1,910 research outputs found

    Two fossil groups of galaxies at z≈ 0.4 in the Cosmic Evolution Survey: accelerated stellar-mass build-up, different progenitors

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    We report on two fossil groups of galaxies at redshifts z= 0.425 and 0.372 discovered in the Cosmic Evolution Survey (COSMOS) area. Selected as X-ray extended sources, they have total masses (M_(200)) equal to 1.9(±0.41) × 10^(13) and 9.5(±0.42) × 10^(13) M_⊙, respectively, as obtained from a recent X-ray luminosity–mass scaling relation. The lower mass system appears isolated, whereas the other sits in a well-known large-scale structure (LSS) populated by 27 other X-ray emitting groups. The identification as fossil is based on the i-band photometry of all the galaxies with a photometric redshift consistent with that of the group at the 2σ confidence level and within a projected groupcentric distance equal to 0.5R_(200), and i_(AB)≤ 22.5 mag limited spectroscopy. Both fossil groups exhibit high stellar-to-total mass ratios compared to all the X-ray selected groups of similar mass at 0.3 ≤z≤ 0.5 in the COSMOS. At variance with the composite galaxy stellar mass functions (GSMFs) of similarly massive systems, both fossil group GSMFs are dominated by passively evolving galaxies down to M^(stars)∼ 10^(10) M_⊙ (according to the galaxy broad-band spectral energy distributions). The relative lack of star-forming galaxies with 10^(10) ≤ M^(stars) ≤ 10^(11) M_⊙ is confirmed by the galaxy distribution in the b−r versus i colour–magnitude diagram. Hence, the two fossil groups appear as more mature than the coeval, similarly massive groups. Their overall star formation activity ended rapidly after an accelerated build up of the total stellar mass; no significant infall of galaxies with M^(stars) ≥ 10^(10) M_⊙ took place in the last 3 to 6 Gyr. This similarity holds although the two fossil groups are embedded in two very different density environments of the LSS, which suggests that their galaxy populations were shaped by processes that do not depend on the LSS. However, their progenitors may do so. We discuss why the late merging of a compact group is favoured over the early assembly as a formation scenario for the isolated, low-mass fossil group

    Synthesizing and databasing fossil calibrations: Divergence dating and beyond

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    Divergence dating studies, which combine temporal data from the fossil record with branch length data from molecular phylogenetic trees, represent a rapidly expanding approach to understanding the history of life. National Evolutionary Synthesis Center hosted the first Fossil Calibrations Working Group (3–6 March, 2011, Durham, NC, USA), bringing together palaeontologists, molecular evolutionists and bioinformatics experts to present perspectives from disciplines that generate, model and use fossil calibration data. Presentations and discussions focused on channels for interdisciplinary collaboration, best practices for justifying, reporting and using fossil calibrations and roadblocks to synthesis of palaeontological and molecular data. Bioinformatics solutions were proposed, with the primary objective being a new database for vetted fossil calibrations with linkages to existing resources, targeted for a 2012 launch

    Ciliates - Protists with complex morphologies and ambiguous early fossil record

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    Since ciliates rarely possess structures that easily fossilize, we are limited in our ability to use paleontological studies to reconstruct the early evolution of this large and ecologically important clade of protists. Tintinnids, a group of loricate (house-forming) planktonic ciliates, are the only group that has a significant fossil record. Putative tintinnid fossils from rocks older than Jurassic, however, possess few to no characters that can be found in extant ciliates; these fossils are best described as 'incertae sedis eukaryotes'. Here, we review the Devonian fossil Nassacysta reticulata and propose that it is likewise another 'incertae sedis eukaryote due to the lack of any unambiguous ciliate characters. Future tintinnid fossil descriptions would be most helpful if: (i) neutral terminology is used in the descriptions but ciliate-specific terminology in the interpretations; (ii) the current ciliate classification is used, although fossil data may expand or modify classifications based on modem forms; (iii) close collaboration with specialists studying extant ciliates is done; and (iv) editors include an expert of extant ciliates in the review process. (C) 2015 Elsevier B.V. All rights reserved.Since ciliates rarely possess structures that easily fossilize, we are limited in our ability to use paleontological studies to reconstruct the early evolution of this large and ecologically important clade of protists. Tintinnids, a group of loricate (house-forming) planktonic ciliates, are the only group that has a significant fossil record. Putative tintinnid fossils from rocks older than Jurassic, however, possess few to no characters that can be found in extant ciliates; these fossils are best described as 'incertae sedis eukaryotes'. Here, we review the Devonian fossil Nassacysta reticulata and propose that it is likewise another 'incertae sedis eukaryote due to the lack of any unambiguous ciliate characters. Future tintinnid fossil descriptions would be most helpful if: (i) neutral terminology is used in the descriptions but ciliate-specific terminology in the interpretations; (ii) the current ciliate classification is used, although fossil data may expand or modify classifications based on modem forms; (iii) close collaboration with specialists studying extant ciliates is done; and (iv) editors include an expert of extant ciliates in the review process. (C) 2015 Elsevier B.V. All rights reserved

    Fossil Fuel (In)Dependency In Agriculture : Communicating complexity through design

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    Despite the destructive and limited nature of fossil fuels, most human-made systems are dependent on the use of oil, gas and coal. Especially agriculture relies on diesel machinery, fertilizer, transport, and cooling systems that are commonly powered by non-renewable energy sources. This independent project in design specifically focuses on the dependency on fossil fuels within agriculture. With the investigation “Vägen mot fossiloberoende jordbruk” (Utredningen om fossiloberoende jordbruk, 2021), or “Pathway to fossil independent agriculture”, Sweden is aspiring to make farming fossil-free by 2030. Consequently, a lot of responsibility to invest in new technologies and alternative energies lies on farmers. In collaboration with Länsstyrelsen Kronoberg, the author explores how farmers can be supported to transition towards renewable energies, focusing on the Swedish region Kronoberg. Through participatory design and design research, notions of fossil fuel (in)dependency are being explored in collaborative ways. Here, the farmers become the ‘experts of their experience’ (Sanders & Stappers, 2012). This independent design project examines ways to transition towards fossil fuel independent agriculture in Sweden, existing challenges and potential solutions. To communicate the complex network of energy and agriculture in Kronoberg to Länsstyrelsen, the author designed an Actor-Network-Model, which highlights the necessity of systems thinking and collaboration.

