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- Sikora, M., et al.
(författare)
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The population history of northeastern Siberia since the Pleistocene
- 2019
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 570:7760
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Tidskriftsartikel (refereegranskat)abstract
- Northeastern Siberia has been inhabited by humans for more than 40,000 years but its deep population history remains poorly understood. Here we investigate the late Pleistocene population history of northeastern Siberia through analyses of 34 newly recovered ancient genomes that date to between 31,000 and 600 years ago. We document complex population dynamics during this period, including at least three major migration events: an initial peopling by a previously unknown Palaeolithic population of 'Ancient North Siberians' who are distantly related to early West Eurasian hunter-gatherers; the arrival of East Asian-related peoples, which gave rise to 'Ancient Palaeo-Siberians' who are closely related to contemporary communities from far-northeastern Siberia (such as the Koryaks), as well as Native Americans; and a Holocene migration of other East Asian-related peoples, who we name 'Neo-Siberians', and from whom many contemporary Siberians are descended. Each of these population expansions largely replaced the earlier inhabitants, and ultimately generated the mosaic genetic make-up of contemporary peoples who inhabit a vast area across northern Eurasia and the Americas.
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- Biberfeld, P, et al.
(författare)
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Lymphoma development in SIV infected monkeys
- 1997
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Ingår i: JOURNAL OF ACQUIRED IMMUNE DEFICIENCY SYNDROMES AND HUMAN RETROVIROLOGY. - 1077-9450. ; 14:4, s. 141-141
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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- Kukli, K., et al.
(författare)
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Atomic layer deposition of ZrO2 and HfO2 on deep trenched and planar silicon
- 2007
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 84:9-10, s. 2010-2013
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Tidskriftsartikel (refereegranskat)abstract
- Conformal ZrO2 and HfO2 thin films were grown by atomic layer deposition using novel liquid cyclopentadienyl precursors at 300 degrees C or 350 degrees C on planar Si wafers and deep trenched Si with an aspect ratio of 60:1. The crystal growth and phase content in as-deposited films depended on the precursor, film thickness, and the material grown. The structural and electrical behaviour of the films were somewhat precursor-dependent, revealing better insulating properties in the films grown from oxygen-containing precursors. Also the HfO2 films showed lower leakage compared to ZrO2.
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- Oehri, Jacqueline, et al.
(författare)
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Vegetation type is an important predictor of the arctic summer land surface energy budget
- 2022
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Despite the importance of high-latitude surface energy budgets (SEBs) for land-climate interactions in the rapidly changing Arctic, uncertainties in their prediction persist. Here, we harmonize SEB observations across a network of vegetated and glaciated sites at circumpolar scale (1994–2021). Our variance-partitioning analysis identifies vegetation type as an important predictor for SEB-components during Arctic summer (June-August), compared to other SEB-drivers including climate, latitude and permafrost characteristics. Differences among vegetation types can be of similar magnitude as between vegetation and glacier surfaces and are especially high for summer sensible and latent heat fluxes. The timing of SEB-flux summer-regimes (when daily mean values exceed 0 Wm−2) relative to snow-free and -onset dates varies substantially depending on vegetation type, implying vegetation controls on snow-cover and SEB-flux seasonality. Our results indicate complex shifts in surface energy fluxes with land-cover transitions and a lengthening summer season, and highlight the potential for improving future Earth system models via a refined representation of Arctic vegetation types.
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- Putkonen, Noora, et al.
(författare)
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Involvement of cyclin-dependent kinase-5 in the kainic acid-mediated degeneration of glutamatergic synapses in the rat hippocampus
- 2011
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Ingår i: European Journal of Neuroscience. - : WILEY-BLACKWELL. - 0953-816X .- 1460-9568. ; 34:8, s. 1212-1221
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Tidskriftsartikel (refereegranskat)abstract
- Increased levels of glutamate causing excitotoxic damage accompany neurological disorders such as ischemia/stroke, epilepsy and some neurodegenerative diseases. Cyclin-dependent kinase-5 (Cdk5) is important for synaptic plasticity and is deregulated in neurodegenerative diseases. However, the mechanisms by which kainic acid (KA)-induced excitotoxic damage involves Cdk5 in neuronal injury are not fully understood. In this work, we have thus studied involvement of Cdk5 in the KA-mediated degeneration of glutamatergic synapses in the rat hippocampus. KA induced degeneration of mossy fiber synapses and decreased glutamate receptor (GluR)6/7 and post-synaptic density protein 95 (PSD95) levels in rat hippocampus in vivo after intraventricular injection of KA. KA also increased the cleavage of Cdk5 regulatory protein p35, and Cdk5 phosphorylation in the hippocampus at 12 h after treatment. Studies with hippocampal neurons in vitro showed a rapid decline in GluR6/7 and PSD95 levels after KA treatment with the breakdown of p35 protein and phosphorylation of Cdk5. These changes depended on an increase in calcium as shown by the chelators 1,2-bis(o-aminophenoxy)ethane-N,N,N?',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM) and glycol-bis (2-aminoethylether)-N,N,N?',N?'-tetra-acetic acid. Inhibition of Cdk5 using roscovitine or employing dominant-negative Cdk5 and Cdk5 silencing RNA constructs counteracted the decreases in GluR6/7 and PSD95 levels induced by KA in hippocampal neurons. The dominant-negative Cdk5 was also able to decrease neuronal degeneration induced by KA in cultured neurons. The results show that Cdk5 is essentially involved in the KA-mediated alterations in synaptic proteins and in cell degeneration in hippocampal neurons after an excitotoxic injury. Inhibition of pathways activated by Cdk5 may be beneficial for treatment of synaptic degeneration and excitotoxicity observed in various brain diseases.
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