| 1. |
- Zamora, Juan Carlos, et al.
(författare)
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Considerations and consequences of allowing DNA sequence data as types of fungal taxa
- 2018
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Ingår i: IMA Fungus. - : INT MYCOLOGICAL ASSOC. - 2210-6340 .- 2210-6359. ; 9:1, s. 167-185
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Tidskriftsartikel (refereegranskat)abstract
- Nomenclatural type definitions are one of the most important concepts in biological nomenclature. Being physical objects that can be re-studied by other researchers, types permanently link taxonomy (an artificial agreement to classify biological diversity) with nomenclature (an artificial agreement to name biological diversity). Two proposals to amend the International Code of Nomenclature for algae, fungi, and plants (ICN), allowing DNA sequences alone (of any region and extent) to serve as types of taxon names for voucherless fungi (mainly putative taxa from environmental DNA sequences), have been submitted to be voted on at the 11th International Mycological Congress (Puerto Rico, July 2018). We consider various genetic processes affecting the distribution of alleles among taxa and find that alleles may not consistently and uniquely represent the species within which they are contained. Should the proposals be accepted, the meaning of nomenclatural types would change in a fundamental way from physical objects as sources of data to the data themselves. Such changes are conducive to irreproducible science, the potential typification on artefactual data, and massive creation of names with low information content, ultimately causing nomenclatural instability and unnecessary work for future researchers that would stall future explorations of fungal diversity. We conclude that the acceptance of DNA sequences alone as types of names of taxa, under the terms used in the current proposals, is unnecessary and would not solve the problem of naming putative taxa known only from DNA sequences in a scientifically defensible way. As an alternative, we highlight the use of formulas for naming putative taxa (candidate taxa) that do not require any modification of the ICN.
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| 2. |
- Horgan, Briony, et al.
(författare)
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Mineralogy, Morphology, and Emplacement History of the Maaz Formation on the Jezero Crater Floor From Orbital and Rover Observations
- 2023
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Ingår i: Journal of Geophysical Research: Planets. - 2169-9097. ; 128:8
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Tidskriftsartikel (refereegranskat)abstract
- The first samples collected by the Perseverance rover on the Mars 2020 mission were from the Maaz formation, a lava plain that covers most of the floor of Jezero crater. Laboratory analysis of these samples back on Earth would provide important constraints on the petrologic history, aqueous processes, and timing of key events in Jezero crater. However, interpreting these samples requires a detailed understanding of the emplacement and modification history of the Maaz formation. Here we synthesize rover and orbital remote sensing data to link outcrop-scale interpretations to the broader history of the crater, including Mastcam-Z mosaics and multispectral images, SuperCam chemistry and reflectance point spectra, Radar Imager for Mars' subsurface eXperiment ground penetrating radar, and orbital hyperspectral reflectance and high-resolution images. We show that the Maaz formation is composed of a series of distinct members corresponding to basaltic to basaltic-andesite lava flows. The members exhibit variable spectral signatures dominated by high-Ca pyroxene, Fe-bearing feldspar, and hematite, which can be tied directly to igneous grains and altered matrix in abrasion patches. Spectral variations correlate with morphological variations, from recessive layers that produce a regolith lag in lower Maaz, to weathered polygonally fractured paleosurfaces and crater-retaining massive blocky hummocks in upper Maaz. The Maaz members were likely separated by one or more extended periods of time, and were subjected to variable erosion, burial, exhumation, weathering, and tectonic modification. The two unique samples from the Maaz formation are representative of this diversity, and together will provide an important geochronological framework for the history of Jezero crater.
