrating that ancient MDV was likely incapable of driving tumor formation. Our results demonstrate the power of ancient DNA approaches to trace the molecular basis of virulence in economically relevant pathogens.
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| 13. |
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| 14. |
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| 15. |
- Joffrin, E., et al.
(författare)
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Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Forskningsöversikt (refereegranskat)abstract
- For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.
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| 16. |
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| 17. |
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| 18. |
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| 19. |
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| 20. |
- Majchrzak, Paulina, et al.
(författare)
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Spectroscopic view of ultrafast charge carrier dynamics in single- and bilayer transition metal dichalcogenide semiconductors
- 2021
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 250
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Tidskriftsartikel (refereegranskat)abstract
- The quasiparticle spectra of atomically thin semiconducting transition metal dichalcogenides (TMDCs) and their response to an ultrafast optical excitation critically depend on interactions with the underlying substrate. Here, we present a comparative time- and angle-resolved photoemission spectroscopy (TR-ARPES) study of the transient electronic structure and ultrafast carrier dynamics in the single- and bilayer TMDCs MoS2 and WS2 on three different substrates: Au(111), Ag(111) and graphene/SiC. The photoexcited quasiparticle bandgaps are observed to vary over the range of 1.9-2.5 eV between our systems. The transient conduction band signals decay on a sub-50 fs timescale on the metals, signifying an efficient removal of photoinduced carriers into the bulk metallic states. On graphene, we instead observe a fast timescale on the order of 170 fs, followed by a slow dynamics for the conduction band decay in MoS2. These timescales are explained by Auger recombination involving MoS2 and in-gap defect states. In bilayer TMDCs on metals we observe a complex redistribution of excited holes along the valence band that is substantially affected by interactions with the continuum of bulk metallic states.
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| 21. |
- Marković, Igor, et al.
(författare)
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Electronically driven spin-reorientation transition of the correlated polar metal Ca3Ru2O7
- 2020
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 117:27, s. 15524-15529
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Tidskriftsartikel (refereegranskat)abstract
- The interplay between spin-orbit coupling and structural inversion symmetry breaking in solids has generated much interest due to the nontrivial spin and magnetic textures which can result. Such studies are typically focused on systems where large atomic number elements lead to strong spin-orbit coupling, in turn rendering electronic correlations weak. In contrast, here we investigate the temperature-dependent electronic structure of Ca3Ru2O7, a 4d oxide metal for which both correlations and spin-orbit coupling are pronounced and in which octahedral tilts and rotations combine to mediate both global and local inversion symmetry-breaking polar distortions. Our angle-resolved photoemission measurements reveal the destruction of a large hole-like Fermi surface upon cooling through a coupled structural and spinreorientation transition at 48 K, accompanied by a sudden onset of quasiparticle coherence. We demonstrate how these result from band hybridization mediated by a hidden Rashba-type spin- orbit coupling. This is enabled by the bulk structural distortions and unlocked when the spin reorients perpendicular to the local symmetry-breaking potential at the Ru sites. We argue that the electronic energy gain associated with the band hybridization is actually the key driver for the phase transition, reflecting a delicate interplay between spin-orbit coupling and strong electronic correlations and revealing a route to control magnetic ordering in solids.
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| 22. |
- Markovic, Slobodan B., et al.
(författare)
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Geomorphological evolution of the Petrovaradin Fortress Palaeolithic site (Novi Sad, Serbia)
- 2021
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Ingår i: Quaternary Research. - : Cambridge University Press. - 0033-5894 .- 1096-0287. ; 103, s. 21-34
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Tidskriftsartikel (refereegranskat)abstract
- Two phases of archaeological investigation were performed in the Novi Sad City Museum at Petrovaradin Fortress. In this study, we summarize the results of geo-archaeological investigations of the second period of excavation inside the Novi Sad City Museum building. The fortress is situated on a Danube terrace with the top of the bedrock at ca.123 m asl. The investigated section consists of undisturbed fine-sandy silt. The grain-size distribution of the sediments indicates clearly its alluvial reworking but shows also a general similarity with typical primary loess in the region. All analyzed proxies indicate slightly stronger weathering in the upper part of the profile. Luminescence ages suggest that the investigated sequence covers the last glacial period and the terrace presumably formed during MIS 4. Subsequently, the Danube started its incision at the start of the next warmer period (MIS 3) onward. This terrace age and elevation enable us to derive an uplift rate of the terrace of ca. 0.73 mm/a for the last 60 ka, which seems to increase towards the present. Basal loessic material, in which artifacts occur, likely in the reworked position, indicate that the area close to today's Petrovaradin Fortress was already inhabited in MIS 5.
