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  • 1
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    Seismic evidence for water deep in Earth's upper mantle (2003)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2003-06-07
    Description: Water in the deep upper mantle can influence the properties of seismic discontinuities in the mantle transition zone. Observations of converted seismic waves provide evidence of a 20- to 35-kilometer-thick discontinuity near a depth of 410 kilometers, most likely explained by as much as 700 parts per million of water by weight.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉van der Meijde, Mark -- Marone, Federica -- Giardini, Domenico -- van der Lee, Suzan -- New York, N.Y. -- Science. 2003 Jun 6;300(5625):1556-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Geophysics, Eidgenossische Technische Hochschule-Honggerberg (HPP)/Swiss Federal Institute of Technology CH-8093 Zurich, Switzerland. mark@tomo.ig.erdw.ethz.ch〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12791988" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Development of teeth and jaws in the earliest jawed vertebrates (2012)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2012-10-19
    Description: Teeth and jaws constitute a model of the evolutionary developmental biology concept of modularity and they have been considered the key innovations underpinning a classic example of adaptive radiation. However, their evolutionary origins are much debated. Placoderms comprise an extinct sister clade or grade to the clade containing chondrichthyans and osteichthyans, and although they clearly possess jaws, previous studies have suggested that they lack teeth, that they possess convergently evolved tooth-like structures or that they possess true teeth. Here we use synchrotron radiation X-ray tomographic microscopy (SRXTM) of a developmental series of Compagopiscis croucheri (Arthrodira) to show that placoderm jaws are composed of distinct cartilages and gnathal ossifications in both jaws, and a dermal element in the lower jaw. The gnathal ossification is a composite of distinct teeth that developed in succession, polarized along three distinct vectors, comparable to tooth families. The teeth are composed of dentine and bone, and show a distinct pulp cavity that is infilled centripetally as development proceeds. This pattern is repeated in other placoderms, but differs from the structure and development of tooth-like structures in the postbranchial lamina and dermal skeleton of Compagopiscis and other placoderms. We interpret this evidence to indicate that Compagopiscis and other arthrodires possessed teeth, but that tooth and jaw development was not developmentally or structurally integrated in placoderms. Teeth did not evolve convergently among the extant and extinct classes of early jawed vertebrates but, rather, successional teeth evolved within the gnathostome stem-lineage soon after the origin of jaws. The chimaeric developmental origin of this model of modularity reflects the distinct evolutionary origins of teeth and of component elements of the jaws.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rucklin, Martin -- Donoghue, Philip C J -- Johanson, Zerina -- Trinajstic, Kate -- Marone, Federica -- Stampanoni, Marco -- England -- Nature. 2012 Nov 29;491(7426):748-51. doi: 10.1038/nature11555. Epub 2012 Oct 17.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ, UK. m.ruecklin@bristol.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23075852" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Australia ; *Biological Evolution ; *Fossils ; Jaw/*anatomy & histology ; Microscopy ; Phylogeny ; Synchrotrons ; Tomography, X-Ray ; Tooth/*anatomy & histology ; Vertebrates/*anatomy & histology/classification
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 3
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    The origin of conodonts and of vertebrate mineralized skeletons (2013)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2013-10-18
    Description: Conodonts are an extinct group of jawless vertebrates whose tooth-like elements are the earliest instance of a mineralized skeleton in the vertebrate lineage, inspiring the 'inside-out' hypothesis that teeth evolved independently of the vertebrate dermal skeleton and before the origin of jaws. However, these propositions have been based on evidence from derived euconodonts. Here we test hypotheses of a paraconodont ancestry of euconodonts using synchrotron radiation X-ray tomographic microscopy to characterize and compare the microstructure of morphologically similar euconodont and paraconodont elements. Paraconodonts exhibit a range of grades of structural differentiation, including tissues and a pattern of growth common to euconodont basal bodies. The different grades of structural differentiation exhibited by paraconodonts demonstrate the stepwise acquisition of euconodont characters, resolving debate over the relationship between these two groups. By implication, the putative homology of euconodont crown tissue and vertebrate enamel must be rejected as these tissues have evolved independently and convergently. Thus, the precise ontogenetic, structural and topological similarities between conodont elements and vertebrate odontodes appear to be a remarkable instance of convergence. The last common ancestor of conodonts and jawed vertebrates probably lacked mineralized skeletal tissues. The hypothesis that teeth evolved before jaws and the inside-out hypothesis of dental evolution must be rejected; teeth seem to have evolved through the extension of odontogenic competence from the external dermis to internal epithelium soon after the origin of jaws.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Murdock, Duncan J E -- Dong, Xi-Ping -- Repetski, John E -- Marone, Federica -- Stampanoni, Marco -- Donoghue, Philip C J -- England -- Nature. 2013 Oct 24;502(7472):546-9. doi: 10.1038/nature12645. Epub 2013 Oct 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24132236" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; *Fossils ; Jaw ; Nevada ; Phylogeny ; Skeleton ; Synchrotrons ; Tomography, X-Ray ; Tooth/*anatomy & histology ; Vertebrates/*anatomy & histology/*classification ; Wyoming
