2,679 research outputs found

    The A-theoretic Farrell–Jones conjecture for virtually solvable groups

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    We prove the A -theoretic Farrell–Jones conjecture for virtually solvable groups. As a corollary, we obtain that the conjecture holds for S -arithmetic groups and lattices in almost connected Lie groups

    On the Farrell–Jones conjecture for Waldhausen’s A–theory

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    Building a Framework for Information Doctrine: A Significant Factor in Managing Air Force Information Resources

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    The information revolution is sweeping through the mIlitary. At the same time, the Air Force has not fully addressed legal requirements to develop an agency-wide framework for managing information resources. This lack of foundation creates a void for Air Force information resources management practitioners. Since the Department of Defense and the Air Force are engaged in doctrinal revolution, the opportunity exists to consider developing Information Doctrine.This thesis explores the definition and role of doctrine in the Air Force, the doctrine development process, and practical examples of doctrine\u27s use in the Air Force and Department of Defense. It also examines the Air Force information environment to determine the definition and role of information resources. By analyzing the applicability of doctrine to the Air Force information environment, this thesis proposes a concept for Air Force Information Doctrine. Similar to other resource doctrine, Information Doctrine could include a description of Information Processes, Principles and Functions; Information Planning Considerations and Support Requirements; and Information Training and Personnel. A well-marketed Information Doctrine could be a significant factor in developing strategic plans and policies involving Air Force Information Resources

    Diagenetic alteration in low-Mg calcite from macrofossils: a review

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    This is the final version of the article. Available from the publisher via the DOI in this record.The quality of palaeoenvironmental reconstructions based on macrofossil car bon ate critically de pends on preservation of the shell material because post-depositional pro cesses can modify its structural, chemical and isotopic composition, potentially over printing or completely erasing palaeoenvironmental information. A suite of methods can be employed to evaluate the impact of diagenetic processes on the primary geochemical signatures of samples. Here we review the benefits and short comings of the most commonly employed optical (optical microscopy, cathodoluminescence microscopy, scanning electron microscopy) and chemical (trace element abundances, isotopic ratios) screening techniques used to assess the alteration degree of low-Mg calcite macrofossils and summarize the findings on diagenetic trends observed for elemental and isotopic systems in such materials. For a robust evaluation of the preservation state of biogenic calcite, it is advisable to combine a set of complementary techniques. Absolute limiting values of element and isotope ratios for discarding diagenetically altered materials cannot be universally applied, but should rather be evaluated on a case to case basis. The evaluation can be improved by analyses of diagenetic carbonate and altered fossil materials, which help constraining the diagenetic trajectories in the sampled specimens. Quantification of post-depositional alteration is possible, but in most cases the complexity of diagenetic systems hampers the possibility of retrieving original proxy values for palaeoenvironmental reconstructions from partially altered materials

    Element/Ca, C and O isotope ratios in modern brachiopods: Species-specific signals of biomineralization

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Fossil brachiopods are of major importance for the reconstruction of palaeoenvironmental conditions, particularly of the Paleozoic. In order to better understand signals of ancient shell materials, modern analogue studies have to be conducted. Here we present C and O isotope data in conjunction with Mg/Ca, Sr/Ca, Mn/Ca and Fe/Ca data for nine modern rhynchonellid and terebratulid brachiopod species from tropical to intermediate latitudes and shallow to very deep marine settings. C and O isotope signals of most species suggest formation of secondary shell layers near or in isotopic equilibrium with ambient seawater. Some species – especially in the suborder Terebratellidina – show partly distinct disequilibrium signals, suggesting some degree of phylogenetic control on the expression of vital effects. Mn/Ca and Fe/Ca ratios measured in the modern species form a baseline to assess fossil preservation, but also yield environmental information. Mg/Ca and Sr/Ca ratios follow previously observed patterns, with all studied brachiopod species comprising low-Mg calcite. Strong covariation of Sr/Ca ratios with Mg/Ca ratios is only observed in rhynchonellids and possibly one terebratulid species, potentially linking the incorporation behaviour of alkaline earth metals to phylogeny. Sr/Ca show a strong negative correlation with δ13C values in terebratellidinid species which exhibit major isotopic disequilibrium and also combined data from three localities for which two species were studied indicate such a negative relation. The observed covariation of Sr/Ca ratios with δ13C values may therefore become a useful tool to detect δ13C disequilibrium and to robustly estimate δ13C values of ambient DIC in deep time.The authors acknowledge comments from two anonymous reviewers and Alberto Pérez-Huerta as well as the editor Michael E. Boettcher which helped to improve the quality and clarity of the manuscript. The authors thank the Museum für Naturkunde Berlin for providing brachiopod specimens of the species F. sanguinolenta (ZMB Bra 1934), M. venosa (ZMB Bra 2028), N. nigricans (ZMB Bra 2441), S. crosnieri (ZMB Bra 2442), C. inconspicua (ZMB Bra 2443), C. racovitzae (ZMB Bra 2444) and L. neozelanica (ZMB Bra 2445) and Andy Gale for providing specimens of T. transversa and Terebratulina sp. The authors are indebted to the crews of RV SONNE during the cruises SO 168 ZEALANDIA and SO 233 WALVIS 2 and their respective shipboard scientific parties. Financial support by the German Ministry of Education and Research (BMBF) within the project SO 168 ZEALANDIA (FKZ: 03G0168) and SO 233 WALVIS 2 (FKZ: 03G0233A) to CL is gratefully acknowledged. CVU acknowledges funding from the Leopoldina – German National Academy of Sciences (grant no. LPDS 2014-08)