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| 3. |
- Karlsson, Svante, 1972-
(författare)
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Att äga rum : En undersökning av skogsägande och lokal utveckling i tre värmländska församlingar
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Karlsson, S. 2007: Att äga rum. En undersökning av skogsägande och lokal utveckling i tre värmländska församlingar. (Ruling Spaces. An Investigation of Forest Ownership and Local Development in Three Parishes in Värmland)This thesis explores the present ownership structure of forest estates in the province of Värmland, and in particular three parishes in Värmland and attempts to explain how the ownership structure has evolved to its present state. The purpose is to reveal the importance of this ownership structure for the development potential, expressed as the local population’s prospects of earning a living in forest regions.The empirical material is based on registers/databases from the tax authorities, Swedish Forest Agency and the County Administration Board. The thesis includes a survey among forest owners (landowners) in the region in focus for the thesis as well as living outside this region. Finally, interviews have been the basis for the work. The survey and the interviews were based on theories of property rights and institutional economy. The primary theoretical framework was based on local development theories.The ownership structure of forest estates in the province of Värmland is characterized by variation within the region. In the Western parts, small scale private ownership is dominant, where a majority of owners live near the estate/property, while in the Eastern parts, that historically has been a base for significant industrialized processing of natural resources, a very large share of the forest land is owned by a single corporation, Bergvik Skog AB. The Northern parts of Värmland are a mosaic of different owners where a large portion of the owners live in cities or regions far away. Another noteworthy actor is the Svenska Kyrkan (Church of Sweden) that locally has a dominant position in Värmland.The evolution of the ownership structure to its present state can be explained in terms of market economy that has nurtured rationalization acquisitions with the purpose of reducing the number of estates to instead arrive at a small number of larges estates. It is concluded that the number of forest owners that does not live near the estate/property has increased in the post-war era. This relationship relates to the urbanization caused by, among other factors, well developed rationalization within the agricultural and forestry sectors in the region. It is also pointed out that the legislation around acquisition of land has influenced the development.The survey together with the interviews conclude that the ownership structure does not have a significant impact on the local population’s development strategies. Nor does the locally high share of owners not living near the estate seem to be an important factor. The thesis is concluded by raising questions around the aspect of obligations when forests are owned by others than the local population.KEY WORDS: Forest owners, property rights, rural development, the province of Värmland, Sweden
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| 4. |
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| 5. |
- Lazaridis, Iosif, et al.
(författare)
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Ancient human genomes suggest three ancestral populations for present-day Europeans
- 2014
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 513:7518, s. 409-
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Tidskriftsartikel (refereegranskat)abstract
- We sequenced the genomes of a similar to 7,000-year-old farmer from Germany and eight similar to 8,000-year-old hunter-gatherers from Luxembourg and Sweden. We analysed these and other ancient genomes(1-4) with 2,345 contemporary humans to show that most present-day Europeans derive from at least three highly differentiated populations: west European hunter-gatherers, who contributed ancestry to all Europeans but not to Near Easterners; ancient north Eurasians related to Upper Palaeolithic Siberians(3), who contributed to both Europeans and Near Easterners; and early European farmers, who were mainly of Near Eastern origin but also harboured west European hunter-gatherer related ancestry. We model these populations' deep relationships and show that early European farmers had similar to 44% ancestry from a 'basal Eurasian' population that split before the diversification of other non-African lineages.
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| 6. |
- Paige, David A., et al.
(författare)
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Ground penetrating radar observations of the contact between the western delta and the crater floor of Jezero crater, Mars
- 2024
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Ingår i: Science Advances. - 2375-2548. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- The delta deposits in Jezero crater contain sedimentary records of potentially habitable conditions on Mars. NASA's Perseverance rover is exploring the Jezero western delta with a suite of instruments that include the RIMFAX ground penetrating radar, which provides continuous subsurface images that probe up to 20 meters below the rover. As Perseverance traversed across the contact between the Jezero crater floor and the delta, RIMFAX detected a distinct discontinuity in the subsurface layer structure. Below the contact boundary are older crater floor units exhibiting discontinuous inclined layering. Above the contact boundary are younger basal delta units exhibiting regular horizontal layering. At one location, there is a clear unconformity between the crater floor and delta layers, which implies that the crater floor experienced a period of erosion before the deposition of the overlying delta strata. The regularity and horizontality of the basal delta sediments observed in the radar cross sections indicate that they were deposited in a low-energy lake environment.
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| 7. |
- Aad, G., et al.
(författare)
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- 2012
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swepub:Mat__t (refereegranskat)
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