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  • 1
    Publikationsdatum: 2013-06-29
    Beschreibung: Environmental Science & Technology DOI: 10.1021/es401096w
    Print ISSN: 0013-936X
    Digitale ISSN: 1520-5851
    Thema: Chemie und Pharmazie , Energietechnik
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
  • 3
    Publikationsdatum: 2014-11-24
    Beschreibung: We present the Early Data Release of the Sydney–AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey. The SAMI Galaxy Survey is an ongoing integral field spectroscopic survey of ~3400 low-redshift ( z  〈 0.12) galaxies, covering galaxies in the field and in groups within the Galaxy And Mass Assembly (GAMA) survey regions, and a sample of galaxies in clusters. In the Early Data Release, we publicly release the fully calibrated data cubes for a representative selection of 107 galaxies drawn from the GAMA regions, along with information about these galaxies from the GAMA catalogues. All data cubes for the Early Data Release galaxies can be downloaded individually or as a set from the SAMI Galaxy Survey website. In this paper we also assess the quality of the pipeline used to reduce the SAMI data, giving metrics that quantify its performance at all stages in processing the raw data into calibrated data cubes. The pipeline gives excellent results throughout, with typical sky subtraction residuals in the continuum of 0.9–1.2 per cent, a relative flux calibration uncertainty of 4.1 per cent (systematic) plus 4.3 per cent (statistical), and atmospheric dispersion removed with an accuracy of 0.09 arcsec, less than a fifth of a spaxel.
    Print ISSN: 0035-8711
    Digitale ISSN: 1365-2966
    Thema: Physik
    Publiziert von Oxford University Press
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  • 4
    Publikationsdatum: 2015-01-15
    Beschreibung: The SAMI Galaxy Survey will observe 3400 galaxies with the Sydney-AAO Multi-object Integral-field spectrograph (SAMI) on the Anglo-Australian Telescope in a 3-yr survey which began in 2013. We present the throughput of the SAMI system, the science basis and specifications for the target selection, the survey observation plan and the combined properties of the selected galaxies. The survey includes four volume-limited galaxy samples based on cuts in a proxy for stellar mass, along with low-stellar-mass dwarf galaxies all selected from the Galaxy And Mass Assembly (GAMA) survey. The GAMA regions were selected because of the vast array of ancillary data available, including ultraviolet through to radio bands. These fields are on the celestial equator at 9, 12 and 14.5 h, and cover a total of 144 deg 2 (in GAMA-I). Higher density environments are also included with the addition of eight clusters. The clusters have spectroscopy from 2-degree Field Galaxy Redshift Survey (2dFGRS) and Sloan Digital Sky Survey (SDSS) and photometry in regions covered by the SDSS and/or VLT Survey Telescope/ATLAS. The aim is to cover a broad range in stellar mass and environment, and therefore the primary survey targets cover redshifts 0.004 〈  z  〈 0.095, magnitudes r pet  〈 19.4, stellar masses 10 7 –10 12  M , and environments from isolated field galaxies through groups to clusters of ~10 15  M .