    Tectonic forcing of Early to Middle Jurassic seawater Sr/Ca

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    types: ArticleThis is the author formatted version of Ullman et al. (2013) Geology 41(12), 1211-1214. doi:10.1130/G34817.1 http://geology.gsapubs.org/content/41/12/1211.full Uploaded under the terms of Green Open Access in GSA's Open Access PolicyThe Jurassic Period (ca. 201–145 Ma) is marked by fundamental reorganizations of paleogeography, paleoceanography, ecosystems, and the progressive shift from aragonite to calcite as the favored marine biogenic carbonate polymorph. Sr/Ca ratios of well-preserved Jurassic oysters and belemnites from sections in the UK and Poland demonstrate that the Sr/Ca ratio of seawater varied systematically throughout the Early and Middle Jurassic in parallel with already documented seawater 87Sr/86Sr. The Sr flux from increased mid-ocean ridge activity in the Early Jurassic outbalanced the input of riverine Sr, leading to gradually lower seawater 87Sr/86Sr associated with the parallel and strong decrease in seawater Sr/Ca ratios. This downward trend was reversed by enhanced continental input in the Toarcian and Aalenian, but resumed in the Bajocian and continued to the Callovian. Parallel changes of seawater 87Sr/86Sr and Sr/Ca suggest a common cause for these long-term variations and are best explained by changes in the balance of continental weathering and hydrothermal fluxes. These findings underline the strong control of global tectonic processes on the evolution of biomineralization and downplay the role of biomineral evolution in influencing strontium chemistry of seawater in the mid-Mesozoi

    Der Einfluss des ökologischen Landbaus auf das Raumnutzungsverhalten von Feldhasen (Lepus europaeus)

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    Agricultural intensification (AI) negatively affects biodiversity due to e.g. high-input farming. Organic farming can counteract this negative trend. Here, we studied movement behavior of the European brown hare (Lepus europaeus), which frequently occurs in agricultural landscapes but also suffers from AI with declining population densities. We measured home range sizes in relation to local field management (organic vs. conventional farming) in Upper Bavarian, Germany. Results showed that home ranges sizes decreased with increasing amount of organically managed area, while there was no relationship between conventional farmed area and hares’ movement behavior. Higher resource availability in organic fields decrease home range sizes and may therefore positively influences individual fitness and possibly boosts hare densities

    Oxygen and carbon isotope and Sr/Ca signatures of high-latitude Permian to Jurassic calcite fossils from New Zealand and New Caledonia

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    Article available online 12 November 2015This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Calcite fossils from New Zealand and New Caledonia provide insight into the Permian to Jurassic climatic history of Southern High Latitudes (southern HL) and Triassic Southern Intermediate Latitudes (southern IL). These results permit comparison with widely studied, coeval sections in Low Latitudes (LL) and IL. Oxygen isotope ratios of well-preserved shell materials indicate a partially pronounced Sea Surface Temperature (SST) gradient in the Permian, whereas for the Triassic no indication of cold climates in the southern HL is found. The Late Jurassic of New Zealand is characterized by a slight warming in the Oxfordian–Kimmeridgian and a subsequent cooling trend in the Tithonian. Systematic variations in the δ13C values of southern HL samples are in concert with those from LL sections and confirm the global nature of the carbon isotope signature and changes in the long-term carbon cycle reported earlier. Systematic changes of Sr/Ca ratios in Late Triassic brachiopods, falling from 1.19 mmol/mol in the Oretian (early Norian) to 0.67 mmol/mol in the Warepan (late Norian) and subsequently increasing to 1.10 mmol/mol in the Otapirian (~ Rhaetian), are observed. Also Sr/Ca ratios of Late Jurassic belemnite genera Belemnopsis and Hibolithes show synchronous changes in composition that may be attributed to secular variations in the seawater Sr/Ca ratio. For the two belemnite genera an increase from 1.17 mmol/mol in the Middle Heterian (~ Oxfordian) to 1.78 mmol/mol in the Mangaoran (~ late Middle Tithonian) and a subsequent decrease to 1.51 mmol/mol in the Waikatoan (~ Late Tithonian) is documented.This project was funded by the Danish Council for Independent Research– Natural Sciences (project 09-072715), the Carlsberg Foundation (project nr 2011-01-0737) provided for CK, and by the University of Copenhagen (IGN). CVU acknowledges funding from the German National Academy of Sciences – Leopoldina (grant nr LPDS 2014-08
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