Variegated squirrel bornavirus 1 in squirrels, Germany and the Netherlands

We screened squirrels in Germany and the Netherlands for the novel zoonotic variegated squirrel bornavirus 1 (VSBV-1). The detection of VSBV-1 in 11 squirrels indicates a considerable risk for transmission to humans handling those animals. Therefore, squirrels in contact with humans should routinely be tested for VSBV-1

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Precessional magnetization dynamics (in the f- and t-domain)

Precessional Magnetization Dynamics VI.1 - 1 B. Koopmans 1 – MACROSPIN DYNAMICS & LLG 1-1 Precessing spin from a quantum mechanical viewpoint 1-2 Landau-Lifzhits Gilbert equation 1-3 Damping of precessional modes 1-4 Small angle precession and Kittel relation for thin film systems 1-5 Precessional switching 2 – MEASURING PRECESSIONAL DYNAMICS 2-1 Time and frequency domain techniques 2-2 FerroMagnetic Resonance 2-3 Brillouin Light Scattering 2-4 Time domain techniques: magnetic field & optical excitation 2-5 Time-Resolved Magneto-Optical Kerr Effect 2-6 Pulsed Inductive Microwave Magnetometer 3 – SPIN WAVES IN THIN FILMS AND MULTILAYERS 3-1 Perpendicular standing spin wave modes 3-2 All-optically probing spin wave dispersion 3-3 Spin wave dispersion for different orientation of M and k 3-4 Emission of spin waves after local excitation 3-5 Damping by spin pumping 4 – MICROMAGNETIC STRUCTURES AND DEVICES 4-1 Spin wave modes in micromagnetic structures 4-2 Mapping of modes by optical means 4-3 Dynamics of multilayered device

Spin transport and magnetoresistance in organic semiconductors

\u3cp\u3eOrganic semiconductors are interesting materials for spintronics applications because of their long spin lifetimes. In addition, organic spintronics offers the possibility to add magnetic functionality to existing organic electronics. Two main topics of organic spintronics are discussed. First, in organic spin valves, spin transport occurs through an organic spacer layer. As a main source of loss of spin polarization the interactions of the spins with random hyperfine fields originating from surrounding hydrogen nuclei has been identified. Recent progress in the development of organic spin valves and related approaches are discussed, addressing conductivity mismatch and the question whether the observed magnetoresistance is from spin injection or direct tunneling. Second, an intrinsic magnetoresistance is observed in many organic semiconductors. This, so-called, organic magnetoresistance (OMAR) is interesting because it shows large effects at room temperature, making it interesting for applications, and poses fundamental questions about spin transport and spin interactions in these organic materials. An overview of the main characteristics of OMAR is given and the three main models are discussed. These models are the bipolaron model, the electron-hole pair model and the exciton-charge interaction model. Finally, a comparison is made between the proposed models and experimental results, where it is concluded that the exact origin of OMAR is still open for debate.\u3c/p\u3

Spin accumulation and dynamics in Inversion-Symmetric van der Waals crystals

Inversion-symmetric materials are forbidden to show an overall spin texture in their band structure in the presence of time-reversal symmetry. However, in van der Waals materials which lack inversion symmetry within a single layer, it has been proposed that a layer-dependent spin texture can arise leading to a coupled spin-layer degree of freedom. Here we use time-resolved Kerr rotation in inversion-symmetric WSe2 and MoSe2 bulk crystals to study this spin-layer polarization and unveil its dynamics. Our measurements show that the spin-layer relaxation time in WSe2 is limited by phonon scattering at high temperatures and that the interlayer hopping can be tuned by a small in-plane magnetic field at low temperatures, enhancing the relaxation rates. We find a significantly lower lifetime for MoSe2 which agrees with theoretical expectations of a spin-layer polarization stabilized by the larger spin-orbit coupling in WSe2