    Print ISSN: 0035-8711
    Digitale ISSN: 1365-2966
    Thema: Physik
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Publikationsdatum: 2004-11-30
    Beschreibung: The widespread extinctions of large mammals at the end of the Pleistocene epoch have often been attributed to the depredations of humans; here we present genetic evidence that questions this assumption. We used ancient DNA and Bayesian techniques to reconstruct a detailed genetic history of bison throughout the late Pleistocene and Holocene epochs. Our analyses depict a large diverse population living throughout Beringia until around 37,000 years before the present, when the population's genetic diversity began to decline dramatically. The timing of this decline correlates with environmental changes associated with the onset of the last glacial cycle, whereas archaeological evidence does not support the presence of large populations of humans in Eastern Beringia until more than 15,000 years later.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shapiro, Beth -- Drummond, Alexei J -- Rambaut, Andrew -- Wilson, Michael C -- Matheus, Paul E -- Sher, Andrei V -- Pybus, Oliver G -- Gilbert, M Thomas P -- Barnes, Ian -- Binladen, Jonas -- Willerslev, Eske -- Hansen, Anders J -- Baryshnikov, Gennady F -- Burns, James A -- Davydov, Sergei -- Driver, Jonathan C -- Froese, Duane G -- Harington, C Richard -- Keddie, Grant -- Kosintsev, Pavel -- Kunz, Michael L -- Martin, Larry D -- Stephenson, Robert O -- Storer, John -- Tedford, Richard -- Zimov, Sergei -- Cooper, Alan -- New York, N.Y. -- Science. 2004 Nov 26;306(5701):1561-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Henry Wellcome Ancient Biomolecules Centre, Oxford University, South Parks Road, Oxford OX13PS, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15567864" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Alaska ; Animals ; Bayes Theorem ; *Bison/classification/genetics ; Canada ; China ; *Climate ; DNA, Mitochondrial/genetics ; Environment ; *Fossils ; Genetic Variation ; Genetics, Population ; Human Activities ; Humans ; North America ; Phylogeny ; Population Dynamics ; Sequence Analysis, DNA ; Time
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Publikationsdatum: 2002-03-23
    Beschreibung: The climatic and environmental changes associated with the last glaciation (90,000 to 10,000 years before the present; 90 to 10 ka B.P.) are an important example of the effects of global climate change on biological diversity. These effects were particularly marked in Beringia (northeastern Siberia, northwestern North America, and the exposed Bering Strait) during the late Pleistocene. To investigate the evolutionary impact of these events, we studied genetic change in the brown bear, Ursus arctos, in eastern Beringia over the past 60,000 years using DNA preserved in permafrost remains. A marked degree of genetic structure is observed in populations throughout this period despite local extinctions, reinvasions, and potential interspecies competition with the short-faced bear, Arctodus simus. The major phylogeographic changes occurred 35 to 21 ka B.P., before the glacial maximum, and little change is observed after this time. Late Pleistocene histories of mammalian taxa may be more complex than those that might be inferred from the fossil record or contemporary DNA sequences alone.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barnes, I -- Matheus, P -- Shapiro, B -- Jensen, D -- Cooper, A -- New York, N.Y. -- Science. 2002 Mar 22;295(5563):2267-70.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Biological Anthropology, University of Oxford, Oxford OX2 6QS, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11910112" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Base Sequence ; Climate ; DNA, Mitochondrial/genetics/isolation & purification ; Diet ; *Ecosystem ; *Evolution, Molecular ; Fossils ; Founder Effect ; Haplotypes/genetics ; Ice ; Molecular Sequence Data ; Phylogeny ; Siberia ; Species Specificity ; Time Factors ; Ursidae/*genetics/physiology
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 7
    Publikationsdatum: 2015-03-25
    Beschreibung: No large group of recently extinct placental mammals remains as evolutionarily cryptic as the approximately 280 genera grouped as 'South American native ungulates'. To Charles Darwin, who first collected their remains, they included perhaps the 'strangest animal[s] ever discovered'. Today, much like 180 years ago, it is no clearer whether they had one origin or several, arose before or after the Cretaceous/Palaeogene transition 66.2 million years ago, or are more likely to belong with the elephants and sirenians of superorder Afrotheria than with the euungulates (cattle, horses, and allies) of superorder Laurasiatheria. Morphology-based analyses have proved unconvincing because convergences are pervasive among unrelated ungulate-like placentals. Approaches using ancient DNA have also been unsuccessful, probably because of rapid DNA degradation in semitropical and temperate