Backscattered Scanning Electron Microscopy and Image Analysis of Sediments and Sedimentary Rocks: D.H. Krinsley, K. Pye, S. Boggs, Jr., N.K. Tovey     

Bernd Zolitschka 《Journal of Paleolimnology》2000,23(2):223-224

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Experimental impact cratering: A summary of the major results of the MEMIN research unit     

Thomas Kenkmann  Alex Deutsch  Klaus Thoma  Matthias Ebert  Michael H. Poelchau  Elmar Buhl  Eva-Regine Carl  Andreas N. Danilewsky  Georg Dresen  Anja Dufresne  Nathanaël Durr  Lars Ehm  Christian Grosse  Max Gulde  Nicole Güldemeister  Christopher Hamann  Lutz Hecht  Stefan Hiermaier  Tobias Hoerth  Astrid Kowitz  Falko Langenhorst  Bernd Lexow  Hanns-Peter Liermann  Robert Luther  Ulrich Mansfeld  Dorothee Moser  Manuel Raith  Wolf Uwe Reimold  Martin Sauer  Frank Schäfer  Ralf Thomas Schmitt  Frank Sommer  Jakob Wilk  Rebecca Winkler  Kai Wünnemann 《Meteoritics & planetary science》2018,53(8):1543-1568

This paper reviews major findings of the Multidisciplinary Experimental and Modeling Impact Crater Research Network (MEMIN). MEMIN is a consortium, funded from 2009 till 2017 by the German Research Foundation, and is aimed at investigating impact cratering processes by experimental and modeling approaches. The vision of this network has been to comprehensively quantify impact processes by conducting a strictly controlled experimental campaign at the laboratory scale, together with a multidisciplinary analytical approach. Central to MEMIN has been the use of powerful two-stage light-gas accelerators capable of producing impact craters in the decimeter size range in solid rocks that allowed detailed spatial analyses of petrophysical, structural, and geochemical changes in target rocks and ejecta. In addition, explosive setups, membrane-driven diamond anvil cells, as well as laser irradiation and split Hopkinson pressure bar technologies have been used to study the response of minerals and rocks to shock and dynamic loading as well as high-temperature conditions. We used Seeberger sandstone, Taunus quartzite, Carrara marble, and Weibern tuff as major target rock types. In concert with the experiments we conducted mesoscale numerical simulations of shock wave propagation in heterogeneous rocks resolving the complex response of grains and pores to compressive, shear, and tensile loading and macroscale modeling of crater formation and fracturing. Major results comprise (1) projectile–target interaction, (2) various aspects of shock metamorphism with special focus on low shock pressures and effects of target porosity and water saturation, (3) crater morphologies and cratering efficiencies in various nonporous and porous lithologies, (4) in situ target damage, (5) ejecta dynamics, and (6) geophysical survey of experimental craters.  相似文献   

Reply to discussion of Gabrielsen et al. (2010) by Nielsen et al. (this volume): Latest Caledonian to present tectonomorphological development of southern Norway     

Roy H. Gabrielsen  Jan Inge Faleide  Christophe Pascal  Alvar Braathen  Johan Petter Nystuen  Bernd Etzelmuller  Sejal O'Donnell 《Marine and Petroleum Geology》2010

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Protecting small cetaceans from coastal development: Impact assessment and mitigation experience in Hong Kong     

Thomas A. Jefferson  Samuel K. Hung  Bernd Würsig 《Marine Policy》2009

Since the early 1990s, there has been an active program in Hong Kong to manage and protect local populations of small cetaceans from the effects of massive development in the area. This paper reviews the progress that has been made. Only two species regularly occur there: the Indo-Pacific humpback dolphin and the finless porpoise. Because most development has occurred in the western waters of Hong Kong, where generally only the humpback dolphin occurs, most of the work has been conducted on that species. Development of large infrastructure projects (such as airports, bridges, expressways, power plants, fuel facilities, and container ports) in Hong Kong often results in land reclamation, dredging and dumping of spoils, pipe and cable laying, percussive and bored piling work, underwater blasting, large increases in vessel traffic, and other impacts. Several mitigation measures have been used with varying levels of success, including bubble curtains/jackets, exclusion zones, ramping up of piling hammers, acoustic decoupling of noisy equipment, vessel speed limits, no-dumping policies, and silt curtains. Baseline, construction-phase, and operational-phase cetacean monitoring is often conducted to evaluate the success of conservation measures put into place. The Environmental Impact Assessment process in Hong Kong has involved cetaceans to a degree perhaps higher than anywhere else in the world, and much can be learned from studying the successes and failures of this situation.  相似文献   

The curse of physiology—challenges and opportunities in the interpretation of geochemical data from mollusk shells     

