Annama H chondrite—Mineralogy,physical properties,cosmic ray exposure,and parent body history          下载免费PDF全文

Tomáš Kohout  Jakub Haloda  Patricie Halodová  Matthias M. M. Meier  Colin Maden  Henner Busemann  Matthias Laubenstein  Marc. W. Caffee  Kees C. Welten  Jens Hopp  Mario Trieloff  Ramakant R. Mahajan  Sekhar Naik  Josep M. Trigo‐Rodriguez  Carles E. Moyano‐Cambero  Michael I. Oshtrakh  Alevtina A. Maksimova  Andrey V. Chukin  Vladimir A. Semionkin  Maksim S. Karabanalov  Israel Felner  Evgeniya V. Petrova  Evgeniia V. Brusnitsyna  Victor I. Grokhovsky  Grigoriy A. Yakovlev  Maria Gritsevich  Esko Lyytinen  Jarmo Moilanen  Nikolai A. Kruglikov  Aleksey V. Ishchenko 《Meteoritics & planetary science》2017,52(8):1525-1541

The fall of the Annama meteorite occurred early morning (local time) on April 19, 2014 on the Kola Peninsula (Russia). Based on mineralogy and physical properties, Annama is a typical H chondrite. It has a high Ar‐Ar age of 4.4 Ga. Its cosmic ray exposure history is atypical as it is not part of the large group of H chondrites with a prominent 7–8 Ma peak in the exposure age histograms. Instead, its exposure age is within uncertainty of a smaller peak at 30 ± 4 Ma. The results from short‐lived radionuclides are compatible with an atmospheric pre‐entry radius of 30–40 cm. However, based on noble gas and cosmogenic radionuclide data, Annama must have been part of a larger body (radius >65 cm) for a large part of its cosmic ray exposure history. The ¹⁰Be concentration indicates a recent (3–5 Ma) breakup which may be responsible for the Annama parent body size reduction to 30–35 cm pre‐entry radius.  相似文献   

An Electron-Balance Based Approach to Predict the Decreasing Denitrification Potential of an Aquifer     

Matthias Loschko  Thomas Wöhling  David L. Rudolph  Olaf A. Cirpka 《Ground water》2019,57(6):925-939

Numerical models for reactive transport can be used to estimate the breakthrough of a contaminant in a pumping well or at other receptors. However, as natural aquifers are highly heterogeneous with unknown spatial details, reactive transport predictions on the aquifer scale require a stochastic framework for uncertainty analysis. The high computational demand of spatially explicit reactive-transport models hampers such analysis, thus motivating the search for simplified estimation tools. We suggest performing an electron balance between the reactants in the infiltrating solution and in the aquifer matrix to obtain the hypothetical time of dissolved-reactant breakthrough at a receptor if the reaction with the matrix was instantaneous. This time we denote as the advective breakthrough time for instantaneous reaction (τ_inst ). It depends on the amount of the reaction partner present in the matrix, the mass flux of the dissolved reactant, and the stoichiometry. While the shape of the reactive-species breakthrough curve depends on various kinetic parameters, the overall timing scales with τ_inst . We calculate the latter by particle tracking. The effort of computing τ_inst is so low that stochastic calculations become feasible. We apply the concept to a two-dimensional test case of aerobic respiration and denitrification. A detailed spatially explicit reactive-transport model includes microbial dynamics. Scaling the time of local breakthrough curves observed at individual points by τ_inst decreased the variability of electron-donor breakthrough curves significantly. We conclude that the advective breakthrough time for instantaneous reaction is efficient in estimating the time over which an aquifer retains its degradation potential.  相似文献   

Robust optical tracking of individual ejecta particles in hypervelocity impact experiments          下载免费PDF全文

Max Gulde  Lukas Kortmann  Matthias Ebert  Erkai Watson  Jakob Wilk  Frank Schäfer 《Meteoritics & planetary science》2018,53(8):1696-1704

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“This venue is brought to you by…”: the diffusion of sports and entertainment facility name sponsorship in urban Europe     

