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- Gambardella, P., et al.
(författare)
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Supramolecular control of the magnetic anisotropy in two-dimensional high-spin Fe arrays at a metal interface
- 2009
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Ingår i: Nature Materials. - 1476-4660 .- 1476-1122. ; 8:3, s. 189-193
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic atoms at surfaces may provide the ultimate paradigm of a solid-state magnetic memory exhibiting either classical , or quantum , behaviour. Individual atoms, however, are difficult to arrange in regular patterns1,2,3,4, . Moreover, their magnetic properties are dominated by interaction with the substrate, which, as in the case of Kondo systems, often leads to a decrease or quench of their local magnetic moment , . Here we show that the supramolecular assembly of Fe and 1,4-benzenedicarboxylic acid molecules on a Cu surface results in ordered arrays of high-spin mononuclear Fe centres on a 1.5 nm square grid. Lateral coordination with the molecular ligands yields unsaturated yet stable coordination bonds, which allow for the chemical modification of the electronic and magnetic properties of the Fe atoms independently from the substrate. The easy magnetization direction of the Fe centres can be switched by oxygen adsorption, thus opening a way to control the magnetic anisotropy in supramolecular layers akin to that employed in metallic thin films , , , .
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| 6. |
- Salazar-Alvarez, German, et al.
(författare)
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Direct evidence of imprinted vortex states in the antiferromagnet of exchange biased microdisks
- 2009
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 95:1, s. 012510-
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic domain structure of patterned antiferromagnetic/ferromagnetic Ir20Mn80/Ni80Fe20 bilayer microdisk arrays has been investigated using layer-specific polarized x-ray photoemission electron microscopy and magnetic circular dichroism. Magnetic imaging at the Fe and Mn L-edge resonances provided direct evidence of a vortex state imprinted into the antiferromagnet at the interface. The opposite magnetic contrast between the layers indicated a reversed chirality of the imprinted vortex state, and a quantitative analysis of the magnetic moment from the dichroism spectra showed that uncompensated Mn spins equivalent to about 60% of a monolayer of bulk Ir20Mn80 contributed to the imprinted information at the interface.
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- Carbone, C., et al.
(författare)
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Correlated Electrons Step by Step : Itinerant-to-Localized Transition of Fe Impurities in Free-Electron Metal Hosts
- 2010
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 104:11, s. 117601-
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution photoemission spectroscopy and ab initio calculations have been employed to analyze the onset and progression of d-sp hybridization in Fe impurities deposited on alkali metal films. The interplay between delocalization, mediated by the free-electron environment, and Coulomb interaction among d electrons gives rise to complex electronic configurations. The multiplet structure of a single Fe atom evolves and gradually dissolves into a quasiparticle peak near the Fermi level with increasing host electron density. The effective multiorbital impurity problem within the exact diagonalization scheme describes the whole range of hybridizations.
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| 10. |
- Dieny, B., et al.
(författare)
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Opportunities and challenges for spintronics in the microelectronics industry
- 2020
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Ingår i: Nature Electronics. - : Springer Science and Business Media LLC. - 2520-1131. ; 3:8, s. 446-459
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Tidskriftsartikel (refereegranskat)abstract
- This Review Article examines the potential of spintronics in four key areas of application -memories, sensors, microwave devices, and logic devices - and discusses the challenges that need be addressed in order to integrate spintronic materials and functionalities into mainstream microelectronic platforms. Spintronic devices exploit the spin, as well as the charge, of electrons and could bring new capabilities to the microelectronics industry. However, in order for spintronic devices to meet the ever-increasing demands of the industry, innovation in terms of materials, processes and circuits are required. Here, we review recent developments in spintronics that could soon have an impact on the microelectronics and information technology industry. We highlight and explore four key areas: magnetic memories, magnetic sensors, radio-frequency and microwave devices, and logic and non-Boolean devices. We also discuss the challenges-at both the device and the system level-that need be addressed in order to integrate spintronic materials and functionalities into mainstream microelectronic platforms.
