University of Bremen

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.

A Holistic Approach to Marine Eco-Systems Biology

Abstract: With biology becoming quantitative, systems-level studies can now be performed at spatial scales ranging from molecules to ecosystems. Biological data generated consistently across scales can be integrated with physico-chemical contextual data for a truly holistic approach, with a profound impact on our understanding of life [1]–[5]. Marine ecosystems are crucial in the regulation of Earth's biogeochemical cycles and climate [6],[7]. Yet their organization, evolution, and dynamics remain poorly understood [8],[9]. The Tara Oceans project was launched in September 2009 for a 3-year study of the global ocean ecosystem aboard the ship Tara. A unique sampling programme encompassing optical and genomic methods to describe viruses, bacteria, archaea, protists, and metazoans in their physico-chemical environment has been implemented. Starting as a grassroots initiative of a few scientists, the project has grown into a global consortium of over 100 specialists from diverse disciplines, including oceanography, microbial ecology, genomics, molecular, cellular, and systems biology, taxonomy, bioinformatics, data management, and ecosystem modeling. This multidisciplinary community aims to generate systematic, open access datasets usable for probing the morphological and molecular makeup, diversity, evolution, ecology, and global impacts of plankton on the Earth system.

Himalayan-type indenter-escape tectonics model for the southern part of the late Neoproterozoic–early Paleozoic East African– Antarctic orogen

Abstract: The East African–Antarctic orogen is one of the largest orogenic belts on the planet. It resulted from the collision of various parts of proto–East and West Gondwana during late Neoproterozoic–early Paleozoic time (between 650 and 500 Ma). We propose that the southern part of this Himalayan-type orogen can be interpreted in terms of a lateral-escape tectonic model. Modern Gondwana reconstructions show that the southern part of the East African– Antarctic orogen can best be reassembled when a number of microplates (the Falkland, Ellsworth-Haag, and Filchner blocks) are positioned between southern Africa and East Antarctica. This microplate assemblage is unusual. The microplates probably represent shear-zone–bounded blocks, produced by tectonic translation during lateral escape, similar to those currently evolving in Southeast Asia. One of the escape-related shear zones is exposed as the 20-km-wide Heimefront transpression zone in western Dronning Maud Land. Coats Land, a crustal block within the orogen, probably represents a block of older crust that was not subjected to tectonometamorphic reworking ca. 500 Ma by lateral tectonic escape. The southern part of the orogen is also typified by very large volumes of late-tectonic A2-type granitoids, intruded ca. 530–490 Ma, probably as a consequence of delamination of the orogenic root and the subsequent influx of hot asthenospheric mantle during tectonic escape. Erosional unroofing of the orogen is documented by the remnants of originally massive areas covered by Cambrian– Ordovician molasse-type sedimentary rocks throughout Africa, Arabia, and Antarctica, testifying to the past extent and size of this largest of orogens.

Seafloor microplastic hotspots controlled by deep-sea circulation.

Abstract: Although microplastics are known to pervade the global seafloor, the processes that control their dispersal and concentration in the deep sea remain largely unknown. Here, we show that thermohaline-driven currents, which build extensive seafloor sediment accumulations, can control the distribution of microplastics and create hotspots with the highest concentrations reported for any seafloor setting (190 pieces per 50 grams). Previous studies propose that microplastics are transported to the seafloor by vertical settling from surface accumulations; here, we demonstrate that the spatial distribution and ultimate fate of microplastics are strongly controlled by near-bed thermohaline currents (bottom currents). These currents are known to supply oxygen and nutrients to deep-sea benthos, suggesting that deep-sea biodiversity hotspots are also likely to be microplastic hotspots.

Photon Regions and Shadows of Kerr-Newman-NUT Black Holes with a Cosmological Constant

Abstract: We consider the Pleba\ifmmode \acute{n}\else \'{n}\fi{}ski class of electrovacuum solutions to the Einstein equations with a cosmological constant. These space-times, which are also known as the Kerr-Newman-NUT--(anti--)de Sitter space-times, are characterized by a mass $m$, a spin $a$, a parameter $\ensuremath{\beta}$ that comprises electric and magnetic charge, a NUT parameter $\ensuremath{\ell}$ and a cosmological constant $\mathrm{\ensuremath{\Lambda}}$. Based on a detailed discussion of the photon regions in these space-times (i.e., of the regions in which spherical lightlike geodesics exist), we derive an analytical formula for the shadow of a Kerr-Newman-NUT--(anti--)de Sitter black hole for an observer at given Boyer-Lindquist coordinates $({r}_{O},{\ensuremath{\vartheta}}_{O})$ in the domain of outer communication. We visualize the photon regions and the shadows for various values of the parameters.