| 1. |
- Allington, Megan L., et al.
(författare)
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Obtaining archaeointensity data from British Neolithic pottery : A feasibility study
- 2021
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Ingår i: Journal of Archaeological Science: Reports. - : Elsevier BV. - 2352-409X. ; 37
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Tidskriftsartikel (refereegranskat)abstract
- There is a significant lack of geomagnetic field strength (archaeointensity) measurements for many archaeological time periods in the United Kingdom (UK). This not only makes past geomagnetic secular variation difficult to model but also limits the development of archaeointensity dating. This paper presents the first archaeointensity study on UK Neolithic material. In this study, twenty-five sherds of Neolithic Grooved Ware pottery from the Ness of Brodgar, Orkney, UK, some with direct radiocarbon dates, were subjected to a full archaeomagnetic investigation with the aim of increasing the amount of archaeointensity data for the UK. Both thermal Thellier and microwave palaeointensity experiments were used to determine which technique would be most suitable for British Neolithic pottery. Three successful archaeointensity results between 35 and 40μT were obtained using thermal Thellier method, which is consistent with the limited data available within a 15° radius and geomagnetic field model predictions from the same time. We separated the results into four different types with an intention of explaining the behaviours that determine the likelihood of achieving an acceptable archaeointensity estimate. The feasibility of obtaining geomagnetic field strength information during the UK Neolithic from ceramics has been demonstrated and the results provide a solid basis for improving our knowledge of geomagnetic secular variation during archaeological time in Britain.
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| 2. |
- Condello, Carlo, et al.
(författare)
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Structural heterogeneity and intersubject variability of A beta in familial and sporadic Alzheimer's disease
- 2018
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 115:4, s. E782-E791
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Tidskriftsartikel (refereegranskat)abstract
- Point mutations in the amyloid-beta (A beta) coding region produce a combination of mutant and WT A beta isoforms that yield unique clinicopathologies in familial Alzheimer's disease (fAD) and cerebral amyloid angiopathy (fCAA) patients. Here, we report a method to investigate the structural variability of amyloid deposits found in fAD, fCAA, and sporadic AD (sAD). Using this approach, we demonstrate that mutant A beta determines WT A beta conformation through prion template-directed misfolding. Using principal component analysis of multiple structure-sensitive fluorescent amyloid-binding dyes, we assessed the conformational variability of A beta deposits in fAD, fCAA, and sAD patients. Comparing many deposits from a given patient with the overall population, we found that intrapatient variability is much lower than interpatient variability for both disease types. In a given brain, we observed one or two structurally distinct forms. When two forms coexist, they segregate between the parenchyma and cerebrovasculature, particularly in fAD patients. Compared with sAD samples, deposits from fAD patients show less intersubject variability, and little overlap exists between fAD and sAD deposits. Finally, we examined whether E22G (Arctic) or E22Q (Dutch) mutants direct the misfolding of WT A beta, leading to fAD-like plaques in vivo. Intracerebrally injecting mutant A beta 40 fibrils into transgenic mice expressing only WT A beta induced the deposition of plaques with many biochemical hallmarks of fAD. Thus, mutant A beta 40 prions induce a conformation of WT A beta similar to that found in fAD deposits. These findings indicate that diverse AD phenotypes likely arise from one or more initial A beta prion conformations, which kinetically dominate the spread of prions in the brain.
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