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Abstract The optical intersite spin transfer (OISTR) effect was recently verified in Fe50Ni50 using extreme ultraviolet magneto-optical Kerr measurements. However, one of the main experimental signatures analyzed in this work, namely a magnetic moment increase at a specific energy in Ni, was subsequently found also in pure Ni, where no transfer from one element to another is possible. Hence, it is a much-discussed issue whether OISTR in FeNi alloys is real and whether it can be verified experimentally or not. Here, we present a comparative study of spin transfer in Fe50Ni50, Fe19Ni81 and pure Ni. We conclusively show that an increase in the magneto-optical signal is indeed insufficient to verify OISTR. However, we also show how an extended data analysis overcomes this problem and allows to unambiguously identify spin transfer effects. Concomitantly, our work solves the long-standing riddle about the origin of delayed demagnetization behavior of Ni in FeNi alloys.

The magneto-optical Kerr effect (MOKE) in the extreme ultraviolet (EUV) regime has helped to elucidate some of the key processes that lead to the manipulation of magnetism on ultrafast timescales. However, as we show in this paper, the recently introduced spectrally resolved analysis of such data can lead to surprising experimental observations, which might cause misinterpretations. Therefore, an extended analysis of the EUV magneto-optics is necessary. Via experimental determination of the dielectric tensor, we find here that the nonequilibrium excitation in an ultrafast magnetization experiment can cause a rotation of the off-diagonal element of the dielectric tensor in the complex plane. In direct consequence, the commonly analyzed magneto-optic asymmetry may show time-dependent behavior that is not directly connected to the magnetic properties of the sample. We showcase such critical observations for the case of ultrafast magnetization dynamics in Ni, and give guidelines for the future analysis of spectrally resolved magneto-optical data and its comparison with theory.

Abstract Spin injection across interfaces driven by ultrashort optical pulses on femtosecond timescales constitutes a new way to design spintronics applications. Targeted utilization of this phenomenon requires knowledge of the efficiency of non‐equilibrium spin injection. From a quantitative comparison of ab initio time‐dependent density functional theory and interface‐sensitive, time‐resolved non‐linear optical experiment, the spin injection efficiency (SIE) at the Co/Cu(001) interface is determined, and its microscopic origin, i.e., the influence of spin‐orbit coupling and the interface electronic structure, is discussed. Moreover, we theoretically predict that the SIE at ferromagnetic–metal interfaces can be optimized through laser pulse and materials parameters, namely the fluence, pulse duration, and substrate material.

Abstract Background To provide a model for Public involvement (PI) in instrument development and other research based on lessons learnt in the co-production of a recently developed mental health patient reported outcome measure called Recovering Quality of Life (ReQoL). While service users contributed to the project as research participants, this paper focuses on the role of expert service users as research partners, hence referred to as expert service users or PI. Methods At every stage of the development, service users influenced the design, content and face validity of the measure, collaborating with other researchers, clinicians and stakeholders who were central to this research. Expert service users were integral to the Scientific Group which was the main decision-making body, and also provided advice through the Expert Service User Group. Results During the theme and item generation phase (stage 1) expert service users affirmed the appropriateness of the seven domains of the Patient Reported Outcome Measure (activity, hope, belonging and relationships, self-perception, wellbeing, autonomy, and physical health). Expert service users added an extra 58 items to the pool of 180 items and commented on the results from the face and content validity testing (stage 2) of a refined pool of 88. In the item reduction and scale generation phase (stage 3), expert service users contributed to discussions concerning the ordering and clustering of the themes and items and finalised the measures. Expert service users were also involved in the implementation and dissemination of ReQoL (stage 4). Expert service users contributed to the interpretation of findings, provided inputs at every stage of the project and were key decision-makers. The challenges include additional work to make the technical materials accessible, extra time to the project timescales, including time to achieve consensus from different opinions, sometimes strongly held, and extra costs. Conclusion This study demonstrates a successful example of how PI can be embedded in research, namely in instrument development. The rewards of doing so cannot be emphasised enough but there are challenges, albeit surmountable ones. Researchers should anticipate and address those challenges during the planning stage of the project.

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Optically induced spin transfer (OISTR) is a pathway to control magnetization dynamics in complex materials on femto- to attosecond timescales. The direct interaction of the laser field with the material creates transient nonequilibrium states, which can exhibit an efficient spin transfer between different magnetic subsystems. How far this spin manipulation via OISTR is a general phenomenon or restricted to a subset of materials with specific properties is an open experimental and theoretical question. Using time-resolved magneto-optical Kerr measurements and time-dependent density functional theory we investigate OISTR in Heusler compounds. We show that the half-Heusler materials NiMnSb and CoMnSb exhibit strong signatures of OISTR, whereas this is less pronounced in the full-Heusler compounds Co_{2}MnSi, Co_{2}FeSi, and Co_{2}FeAl in agreement with ab initio calculations. Our work opens up a systematic path for coherent manipulation of spin dynamics by direct light-matter interaction.

Gran parte de la economía moderna, incluidos en particular los paradigmas dominantes en macroeconomía y economía financiera, supone que hay un modelo “verdadero” del mundo, el cual se puede deducir de un conjunto de axiomas basados en la elección racional. Pero en realidad no hay, ni puede haber, un modelo que describa “el mundo tal como es realmente”. Los modelos son herramientas útiles en economía, e incluso indispensables, pero son necesariamente parciales, provisionales y específicos al contexto. El enfoque de la economía debe ser pluralista, es decir, debe usar el razonamiento inductivo y el razonamiento deductivo. El mapa no es el territorio.