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- Ahmed, Bestoun S., 1982-, et al.
(författare)
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A new approach to speed up combinatorial search strategies using stack and hash table
- 2016
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Ingår i: Proceedings of 2016 SAI Computing Conference, SAI 2016. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781467384605 ; , s. 1217-1222
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Konferensbidrag (refereegranskat)abstract
- Owing to the significance of combinatorial search strategies both for academia and industry, the introduction of new techniques is a fast growing research field these days. These strategies have really taken different forms ranging from simple to complex strategies in order to solve all forms of combinatorial problems. Nonetheless, despite the kind of problem these approaches solve, they are prone to heavy computation with the number of combinations and growing search space dimensions. This paper presents a new approach to speed up the generation and search processes using a combination of stack and hash table data structures. This approach could be put to practice for the combinatorial approaches to speed up the generation of combinations and search process in the search space. Furthermore, this new approach proved its performance in diverse stages better than other known strategies. © 2016 IEEE.
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| 14. |
- Ahmed, Bestoun S., 1982-, et al.
(författare)
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Handling constraints in combinatorial interaction testing in the presence of multi objective particle swarm and multithreading
- 2017
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Ingår i: Information and Software Technology. - : Elsevier. - 0950-5849 .- 1873-6025. ; 86, s. 20-36
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Tidskriftsartikel (refereegranskat)abstract
- Context: Combinatorial testing strategies have lately received a lot of attention as a result of their diverse applications. In its simple form, a combinatorial strategy can reduce several input parameters (configurations) of a system into a small set based on their interaction (or combination). In practice, the input configurations of software systems are subjected to constraints, especially in case of highly configurable systems. To implement this feature within a strategy, many difficulties arise for construction. While there are many combinatorial interaction testing strategies nowadays, few of them support constraints. Objective: This paper presents a new strategy, to construct combinatorial interaction test suites in the presence of constraints. Method: The design and algorithms are provided in detail. To overcome the multi-judgement criteria for an optimal solution, the multi-objective particle swarm optimisation and multithreading are used. The strategy and its associated algorithms are evaluated extensively using different benchmarks and comparisons. Results: Our results are promising as the evaluation results showed the efficiency and performance of each algorithm in the strategy. The benchmarking results also showed that the strategy can generate constrained test suites efficiently as compared to state-of-the-art strategies. Conclusion: The proposed strategy can form a new way for constructing of constrained combinatorial interaction test suites. The strategy can form a new and effective base for future implementations. (C) 2017 Elsevier B.V. All rights reserved.
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| 15. |
- Ahmed, Bestoun S., 1982-, et al.
(författare)
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Optimum Design of (PID mu)-D-lambda controller for an automatic voltage regulator system using combinatorial test design
- 2016
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Ingår i: PLOS ONE. - : PUBLIC LIBRARY OF SCIENCE. - 1932-6203. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- Combinatorial test design is a plan of test that aims to reduce the amount of test cases systematically by choosing a subset of the test cases based on the combination of input variables. The subset covers all possible combinations of a given strength and hence tries to match the effectiveness of the exhaustive set. This mechanism of reduction has been used successfully in software testing research with t-way testing (where t indicates the interaction strength of combinations). Potentially, other systems may exhibit many similarities with this approach. Hence, it could form an emerging application in different areas of research due to its usefulness. To this end, more recently it has been applied in a few research areas successfully. In this paper, we explore the applicability of combinatorial test design technique for Fractional Order (FO), Proportional-Integral-Derivative (PID) parameter design controller, named as FOPID, for an automatic voltage regulator (AVR) system. Throughout the paper, we justify this new application theoretically and practically through simulations. In addition, we report on first experiments indicating its practical use in this field. We design different algorithms and adapted other strategies to cover all the combinations with an optimum and effective test set. Our findings indicate that combinatorial test design can find the combinations that lead to optimum design. Besides this, we also found that by increasing the strength of combination, we can approach to the optimum design in a way that with only 4-way combinatorial set, we can get the effectiveness of an exhaustive test set. This significantly reduced the number of tests needed and thus leads to an approach that optimizes design of parameters quickly.
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| 16. |
- Ahmed, B. S., et al.
(författare)
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Optimum design of PIλDμ controller for an automatic voltage regulator system using combinatorial test design
- 2016
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- Combinatorial test design is a plan of test that aims to reduce the amount of test cases systematically by choosing a subset of the test cases based on the combination of input variables. The subset covers all possible combinations of a given strength and hence tries to match the effectiveness of the exhaustive set. This mechanism of reduction has been used successfully in software testing research with t-way testing (where t indicates the interaction strength of combinations). Potentially, other systems may exhibit many similarities with this approach. Hence, it could form an emerging application in different areas of research due to its usefulness. To this end, more recently it has been applied in a few research areas successfully. In this paper, we explore the applicability of combinatorial test design technique for Fractional Order (FO), Proportional-Integral-Derivative (PID) parameter design controller, named as FOPID, for an automatic voltage regulator (AVR) system. Throughout the paper, we justify this new application theoretically and practically through simulations. In addition, we report on first experiments indicating its practical use in this field. We design different algorithms and adapted other strategies to cover all the combinations with an optimum and effective test set. Our findings indicate that combinatorial test design can find the combinations that lead to optimum design. Besides this, we also found that by increasing the strength of combination, we can approach to the optimum design in a way that with only 4-way combinatorial set, we can get the effectiveness of an exhaustive test set. This significantly reduced the number of tests needed and thus leads to an approach that optimizes design of parameters quickly. © 2016 Ahmed et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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| 17. |
- Beiras, R., et al.
(författare)
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Ingestion and contact with polyethylene microplastics does not cause acute toxicity on marine zooplankton
- 2018
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Ingår i: Journal of Hazardous Materials. - : Elsevier. - 0304-3894 .- 1873-3336. ; 360, s. 452-460
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Tidskriftsartikel (refereegranskat)abstract
- Toxicity of polyethylene microplastics (PE-MP) of size ranges similar to their natural food to zooplanktonic organisms representative of the main taxa present in marine plankton, including rotifers, copepods, bivalves, echinoderms and fish, was evaluated. Early life stages (ELS) were prioritized as testing models in order to maximize sensitivity. Treatments included particles spiked with benzophenone-3 (BP-3), a hydrophobic organic chemical used in cosmetics with direct input in coastal areas. Despite documented ingestion of both virgin and BP-3 spiked microplastics no acute toxicity was found at loads orders of magnitude above environmentally relevant concentrations on any of the invertebrate models. In fish tests some effects, including premature or reduced hatching, were observed after 12 d exposure at 10 mg L-1 of BP-3 spiked PE-MP. The results obtained do not support environmentally relevant risk of microplastics on marine zooplankton. Similar approaches testing more hydrophobic chemicals with higher acute toxicity are needed before these conclusions could be extended to other organic pollutants common in marine ecosystems. Therefore, the replacement of these polymers in consumer products must be carefully considered.
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| 18. |
- Grover, A, et al.
(författare)
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Single-cell RNA sequencing reveals molecular and functional platelet bias of aged haematopoietic stem cells
- 2016
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7, s. 11075-
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Tidskriftsartikel (refereegranskat)abstract
- Aged haematopoietic stem cells (HSCs) generate more myeloid cells and fewer lymphoid cells compared with young HSCs, contributing to decreased adaptive immunity in aged individuals. However, it is not known how intrinsic changes to HSCs and shifts in the balance between biased HSC subsets each contribute to the altered lineage output. Here, by analysing HSC transcriptomes and HSC function at the single-cell level, we identify increased molecular platelet priming and functional platelet bias as the predominant age-dependent change to HSCs, including a significant increase in a previously unrecognized class of HSCs that exclusively produce platelets. Depletion of HSC platelet programming through loss of the FOG-1 transcription factor is accompanied by increased lymphoid output. Therefore, increased platelet bias may contribute to the age-associated decrease in lymphopoiesis.
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