Institution
University of Bremen
Education•Bremen, Germany•
About: University of Bremen is a education organization based out in Bremen, Germany. It is known for research contribution in the topics: Population & Glacial period. The organization has 14563 authors who have published 37279 publications receiving 970381 citations. The organization is also known as: Universität Bremen.
Topics: Population, Glacial period, SCIAMACHY, Sea ice, Holocene
Papers published on a yearly basis
Papers
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11 Jul 2009TL;DR: A novel approach to CQ answering that enables the use of standard relational database systems as the basis for query execution is proposed.
Abstract: Conjunctive queries (CQ) are fundamental for accessing description logic (DL) knowledge bases. We study CQ answering in (extensions of) the DL EL, which is popular for large-scale ontologies and underlies the designated OWL2-EL profile of OWL2. Our main contribution is a novel approach to CQ answering that enables the use of standard relational database systems as the basis for query execution. We evaluate our approach using the IBM DB2 system, with encouraging results.
235 citations
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TL;DR: The hidden sulfur cycle in wetlands and the fact that wetland SRM are not well represented by described SRM species explains their so far neglected role as important actors in carbon cycling and climate change.
Abstract: Freshwater wetlands are a major source of the greenhouse gas methane but at the same time can function as carbon sink. Their response to global warming and environmental pollution is one of the largest unknowns in the upcoming decades to centuries. In this review, we highlight the role of sulfate-reducing microorganisms (SRM) in the intertwined element cycles of wetlands. Although regarded primarily as methanogenic environments, biogeochemical studies have revealed a previously hidden sulfur cycle in wetlands that can sustain rapid renewal of the small standing pools of sulfate. Thus, dissimilatory sulfate reduction, which frequently occurs at rates comparable to marine surface sediments, can contribute up to 36–50% to anaerobic carbon mineralization in these ecosystems. Since sulfate reduction is thermodynamically favored relative to fermentative processes and methanogenesis, it effectively decreases gross methane production thereby mitigating the flux of methane to the atmosphere. However, very little is known about wetland SRM. Molecular analyses using dsrAB [encoding subunit A and B of the dissimilatory (bi)sulfite reductase] as marker genes demonstrated that members of novel phylogenetic lineages, which are unrelated to recognized SRM, dominate dsrAB richness and, if tested, are also abundant among the dsrAB-containing wetland microbiota. These discoveries point towards the existence of so far unknown SRM that are an important part of the autochthonous wetland microbiota. In addition to these numerically dominant microorganisms, a recent stable isotope probing study of SRM in a German peatland indicated that rare biosphere members might be highly active in situ and have a considerable stake in wetland sulfate reduction. The hidden sulfur cycle in wetlands and the fact that wetland SRM are not well represented by described SRM species explains their so far neglected role as important actors in carbon cycling and climate change.
234 citations
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TL;DR: In this paper, the authors show how miniaturized RFID temperature loggers can be adapted to analyze the amount of local deviations, detect temperature gradients, and estimate the minimum number of sensors that are necessary for reliable monitoring inside a truck or container.
234 citations
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TL;DR: An artificial neural network trained with 199 sulfate profiles is developed, constrained with geomorphological and geochemical maps to estimate global sulfate-reduction rate distributions, showing how deeply sulfates penetrate marine sediments worldwide and how quickly that sulfate is chemically reduced by microbes in the sub–sea-floor.
Abstract: Sulfate reduction is a globally important yet poorly quantified redox process in marine sediments. We developed an artificial neural network trained with 199 sulfate profiles, constrained with geomorphological and geochemical maps to estimate global sulfate reduction rate distributions. Globally, 11.3 Tmol sulfate are reduced yearly, ~15% of previous estimates, accounting for the oxidation of 12-29% of the organic carbon flux to the sea floor. Combined with global cell distributions in marine sediments, these results indicate a strong contrast in sub–sea-floor prokaryote habitats: in continental margins global cell numbers in sulfate-depleted sediment exceed those in the overlying sulfate-bearing sediment by an order of magnitude, whereas in the abyss most life occurs in oxic and/or sulfate-reducing sediments.
234 citations
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TL;DR: The findings argue for a multistep mechanism of placode induction, support a combinatorial model of placodes specification, and suggest that different placodes evolved from a common placodal primordium by successive recruitment of new inducers and target genes.
234 citations
Authors
Showing all 14961 results
Name | H-index | Papers | Citations |
---|---|---|---|
Roger Y. Tsien | 163 | 441 | 138267 |
Klaus-Robert Müller | 129 | 764 | 79391 |
Ron Kikinis | 126 | 684 | 63398 |
Ulrich S. Schubert | 122 | 2229 | 85604 |
Andreas Richter | 110 | 769 | 48262 |
Michael Böhm | 108 | 755 | 66103 |
Juan Bisquert | 107 | 450 | 46267 |
John P. Sumpter | 101 | 266 | 46184 |
Jos Lelieveld | 100 | 570 | 37657 |
Michael Schulz | 100 | 759 | 50719 |
Peter Singer | 94 | 702 | 37128 |
Charles R. Tyler | 92 | 325 | 31724 |
John P. Burrows | 90 | 815 | 36169 |
Hans-Peter Kriegel | 89 | 444 | 73932 |
Harald Haas | 85 | 750 | 34927 |