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 4
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    Exceptional preservation of tiny embryos documents seed dormancy in early angiosperms (2015)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2015-12-18
    Description: The rapid diversification of angiosperms through the Early Cretaceous period, between about 130-100 million years ago, initiated fundamental changes in the composition of terrestrial vegetation and is increasingly well understood on the basis of a wealth of palaeobotanical discoveries over the past four decades and their integration with improved knowledge of living angiosperms. Prevailing hypotheses, based on evidence both from living and from fossil plants, emphasize that the earliest angiosperms were plants of small stature with rapid life cycles that exploited disturbed habitats in open, or perhaps understorey, conditions. However, direct palaeontogical data relevant to understanding the seed biology and germination ecology of Early Cretaceous angiosperms are sparse. Here we report the discovery of embryos and their associated nutrient storage tissues in exceptionally well-preserved angiosperm seeds from the Early Cretaceous. Synchrotron radiation X-ray tomographic microscopy of the fossil embryos from many taxa reveals that all were tiny at the time of dispersal. These results support hypotheses based on extant plants that tiny embryos and seed dormancy are basic for angiosperms as a whole. The minute size of the fossil embryos, and the modest nutrient storage tissues dictated by the overall small seed size, is also consistent with the interpretation that many early angiosperms were opportunistic, early successional colonizers of disturbance-prone habitats.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Friis, Else Marie -- Crane, Peter R -- Pedersen, Kaj Raunsgaard -- Stampanoni, Marco -- Marone, Federica -- England -- Nature. 2015 Dec 24;528(7583):551-4. doi: 10.1038/nature16441. Epub 2015 Dec 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Palaeobiology, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden. ; Yale School of Forestry and Environmental Studies, 195 Prospect Street, New Haven, Connecticut 06511, USA. ; Department of Earth Science, University of Aarhus, DK-8000 Aarhus, Denmark. ; Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland. ; Institute for Biomedical Engineering, ETZ F 85, Swiss Federal Institute of Technology Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26675723" target="_blank"〉PubMed〈/a〉
    Keywords: Angiosperms/*anatomy & histology/cytology/*embryology ; Body Size ; Cotyledon/anatomy & histology/embryology ; *Fossils ; Germination ; Microscopy ; *Plant Dormancy ; Seeds/*anatomy & histology/cytology/*embryology ; Synchrotrons ; Tomography, X-Ray
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 5
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    Fossilized nuclei and germination structures identify Ediacaran "animal embryos" as encysting protists (2011)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2011-12-24
    Description: Globular fossils showing palintomic cell cleavage in the Ediacaran Doushantuo Formation, China, are widely regarded as embryos of early metazoans, although metazoan synapomorphies, tissue differentiation, and associated juveniles or adults are lacking. We demonstrate using synchrotron-based x-ray tomographic microscopy that the fossils have features incompatible with multicellular metazoan embryos. The developmental pattern is comparable with nonmetazoan holozoans, including germination stages that preclude postcleavage embryology characteristic of metazoans. We conclude that these fossils are neither animals nor embryos. They belong outside crown-group Metazoa, within total-group Holozoa (the sister clade to Fungi that includes Metazoa, Choanoflagellata, and Mesomycetozoea) or perhaps on even more distant branches in the eukaryote tree. They represent an evolutionary grade in which palintomic cleavage served the function of producing propagules for dispersion.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Huldtgren, Therese -- Cunningham, John A -- Yin, Chongyu -- Stampanoni, Marco -- Marone, Federica -- Donoghue, Philip C J -- Bengtson, Stefan -- New York, N.Y. -- Science. 2011 Dec 23;334(6063):1696-9. doi: 10.1126/science.1209537.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Palaeozoology, Swedish Museum of Natural History, Stockholm, Sweden.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22194575" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biological Evolution ; Cell Division ; Cell Nucleus/*ultrastructure ; Cell Shape ; China ; Embryo, Nonmammalian ; Eukaryota/classification/cytology/*growth & development/ultrastructure ; *Fossils ; Imaging, Three-Dimensional ; Life Cycle Stages ; Mesomycetozoea/classification/cytology/growth & development ; Phylogeny ; Synchrotrons ; Tomography, X-Ray
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 6
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    Visualization and quantification of electrochemical and mechanical degradation in Li ion batteries (2013)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2013-10-19