Bernd R. Schöne 《Geo-Marine Letters》2008,28(5-6):269-285

Physiology corrupts geochemical records of mollusk shells in many ways, e.g., by actively controlling the incorporation of trace elements in the skeleton. However, the effects of variable biomineralization rates and growth cessation have largely remained unconsidered. Mediated by endogenous timekeeping mechanisms, mollusks stop growing skeletal material on a regular basis ranging from ultradian to annual timescales. During growth cessation, the shells do not record environmental conditions. Shell growth also stops when environmental conditions are beyond the physiological tolerance of the organism, e.g., above and below genetically determined, species-specific thermal extremes where shell growth slows and eventually ceases. Such growth disruptions can occur at non-periodic time intervals. Due to growth retardations and halts, proxy records of mollusk shells are thus incomplete, and reconstructed environmental amplitudes prone to truncation. Furthermore, environmental records are biased toward the physiological optimum of the animal. Favorable environmental conditions increase shell growth, whereas adverse environmental conditions result in reduced shell production and lowered overall metabolism. Not least, the duration of the growing season and overall growth rate decrease as the mollusk grows older. Mathematical modeling approaches can significantly improve proxy records obtained from mollusk shells. For example, if the duration of growth cessation is known, it may be possible to model the missing environmental record. It is also fairly easy to account for age-related growth trends, or variable time-averaging in different portions of the shell. However, a major premise for a reliable interpretation of proxy records from a mollusk shell or other organisms secreting biogenic hard parts is a proper understanding of the physiology, and of course, a high-resolution record of the many different environmental factors that may influence physiology and shell growth. The present paper reviews examples from the literature, and unpublished data on how physiology influences geochemical proxy records from mollusk shells, and presents methods how to eliminate such adverse effects.  相似文献   

Spatial crime distribution and prediction for sporting events using social media     

Alina Ristea  Mohammad Al Boni  Bernd Resch  Matthew S. Gerber  Michael Leitner 《International journal of geographical information science》2020,34(9):1708-1739

ABSTRACT

Sporting events attract high volumes of people, which in turn leads to increased use of social media. In addition, research shows that sporting events may trigger violent behavior that can lead to crime. This study analyses the spatial relationships between crime occurrences, demographic, socio-economic and environmental variables, together with geo-located Twitter messages and their ‘violent’ subsets. The analysis compares basketball and hockey game days and non-game days. Moreover, this research aims to analyze crime prediction models using historical crime data as a basis and then introducing tweets and additional variables in their role as covariates of crime. First, this study investigates the spatial distribution of and correlation between crime and tweets during the same temporal periods. Feature selection models are applied in order to identify the best explanatory variables. Then, we apply localized kernel density estimation model for crime prediction during basketball and hockey games, and on non-game days. Findings from this study show that Twitter data, and a subset of violent tweets, are useful in building prediction models for the seven investigated crime types for home and away sporting events, and non-game days, with different levels of improvement.  相似文献   

Northern Eurasian lakes – late Quaternary glaciation and climate history – introduction     

Martin Melles  John Inge Svendsen  Grigory Fedorov  Bernd Wagner 《Boreas: An International Journal of Quaternary Research》2019,48(2):269-272

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Impact of the water salinity on the hydraulic conductivity of fen peat          下载免费PDF全文

Lennart Gosch  Manon Janssen  Bernd Lennartz 《水文研究》2018,32(9):1214-1222

Coastal peatlands represent an interface between marine and terrestrial ecosystems; their hydrology is affected by salt and fresh water inflow alike. Previous studies on bog peat have shown that pore water salinity can have an impact on the saturated hydraulic conductivity (K_s) of peat because of chemical pore dilation effects. In this study, we aimed at quantifying the impact of higher salinities (up to 3.5% NaCl) on K_s of fen peat. Two experiments employing a constant‐head upward‐flow permeameter and differing in measurement and salinity change duration were conducted. Additionally, a third experiment to determine the impact of water salinity on the release of dissolved organic carbon (DOC) of the studied peat type was carried out. The results show a decrease of K_s with time, which does not depend on the water salinity but is differently shaped for different peat types. We assume pore clogging due to a conglomerate of physical, chemical, and biological processes, which rather depend on water movement rate and time than on water salinity. However, an increased water salinity did increase the DOC release. We conclude that salinity‐dependent behaviour of K_s is a function of peat chemistry and that for some peat types, salinity may only affect the DOC release without having a pronounced impact on water flow.  相似文献   

Remotely sensed agricultural modification improves prediction of suitable habitat for a threatened lizard     

David T. Y. Wong  William S. Osborne  Stephen D. Sarre  Bernd Gruber 《International journal of geographical information science》2018,32(5):1006-1025

The geographical distribution of a species is limited by factors such as climate, resources, disturbances and species interactions. Environmental niche models attempt to encapsulate these limits and represent them spatially but do not always incorporate disturbance factors. We constructed MaxEnt models derived from a remotely sensed vegetation classification with, and without, an agricultural modification variable. Including agricultural modification improved model performance and led to more sites with native vegetation and fewer sites with exotic or degraded native vegetation being predicted suitable for A. parapulchella. Analysis of a relatively well-surveyed sub-area indicated that including agricultural modification led to slightly higher omission rates but markedly fewer likely false positives. Expert assessment of the model based on mapped habitat also suggested that including agricultural modification improved predictions. We estimate that agricultural modification has led to the destruction or decline of approximately 30–35% of the most suitable habitat in the sub-area studied and approximately 20–25% of suitable habitat across the entire study area, located in the Australian Capital Territory, Australia. Environmental niche models for a range of species, particularly habitat specialists, are likely to benefit from incorporating agricultural modification. Our findings are therefore relevant to threatened species planning and management, particularly at finer spatial scales.  相似文献   

Stable carbon and oxygen isotope fractionation in bivalve (Placopecten magellanicus) larval aragonite     

Erin F. Owen  Alan D. Wanamaker Jr.  Bernd R. Schöne 《Geochimica et cosmochimica acta》2008,72(19):4687-4698

The relationship between stable isotope composition (δ¹³C and δ¹⁸O) in seawater and in larval shell aragonite of the sea scallop, Placopecten magellanicus, was investigated in a controlled experiment to determine whether isotopes in larval shell aragonite can be used as a reliable proxy for environmental conditions. The linear relationship between δ¹³C_DIC and δ¹³C_aragonite (r² = 0.97, p < 0.0001, RMSE = 0.18) was: