| 1. |
- Telloni, Daniele, et al.
(författare)
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Observation and Modeling of the Solar Wind Turbulence Evolution in the Sub-Mercury Inner Heliosphere
- 2022
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Ingår i: Astrophysical Journal Letters. - : Institute of Physics Publishing (IOPP). - 2041-8205 .- 2041-8213. ; 938:2
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Tidskriftsartikel (refereegranskat)abstract
- This letter exploits the radial alignment between the Parker Solar Probe and BepiColombo in late 2022 February, when both spacecraft were within Mercury's orbit. This allows the study of the turbulent evolution, namely, the change in spectral and intermittency properties, of the same plasma parcel during its expansion from 0.11 to 0.33 au, a still unexplored region. The observational analysis of the solar wind turbulent features at the two different evolution stages is complemented by a theoretical description based on the turbulence transport model equations for nearly incompressible magnetohydrodynamics. The results provide strong evidence that the solar wind turbulence already undergoes significant evolution at distances less than 0.3 au from the Sun, which can be satisfactorily explained as due to evolving slab fluctuations. This work represents a step forward in understanding the processes that control the transition from weak to strong turbulence in the solar wind and in properly modeling the heliosphere.
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| 2. |
- Engert, Andreas, et al.
(författare)
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The European Hematology Association Roadmap for European Hematology Research : a consensus document
- 2016
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Ingår i: Haematologica. - Pavia, Italy : Ferrata Storti Foundation (Haematologica). - 0390-6078 .- 1592-8721. ; 101:2, s. 115-208
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Tidskriftsartikel (refereegranskat)abstract
- The European Hematology Association (EHA) Roadmap for European Hematology Research highlights major achievements in diagnosis and treatment of blood disorders and identifies the greatest unmet clinical and scientific needs in those areas to enable better funded, more focused European hematology research. Initiated by the EHA, around 300 experts contributed to the consensus document, which will help European policy makers, research funders, research organizations, researchers, and patient groups make better informed decisions on hematology research. It also aims to raise public awareness of the burden of blood disorders on European society, which purely in economic terms is estimated at (sic)23 billion per year, a level of cost that is not matched in current European hematology research funding. In recent decades, hematology research has improved our fundamental understanding of the biology of blood disorders, and has improved diagnostics and treatments, sometimes in revolutionary ways. This progress highlights the potential of focused basic research programs such as this EHA Roadmap. The EHA Roadmap identifies nine 'sections' in hematology: normal hematopoiesis, malignant lymphoid and myeloid diseases, anemias and related diseases, platelet disorders, blood coagulation and hemostatic disorders, transfusion medicine, infections in hematology, and hematopoietic stem cell transplantation. These sections span 60 smaller groups of diseases or disorders. The EHA Roadmap identifies priorities and needs across the field of hematology, including those to develop targeted therapies based on genomic profiling and chemical biology, to eradicate minimal residual malignant disease, and to develop cellular immunotherapies, combination treatments, gene therapies, hematopoietic stem cell treatments, and treatments that are better tolerated by elderly patients.
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| 3. |
- Sorriso-Valvo, Luca, et al.
(författare)
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Turbulence-Driven Ion Beams in the Magnetospheric Kelvin-Helmholtz Instability
- 2019
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 122:3
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Tidskriftsartikel (refereegranskat)abstract
- The description of the local turbulent energy transfer and the high-resolution ion distributions measured by the Magnetospheric Multiscale mission together provide a formidable tool to explore the cross-scale connection between the fluid-scale energy cascade and plasma processes at subion scales. When the small-scale energy transfer is dominated by Alfvenic, correlated velocity, and magnetic field fluctuations, beams of accelerated particles are more likely observed. Here, for the first time, we report observations suggesting the nonlinear wave-particle interaction as one possible mechanism for the energy dissipation in space plasmas.
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| 4. |
- Carbone, Francesco, et al.
