| 1. |
- Allentoft, Morten E., et al.
(author)
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100 ancient genomes show repeated population turnovers in Neolithic Denmark
- 2024
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In: Nature. - 0028-0836 .- 1476-4687. ; 625, s. 329-337
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Journal article (peer-reviewed)abstract
- Major migration events in Holocene Eurasia have been characterized genetically at broad regional scales1–4. However, insights into the population dynamics in the contact zones are hampered by a lack of ancient genomic data sampled at high spatiotemporal resolution5–7. Here, to address this, we analysed shotgun-sequenced genomes from 100 skeletons spanning 7,300 years of the Mesolithic period, Neolithic period and Early Bronze Age in Denmark and integrated these with proxies for diet (13C and 15N content), mobility (87Sr/86Sr ratio) and vegetation cover (pollen). We observe that Danish Mesolithic individuals of the Maglemose, Kongemose and Ertebølle cultures form a distinct genetic cluster related to other Western European hunter-gatherers. Despite shifts in material culture they displayed genetic homogeneity from around 10,500 to 5,900 calibrated years before present, when Neolithic farmers with Anatolian-derived ancestry arrived. Although the Neolithic transition was delayed by more than a millennium relative to Central Europe, it was very abrupt and resulted in a population turnover with limited genetic contribution from local hunter-gatherers. The succeeding Neolithic population, associated with the Funnel Beaker culture, persisted for only about 1,000 years before immigrants with eastern Steppe-derived ancestry arrived. This second and equally rapid population replacement gave rise to the Single Grave culture with an ancestry profile more similar to present-day Danes. In our multiproxy dataset, these major demographic events are manifested as parallel shifts in genotype, phenotype, diet and land use.
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| 2. |
- Allentoft, Morten E., et al.
(author)
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Population genomics of post-glacial western Eurasia
- 2024
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In: Nature. - 0028-0836 .- 1476-4687. ; 625:7994, s. 301-311
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Journal article (peer-reviewed)abstract
- Western Eurasia witnessed several large-scale human migrations during the Holocene1–5. Here, to investigate the cross-continental effects of these migrations, we shotgun-sequenced 317 genomes—mainly from the Mesolithic and Neolithic periods—from across northern and western Eurasia. These were imputed alongside published data to obtain diploid genotypes from more than 1,600 ancient humans. Our analyses revealed a ‘great divide’ genomic boundary extending from the Black Sea to the Baltic. Mesolithic hunter-gatherers were highly genetically differentiated east and west of this zone, and the effect of the neolithization was equally disparate. Large-scale ancestry shifts occurred in the west as farming was introduced, including near-total replacement of hunter-gatherers in many areas, whereas no substantial ancestry shifts happened east of the zone during the same period. Similarly, relatedness decreased in the west from the Neolithic transition onwards, whereas, east of the Urals, relatedness remained high until around 4,000 bp, consistent with the persistence of localized groups of hunter-gatherers. The boundary dissolved when Yamnaya-related ancestry spread across western Eurasia around 5,000 bp, resulting in a second major turnover that reached most parts of Europe within a 1,000-year span. The genetic origin and fate of the Yamnaya have remained elusive, but we show that hunter-gatherers from the Middle Don region contributed ancestry to them. Yamnaya groups later admixed with individuals associated with the Globular Amphora culture before expanding into Europe. Similar turnovers occurred in western Siberia, where we report new genomic data from a ‘Neolithic steppe’ cline spanning the Siberian forest steppe to Lake Baikal. These prehistoric migrations had profound and lasting effects on the genetic diversity of Eurasian populations.
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| 3. |
- Andersen, Julie Swartz, et al.
(author)
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Economic comparison of mass timber and concrete construction in the nordic region
- 2023
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In: 13th World Conference on Timber Engineering, WCTE 2023. ; 7, s. 4360-4369
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Conference paper (peer-reviewed)abstract
- The timber sector has been growing strongly in various regions of the world. Yet, the construction industry is still far from being sustainable. One barrier is the economic concern in planning and construction works of timber constructions. This study aims to provide insights on the cost performance of Cross Laminated Timber (CLT) constructions for stakeholders to make an informed decision. It analysed the production cost of multi-story residential buildings with CLT in comparison to concrete in Norway and Sweden. The production cost data of various construction projects with either CLT or concrete was collected and analysed. Interviews with stakeholders were conducted to complement the interpretation of the cost data. The result showed that each project had its individual conditions in the economic background and requirements by client, and thus it was difficult to formulate a general tendency on the cost performance. The variability of the cost was larger and the average production cost was higher in CLT cases. Yet, there are high incentives of contractors and clients for a more sustainable alternative in general. The incentive is also reinforced by the general experience of contractors that the construction cost is better optimized as the contractor gains more experiences.
