| 1. |
- Buntgen, U., et al.
(författare)
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Tree rings reveal globally coherent signature of cosmogenic radiocarbon events in 774 and 993 CE
- 2018
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Though tree-ring chronologies are annually resolved, their dating has never been independently validated at the global scale. Moreover, it is unknown if atmospheric radiocarbon enrichment events of cosmogenic origin leave spatiotemporally consistent fingerprints. Here we measure the 14C content in 484 individual tree rings formed in the periods 770–780 and 990–1000 CE. Distinct 14C excursions starting in the boreal summer of 774 and the boreal spring of 993 ensure the precise dating of 44 tree-ring records from five continents. We also identify a meridional decline of 11-year mean atmospheric radiocarbon concentrations across both hemispheres. Corroborated by historical eye-witness accounts of red auroras, our results suggest a global exposure to strong solar proton radiation. To improve understanding of the return frequency and intensity of past cosmic events, which is particularly important for assessing the potential threat of space weather on our society, further annually resolved 14C measurements are needed.
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| 2. |
- Johnson, Taryn, et al.
(författare)
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Working Ethically with Ancient DNA from Composites in the United States
- 2024
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Ingår i: Advances in archaeological practice. - 2326-3768.
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Tidskriftsartikel (refereegranskat)abstract
- This article discusses ethical frameworks for planning and implementing composite research in the United States. Composites, defined here as archaeological materials with multiple genetic sources, include materials such as sediment, coprolites, birch pitch, and dental calculus. Although composites are increasingly used in genetic research, the ethical considerations of their use in ancient DNA studies have not been widely discussed. Here, we consider how composites' compositions, contexts, and potential to act as proxies can affect research plans and offer an overview of the primary ethical concerns of ancient DNA research. It is our view that ethical principles established for analyses of Ancestral remains and related materials can be used to inform research plans when working with composite evidence. This work also provides a guide to archaeologists unfamiliar with genetics analyses in planning research when using composite evidence from the United States with a focus on collaboration, having a clear research plan, and using lab methods that provide the desired data with minimal destruction. Following the principles discussed in this article and others allows for engaging in composite research while creating and maintaining positive relationships with stakeholders. El presente trabajo analiza las preocupaciones eticas para la planificacion e implementacion de investigaciones compuestas en los Estados Unidos. Los compuestos, definidos aqui como muestras arqueologicas con multiples fuentes geneticas, incluyen materiales como sedimentos, paleofecas, brea de abedul y calculo dental. Sin embargo, si bien los compuestos se han utilizado cada vez mas en la investigacion genetica arqueologica, las consideraciones eticas de su uso en estudios de aADN no se han discutido ampliamente. Aqui consideramos como las composiciones, los contextos y el potencial de los compuestos para actuar como sustitutos pueden afectar los planes de investigacion y ofrecer una vision general de las principales preocupaciones eticas de la investigacion del ADN antiguo. Es la opinion de los autores que los principios eticos establecidos para los analisis de restos humanos y materiales relacionados se pueden utilizar para informar los planes de investigacion cuando se trabaja con evidencia compuesta. Este trabajo ofrece tambien una guia para planificar la investigacion cuando se utiliza evidencia compuesta con un enfoque en la colaboracion, en planes de investigacion claros y uso de metodos de laboratorio que proporcionen los datos deseados con una destruccion minima de la muestra. Seguir los principios descritos en este documento permite participar en la investigacion compuesta sin dejar de lado la creacion y mantencion de relaciones positivas con las partes interesadas.
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