(författare)
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Chaotic advection and particle pairs diffusion in a low-dimensional truncation of two-dimensional magnetohydrodynamics
- 2022
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Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 138:5
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Tidskriftsartikel (refereegranskat)abstract
- The chaotic advection of fluid particle pairs is investigated though a low-order model of two-dimensional magnetohydrodynamic (MHD), where only five nonlinearly interacting modes are retained. The model is inthrinsically inhomogeneous and anisotropic because of the influence of large-scale fluctuations. Therefore, even though dynamically chaotic, the fields are unable to form the typical scaling laws of fully developed turbulence. Results show that a super-ballistic dynamics, reminiscent of the Richardson law of particle-pairs diffusion in turbulent flows, is robustly obtained using the truncated model. Indeed, even in the strongly reduced truncation presented here, particle diffusion in MHD turbulence has the same laws as the separation of velocity of particle pairs. The inherent anisotropy only affects the scaling of diffusivity, by enhancing the diffusion properties along one direction for small time-scales. Finally, when further anisotropy is introduced in the system through Alfven waves, fluid particles are trapped by these, and super-ballistic diffusion is replaced by Brownian-like diffusion. On the other hand, when the magnetic field is removed, the kinetic counterpart of the model does not show super-ballistic dynamics.
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| 5. |
- Carbone, Francesco, et al.
(författare)
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Local dimensionality and inverse persistence analysis of atmospheric turbulence in the stable boundary layer
- 2022
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Ingår i: Physical review. E. - : American Physical Society. - 2470-0045 .- 2470-0053. ; 106:6
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics across different scales in the stable atmospheric boundary layer has been investigated by means of two metrics, based on instantaneous fractal dimensions and grounded in dynamical systems theory. The wind velocity fluctuations obtained from data collected during the Cooperative Atmosphere-Surface Exchange Study- 1999 experiment were analyzed to provide a local (in terms of scales) and an instantaneous (in terms of time) description of the fractal properties and predictability of the system. By analyzing the phase-space projections of the continuous turbulent, intermittent, and radiative regimes, a progressive transformation, characterized by the emergence of multiple low-dimensional clusters embedded in a high-dimensional shell and a two-lobe mirror symmetrical structure of the inverse persistence, have been found. The phase space becomes increasingly complex and anisotropic as the turbulent fluctuations become uncorrelated. The phase space is characterized by a three-dimensional structure for the continuous turbulent samples in a range of scales compatible with the inertial subrange, where the phase-space-filling turbulent fluctuations dominate the dynamics, and is low dimensional in the other regimes. Moreover, lower-dimensional structures present a stronger persistence than the higher-dimensional structures. Eventually, all samples recover a three-dimensional structure and higher persistence level at large scales, far from the inertial subrange. The two metrics obtained in the analysis can be considered as proxies for the decorrelation time and the local anisotropy in the turbulent flow.
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| 6. |
- Carbone, Francesco, et al.
(författare)
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Modulation of Solar Wind Impact on the Earth's Magnetosphere during the Solar Cycle
- 2022
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Ingår i: Universe. - : MDPI. - 2218-1997. ; 8:6
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Tidskriftsartikel (refereegranskat)abstract
- The understanding of extreme geomagnetic storms is one of the key issues in space weather. Such phenomena have been receiving increasing attention, especially with the aim of forecasting strong geomagnetic storms generated by high-energy solar events since they can severely perturb the near-Earth space environment. Here, the disturbance storm time index Dst, a crucial geomagnetic activity proxy for Sun-Earth interactions, is analyzed as a function of the energy carried by different solar wind streams. To determine the solar cycle activity influence on Dst, a 12-year dataset was split into sub-periods of maximum and minimum solar activity. Solar wind energy and geomagnetic activity were closely correlated for both periods of activity. Slow wind streams had negligible effects on Earth regardless of their energy, while high-speed streams may induce severe geomagnetic storming depending on the energy (kinetic or magnetic) carried by the flow. The difference between the two periods may be related to the higher rate of geo-effective events during the maximum activity, where coronal mass ejections represent the most energetic and geo-effective driver. During the minimum period, despite a lower rate of high energetic events, a moderate disturbance in the Dst index can be induced.
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| 7. |
- Carbone, Francesco, et al.