deposits. Here we apply proteomic analysis to screen bone samples of the Late Quaternary South American native ungulate taxa Toxodon (Notoungulata) and Macrauchenia (Litopterna) for phylogenetically informative protein sequences. For each ungulate, we obtain approximately 90% direct sequence coverage of type I collagen alpha1- and alpha2-chains, representing approximately 900 of 1,140 amino-acid residues for each subunit. A phylogeny is estimated from an alignment of these fossil sequences with collagen (I) gene transcripts from available mammalian genomes or mass spectrometrically derived sequence data obtained for this study. The resulting consensus tree agrees well with recent higher-level mammalian phylogenies. Toxodon and Macrauchenia form a monophyletic group whose sister taxon is not Afrotheria or any of its constituent clades as recently claimed, but instead crown Perissodactyla (horses, tapirs, and rhinoceroses). These results are consistent with the origin of at least some South American native ungulates from 'condylarths', a paraphyletic assembly of archaic placentals. With ongoing improvements in instrumentation and analytical procedures, proteomics may produce a revolution in systematics such as that achieved by genomics, but with the possibility of reaching much further back in time.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Welker, Frido -- Collins, Matthew J -- Thomas, Jessica A -- Wadsley, Marc -- Brace, Selina -- Cappellini, Enrico -- Turvey, Samuel T -- Reguero, Marcelo -- Gelfo, Javier N -- Kramarz, Alejandro -- Burger, Joachim -- Thomas-Oates, Jane -- Ashford, David A -- Ashton, Peter D -- Rowsell, Keri -- Porter, Duncan M -- Kessler, Benedikt -- Fischer, Roman -- Baessmann, Carsten -- Kaspar, Stephanie -- Olsen, Jesper V -- Kiley, Patrick -- Elliott, James A -- Kelstrup, Christian D -- Mullin, Victoria -- Hofreiter, Michael -- Willerslev, Eske -- Hublin, Jean-Jacques -- Orlando, Ludovic -- Barnes, Ian -- MacPhee, Ross D E -- England -- Nature. 2015 Jun 4;522(7554):81-4. doi: 10.1038/nature14249. Epub 2015 Mar 18.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] BioArCh, University of York, York YO10 5DD, UK [2] Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany. ; BioArCh, University of York, York YO10 5DD, UK. ; Department of Earth Sciences, Natural History Museum, London SW7 5BD, UK. ; Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Oster Voldgade 5-7, 1350 Copenhagen K, Denmark. ; Institute of Zoology, Zoological Society of London, London NW1 4RY, UK. ; CONICET- Division Paleontologia de Vertebrados, Museo de La Plata. Facultad de Ciencias Naturales y Museo de La Plata, Universidad Nacional de La Plata. Paseo del Bosque s/n, B1900FWA, La Plata, Argentina. ; Seccion Paleontologia de Vertebrados. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", 470 Angel Gallardo Av., C1405DJR, Buenos Aires, Argentina. ; Institute of Anthropology, Johannes Gutenberg-University, Anselm-Franz-von-Bentzel-Weg 7, D-55128 Mainz, Germany. ; Department of Chemistry, University of York, York YO10 5DD, UK. ; Bioscience Technology Facility, Department of Biology, University of York, York YO10 5DD, UK. ; Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA. ; Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7FZ, UK. ; Applications Development, Bruker Daltonik GmbH, 28359 Bremen, Germany. ; Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3b, 2200 Copenhagen, Denmark. ; Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, UK. ; Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, Ireland. ; 1] BioArCh, University of York, York YO10 5DD, UK [2] Institute for Biochemistry and Biology, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam OT Golm, Germany. ; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany. ; Department of Mammalogy, American Museum of Natural History, New York, New York 10024, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25799987" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Amino Acid Sequence ; Animals ; Bone and Bones/chemistry ; Cattle ; Collagen Type I/*chemistry/genetics ; Female ; *Fossils ; Mammals/*classification ; Perissodactyla/classification ; *Phylogeny ; Placenta ; Pregnancy ; Proteomics ; South America
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 8
    Publikationsdatum: 2014-02-14