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| 23. |
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| 24. |
- Obreht, Igor, et al.
(författare)
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Shift of large-scale atmospheric systems over Europe during late MIS 3 and implications for Modern Human dispersal
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the past dynamics of large-scale atmospheric systems is crucial for our knowledge of the palaeoclimate conditions in Europe. Southeastern Europe currently lies at the border between Atlantic, Mediterranean, and continental climate zones. Past changes in the relative influence of associated atmospheric systems must have been recorded in the region’s palaeoarchives. By comparing high-resolution grain-size, environmental magnetic and geochemical data from two loess-palaeosol sequences in the Lower Danube Basin with other Eurasian palaeorecords, we reconstructed past climatic patterns over Southeastern Europe and the related interaction of the prevailing large-scale circulation modes over Europe, especially during late Marine Isotope Stage 3 (40,000–27,000 years ago). We demonstrate that during this time interval, the intensification of the Siberian High had a crucial influence on European climate causing the more continental conditions over major parts of Europe, and a southwards shift of the Westerlies. Such a climatic and environmental change, combined with the Campanian Ignimbrite/Y-5 volcanic eruption, may have driven the Anatomically Modern Human dispersal towards Central and Western Europe, pointing to a corridor over the Eastern European Plain as an important pathway in their dispersal.
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| 25. |
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| 26. |
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| 27. |
- Perić, Zoran M., et al.
(författare)
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Dataset of dust mass accumulation rates for the loess-palaeosol sequences from the Carpathian Basin
- 2022
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Ingår i: Data in Brief. - : Elsevier BV. - 2352-3409. ; 44
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Tidskriftsartikel (refereegranskat)abstract
- In this article, a dataset of age-depth modelling data, sedimentation rates and dust mass accumulation rates (MAR) from four loess-palaeosol sequences from the Carpathian Basin is presented. The dataset is related to the article “Detailed luminescence dating of dust mass accumulation rates over the last two glacial-interglacial cycles from the Irig loess-palaeosol sequence, Carpathian Basin”, published in the journal Global and Planetary Change by Perić et al. [1]. In the dataset, luminescence ages from the loess sites Irig, Nosak, Stari Slankamen and Crvenka were modeled using the r.bacon software after which the dust mass accumulation rates were calculated. For a more realistic representation the MARs were subsequently smoothed using the SigmaPlot software. For all sites, minimum, maximum, median and mean values for the modelled ages and accumulation rates are calculated and presented.
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| 28. |
- Perić, Zoran M., et al.
(författare)
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Detailed luminescence dating of dust mass accumulation rates over the last two glacial-interglacial cycles from the Irig loess-palaeosol sequence, Carpathian Basin
- 2022
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Ingår i: Global and Planetary Change. - : Elsevier. - 0921-8181 .- 1872-6364. ; 215
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Tidskriftsartikel (refereegranskat)abstract
- Mineral dust records distant from dust sources are crucial in establishing wider atmospheric dust loads in the past. However, detailed, independent chronologies for loess-palaeosol sequences distant from local dust sources are still rare in Europe. In this study we present a high-resolution OSL and pIRIR(290) chronology and multi-proxy investigation of the Irig loess-palaeosol sequence (LPS), Vojvodina, Serbia. Our results show that 4-11 mu m quartz is a reliable dosimeter only up to similar to 59 ka (179 Gy), after which the OSL ages underestimate the expected ages based on stratigraphy. The pIRIR 290 signal displays generally good luminescence behaviour and resultant ages show good agreement with the expected stratigraphic ages, although with apparent 15 kyr and 35 kyr age underestimations at the L2-52 and 52-L3 boundaries, respectively. The calculated dust mass accumulation rates (MAR) reveal large fluctuations during the last two glacial-interglacial cycles. During the penultimate glacial, the highest MARs were observed between 171 and 181 ka, subsequently decreasing rapidly during MIS 5. During the last glacial period, dust MARs display maximum values during MIS 2 and MIS 4, while the lowest dust input was observed during the Holocene, followed by MIS 3. Dust MAR and grain-size shifts appear to lead changes in magnetic susceptibility by several kyr. Our results imply that changes in dust availability and wind dynamics occurred prior to changes in climate-controlled soil moisture conditions at the Irig LPS. Moreover, our results reveal a close coupling of the dust MAR and grain-size variations during the Mid-Late Pleistocene. These patterns suggest that the Irig site is likely representative of regional dust dynamics, which separates it from more source proximal loess sites, such as those close to major rivers, which are likely more affected by local dust availability and river discharge.
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| 29. |
- Peric, Zoran, et al.