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| 4. |
- Hansted Andersen, Julie, et al.
(author)
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Construction cost of timber buildings
- 2022
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Reports (other academic/artistic)abstract
- There are increasing interests and practices in modern large timber constructions globally for the renewability and carbon storage function of wood. However, many stakeholders with limited knowledge and experience with timber still feel uncertain on how to carry out construction projects with timber. The common notion is that timber constructions would become more costly than a conventional alternative such as concrete. In order to inform wide spectrum of construction stakeholders in Scandinavia, this report presents a study on construction cost of cross laminated timber (CLT) buildings compared with concrete/steel buildings in Denmark, Norway and Sweden. The study investigated the actual cost of 9 recent multi-storey residential buildings, 5 constructed with a load-bearing system in primarily CLT and 4 constructed in primarily concrete in Norway and Sweden. Due to the nature of the chronological and geographical differences of market conditions, the cost data were evaluated separately for Norway and Sweden. In addition to the case building analysis, interviews were conducted with stakeholders from the case building projects as well as those from the industry with experiences with CLT buildings. The interviews contributed to a broader perspective of the cost analysis, with explanations of the projects and experiences of advantages and disadvantages for CLT building and concrete buildings. The results showed a tendency that the construction cost of the Norwegian CLT projects were higher than the Norwegian concrete projects. For the Swedish projects the concrete building had a higher cost compared to the CLT projects, however it can't be concluded as a tendency for the Swedish projects, since investigation only included one concrete project and two CLT projects. The results showed that often the material-related costs were higher for CLT buildings than concrete buildings. Such costs are for example the material cost itself and transportation cost for a long distance. Furthermore, the fire protection and measures for the finalized building according to fire safety resulted in a higher cost in the CLT cases. However, the construction time is often shorter for CLT buildings than concrete buildings, and CLT buildings are lighter and therefore the foundation can be dimensioned smaller. Although such observations were made, throughout the interviews it was stated that one should be careful comparing the cost of two buildings since the cost is very much depended on the specific project. Thus, the results shown in this report must be seen as tendencies and not as a forecast for specific cost difference between CLT building and concrete buildings. This study was an investigation of construction costs and advantages and disadvantages of CLT buildings in relation to the construction cost up till 2022. When there is a major change in the economy and legislations of the construction sector, the cost structure may be substantially affected. One of such factors may be the increasing focus on the reduction of greenhouse gas (GHG) emissions from the construction industry. The availability of resource might be also a key factor for the future cost development for both CLT and concrete.
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| 5. |
- Kattge, Jens, et al.
(author)
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TRY plant trait database - enhanced coverage and open access
- 2020
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In: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
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Journal article (peer-reviewed)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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| 6. |
- Liu, Beibei, et al.
(author)
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Pebble-driven planet formation around very low-mass stars and brown dwarfs
- 2020
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 638
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Journal article (peer-reviewed)abstract
- We conduct a pebble-driven planet population synthesis study to investigate the formation of planets around very low-mass stars and brown dwarfs in the (sub)stellar mass range between 0.01 M- and 0.1 M-. Based on the extrapolation of numerical simulations of planetesimal formation by the streaming instability, we obtain the characteristic mass of the planetesimals and the initial mass of the protoplanet (largest body from the planetesimal populations), in either the early self-gravitating phase or the later non-self-gravitating phase of the protoplanetary disk evolution. We find that the initial protoplanets form with masses that increase with host mass and orbital distance, and decrease with age. Around late M-dwarfs of 0.1 M-, these protoplanets can grow up to Earth-mass planets by pebble accretion. However, around brown dwarfs of 0.01 M-, planets do not grow to the masses that are greater than Mars when the initial protoplanets are born early in self-gravitating disks, and their growth stalls at around 0.01 Earth-mass when they are born late in non-self-gravitating disks. Around these low-mass stars and brown dwarfs we find no channel for gas giant planet formation because the solid cores remain too small. When the initial protoplanets form only at the water-ice line, the final planets typically have 15% water mass fraction. Alternatively, when the initial protoplanets form log-uniformly distributed over the entire protoplanetary disk, the final planets are either very water rich (water mass fraction 15%) or entirely rocky (water mass fraction 5%).
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