    Beschreibung: Clovis, with its distinctive biface, blade and osseous technologies, is the oldest widespread archaeological complex defined in North America, dating from 11,100 to 10,700 (14)C years before present (bp) (13,000 to 12,600 calendar years bp). Nearly 50 years of archaeological research point to the Clovis complex as having developed south of the North American ice sheets from an ancestral technology. However, both the origins and the genetic legacy of the people who manufactured Clovis tools remain under debate. It is generally believed that these people ultimately derived from Asia and were directly related to contemporary Native Americans. An alternative, Solutrean, hypothesis posits that the Clovis predecessors emigrated from southwestern Europe during the Last Glacial Maximum. Here we report the genome sequence of a male infant (Anzick-1) recovered from the Anzick burial site in western Montana. The human bones date to 10,705 +/- 35 (14)C years bp (approximately 12,707-12,556 calendar years bp) and were directly associated with Clovis tools. We sequenced the genome to an average depth of 14.4x and show that the gene flow from the Siberian Upper Palaeolithic Mal'ta population into Native American ancestors is also shared by the Anzick-1 individual and thus happened before 12,600 years bp. We also show that the Anzick-1 individual is more closely related to all indigenous American populations than to any other group. Our data are compatible with the hypothesis that Anzick-1 belonged to a population directly ancestral to many contemporary Native Americans. Finally, we find evidence of a deep divergence in Native American populations that predates the Anzick-1 individual.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rasmussen, Morten -- Anzick, Sarah L -- Waters, Michael R -- Skoglund, Pontus -- DeGiorgio, Michael -- Stafford, Thomas W Jr -- Rasmussen, Simon -- Moltke, Ida -- Albrechtsen, Anders -- Doyle, Shane M -- Poznik, G David -- Gudmundsdottir, Valborg -- Yadav, Rachita -- Malaspinas, Anna-Sapfo -- White, Samuel Stockton 5th -- Allentoft, Morten E -- Cornejo, Omar E -- Tambets, Kristiina -- Eriksson, Anders -- Heintzman, Peter D -- Karmin, Monika -- Korneliussen, Thorfinn Sand -- Meltzer, David J -- Pierre, Tracey L -- Stenderup, Jesper -- Saag, Lauri -- Warmuth, Vera M -- Lopes, Margarida C -- Malhi, Ripan S -- Brunak, Soren -- Sicheritz-Ponten, Thomas -- Barnes, Ian -- Collins, Matthew -- Orlando, Ludovic -- Balloux, Francois -- Manica, Andrea -- Gupta, Ramneek -- Metspalu, Mait -- Bustamante, Carlos D -- Jakobsson, Mattias -- Nielsen, Rasmus -- Willerslev, Eske -- BB/H005854/1/Biotechnology and Biological Sciences Research Council/United Kingdom -- BB/H008802/1/Biotechnology and Biological Sciences Research Council/United Kingdom -- P25032/Biotechnology and Biological Sciences Research Council/United Kingdom -- England -- Nature. 2014 Feb 13;506(7487):225-9. doi: 10.1038/nature13025.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Oster Voldgade 5-7, DK-1350 Copenhagen K, Denmark [2]. ; 1] Anzick Family, 31 Old Clyde Park Road, Livingston, Montana 59047, USA [2]. ; Center for the Study of the First Americans, Departments of Anthropology and Geography, Texas A&M University, 4352 TAMU, College Station, Texas 77843-4352, USA. ; Department of Evolutionary Biology, Uppsala University, Norbyvagen 18D, 752 36 Uppsala, Sweden. ; 1] Department of Integrative Biology, University of California, Berkeley, 4134 Valley Life Sciences Building, Berkeley, California 94720, USA [2] Earth Sciences Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK (I.B.); Department of Biology, Pennsylvania State University, 502 Wartik Laboratory, University Park, Pennsylvania 16802, USA (M.D.). ; 1] Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Oster Voldgade 5-7, DK-1350 Copenhagen K, Denmark [2] AMS 14C Dating Centre, Department of Physics & Astronomy, University of Aarhus, Ny Munkegade 120, DK-8000 Aarhus C, Denmark. ; Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Kemitorvet 208, Kgs. Lyngby DK-2800, Denmark. ; 1] The Bioinformatics Centre, Department of Biology, University of Copenhagen, Ole Maaloes Vej 5, DK-2200 Copenhagen N, Denmark [2] Department of Human Genetics, University of Chicago, 920 E. 58th Street, CLSC 4th floor, Chicago, Illinois 60637, USA. ; The Bioinformatics Centre, Department of Biology, University of Copenhagen, Ole Maaloes Vej 5, DK-2200 Copenhagen N, Denmark. ; Education Department, Montana State University, Box 5103, Bozeman, Montana 59717, USA. ; Program in Biomedical Informatics and Department of Statistics, Stanford University, Stanford, California 94305, USA. ; Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Oster Voldgade 5-7, DK-1350 Copenhagen K, Denmark. ; Anthropology Department, PhD Program, University of Montana, 4100 Mullan Road, no. 217, Missoula, Montana 59808, USA. ; School of Biological Sciences, Washington State University, PO Box 644236, Eastlick Hall 395, Pullman, Washington 99164, USA. ; Department of Evolutionary Biology, Estonian Biocentre and University of Tartu, Riia 23b, 51010 Tartu, Estonia. ; 1] Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK [2] Integrative Systems Biology Laboratory, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia. ; School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK. ; Department of Anthropology, Southern Methodist University, Dallas, Texas 75275, USA. ; 1] Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK [2] Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK. ; Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK. ; Department of Anthropology and Institute for Genomic Biology, University of Illinois Urbana-Champaign, 209F Davenport Hall, 607 Matthews Avenue, Urbana, Illinois 