Jani Vuolteenaho  Matthias Wolny  Guy Puzey 《Urban geography》2019,40(6):762-783

ABSTRACT

Drawing on a database of 193 football (soccer) grounds and 115 indoor arenas, as well as press releases and media reports associated with them, this study charts the diffusion of sporting and entertainment facility name sponsorship across metropolises, cities, towns, and smaller settlements in six European contexts. Our results show the emergence of naming rights deals in the 1990s, their peak in the mid-2000s, and the current situation with a steadier growth of name sponsorship. Thus far, the corporate re-branding of venues has remained less prevalent in Italy, Norway, and Scotland than in England and Wales, Finland, and above all Germany. In financing newly built venues, however, the corporatized landmark language in focus has become a practically invariable part of local growth, austerity and (re)branding policies. Despite voices of resistance in all regions studied here, pressure towards the corporate renaming of even hereditary, communally endorsed football stadiums is increasingly being felt by municipal and private-sector venue owners.  相似文献   

A review of the magnitude and response times for sediment yield reductions following the rehabilitation of gullied landscapes     

Rebecca Bartley  Jean Poesen  Scott Wilkinson  Matthias Vanmaercke 《地球表面变化过程与地形》2020,45(13):3250-3279

Gully erosion is a major driver of elevated sediment yields across many areas of the globe, and considerable rehabilitation has occurred to reduce the amount of sediment eroded from gullies. However, compared to other forms of erosion, there has been little systematic review of the effectiveness of gully rehabilitation on reducing sediment yields. This study reviewed the global literature to provide an understanding of the potential sediment yield reductions that can occur following the rehabilitation of gullied landscapes. We focused on studies reporting a measured response on how gully and catchment sediment yield has changed since treatment. A total of 37 studies were found that met this criterion. The studies were partitioned into three broad categories, including those focused on: (i) treating the catchment above the gully; (ii) installing treatments in the actual gully channel; and (iii) a combination of approaches which include treating both the catchment and the gully channel. All the studies demonstrated a reduction in sediment yield following gully rehabilitation, with reported values ranging between 12 and 94%. The timeframes associated with the reductions in sediment yield varied considerably (2–80 years). Applying a variety of rehabilitation measures, which generally includes treating both the hillslope above the gully, and trapping sediment within the gully, appears to result in shorter (median) timescales for sediment yield reduction. Overall, this review indicates that gully rehabilitation strategies combining both engineering and vegetation measures are often the most successful. Engineering measures such as check dams are important for stabilizing sites in the early phases to support the revegetation of gullies and adjacent hillslopes. However, vegetation is the key to the long-term success of gully rehabilitation. This is because many engineering structures eventually fail, or they have a limited life span as an active sediment trap. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd  相似文献   

Predicting gully densities at sub-continental scales: a case study for the Horn of Africa     

Matthias Vanmaercke  Yixian Chen  Nigussie Haregeweyn  Sofie De Geeter  Benjamin Campforts  Wouter Heyndrickx  Atsushi Tsunekawa  Jean Poesen 《地球表面变化过程与地形》2020,45(15):3763-3779

Despite its environmental and scientific significance, predicting gully erosion remains problematic. This is especially so in strongly contrasting and degraded regions such as the Horn of Africa. Machine learning algorithms such as random forests (RF) offer great potential to deal with the complex, often non-linear, nature of factors controlling gully erosion. Nonetheless, their applicability at regional to continental scales remains largely untested. Moreover, such algorithms require large amounts of observations for model training and testing. Collecting such data remains an important bottleneck. Here we help to address these gaps by developing and testing a methodology to simulate gully densities across Ethiopia, Eritrea and Djibouti (total area: 1.2 million km²). We propose a methodology to quickly assess the gully head density (GHD) for representative 1 km² study sites by visually scoring the presence of gullies in Google Earth and then converting these scores to realistic estimates of GHD. Based on this approach, we compiled GHD observations for 1,700 sites. We used these data to train sets of RF regression models that simulate GHD at a 1 km² resolution, based on topographic/geomorphic, land cover, soil and rainfall conditions. Our approach also accounts for uncertainties in GHD observations. Independent validations showed generally acceptable simulations of regional GHD patterns. We further show that: (i) model performance strongly depends on the amount of training data used, (ii) large prediction errors mainly occur in areas where also the predicted uncertainty is large and (iii) collecting additional training data for these areas results in more drastic model performance improvements. Analyses of the feature importance of predictor variables further showed that patterns of GHD across the Horn of Africa strongly depend on NDVI and annual rainfall, but also on normalized steepness index (k_sn) and distance to rivers. Overall, our work opens promising perspectives to assess gully densities at continental scales. © 2020 John Wiley & Sons, Ltd.  相似文献   

