| 1. |
- Johansson, Emil, et al.
(författare)
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Aspects of Modeling Human Behavior in Agent-Based Social Simulation – What Can We Learn from the COVID-19 Pandemic?
- 2024
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Ingår i: Multi-Agent-Based Simulation XXIV. - : Springer. - 9783031610332 - 9783031610349 ; , s. 83-98
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Konferensbidrag (refereegranskat)abstract
- Proper modeling of human behavior is crucial when developing agent-based models to investigate the effects of policies, such as the potential consequences of interventions during a pandemic. It is, however, unclear, how sophisticated behavior models need to be for being considered suitable to support policy making. The goal of this paper is to identify recommendations on how human behavior should be modeled in Agent-Based Social Simulation (ABSS) as well as to investigate to what extent these recommendations are actually followed by models explicitly developed for policy making. By analyzing the literature, we identify seven relevant aspects of human behavior for consideration in ABSS. Based on these aspects, we review how human behavior is modeled in ABSS of COVID-19 interventions, in order to investigate the capabilities and limitations of these models to provide policy advice. We focus on models that were published within six months of the start of the pandemic as this is when policy makers needed the support provided by ABSS the most. It was found that most models did not include the majority of the identified relevant aspects, in particular norm compliance, agent deliberation, and interventions’ affective effects on individuals. We argue that ABSS models need a higher level of descriptiveness than what is present in most of the studied early COVID-19 models to support policymaker decisions.
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| 2. |
- Johansson, Emil, et al.
(författare)
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HIV-2 mediated effects on target and bystander cells induce plasma proteome remodeling
- 2024
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Ingår i: iScience. - : Cell Press. - 2589-0042. ; 27:4
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Tidskriftsartikel (refereegranskat)abstract
- Despite low or undetectable plasma viral load, people living with HIV-2 (PLWH2) typically progress toward AIDS. The driving forces behind HIV-2 disease progression and the role of viremia are still not known, but low-level replication in tissues is believed to play a role. To investigate the impact of viremic and aviremic HIV-2 infection on target and bystander cell pathology, we used data-independent acquisition mass spectrometry to determine plasma signatures of tissue and cell type engagement. Proteins derived from target and bystander cells in multiple tissues, such as the gastrointestinal tract and brain, were detected at elevated levels in plasma of PLWH2, compared with HIV negative controls. Moreover, viremic HIV-2 infection appeared to induce enhanced release of proteins from a broader range of tissues compared to aviremic HIV-2 infection. This study expands the knowledge on the link between plasma proteome remodeling and the pathological cell engagement in tissues during HIV-2 infection.
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| 3. |
- Johansson, Emil, 1987-
(författare)
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Reflective conversations at practicum : A matter of control
- 2024
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Ingår i: Book of Abstracts. - 9789528601586 ; , s. 462-463
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Konferensbidrag (refereegranskat)abstract
- The purpose of the case study is to contribute knowledge about how supervisors guide student teachers (ST) in reflective conversations before and after their teaching at practicum, and how supervisors seem to influence STs to experience their practicums in constructive ways. The methodology consisted of me observing two STs teaching on three occasions, recording the reflecting conversation they had with their supervisor after the lesson, and conducting an in-depth interview with the STs after their practicum period. The focus when collecting the empirical material was to shed light on how the supervisors seemed to influence STs’ reflections on their teaching during practicum, and how these reflections affect what experiences STs gain from their teaching practice and stimulate their further growth as professional teachers. When analyzing the material, I focused on how controlling the supervisor’s guidance was in the reflecting conversations, whether they asked questions, explained, or instructed, and how the PETE students responded to their guidance. To do that, I used Biesta’s (2022) concept “act of pointing”, which describes what and how educators direct students to focus on. Then in the next step, I focused on how the STs experienced their practicum based on these reflective conversations and the in-depth interview. For this, I used Dewey’s (2015) understanding of what separates the meaning of experiencing and having an experience, and how different experiences can be described as educative, non-educative, or mis-educative. The results indicate that the supervisors’ guidance varied regarding how controlling they were, and I identified four different acts of pointing in the reflective conversations: - The restrained and constructive ‘act of pointing’, - The rule-focused ‘act of pointing’, - The direct and technical ‘act of pointing’ - The restricted and condemning ‘act of pointing’ Based on these various acts of pointing, I describe the STs' gained experiences as two different kinds of journeys during their practicum. ST A gained educative experiences - he experienced an adventurous journey because he got the opportunity to experience unexpected situations during practicum and thoroughly reflect on them. ST B gained non-edu-cative, or maybe even mis-educative experiences - he was restricted and often told what to do, making his reflections technical and superficial. Enabling STs to find their own path as teacher can stimulate their professional growth as teachers and make them gain educative experiences, that stimulate their growth in a constructive direction. However, supervisors’ control over STs cannot be too free, they need to control them somehow – it is a matter of loosening the control, but never losing it.Biesta, G. (2022). World-centered education: a view for the present. Routledge.Dewey, J. (2015). Experience And Education (Reprint ed.). Free Press.