61801, USA. ; 1] School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK [2] Earth Sciences Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK (I.B.); Department of Biology, Pennsylvania State University, 502 Wartik Laboratory, University Park, Pennsylvania 16802, USA (M.D.). ; BioArCh, Departments of Biology, Archaeology and Chemistry, University of York, Wentworth Way, York YO10 5DD, UK. ; MRC Centre for Outbreak, Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, Imperial College Faculty of Medicine, London W2 1PG, UK. ; Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. ; 1] Department of Genetics, School of Medicine, Stanford University, Littlefield Center, Stanford, California 94305, USA [2] Center for Evolutionary and Human Genomics, Stanford University, Littlefield Center, Stanford, California 94305, USA. ; 1] Department of Evolutionary Biology, Uppsala University, Norbyvagen 18D, 752 36 Uppsala, Sweden [2] Science for Life Laboratory, Uppsala University, Norbyvagen 18D, 752 36 Uppsala, Sweden. ; Department of Integrative Biology, University of California, Berkeley, 4134 Valley Life Sciences Building, Berkeley, California 94720, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24522598" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Archaeology ; Asia/ethnology ; Bone and Bones ; Burial ; Chromosomes, Human, Y/genetics ; DNA, Mitochondrial/genetics ; Emigration and Immigration/history ; Europe/ethnology ; Gene Flow/genetics ; Genome, Human/*genetics ; Haplotypes/genetics ; History, Ancient ; Humans ; Indians, North American/*genetics ; Infant ; Male ; Models, Genetic ; Molecular Sequence Data ; Montana ; *Phylogeny ; Population Dynamics ; Radiometric Dating
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 9
    Publikationsdatum: 2013-07-16
    Beschreibung: The petrogenesis of sulphide ores in the O’okiep district has remained controversial. Based mainly on the concentration of chalcophile metals (PGE, Cu, Ni), it is proposed that the sulphides segregated from a basaltic magma generated during melting of sub-continental lithospheric mantle. Sulphide saturation of the magma was delayed due to relatively high f O 2 until crustal contamination occurred during the advanced stages of differentiation. The immiscible sulphide melt was entrained and fractionated in dynamic magma conduits. Sulphides enriched in monosulphide solid solution (mss) component precipitated at depth in the Kliprand area of southern Namaqualand to form the Hondekloof deposits, whereas the O’okiep ores crystallised at shallower levels from highly fractionated residual sulphide liquids enriched in intermediate solid solution (iss). Sulphides of intermediate composition occur at Ezelsfontein. In the context of this model, the O’okiep intrusions could represent the proximal magmatic members of an IOCG suite of deposits, raising the prospect for additional IOCG deposits elsewhere in southern Africa. The model also predicts an enhanced potential at O’okiep for undiscovered Ni sulphide ores at depth.
    Print ISSN: 1012-0750
    Thema: Geologie und Paläontologie
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  • 10
    Publikationsdatum: 2017-08-16
    Beschreibung: We report on a spectral environment evaluation and recording (SEER) system, for instantaneously wideband spectral capture and characterization in the HF and lower VHF band, utilizing a direct digital receiver coupled to a data recorder. The system is designed to contend with a wide variety of electro-magnetic environments, and to provide accurately calibrated spectral characterization and display from very short (ms) to synoptic scales. The system incorporates a novel RF front end involving automated gain and equalization filter selection which provides an analogue frequency dependent gain characteristic that mitigates the high dynamic range found across the HF and lower VHF spectrum. The system accurately calibrates its own internal noise, and automatically subtracts this from low variance, external spectral estimates, further extending the dynamic range over which robust characterization is possible. Laboratory and field experiments demonstrate the implementation of these concepts has been effective. Sensitivity to varying antenna load impedance of the internal noise reduction process has been examined. Examples of software algorithms to provide extraction and visualization of spectral behavior over narrowband, wideband, short, and synoptic scales are provided. Application in HF noise spectral density monitoring, spectral signal strength assessment and electromagnetic interference detection is possible with examples provided. The instantaneously full bandwidth collection provides some innovative application, and this is demonstrated by the collection of discrete lightning emissions, which form fast ionograms called “flashagrams” in power-delay-frequency plots.
    Print ISSN: 0048-6604
    Digitale ISSN: 1944-799X
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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