The effect of sewage plant effluent on brown trout (Salmo trutta fario): a cage experiment     

Matthias Escher  Thomas Wahli  Sabina Büttner  Willy Meier  Patricia Burkhardt-Holm 《Aquatic Sciences - Research Across Boundaries》1999,61(2):93-110

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The IWC and the decimation of whale stocks     

Matthias Tomczak 《Marine Policy》1980,4(1):79-82

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Interrelations between geostatistics and information theory and their practical use     

Gerald J. Peschel  Matthias Mokosch 《Mathematical Geology》1991,23(1):3-7

Well-defined analytical interrelations exist between the geostatistical estimation variance performing an expression of degree of geological exploration and the task-oriented entropy as a concept of information theory. The example of normal distribution shows that this relationship can be expressed in mathematical terms. An extensive practical use could consist in the improvement of exploration optimization on the common basis of continuous geological parameters as is demonstrated by means of an example.  相似文献   

Algen als Faziesindikatoren: Bioherme und Biostrome im Unter-Kambrium von SW-Sardinien     

Dr. Matthias Selg 《International Journal of Earth Sciences》1986,75(3):693-702

Archaeocythan limestones of the Lower Cambrian Nebida Fm. (SW-Sardinia) form bioherms (lower Nebida Fm. = Matoppa Mbr.) as well as biostromes (upper Nebida Fm. = Punta Manna Mbr.). In both cases algae are the main rock forming organisms; they act as sediment binding and sediment baffling organisms and thus are responsible for the growth of these carbonates.Both bioherms and biostromes derive from a low energy environment of shallow water depth. While the bioherms developed in an open marine setting, the biostromes belong to a restricted lagoonal area. Apparently, this is the reason for the growth of different algae:Renalcis andEpiphyton in the bioherms,Girvanella in the lagoonal biostromes. Moreover, facies analysis and occurence of archaeocyathans show that these organisms could flourish well above the water depth of 20–50 m mentioned byHill (1972).

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Zusammenfassung Archaeocyathen führende Kalke der unterkambrischen Nebida Fm. (SW-Sardinien) treten sowohl als Bioherme (tiefere Nebida Fm. = Matoppa Mbr.) auf, als auch in Form von Biostromen (höhere Nebida Fm. = Punta Manna Mbr.). Als Hauptgesteinsbildner treten in beiden Fällen Algen auf, die als Sediment bindende und Sediment fangende Organismen für die Entstehung dieser Karonate verantwortlich sind. Sowohl Bioherme wie auch Biostrome entstammen Bereichen geringer Wassertiefe und nur mä\iger Wasserbewegung. Während aber die Bioherme wohl in einem offen-marinen Bereich entstanden sind, lassen sich die Biostrome einem geschützten Lagunenbereich zuordnen. Hierin scheint der Grund für das Auftreten unterschiedlicher Algen zu liegen:Renalcis undEpiphyton in den Biohermen,Girvanella in den lagunären Biostromen. Faziesanalyse und Auftreten von Archaeocyathen legen ferner nahe, da\ diese auch oberhalb der vonHill (1972) als bevorzugt angegebenen Tiefe von 20–50 m recht gut existieren konnten.

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Résumé Les calcaires à Archéocyathes de la formation du Nedida au Cambrien inférieur (Sardaigne du Sud-Ouest) forment non seulement des bioherms (formation du Nebida inférieure = membre de Matoppa) mais encore des biostromes (formation du Nebida supérieure = membre de Punta Manna). On considère que les algues sont les organismes responsables de l'édification de ces calcaires, tant comme »cimenteurs« que comme capteurs des sédiments. Non seulement les biostromes, mais encores les-faible profondeur. Tandis que les bioherms se formaient dans un milieu marin ouvert, on peut attribuer les biostromes à un milieu confiné. Ceci semle Être la raison de la présence d'algues différentes:Renalcis etEpiphyton dans les bioherms,Girvanella dans les biostromes lagunaires. L'analyse du facies et la présence des Archéocythes indiquent que ceux-ci peuvent aussi exister au-dessus de la profondeur de 20 à 50 m proposée parHill (1972).

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