@article{QuiricoMorozSchmittetal.2016, author = {Quirico, E. and Moroz, Liubov V. and Schmitt, B. and Arnold, Gabriele and Faure, M. and Beck, P. and Bonal, L. and Ciarniello, M. and Capaccioni, F. and Filacchione, G. and Erard, S. and Leyrat, C. and Bockelee-Morvan, D. and Zinzi, A. and Palomba, E. and Drossart, P. and Tosi, F. and Capria, M. T. and De Sanctis, M. C. and Raponi, A. and Fonti, S. and Mancarella, F. and Orofino, V. and Barucci, A. and Blecka, M. I. and Carlson, R. and Despan, D. and Faure, A. and Fornasier, S. and Gudipati, M. S. and Longobardo, A. and Markus, K. and Mennella, V. and Merlin, F. and Piccioni, G. and Rousseau, B. and Taylor, F.}, title = {Refractory and semi-volatile organics at the surface of comet 67P/Churyumov-Gerasimenko: Insights from the VIRTIS/Rosetta imaging spectrometer}, series = {Icarus : international journal of solar system studies}, volume = {272}, journal = {Icarus : international journal of solar system studies}, publisher = {Elsevier}, address = {San Diego}, organization = {Rosetta VIRTIS Team}, issn = {0019-1035}, doi = {10.1016/j.icarus.2016.02.028}, pages = {32 -- 47}, year = {2016}, abstract = {The VIRTIS (Visible, Infrared and Thermal Imaging Spectrometer) instrument aboard the Rosetta spacecraft has performed extensive spectral mapping of the surface of comet 67P/Churyumov-Gerasimenko in the range 0.3-5 mu m. The reflectance spectra collected across the surface display a low reflectance factor over the whole spectral range, two spectral slopes in the visible and near-infrared ranges and a broad absorption band centered at 3.2 mu m. The first two of these characteristics are typical of dark small bodies of the Solar System and are difficult to interpret in terms of composition. Moreover, solar wind irradiation may modify the structure and composition of surface materials and there is no unequivocal interpretation of these spectra devoid of vibrational bands. To circumvent these problems, we consider the composition of cometary grains analyzed in the laboratory to constrain the nature of the cometary materials and consider results on surface rejuvenation and solar wind processing provided by the OSIRIS and ROSINA instruments, respectively. Our results lead to five main conclusions: (i) The low albedo of comet 67P/CG is accounted for by a dark refractory polyaromatic carbonaceous component mixed with opaque minerals. VIRTIS data do not provide direct insights into the nature of these opaque minerals. However, according to the composition of cometary grains analyzed in the laboratory, we infer that they consist of Fe-Ni alloys and FeS sulfides. (ii) A semi-volatile component, consisting of a complex mix of low weight molecular species not volatilized at T similar to 220 K, is likely a major carrier of the 3.2 p.m band. Water ice contributes significantly to this feature in the neck region but not in other regions of the comet. COOH in carboxylic acids is the only chemical group that encompasses the broad width of this feature. It appears as a highly plausible candidate along with the NH4+ ion. (iii) Photolytic/thermal residues, produced in the laboratory from interstellar ice analogs, are potentially good spectral analogs. (iv) No hydrated minerals were identified and our data support the lack of genetic links with the CI, CR and CM primitive chondrites. This concerns in particular the Orgueil chondrite, previously suspected to have been of cometary origin. (v) The comparison between fresh and aged terrains revealed no effect of solar wind irradiation on the 3.2 mu m band. This is consistent with the presence of efficient resurfacing processes such as dust transport from the interior to the surface, as revealed by the OSIRIS camera. (C) 2016 Elsevier Inc. All rights reserved.}, language = {en} } @article{RousseauErardBecketal.2018, author = {Rousseau, Batiste and Erard, St{\´e}phane and Beck, P. and Quirico, Eric and Schmitt, B. and Brissaud, O. and Montes-Hernandez, G. and Capaccioni, F. and Filacchione, Gianrico and Bockelee-Morvan, Dominique and Leyrat, C. and Ciarniello, M. and Raponi, Andrea and Kappel, David and Arnold, G. and Moroz, L. V. and Palomba, Ernesto and Tosi, Federico}, title = {Laboratory simulations of the Vis-NIR spectra of comet 67P using sub-mu m sized cosmochemical analogues}, series = {Icarus : international journal of solar system studies}, volume = {306}, journal = {Icarus : international journal of solar system studies}, publisher = {Elsevier}, address = {San Diego}, organization = {VIRTIS Team}, issn = {0019-1035}, doi = {10.1016/j.icarus.2017.10.015}, pages = {306 -- 318}, year = {2018}, abstract = {Laboratory spectral measurements of relevant analogue materials were performed in the framework of the Rosetta mission in order to explain the surface spectral properties of comet 67P. Fine powders of coal, iron sulphides, silicates and their mixtures were prepared and their spectra measured in the Vis-IR range. These spectra are compared to a reference spectrum of 67P nucleus obtained with the VIRTIS/Rosetta instrument up to 2.7 mu m, excluding the organics band centred at 3.2 mu m. The species used are known to be chemical analogues for cometary materials which could be present at the surface of 67P. Grain sizes of the powders range from tens of nanometres to hundreds of micrometres. Some of the mixtures studied here actually reach the very low reflectance level observed by VIRTIS on 67P. The best match is provided by a mixture of sub-micron coal, pyrrhotite, and silicates. Grain sizes are in agreement with the sizes of the dust particles detected by the GIADA, MIDAS and COSIMA instruments on board Rosetta. The coal used in the experiment is responsible for the spectral slope in the visible and infrared ranges. Pyrrhotite, which is strongly absorbing, is responsible for the low albedo observed in the NIR. The darkest components dominate the spectra, especially within intimate mixtures. Depending on sample preparation, pyrrhotite can coat the coal and silicate aggregates. Such coating effects can affect the spectra as much as particle size. In contrast, silicates seem to play a minor role. (c) 2017 Elsevier Inc. All rights reserved.