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| 4. |
- Johansson, Emil, 1987-
(författare)
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Supervisors’ guidance of PETE students’ reflections at practicum: creating conditions for different learning journeys
- 2024
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Ingår i: Reflective Practice. - : Taylor & Francis. - 1462-3943 .- 1470-1103. ; , s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Physical education teacher education (PETE) students’ reflections on their practicums are influenced by how their supervisors guide them. Supervisors often evaluate and discuss PETE students’ teaching by guiding their focus on essential aspects to consider. This exploratory case study focuses on how supervisors’ guiding styles in reflective conversations affect how PETE students make meaning of their teaching. Reflective practitioners, in this case PETE students, make sense of practical situations from their own perspectives as part of their teaching practice. Supervisors’ guidance is essential here, because it can change PETE students’ understanding by (re)directing their attention to meaningful aspects when framing their teaching and help them to examine it from new perspectives. However, the findings indicate that supervisors’ various guidance affect how PETE students experience their learning journeys during practicum. In this study, the participating PETE students’ experiences of practicum differed: either they experienced a controlled journey that restricted their teaching due to predefined rules and condemning attitude toward pupils, or they experienced an adventurous journey that enabled them to find their own paths as a teachers.
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| 5. |
- König, J. Lukas K., 1996-, et al.
(författare)
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Nodal phases in non-Hermitian wallpaper crystals
- 2024
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Ingår i: Applied Physics Letters. - 0003-6951 .- 1077-3118. ; 124:5
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Tidskriftsartikel (refereegranskat)abstract
- Symmetry and non-Hermiticity play pivotal roles in photonic lattices. While symmetries, such as parity-time (PT) symmetry, have attracted ample attention, more intricate crystalline symmetries have been neglected in comparison. Here, we investigate the impact of the 17 wallpaper space groups of two-dimensional crystals on non-Hermitian band structures. We show that the non-trivial space group representations enforce degeneracies at high symmetry points and dictate their dispersion away from these points. In combination with either T or PT, the symmorphic p4 mm symmetry and the non-symmorphic p2mg, p2gg, and p4gm symmetries protect exceptional chains intersecting at the pertinent high symmetry points.
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| 6. |
- Slootman, E., et al.
(författare)
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Breaking and resurgence of symmetry in the non-Hermitian Su-Schrieffer-Heeger model in photonic waveguides
- 2024
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Ingår i: Physical Review Research. - 2643-1564. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- Symmetry is one of the cornerstones of modern physics and has profound implications in different areas. In symmetry-protected topological systems, symmetries are responsible for protecting surface states, which are at the heart of the fascinating properties exhibited by these materials. When the symmetry protecting the edge mode is broken, the topological phase becomes trivial. By engineering losses that break the symmetry protecting a topological Hermitian phase, we show that a new genuinely non-Hermitian symmetry emerges, which protects and selects one of the boundary modes: the topological monomode. Moreover, the topology of the non-Hermitian system can be characterized by an effective Hermitian Hamiltonian in a higher dimension. To corroborate the theory, we experimentally investigated the non-Hermitian one- and two-dimensional SSH models using photonic lattices and observed dynamically generated monomodes in both cases. We classify the systems in terms of the (non-Hermitian) symmetries that are present and calculate the corresponding topological invariants.
