Brage Nord Open Research Archive
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Single-cell RNA sequencing reveals the immune cell landscape of head kidney in the Perciform fish (Micropterus salmoides)
Full text linkTeleost fish, a key transitional group in vertebrate evolution, possess immune systems that diverge substantially from those of mammals in structure, composition, and function. Within this group, the order Perciformes stands out for its ecological breadth, evolutionary significance, and value as a model for immunological research. However, the cellular complexity and developmental dynamics of their immune system remain insufficiently characterized. In this study, we employed single-cell RNA sequencing (scRNA-seq) to construct a comprehensive transcriptomic atlas of the head kidney in largemouth bass (Micropterus salmoides), a representative perciform species. We identified and annotated eight major hematopoietic and stromal cell populations, including hematopoietic stem/progenitor cells (HSPCs), erythrocytes (Eryt), granulocytes (Gran), macrophages (Mac), dendritic cells (DC), T and B cells, and mesenchymal stromal cells (MSCs). Subsequent analyses revealed extensive subpopulation heterogeneity across these lineages. We delineated early progenitor subsets, mapped B cell developmental trajectories, and characterized functionally distinct Mac and T cell subtypes. Notably, we identified Eryt cells exhibiting high MHC class II expression, supporting immunological roles beyond oxygen transport. A dot plot of core erythrocyte genes revealed largely lineage-restricted expression. However, several hemoglobin paralogs were also expressed in non-erythroid cells, suggesting functional divergence. Additionally, we identified a putative Gran-erythroid progenitor population and Mac subsets with distinct transcriptional profiles, underscoring the complexity, potential functionality, and wide diversity of specialized immune cell dynamics in Perciformes. Together, these findings significantly advance our understanding of teleost immune cell diversity and lineage specialization. The generated cell atlas provides a valuable resource and novel perspectives for deciphering fish immunity and hematopoiesis, advancing comparative immunology, and informing aquaculture health management.publishedVersio
Toward more sustainable road freight transport
Full text linkDoctoral thesis (PhD) - Nord University, 2025publishedVersio
Patient Transfer Process From Pre-Hospital to the Hospital Emergency Department: A Grounded Theory Study
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Working Capital and Liquidity Management: A Dynamic Pathway to Enhancing Corporate Performance
Full text linkDoctoral thesis (PhD) - Nord University, 2025publishedVersio
Climatic variation affects seasonal survival of an alpine bird species
Full text linkMountains are particularly exposed to climate change, and empirical studies haveshown that montane bird species are highly sensitive to the ongoing changes. Modellingmortality risks under climatic variation will give insight into species-specific sensitivity.Willow ptarmigan Lagopus l. lagopus is a common resident species in many northernalpine ecosystems, with an important role in predator–prey dynamics. Willow ptar-migan moult into white feathers during autumn, which provides camouflage in thewinter snow. With shorter periods of snow cover, a phenological mismatch betweensnow cover and moulting time may affect mortality risk. Simultaneously, snow covermay affect mortality risk through limiting the access to nutrient-rich food and increas-ing risk-taking. Detailed relationships between snow cover and mortality risk requirehigh-resolution data to uncover. We collected data from willow ptarmigan (n = 272)equipped with VHF transmitters over seven years in central Norway. Field data collec-tion was performed on a monthly basis, except in the darkest period of winter. UsingCox proportional hazards models, we estimated whether variation in mortality risk wasrelated to variation in snow cover in the spring and autumn seasons. We found thatan earlier arrival of winter led to increased mortality risk for yearlings, but not adults,in the following spring. Further, spring mortality was lower when there was less snowin the spring. In autumn, mortality risk differed only between sexes. In our study wehave shown that spring survival in a common montane species is affected by climaticvariation, where the magnitude of effects on population dynamics will depend on theage distribution in the population. We hypothesise that there are competing risks con-nected with a moulting mismatch versus increased risk-taking under limited access tofood resources, that may have different importance under different conditions. age, alpine ecosystem, autumn, climate, colour change, competing risks,grouse, individual-based, lagopus, mortality, snow, spring, willow ptarmiganpublishedVersio
Characterization and Modelling of Potential Seaborne Disasters, in the ANA Region
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Assessing the robustness and implications of econometric estimates of climate sensitivity
Full text linkEarth's transient climate response (TCR) quantifies the global mean surface air temperature change due to a doubling of atmospheric CO2 concentration after 70 years of a compounding 1% per year increase. TCR is highly correlated with near-term climate projections, and thus of relevance for climate policy, but remains poorly constrained in part due to uncertainties in the representation of key physical processes in Earth System Models (ESMs). Within state-of-the-art ESMs participating in the Coupled Model Intercomparison Project (CMIP6), the TCR range (1.1 ºC–2.9 ºC) is too wide to offer useful guidance to policymakers. Similarly, the sixth report of the Intergovernmental Panel on Climate Change, while not solely reliant on ESMs for its TCR assessment, produced a very likely range of 1.2 ºC–2.4 ºC. To complement earlier, ESM-based, estimates, we here present a new TCR estimate of 2.17 (1.72–2.77) ºC (95% confidence interval), derived based on a statistical relationship between surface air temperature and observational proxies for its main drivers, i.e. changes in atmospheric greenhouse gases and aerosols. We show that, within uncertainty, this method correctly diagnoses TCR from 20 CMIP6 ESMs if the same input variables are taken from the ESMs that are available from observations. This increases confidence in the new observation-based central estimate and range, which is respectively higher and narrower than the mean and spread of the estimates from the entire ensemble of CMIP6. Many ESM-based estimates tend to produce TCRs lower than the observational range reported here. Our findings suggest that a misrepresentation of the aerosol cooling effect could be the cause of this discrepancy. Further, the revised TCR estimate suggests a downward revision of the remaining carbon budgets aligned with the overarching goal of the Paris agreement.publishedVersio
Modelled surface climate response to effusive Icelandic volcanic eruptions: sensitivity to season and size
Full text linkEffusive, long-lasting volcanic eruptions impact climate through the emission of gases and the subsequent production of aerosols. Previous studies, both modelling and observational, have made efforts to quantify these impacts and untangle them from natural variability. However, due to the scarcity of large and well-observed effusive volcanic eruptions, our understanding remains patchy. Here, we use an Earth system model to systematically investigate the climate response to high-latitude, effusive volcanic eruptions, similar to the 2014–2015 Holuhraun eruption in Iceland, as a function of eruption season and size. The results show that the climate response is regional and strongly modulated by different seasons, exhibiting midlatitude cooling during summer and Arctic warming during winter. Furthermore, as eruptions increase in size in terms of sulfur dioxide emissions, the climate response becomes increasingly insensitive to variations in emission strength, levelling off for eruptions between 20 and 30 times the size of the 2014–2015 Holuhraun eruption. Volcanic eruptions are generally considered to lead to surface cooling, but our results indicate that this is an oversimplification, especially in the Arctic, where warming is found to be the dominant response during autumn and winter.publishedVersio