    Fossil Fuel (In)Dependency In Agriculture : Communicating complexity through design

    No full text
    Despite the destructive and limited nature of fossil fuels, most human-made systems are dependent on the use of oil, gas and coal. Especially agriculture relies on diesel machinery, fertilizer, transport, and cooling systems that are commonly powered by non-renewable energy sources. This independent project in design specifically focuses on the dependency on fossil fuels within agriculture. With the investigation “Vägen mot fossiloberoende jordbruk” (Utredningen om fossiloberoende jordbruk, 2021), or “Pathway to fossil independent agriculture”, Sweden is aspiring to make farming fossil-free by 2030. Consequently, a lot of responsibility to invest in new technologies and alternative energies lies on farmers. In collaboration with Länsstyrelsen Kronoberg, the author explores how farmers can be supported to transition towards renewable energies, focusing on the Swedish region Kronoberg. Through participatory design and design research, notions of fossil fuel (in)dependency are being explored in collaborative ways. Here, the farmers become the ‘experts of their experience’ (Sanders & Stappers, 2012). This independent design project examines ways to transition towards fossil fuel independent agriculture in Sweden, existing challenges and potential solutions. To communicate the complex network of energy and agriculture in Kronoberg to Länsstyrelsen, the author designed an Actor-Network-Model, which highlights the necessity of systems thinking and collaboration.

    The NOW Database of Fossil Mammals

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    NOW (New and Old Worlds) is a global database of fossil mammal occurrences, currently containing around 68,000 locality-species entries. The database spans the last 66 million years, with its primary focus on the last 23 million years. Whereas the database contains recordsNOW Databaserecords from all continents, the main focus and coverage of the database historically has been on Eurasia. The database includes primarily, but not exclusively, terrestrial mammals. It covers a large part of the currently known mammalian fossil record, focusing on classical and actively researched fossil localities. The database is managed in collaboration with an international advisory board of experts. Rather than a static archive, it emphasizes the continuous integration of new knowledge of the communityNOW Databasedatacuration in, data curationDatacuration, and consistencyNOW Databaseconsistency of scientific interpretations. The database records species occurrences at localities worldwide, as well as ecologicalEcological characteristics of fossil species, geological contextsGeologic/geologicalcontext of localities and more. The NOW database is primarily used for two purposes: (1) queries about occurrences of particular taxa, their characteristics and properties of localities in the spirit of an encyclopedia; and (2) large scale research and quantitative analyses of evolutionary processes, patterns, reconstructing past environments, as well as interpreting evolutionary contexts. The data are fully open, no logging in or community membership is necessary for using the data for any purpose.Peer reviewe

    Coal Modeling Investigations in International Collaboration in the Light of Bibliometric Analysis of the Problem

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    The article concerns an analysis of records registered in Web of Science (WoS) database related to the problem of coal modeling. All publications registered in the WoS from the time period 1951–2021 were analyzed, mostly in terms of international collaboration, merit content and research areas. It appeared that international scientific cooperation on this topic is differently considered, depending on the country. The leader in terms of the number of documents remains China, while the highest citation counts were gained by research teams, with the USA as the leader. Several sub-categories within research areas could be also divided on the basis of key words, while the most popular topic is connected with energetical aspects of coal utilization

    What is the evidence that scarcity and shocks in freshwater resources can cause conflict instead of promoting collaboration

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    Anthropogenic activities such as the combustion of fossil fuels, land-use change and intensive agriculture are increasingly influencing the Earth‘s climate and exerting pressure on ecosystems. These changes have amplified the risk of scarcity and shocks (discrete and sudden events) in natural renewable resource (henceforth, NRR) scarcity across the spectrum of spatial scales. The interplay between freshwater scarcity and conflict/collaboration is the most prominent and referenced of the environment-conflict issues in the Third and Fourth Assessment Reports of the IPCC. Discussions with the review user-group, confirmed that a systematic mapping of the literature in this particular field was a priority

    Excavation, conservation, and preservation of the Mt Gambier underwater fossil deposits

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    This paper will examine the history of underwater fossil research in the Mt Gambier region, Australia, focusing on ongoing efforts to study, conserve, and protect underwater resources found in the freshwater sinkholes and limestone caves of the region; as such, the topic of this abstract fits best within the session The Archaeology of Submerged Landscapes and Inland Waters because it is concerned with cave sites that have become flooded. I will describe the considerable past efforts that were undertaken to extract fossils from Green Waterhole, as well as recently successful efforts to have this site registered as a South Australian Heritage Listed site, ensuring legislated protection for the cave and its deposits into the future. In addition, a new research program funded by the Australian Research Council and in collaboration with the Cave Divers Association of Australia and the South Australian Museum will be presented. The new work includes efforts to successfully recover fossils with as much contextual information as possible, especially geochronological and environmental data. Using these data, we expect to determine the geological age of the extinct megafauna recovered from the sites and the environments they inhabited; data critical for determining the degree to which humans or environmental change contributed to their demise. We will also evaluate the impact of such research on the preservation of the caves, ongoing efforts to conserve the geoheritage potential of the sites, and means of educating the public on the unique underwater resources they represent.Full Tex
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