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  • 1
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    PANGAEA
    In:  Supplement to: Martinez, Mathieu; Kotov, Sergey; De Vleeschouwer, David; Pas, Damien; Pälike, Heiko (2016): Testing the impact of stratigraphic uncertainty on spectral analyses of sedimentary series. Climate of the Past, 12(9), 1765-1783, https://doi.org/10.5194/cp-12-1765-2016
    Publication Date: 2019-04-30
    Description: Spectral analysis is a key tool for identifying periodic patterns in sedimentary sequences, including astronomically related orbital signals. While most spectral analysis methods require equally spaced samples, this condition is rarely achieved either in the field or when sampling sediment core. Here, we propose a method to assess the impact of the uncertainty or error made in the measurement of the sample stratigraphic position on the resulting power spectra. We apply a Monte Carlo procedure to randomise the sample steps of depth series using a gamma distribution. Such a distribution preserves the stratigraphic order of samples and allows controlling the average and the variance of the distribution of sample distances after randomisation. We apply the Monte Carlo procedure on two geological datasets and find that gamma distribution of sample distances completely smooths the spectrum at high frequencies and decreases the power and significance levels of the spectral peaks in an important proportion of the spectrum. At 5 % of stratigraphic uncertainty, a small portion of the spectrum is completely smoothed. Taking at least three samples per thinnest cycle of interest should allow this cycle to be still observed in the spectrum, while taking at least four samples per thinnest cycle of interest should allow its significance levels to be preserved in the spectrum. At 10 and 15 % uncertainty, these thresholds increase, and taking at least four samples per thinnest cycle of interest should allow the targeted cycles to be still observed in the spectrum. In addition, taking at least 10 samples per thinnest cycle of interest should allow their significance levels to be preserved. For robust applications of the power spectrum in further studies, we suggest providing a strong control of the measurement of the sample position. A density of 10 samples per putative precession cycle is a safe sampling density for preserving spectral power and significance level in the Milankovitch band. For lower sampling density, the use of gamma-law simulations should help in assessing the impact of stratigraphic uncertainty in the power spectrum in the Milankovitch band. Gamma-law simulations can also model the distortions of the Milankovitch record in sedimentary series due to variations in the sedimentation rate.
    Type: Dataset
    Format: text/tab-separated-values, 4 data points
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  • 2
    facet.materialart.
    Unknown
    PANGAEA
    In:  Supplement to: Martinez, Mathieu; Pellenard, Pierre; Deconinck, J F; Monna, Fabrice; Riquier, Laurent; Boulila, Slah; Moiroud, Mathieu; Company, M (2012): An orbital floating time scale of the Hauterivian/Barremian GSSP from a mangetic susceptibility signal (Rio Argos, Spain). Cretaceous Research, 36, 106-115, https://doi.org/10.1016/j.cretres.2012.02.015
    Publication Date: 2018-10-20
    Description: An orbital floating time scale of the Hauterivian-Barremian transition (Early Cretaceous) is proposed using high-resolution magnetic susceptibility measurements. Orbital tuning was performed on the Río Argos section (southeast Spain), the candidate for a Global boundary Stratotype Section and Point (GSSP) for the Hauterivian-Barremian transition. Spectral analyses of MS variations, coupled with the frequency ratio method, allow the recognition of precession, obliquity and eccentricity frequency bands. Orbitally-tuned magnetic susceptibility provides minimum durations for ammonite biozones. The durations of well-constrained ammonite zones are assessed at 0.78 myr for Pseudothurmannia ohmi (Late Hauterivian) and 0.57 myr for Taveraidiscus hugii (Early Barremian). These results are consistent with previous estimates from the other reference section (Angles, southeast France) and tend to show that the Río Argos section displays a complete succession for this time interval. They differ significantly from those proposed in the Geologic Time Scale 2008 and may help to improve the next compilation. The Faraoni Oceanic Anoxic Event, a key Early Cretaceous oceanographic perturbation occurring at the P. ohmi/P. catulloi subzone boundary has a duration estimated at 0.10-0.15 myr, which is similar to previous assessments.
    Type: Dataset
    Format: text/tab-separated-values, 808 data points
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  • 3
    facet.materialart.
    Unknown
    PANGAEA
    In:  Supplement to: Bajnai, David; Pálfy, József; Martinez, Mathieu; Price, Gregory D; Nyerges, Anita; Fözy, István (2017): Multi-proxy record of orbital-scale changes in climate and sedimentation during the Weissert Event in the Valanginian Bersek Marl Formation (Gerecse Mts., Hungary). Cretaceous Research, 75, 45-60, https://doi.org/10.1016/j.cretres.2017.02.021
    Publication Date: 2019-09-09
    Description: The Valanginian positive carbon isotope excursion and associated environmental changes, known as the Weissert Event, is the first in the series of Cretaceous Earth system perturbations. Here, we develop a multiproxy cyclostratigraphy from a 31.2-m-thick Upper Valanginian to lowermost Hauterivian section of the Bersek Marl Formation in Gerecse Mountains, Hungary, comprising alternating marlstone layers of varying clay and carbonate content. The bulk carbonate d13C signal shows sustained, elevated values (up to 2.7 per mil) up to 19.2 m, followed by a decreasing trend upsection. Together with biostratigraphic data, this suggests that the lower part of the section was deposited during the plateau phase of the Valanginian Weissert Event. Spectral analyses of the multiproxy dataset, including magnetic susceptibility measurements and gamma-ray spectroscopy on the lower part of the section led to the identification of precession, obliquity, long and short eccentricity signals. A mean sedimentation rate of 14 m/Myr was calculated based on astronomical tuning. The cyclicity in the proxy signals reflects dilution cycles by detrital inputs in the basin, which supports the idea that orbitally-forced humid-arid cycles controlled the pelagic alternating sedimentation during the Early Cretaceous throughout the Tethyan area.