    Description: High-energy-density materials that undergo conversion and/or alloying reactions hold promise for next-generation lithium (Li) ion batteries. However, these materials experience substantial volume change during electrochemical operation, which causes mechanical fracture of the material and structural disintegration of the electrode, leading to capacity loss. In this work, we use x-ray tomography during battery operation to visualize and quantify the origins and evolution of electrochemical and mechanical degradation. Tomography provides the time-resolved, three-dimensional chemical composition and morphology within individual particles and throughout the electrode. In the model material tin(II) oxide, we witness distributions in onset and rate of core-shell lithiation, crack initiation and growth along preexisting defects, and irreversible distortion of the electrode, highlighting tomography as a tool to guide the development of durable materials and strain-tolerant electrodes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ebner, Martin -- Marone, Federica -- Stampanoni, Marco -- Wood, Vanessa -- New York, N.Y. -- Science. 2013 Nov 8;342(6159):716-20. doi: 10.1126/science.1241882. Epub 2013 Oct 17.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory for Nanoelectronics, ETH Zurich, Gloriastrasse 35 CH-8092 Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24136360" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
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    In situ observation of the percolation threshold in multiphase magma analogues (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-23
    Description: Magmas vesiculate during ascent, producing complex interconnected pore networks, which can act as outgassing pathways and then deflate or compact to volcanic plugs. Similarly, in-conduit fragmentation events during dome-forming eruptions create open systems transiently, before welding causes pore sealing. The percolation threshold is the first-order transition between closed- and open-system degassing dynamics. Here, we use time-resolved, synchrotron-source X-ray tomography to image synthetic magmas that go through cycles of opening and closing, to constrain the percolation threshold ΦC at a range of melt crystallinity, viscosity and overpressure pertinent to shallow magma ascent. During vesiculation, we observed different percolative regimes for the same initial bulk crystallinity depending on melt viscosity and gas overpressure. At high viscosity (〉 106 Pa s) and high overpressure (~ 1–4 MPa), we found that a brittle-viscous regime dominates in which brittle rupture allows system-spanning coalescence at a low percolation threshold (ΦC~0.17) via the formation of fracture-like bubble chains. Percolation was followed by outgassing and bubble collapse causing densification and isolation of the bubble network, resulting in a hysteresis in the evolution of connectivity with porosity. At low melt viscosity and overpressure, we observed a viscous regime with much higher percolation threshold (ΦC 〉 0.37) due to spherical bubble growth and lower degree of crystal connection. Finally, our results also show that sintering of crystal-free and crystal-bearing magma analogues is characterised by low percolation thresholds (ΦC = 0.04 – 0.10). We conclude that the presence of crystals lowers the percolation threshold during vesiculation and may promote outgassing in shallow, crystal-rich magma at initial stages of Vulcanian and Strombolian eruptions.
    Description: Paul Scherrer Institut http://dx.doi.org/10.13039/501100004219
    Description: European Research Council http://dx.doi.org/10.13039/501100000781
    Description: NERC
    Description: Deutsche Forschungsgemeinschaft
    Keywords: ddc:550.724 ; Effusive-explosive transition ; Percolation threshold ; Outgassing ; Crystal-rich magma ; Magma viscosity ; Gas overpressure ; Porosity ; Pore connectivity ; Hysteresis ; Strombolian/Vulcanian eruptions ; Dome-forming eruptions
    Language: English
    Type: doc-type:article
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  • 8
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    Virtual taphonomy using synchrotron tomographic microscopy reveals cryptic features and internal structure of modern and fossil plants (2009)
    National Academy of Sciences
    Details
    Publication Date: 2009-07-02
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 9
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    Low-dose, simple, and fast grating-based X-ray phase-contrast imaging (2010)
    National Academy of Sciences
    Details
    Publication Date: 2010-07-19
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 10
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    Gas-driven filter pressing in magmas: Insights into in-situ melt segregation from crystal mushes (2015)
    Geological Society of America (GSA)
    In: Geology
    Details
    Publication Date: 2015-07-30
    Description: Gas-driven filter pressing is the process of melt expulsion from a volatile-saturated crystal mush, induced by the buildup and subsequent release of gas pressure. Filter pressing is inferred to play a major role in magma fractionation at shallow depths (〈10 km) by moving melt and gas relative to the solid, crystalline framework. However, the magmatic conditions at which this process operates remain poorly constrained. We present novel experimental data that illustrate how the crystal content of the mush affects the ability of gas-driven filter pressing to segregate melt. Hydrous haplogranite (2.1 wt% water in the melt) and dacite (4.2 wt% water in the melt) crystal mushes, with a wide range of crystallinities (34–80 vol% crystals), were investigated using in-situ, high-temperature (500–800 °C) synchrotron X-ray tomographic microscopy with high spatial (3 μm/pixel) and temporal resolution (~8 s per three-dimensional data set). Our experimental results show that gas-driven filter pressing operates only below the maximum packing of bubbles and crystals (~74 vol%). Above this threshold, the mush tends to fracture and gas escapes via fractures. Therefore, the efficiency of gas-driven filter pressing is promoted close to the percolation threshold and in situations where a mush inflates slowly relative to build-up of pressure and expulsion of melt. Such observations offer a likely explanation for the production of eruptible, crystal-poor magmas within Earth’s crust.
    Print ISSN: 0091-7613
    Electronic ISSN: 1943-2682
    Topics: Geosciences
    Published by Geological Society of America (GSA)
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