Ultrafast control over the magnetic orientation of matter represents a vital element of potential future spin-based electronics ("spintronics"). While physical mechanisms underpinning spin switching are established for picosecond time scales, we here present a physical route to magnetization toggle control, i.e., multiple switching events, at <100 femtoseconds. A minority spin current injected into a ferromagnet is shown to generate rapid depopulation of the minority channel below the ground-state Fermi level, creating a minority "spin vacuum" that then drives rapid charge redistribution from the majority channel and spin switching. We demonstrate that this mechanism reproduces many of the features of recent subpicosecond switching of ferromagnetic Co/Pt multilayers and provide simple practical rules for the design of materials via tailoring the electronic density of states to optimize spin vacuum control over magnetic order. [ABSTRACT FROM AUTHOR]

Abstract Little is known about the pathobiology of SARS-CoV-2 infection in sub-Saharan Africa, where severe COVID-19 fatality rates are among the highest in the world and the immunological landscape is unique. In a prospective cohort study of 306 adults encompassing the entire clinical spectrum of SARS-CoV-2 infection in Uganda, we profile the peripheral blood proteome and transcriptome to characterize the immunopathology of COVID-19 across multiple phases of the pandemic. Beyond the prognostic importance of myeloid cell-driven immune activation and lymphopenia, we show that multifaceted impairment of host protein synthesis and redox imbalance define core biological signatures of severe COVID-19, with central roles for IL-7, IL-15, and lymphotoxin-α in COVID-19 respiratory failure. While prognostic signatures are generally consistent in SARS-CoV-2/HIV-coinfection, type I interferon responses uniquely scale with COVID-19 severity in persons living with HIV. Throughout the pandemic, COVID-19 severity peaked during phases dominated by A.23/A.23.1 and Delta B.1.617.2/AY variants. Independent of clinical severity, Delta phase COVID-19 is distinguished by exaggerated pro-inflammatory myeloid cell and inflammasome activation, NK and CD8+ T cell depletion, and impaired host protein synthesis. Combining these analyses with a contemporary Ugandan cohort of adults hospitalized with influenza and other severe acute respiratory infections, we show that activation of epidermal and platelet-derived growth factor pathways are distinct features of COVID-19, deepening translational understanding of mechanisms potentially underlying SARS-CoV-2-associated pulmonary fibrosis. Collectively, our findings provide biological rationale for use of broad and targeted immunotherapies for severe COVID-19 in sub-Saharan Africa, illustrate the relevance of local viral and host factors to SARS-CoV-2 immunopathology, and highlight underemphasized yet therapeutically exploitable immune pathways driving COVID-19 severity.

BackgroundChikungunya virus (CHIKV) and O'nyong nyong virus (ONNV) are phylogenetically related alphaviruses in the Semliki Forest Virus (SFV) antigenic complex of the Togaviridae family. There are limited data on the circulation of these two viruses in Burkina Faso. The aim of our study was to assess their circulation in the country by determining seroprevalence to each of the viruses in blood donor samples and by retrospective molecular and serological testing of samples collected as part of national measles and rubella surveillance.Methodology/principal findingsAll blood donor samples were analyzed on the Luminex platform using CHIKV and ONNV E2 antigens. Patient samples collected during national measles-rubella surveillance were screened by an initial ELISA for CHIKV IgM (CHIKjj Detect IgM ELISA) at the national laboratory. The positive samples were then analyzed by a second ELISA test for CHIKV IgM (CDC MAC-ELISA) at the reference laboratory. Finally, samples that had IgM positive results for both ELISA tests and had sufficient residual volume were tested by plaque reduction neutralization testing (PRNT) for CHIKV and ONNV. These same patient samples were also analyzed by rRT-PCR for CHIKV. Among the blood donor specimens, 55.49% of the samples were positive for alphaviruses including both CHIKV and ONNV positive samples. Among patient samples collected as part of national measles and rubella surveillance, 3.09% were IgM positive for CHIKV, including 2.5% confirmed by PRNT. PRNT failed to demonstrate any ONNV infections in these samples. No samples tested by RT-qPCR. had detectable CHIKV RNA.Conclusions/significanceOur results suggest that CHIKV and ONNV have been circulating in the population of Burkina Faso and may have been confused with malaria, dengue fever or other febrile diseases such as measles or rubella. Our study underscores the necessity to enhance arbovirus surveillance systems in Burkina Faso.

Objectives: Understanding the immune response in very mild and asymptomatic COVID-19 is crucial for developing effective vaccines and immunotherapies, yet remains poorly characterized. This longitudinal study examined the evolution of interferon (IFN)-γ responses to SARS-CoV-2 peptides in 109 asymptomatic or mildly symptomatic Ugandan COVID-19 patients across 365 days and explored their association with antibody generation. Methods: T-cell responses to spike-containing clusters of differentiation (CD4)-S and CD8 nCoV-A (CD8-A) megapools, and the non-spike CD4-R and CD8 nCoV-B (CD8-B) megapools, were assessed and correlated with demographic and temporal variables. Results: SARS-CoV-2-specific IFN-γ responses were consistently detected in all peptide pools and time points, with the spike-targeted response exhibiting higher potency and durability than the non-spike responses. Throughout the entire 365-day infection timeline, a robust positive correlation was observed between CD4 T-cell responses to the spike-derived peptides and anti-spike immunoglobulin G antibody levels, underscoring their interdependent dynamics in the immune response against SARS-CoV-2; in contrast, CD8 T-cell responses exhibited no such correlation, highlighting their distinctive, autonomous role in defense. No meaningful variations in complete blood count parameters were observed between individuals with COVID-19 infection and those without, indicating clinical insignificance. Conclusions: This study highlights the dominant role of spike-directed T-cell responses in mild and asymptomatic disease and provides crucial longitudinal data from Sub-Saharan African settings. The findings provide valuable insights into the dynamics of T-cell responses and their potential significance in developing effective strategies for combating COVID-19.