| 1. |
- Dunér, David, et al.
(författare)
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Copernican Principle
- 2021
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Ingår i: Encyclopedia of Astrobiology. - Berlin/Heidelberg : Springer Berlin/Heidelberg. ; 1:1, s. 1-3
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Tidskriftsartikel (refereegranskat)abstract
- The Copernican principle states that Earth has not any privileged position in the universe. In astrobiological terms, it means that terrestrial life, including the human beings, has not any particularly privileged, special, or unique position in the universe, which leads to the assumption that, given the presence of life on Earth, life will exist also in other places in the universe.
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| 2. |
- Dunér, David, et al.
(författare)
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Great Chain of Being
- 2021
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Ingår i: Encyclopedia of Astrobiology. - Berlin/Heidelberg : Springer Berlin/Heidelberg. ; 1:1, s. 1-2
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Tidskriftsartikel (refereegranskat)abstract
- A prevailing idea through the ages is that of the Great Chain of Being, understanding the universe as a hierarchy of beings, an unbroken chain of existence, from the simplest forms to the most complex ones, from non-living matter to the most rational creatures (Lovejoy 1936). In his History of Animals from the fourth century BCE, Aristotle arranged all beings in a ladder of nature, a scala naturae, a gradation of natural things from minerals, through plants and animals, to the human being. The chain of being got biological significance with, among others, Gottfried Wilhelm Leibniz, Carl Linnaeus, Georges-Louis Leclerc de Buffon, and Charles Bonnet. Nature does not make jumps, Natura non-facit saltus, as Carl Linnaeus formulated it in Philosophia Botanica (1751). There is continuity in nature. In that respect, the Great Chain of Being is connected to the Principle of Plenitude, the fullness of being. The principle suggests that every possible form of creature exists. This could also be understood in a temporal sense that every possible form of creature, even though not existing right now, might have existed before or could be realized at some stage in the future. Continuity is an idea implicit in that of plenitude. In the early nineteenth century, this continuity of nature became understood in temporal meaning. Jean-Baptiste de Lamarck went from a static concept of the series of life-forms to a theory of species transformation that life had developed over time from simpler to more complex forms. During the nineteenth century, the Great Chain of Being was replaced by another metaphor, the Tree of Life, which also stressed on the continuity of nature, but took into account the genealogy and evolution of life-forms, as in Lamarck’s Philosophie zoologique (1809) and Darwin’s Origin of Species (1859).
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| 3. |
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| 4. |
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| 5. |
- Dunér, David, et al.
(författare)
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Principle of Plenitude
- 2022
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Ingår i: Encyclopedia of Astrobiology. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783642278334 ; 1:1, s. 1-3
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Fernández-Remolar, David, et al.
(författare)
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A mineralogical archive of the biogeochemical sulfur cycle preserved in the subsurface of the Río Tinto system
- 2018
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Ingår i: American Mineralogist. - : Walter de Gruyter. - 0003-004X .- 1945-3027. ; 103:3, s. 394-411
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Tidskriftsartikel (refereegranskat)abstract
- The search for extinct and extant life on Mars is based on the study of biosignatures that could be preserved under Mars-like, extreme conditions that are replicated in different terrestrial analog environments. The mineral record in the subsurface of the Río Tinto system is one example of a Mars analog site that has been exposed to weathering conditions, including the biogeochemical activity of Fe and S chemolithotrophic bacteria, for millions of years. The SEM-EDAX analysis of different samples recovered in the Peña de Hierro area from four boreholes, ranging from 166 to 610 m in depth, has provided the identification of microbial structures that have affected a suite of hydrothermal minerals (~345 Ma) as well as minerals likely produced by biological activity in more recent times (<7 Ma). The hydrothermal minerals correspond to reduced sulfur or sulfate-bearing compounds (e.g., pyrite and barite) that are covered by bacilli- or filamentous-like microbial structures and/or secondary ferrous carbonates (e.g., siderite) with laminar to spherical structures. The secondary iron carbonates can be in direct contact or above an empty interphase with the primary hydrothermal minerals following a wavy to bent contact. Such an empty interphase is usually filled with nanoscale, straight filamentous structures that have a carbonaceous composition. The occurrence of a sulfur and iron chemolithotrophic community in the Río Tinto basement strongly suggests that the association between sulfur-bearing minerals, dissolution scars and secondary minerals of biological origin is a complex process involving the microbial attack on mineral surfaces by sulfur reducing bacteria followed by the precipitation of iron-rich carbonates. In this scenario, iron sulfide compounds such as pyrite would act as electron donors under microbial oxidation, while sulfate minerals such as barite would act as electron acceptors through sulfate reduction. Furthermore, the formation of siderite would have resulted from carbonate biomineralization of iron chemoheterotrophic organims or other microorganisms that concentrate carbonate through metabolic pathways. Although the distribution of the mineral biosignatures at depth clearly follows a redox gradient, they show some irregular allocation underground, suggesting that the geochemical conditions governing the microbial activity are affected by local changes associated with the fracturing pattern of the Río Tinto basement. The abundance of sulfur- and iron-bearing minerals in the Mars crust suggests that the Río Tinto mineral biosignatures can be useful in the search for extant and extinct subsurface life on the red planet
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| 7. |
- Fernández-Remolar, David C., et al.