(författare)
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Transition to turbulence in a five-mode Galerkin truncation of two-dimensional magnetohydrodynamics
- 2021
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Ingår i: Physical review. E. - : American Physical Society. - 2470-0045 .- 2470-0053. ; 104:2
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Tidskriftsartikel (refereegranskat)abstract
- The chaotic dynamics of a low-order Galerkin truncation of the two-dimensional magnetohydrodynamic system, which reproduces the dynamics of fluctuations described by nearly incompressible magnetohydrodynamic in the plane perpendicular to a background magnetic field, is investigated by increasing the external forcing terms. Although this is the case closest to two-dimensional hydrodynamics, which shares some aspects with the classical Feigenbaum scenario of transition to chaos, the presence of magnetic fluctuations yields a very complex interesting route to chaos, characterized by the splitting into multiharmonic structures of the field amplitudes, and a mixing of phase-locking and free phase precession acting intermittently. When the background magnetic field lies in the plane, the system supports the presence of Alfven waves thus lowering the nonlinear interactions. Interestingly enough, the dynamics critically depends on the angle between the direction of the magnetic field and the reference system of the wave vectors. Above a certain critical angle, independently from the external forcing, a breakdown of the phase locking appears, accompanied with a suppression of the chaotic dynamics, replaced by a simple periodic motion.
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| 8. |
- Giannoccaro, Ilaria, et al.
(författare)
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Search behavior of individuals working in teams: A behavioral study on complex landscapes
- 2020
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Ingår i: Journal of Business Research. - : ELSEVIER SCIENCE INC. - 0148-2963 .- 1873-7978. ; 118, s. 507-516
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Tidskriftsartikel (refereegranskat)abstract
- Search is a fundamental part of complex problem solving and often involves a choice between the exploration of new ideas and the exploitation of already known solutions. While literature has mainly analyzed search behavior of individuals working alone, we investigate search accomplished by individuals working in teams. We study the interplay of three theoretically grounded factors that can affect the search behavior of individuals in teams: the level of behavioral interdependence among team members, the members limited level of knowledge about the problem, and the performance feedback they receive. We operationalize search behavior in terms of search distance, which reflects the extent of exploration in problem space. Results show that high behavioral interdependence reduces exploration, while limited knowledge promotes exploration. Furthermore, positive performance feedback leads to reduced exploration, the more so the lower behavioral interdependence and the more limited knowledge are. We discuss theoretical and practical implications of these results for team design.
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| 9. |
- Krizek, Filip, et al.
(författare)
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Atomically sharp domain walls in an antiferromagnet
- 2022
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 8:13
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Tidskriftsartikel (refereegranskat)abstract
- The interest in understanding scaling limits of magnetic textures such as domain walls spans the entire field of magnetism from its physical fundamentals to applications in information technologies. Here, we explore antiferromagnetic CuMnAs in which imaging by x-ray photoemission reveals the presence of magnetic textures down to nanoscale, reaching the detection limit of this established microscopy in antiferromagnets. We achieve atomic resolution by using differential phase-contrast imaging within aberration-corrected scanning transmission electron microscopy. We identify abrupt domain walls in the antiferromagnetic film corresponding to the Néel order reversal between two neighboring atomic planes. Our work stimulates research of magnetic textures at the ultimate atomic scale and sheds light on electrical and ultrafast optical antiferromagnetic devices with magnetic field–insensitive neuromorphic functionalities.
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| 10. |
- Reimers, Sonka, et al.
(författare)
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Defect-driven antiferromagnetic domain walls in CuMnAs films
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Efficient manipulation of antiferromagnetic (AF) domains and domain walls has opened up new avenues of research towards ultrafast, high-density spintronic devices. AF domain structures are known to be sensitive to magnetoelastic effects, but the microscopic interplay of crystalline defects, strain and magnetic ordering remains largely unknown. Here, we reveal, using photoemission electron microscopy combined with scanning X-ray diffraction imaging and micromagnetic simulations, that the AF domain structure in CuMnAs thin films is dominated by nanoscale structural twin defects. We demonstrate that microtwin defects, which develop across the entire thickness of the film and terminate on the surface as characteristic lines, determine the location and orientation of 180∘ and 90∘ domain walls. The results emphasize the crucial role of nanoscale crystalline defects in determining the AF domains and domain walls, and provide a route to optimizing device performance.
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