(författare)
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Quartz OSL dating of late quaternary Chinese and Serbian loess : A cross Eurasian comparison of dust mass accumulation rates
- 2019
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Ingår i: Quaternary International. - : Elsevier BV. - 1040-6182 .- 1873-4553. ; 502:Part A, s. 30-44
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Tidskriftsartikel (refereegranskat)abstract
- Reconstructing dust Mass Accumulation Rate (MAR) from loess deposits is critical to understanding past atmospheric mineral dust activity and requires accurate independent age models from loess deposits across Europe and Asia. Previous correlations of loess in Europe and China have tended to focus on multi-millennial timescales, with no detailed examination of dust MAR at the two ends of the Eurasian loess belt on shorter, sub-orbital scales. Here we present a detailed quartz optically stimulated luminescence (OSL) chronology from the Serbian Titel Loess Plateau (Veliki Surduk loess core) and the Chinese Loess Plateau (Lingtai section). The luminescence ages pass internal tests and show consistent increases in age with depth, with no obvious major hiatuses. However, as reported before, it seems the quartz OSL technique is only capable of accurate age determination up to accrued doses of ca. 150 Gy (ca. 30–40 ka) due to approaching field saturation of the quartz OSL signal. Two age-depth models were used to reconstruct dust MARs, where one utilises OSL data solely and the other additionally makes assumptions about sedimentation rates. Although short-term fluctuations in MAR are model dependent, general MAR patterns between the two sites are very similar, with peak MAR occurring rather late in the last glacial (ca. 13–25 ka). This suggests that at least broad scale trends in dust activity within the last glacial period may be similar at a continental scale.
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| 30. |
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| 31. |
- Schaetzl, Randall J., et al.
(författare)
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Approaches and challenges to the study of loess : Introduction to the Loess-Fest Special Issue
- 2018
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Ingår i: Quaternary Research. - : Cambridge University Press (CUP). - 0033-5894 .- 1096-0287. ; 89:3, s. 563-618
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In September 2016, the annual meeting of the International Union for Quaternary Research's Loess and Pedostratigraphy Focus Group, traditionally referred to as a LoessFest, met in Eau Claire, Wisconsin, USA. The 2016 LoessFest focused on thin loess deposits and loess transportation surfaces. This LoessFest included 75 registered participants from 10 countries. Almost half of the participants were from outside the United States, and 18 of the participants were students. This review is the introduction to the special issue for Quaternary Research that originated from presentations and discussions at the 2016 LoessFest. This introduction highlights current understanding and ongoing work on loess in various regions of the world and provides brief summaries of some of the current approaches/strategies used to study loess deposits.
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| 32. |
- Siemann, Gesa R., et al.
(författare)
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Spin-orbit coupled spin-polarised hole gas at the CrSe2-terminated surface of AgCrSe2
- 2023
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Ingår i: npj Quantum Materials. - 2397-4648. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- In half-metallic systems, electronic conduction is mediated by a single spin species, offering enormous potential for spintronic devices. Here, using microscopic-area angle-resolved photoemission, we show that a spin-polarised two-dimensional hole gas is naturally realised in the polar magnetic semiconductor AgCrSe2 by an intrinsic self-doping at its CrSe2-terminated surface. Through comparison with first-principles calculations, we unveil a striking role of spin-orbit coupling for the surface hole gas, unlocked by both bulk and surface inversion symmetry breaking, suggesting routes for stabilising complex magnetic textures in the surface layer of AgCrSe2.
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| 33. |
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| 34. |
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| 35. |
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| 36. |
- Volckaert, Klara, et al.
(författare)
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Momentum-resolved linear dichroism in bilayer MoS2
- 2019
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 100:24
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Tidskriftsartikel (refereegranskat)abstract
- In solid state photoemission experiments it is possible to extract information about the symmetry and orbital character of the electronic wave functions via the photoemission selection rules that shape the measured intensity. This approach can be expanded in a pump-probe experiment where the intensity contains additional information about interband excitations induced by an ultrafast laser pulse with tunable polarization. Here, we find an unexpected strong linear dichroism effect (up to 42.4%) in the conduction band of bilayer MoS2, when measuring energy- and momentum-resolved snapshots of excited electrons by time- and angle-resolved photoemission spectroscopy. We model the polarization-dependent photoemission intensity in the transiently populated conduction band using the semiconductor Bloch equations. Our theoretical analysis reveals a strongly anisotropic momentum dependence of the optical excitations due to intralayer single-particle hopping, which explains the observed linear dichroism.
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| 37. |
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- 2018
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 58:1
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Forskningsöversikt (refereegranskat)
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