(författare)
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Productivity contribution of Paleozoic woodlands to the formation of shale hosted massive sulfide deposits in the Iberian Pyrite Belt (Tharsis, Spain)
- 2018
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Ingår i: Journal of Geophysical Research - Biogeosciences. - : John Wiley & Sons. - 2169-8953 .- 2169-8961. ; 123:3, s. 1017-1040
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Tidskriftsartikel (refereegranskat)abstract
- The geological materials produced during catastrophic and destructive events are an essential source of paleobiological knowledge. The paleobiological information recorded by such events can be rich in information on the size, diversity, and structure of paleocommunities. In this regard, the geobiological study of late Devonian organic matter sampled in Tharsis (Iberian Pyrite Belt) provided some new insights into a Paleozoic woodland community,which was recorded as massive sulfides and black shale deposits affected by a catastrophic event. Sample analysis using TOF-SIMS (Time of Flight Secondary Ion Mass Spectrometer), and complemented by GC/MS (Gas Chromatrograph/Mass Spectrometer) identified organic compounds showing a very distinct distribution in the rock. While phytochemical compounds occur homogeneously in the sample matrix that is composed of black shale, the microbial-derived organics are more abundant in the sulfide nodules. The co-occurrence of sulfur bacteria compounds and the overwhelming presence of phytochemicals provide support for the hypothesis that the formation of the massive sulfides resulted from a high rate of vegetal debris production and its oxidation through sulfate reduction under suboxic to anoxic conditions. A continuous supply of iron from hydrothermal activity coupled with microbial activity was strictly necessary to produce this massive orebody. A rough estimate of the woodland biomass was made possible by accounting for the microbial sulfur production activity recorded in the metallic sulfide. As a result, the biomass size of the late Devonian woodland community was comparable to modern woodlands like the Amazon or Congo rainforests.
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| 8. |
- Gurvits, L. I., et al.
(författare)
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The science case and challenges of spaceborne sub-millimeter interferometry: the study case of TeraHertz Exploration and Zooming-in for Astrophysics (THEZA)
- 2021
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Ingår i: Proceedings of the International Astronautical Congress, IAC. - 0074-1795. ; A7
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Konferensbidrag (refereegranskat)abstract
- Ultra-high angular resolution in astronomy has always been an important vehicle for making fundamental discoveries. Recent results in direct imaging of the vicinity of the super-massive black hole in the nucleus of the radio galaxy M87 by the millimeter VLBI system Event Horizon Telescope (EHT) and various pioneering results of the Space VLBI mission RadioAstron provided new momentum in high angular resolution astrophysics. In both mentioned cases, the angular resolution reached the values of about 10−20 microrcseconds (0.05−0.1 nanoradian). Angular resolution is proportional to the observing wavelength and inversely proportional to the interferometer baseline length. In the case of Earth-based EHT, the highest angular resolution was achieved by combining the shortest possible wavelength of 1.3 mm with the longest possible baselines, comparable to the Earth’s diameter. For RadioAstron, operational wavelengths were in the range from 92 cm down to 1.3 cm, but the baselines were as long as ∼350,000 km. However, these two highlights of radio astronomy, EHT and RadioAstron do not”saturate” the interest to further increase in angular resolution. Quite opposite: the science case for further increase in angular resolution of astrophysical studies becomes even stronger. A natural and, in fact, the only possible way of moving forward is to enhance mm/sub-mm VLBI by extending baselines to extraterrestrial dimensions, i.e. creating a mm/sub-mm Space VLBI system. The inevitable move toward space-borne mm/sub-mm VLBI is a subject of several concept studies. In this presentation we will focus on one of them called TeraHertz Exploration and Zooming-in for Astrophysics (THEZA), prepared in response to the ESA’s call for its next major science program Voyage 2050 (Gurvits et al. 2021). The THEZA rationale is focused at the physics of spacetime in the vicinity of super-massive black holes as the leading science drive. However, it will also open up a sizable new range of hitherto unreachable parameters of observational radio astrophysics and create a multi-disciplinary scientific facility and offer a high degree of synergy with prospective “single dish” space-borne sub-mm astronomy (e.g., Wiedner et al. 2021) and infrared interferometry (e.g., Linz et al. 2021). As an amalgam of several major trends of modern observational astrophysics, THEZA aims at facilitating a breakthrough in high-resolution high image quality astronomical studies.
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| 9. |
- Persson, Erik, et al.
(författare)
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Astrobiology as Science
- 2021. - 3
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Ingår i: Encyclopedia of Astrobiology. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783642278334 - 9783642278334
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- “Astrobiology as science” refers to how astrobiology is characterized and discussed in the philosophy of science.
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| 10. |
- Westmeijer, George, et al.
(författare)
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Continental scientific drilling and microbiology : (extremely) low biomass in bedrock of central Sweden
- 2024
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Ingår i: Biogeosciences. - : Copernicus Publications. - 1726-4170 .- 1726-4189. ; 21:2, s. 591-604
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Tidskriftsartikel (refereegranskat)abstract
- Scientific drilling expeditions offer a unique opportunity to characterize microbial communities in the subsurface that have long been isolated from the surface. With subsurface microbial biomass being low in general, biological contamination from the drilling fluid, sample processing, or molecular work is a major concern. To address this, characterization of the contaminant populations in the drilling fluid and negative extraction controls are essential for assessing and evaluating such sequencing data. Here, rock cores down to 2250 m depth, groundwater-bearing fractures, and the drilling fluid were sampled for DNA to characterize the microbial communities using a broad genomic approach. However, even after removing potential contaminant populations present in the drilling fluid, notorious contaminants were abundant and mainly affiliated with the bacterial order Burkholderiales. These contaminant microorganisms likely originated from the reagents used for isolating DNA despite stringent quality standards during the molecular work. The detection of strictly anaerobic sulfate reducers such as Candidatus Desulforudis audaxviator suggested the presence of autochthonous deep biosphere taxa in the sequenced libraries, yet these clades represented only a minor fraction of the sequence counts ( < 0.1 %), hindering further ecological interpretations. The described methods and findings emphasize the importance of sequencing extraction controls and can support experimental design for future microbiological studies in conjunction with continental drilling operations.
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