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| 7. |
- Wistrand Johansson, Emil
(författare)
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The role of UN investigative mechanism in anchoring fairness in the collaborative turn of international criminal investigations
- 2024
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Rapport (refereegranskat)abstract
- Increased solidification of accountability norms in relation to international responses to conflict has led to a collaborative turn where new actors – across international and national, public and private divides – participate and collaborate in investigations of core international crimes. This decentralized and highly relational reality of contemporary investigations challenges established understandings of how fairness is to be safeguarded for suspects, victims and witnesses affected by the practices of investigative and prosecutorial actors. Safeguarding fairness in the collaborative turn is crucial because fairness is at the heart of the identity of international criminal law. It is argued that UN investigative mechanisms for Syria (IIIM), Myanmar (IIMM), Da’esh in Iraq (UNITAD) and other similar UN quasi-prosecutorial mandate-holders are well-placed to play a more active and coordinating role in safeguarding fairness in this collaborative turn, in particular vis-à-vis investigative civil society actors. Although lacking capacity to single-handedly foster fairness in investigative practices in conflict situations, UN investigative mechanisms and investigations have the capacity to anchor the collaborative turn in law and public authority, based on principles of impartiality, independence and fairness.
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| 8. |
- Zelenayova, Maria, et al.
(författare)
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Non-Hermitian extended midgap states and bound states in the continuum
- 2024
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Ingår i: Applied Physics Letters. - 0003-6951 .- 1077-3118. ; 124:4
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Tidskriftsartikel (refereegranskat)abstract
- We investigate anomalous localization phenomena in non-Hermitian systems by solving a class of generalized Su-Schrieffer-Heeger/Rice-Mele models and by relating their provenance to fundamental notions of topology, symmetry-breaking, and biorthogonality. We find two types of bound states in the continuum, both stable even in the absence of chiral symmetry: the first being skin bulk states, which are protected by the spectral winding number. The second type is constituted by boundary modes associated with a quantized biorthogonal polarization. Furthermore, we find an extended state stemming from the boundary state that delocalizes while remaining in the gap at bulk critical points. This state may also delocalize within a continuum of localized (skin) states. These results clarify fundamental aspects of topology and symmetry in light of different approaches to the anomalous non-Hermitian bulk-boundary correspondence and are of direct experimental relevance for mechanical, electrical, and photonic systems.
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| 9. |
- Abouelkomsan, Ahmed, 1995-, et al.
(författare)
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Quantum metric induced phases in Moiré materials
- 2023
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Ingår i: Physical Review Research. - 2643-1564. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- We show that, quite generally, quantum geometry plays a major role in determining the low-energy physics in strongly correlated lattice models at fractional band fillings. We identify limits in which the Fubini-Study metric dictates the ground states and show that this is highly relevant for Moiré materials leading to symmetry breaking and interaction driven Fermi liquids. This phenomenology stems from a remarkable interplay between the quantum geometry and interaction which is absent in continuum Landau levels but generically present in lattice models where these terms tend to destabilize, e.g., fractional Chern insulators. We explain this as a consequence of the fundamental asymmetry between electrons and holes for band projected normal ordered interactions, as well as from the perspective of a self-consistent Hartree-Fock calculation. These basic insights about the role of the quantum metric, when dominant, turn an extremely strongly coupled problem into an effectively weakly coupled one, and may also serve as a guiding principle for designing material setups. We argue that this is a key ingredient for understanding symmetry-breaking phenomena recently observed in Moiré materials.
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| 10. |
- He, Yuchi, et al.
(författare)
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Superconductivity of repulsive spinless fermions with sublattice potentials
- 2023
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Ingår i: Physical Review Research. - 2643-1564. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- We explore unconventional superconductivity of repulsive spinless fermions on square and honeycomb lattices with staggered sublattice potentials. The two lattices can exhibit staggered d-wave and f-wave pairing, respectively, at low doping stemming from an effective two-valley band structure. At higher doping, in particular, the square lattice displays a much richer phase diagram including topological p+ip superconductivity which is induced by a qualitatively different mechanism compared to the d-wave pairing. We illuminate this from several complementary perspectives: We analytically perform sublattice projection to analyze the effective continuum low-energy description and we numerically calculate the binding energies for pair and larger bound states for few-body doping near half filling. Furthermore, for finite doping, we present phase diagrams based on extensive functional renormalization group and and density matrix renormalization group calculations.
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