    Type: Dataset
    Format: text/tab-separated-values, 1074 data points
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  • 4
    Publication Date: 2015-11-18
    Description: Heparan sulfate (HS) is recognized as an important player in a wide range of dynamic steps of inflammatory reactions. Thereby, structural HS remodeling is likely to play an important role in the regulation of inflammatory and immune responses; however little is known about underlying mechanism. In this study, we analyzed the regulation of expression of HS 3- O -sulfotransferases (HS3STs) in response to inflammatory stimuli. We found that among the seven HS3ST isoenzymes, only the expression of HS3ST3B was markedly up-regulated in human primary monocytes and the related cell line THP1 after exposure to TLR agonists. TNF-α was also efficient, to a lesser extent, to increase HS3ST3B expression, while IL-6, IL-4 and IFN-γ were poor inducers. We then analyzed the molecular mechanisms that regulate the high expression of HS3ST3B in response to LPS. Based on the expression of HS3ST3B transcripts and on the response of a reporter gene containing the HS3ST3B1 promoter, we provide evidence that LPS induces a rapid and strong transcription of HS3ST3B1 gene, which was mainly dependent on the activation of NF-κB and JNK signaling pathways. Additionally, active p38 MAPK and de novo synthesized proteins are involved in post-transcriptional mechanisms to maintain a high level of HS3ST3B mRNA to a steady state. Altogether, our findings indicate that HS3ST3B1 gene behaves as a primary response gene, suggesting that it may play an important role in making 3- O -sulfated HS with specific functions in the regulation of inflammatory and immune responses. This article is protected by copyright. All rights reserved
    Electronic ISSN: 0091-7419
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Published by Wiley
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  • 5
  • 6
    Publication Date: 2017-01-12
    Print ISSN: 0078-0421
    Electronic ISSN: 0078-0421
    Topics: Geosciences
    Published by Schweizerbart
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  • 7
  • 8
    Publication Date: 2013-02-01
    Print ISSN: 0009-2541
    Electronic ISSN: 1872-6836
    Topics: Chemistry and Pharmacology , Geosciences
    Published by Elsevier
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  • 9
    Publication Date: 2014-01-16
    Description: This study reports on a ~ 150 m thick macrofossil-barren sequence of siliciclastic sediments from a Burdigalian age (Early Miocene) freshwater lake. The lake was located within an incipient rift system of the Most Basin in the Ohře (Eger) Graben, which was part of the European Cenozoic Rift System, and had an original area of ≈ 1000 km2. Sediments from the HK591 core that cover the entire thickness of the lake deposits and some of the adjacent stratigraphic units were analysed by X-ray fluorescence spectroscopy (a proxy for element composition) and magnetic polarity measurement. The element proxies were subjected to frequency analysis, which provided estimated sedimentation rates, and allowed for sediment dating by magnetostratigraphy and orbital tuning of the age model. Based on the resulting age model and the known biostratigraphy, the lake was present between 17.4 and 16.6 Ma, which includes the onset of the Miocene Climatic Optimum in the latest Early Miocene. The identification of orbital forcing (precession, obliquity and short eccentricity cycles) confirms the stability of the sedimentary environment of the perennial lake in an underfilled basin. The dating allowed the sediment record to be interpreted in the context of the current knowledge of the European climate during that period. The stability of the sedimentary environment confirms that precipitation was relatively stable over the period recorded by the sediments.
    Print ISSN: 0016-7568
    Electronic ISSN: 1469-5081
    Topics: Geosciences
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  • 10
    Publication Date: 2016-09-02
    Description: Spectral analysis is a key tool for identifying periodic patterns in sedimentary sequences, including astronomically related orbital signals. While most spectral analysis methods require equally spaced samples, this condition is rarely achieved either in the field or when sampling sediment core. Here, we propose a method to assess the impact of the uncertainty or error made in the measurement of the sample stratigraphic position on the resulting power spectra. We apply a Monte Carlo procedure to randomise the sample steps of depth series using a gamma distribution. Such a distribution preserves the stratigraphic order of samples and allows controlling the average and the variance of the distribution of sample distances after randomisation. We apply the Monte Carlo procedure on two geological datasets and find that gamma distribution of sample distances completely smooths the spectrum at high frequencies and decreases the power and significance levels of the spectral peaks in an important proportion of the spectrum. At 5% of stratigraphic uncertainty, a small portion of the spectrum is completely smoothed. Taking at least three samples per thinnest cycle of interest should allow this cycle to be still observed in the spectrum, while taking at least four samples per thinnest cycle of interest should allow its significance levels to be preserved in the spectrum. At 10 and 15% uncertainty, these thresholds increase, and taking at least four samples per thinnest cycle of interest should allow the targeted cycles to be still observed in the spectrum. In addition, taking at least 10 samples per thinnest cycle of interest should allow their significance levels to be preserved. For robust applications of the power spectrum in further studies, we suggest providing a strong control of the measurement of the sample position. A density of 10 samples per putative precession cycle is a safe sampling density for preserving spectral power and significance level in the Milankovitch band. For lower sampling density, the use of gamma-law simulations should help in assessing the impact of stratigraphic uncertainty in the power spectrum in the Milankovitch band. Gamma-law simulations can also model the distortions of the Milankovitch record in sedimentary series due to variations in the sedimentation rate.
    Print ISSN: 1814-9324
    Electronic ISSN: 1814-9332
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union (EGU).
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