}, language = {en} } @article{HildebrandtCharbonniereBecketal.2005, author = {Hildebrandt, Niko and Charbonniere, Lo{\"i}c J. and Beck, Michael and Ziessel, Raymond F. and L{\"o}hmannsr{\"o}ben, Hans-Gerd}, title = {Quantum dots as efficient energy acceptors in a time-resolved fluoroimmunoassay}, issn = {1433-7851}, year = {2005}, language = {en} } @article{TritschlerBeckSchlaadetal.2015, author = {Tritschler, U. and Beck, F. and Schlaad, Helmut and C{\"o}lfen, Helmut}, title = {Electrochromic properties of self-organized multifunctional V2O5-polymer hybrid films}, series = {Journal of materials chemistry : C, Materials for optical and electronic devices}, volume = {3}, journal = {Journal of materials chemistry : C, Materials for optical and electronic devices}, number = {5}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2050-7526}, doi = {10.1039/c4tc02138j}, pages = {950 -- 954}, year = {2015}, abstract = {Bio-inspired V2O5-polymer hybrid films were prepared following a one-step self-organization procedure based on liquid crystal formation of organic and inorganic components. These materials were previously reported to exhibit advantageous mechanical properties, comparable to biomaterials, such as human bone and dentin. Here, we show that these hybrid films prepared via a fast and simple synthesis procedure have an additional function as an electrochromic material, exhibiting a long-term cycle stability under alternating potentials. The structures were found to remain intact without visible changes after more than hundred switching cycles and storing the devices for several weeks. Consequently, this multifunctional V2O5-polymer hybrid system shows great promise for various technical applications.}, language = {en} } @misc{BeckBallesterosMejiaBuchmannetal.2012, author = {Beck, Jan and Ballesteros-Mejia, Liliana and Buchmann, Carsten M. and Dengler, J{\"u}rgen and Fritz, Susanne A. and Gruber, Bernd and Hof, Christian and Jansen, Florian and Knapp, Sonja and Kreft, Holger and Schneider, Anne-Kathrin and Winter, Marten and Dormann, Carsten F.}, title = {What's on the horizon for macroecology?}, series = {Ecography : pattern and diversity in ecology ; research papers forum}, volume = {35}, journal = {Ecography : pattern and diversity in ecology ; research papers forum}, number = {8}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0906-7590}, doi = {10.1111/j.1600-0587.2012.07364.x}, pages = {673 -- 683}, year = {2012}, abstract = {Over the last two decades, macroecology the analysis of large-scale, multi-species ecological patterns and processes has established itself as a major line of biological research. Analyses of statistical links between environmental variables and biotic responses have long and successfully been employed as a main approach, but new developments are due to be utilized. Scanning the horizon of macroecology, we identified four challenges that will probably play a major role in the future. We support our claims by examples and bibliographic analyses. 1) Integrating the past into macroecological analyses, e.g. by using paleontological or phylogenetic information or by applying methods from historical biogeography, will sharpen our understanding of the underlying reasons for contemporary patterns. 2) Explicit consideration of the local processes that lead to the observed larger-scale patterns is necessary to understand the fine-grain variability found in nature, and will enable better prediction of future patterns (e.g. under environmental change conditions). 3) Macroecology is dependent on large-scale, high quality data from a broad spectrum of taxa and regions. More available data sources need to be tapped and new, small-grain large-extent data need to be collected. 4) Although macroecology already lead to mainstreaming cutting-edge statistical analysis techniques, we find that more sophisticated methods are needed to account for the biases inherent to sampling at large scale. Bayesian methods may be particularly suitable to address these challenges. To continue the vigorous development of the macroecological research agenda, it is time to address these challenges and to avoid becoming too complacent with current achievements.}, language = {en} } @article{YuanSobolevKindetal.2000, author = {Yuan, X. H and Sobolev, Stephan Vladimir and Kind, Rainer and Oncken, Onno and Bock, G{\"u}nter and Asch, G{\"u}nter and Schurr, B. and Gr{\"a}ber, F. and Rudloff, Alexander and Hanka, W. and Wylegalla, Kurt and Tibi, R. and Haberland, Christian and Rietbrock, Andreas and Giese, Peter and Wigger, Peter and Rower, P. and Zandt, G. and Beck, S. and Wallace, T. and Pardo, M. and Comte, D.}, title = {Subduction and collision processes in the Central Andes constrained by converted seismic phases}, year = {2000}, language = {en} } @article{LupienRussellPearsonetal.2022, author = {Lupien, Rachel L. and Russell, James M. and Pearson, Emma J. and Castaneda, Isla S. and Asrat, Asfawossen and F{\"o}rster, Verena and Lamb, Henry F. and Roberts, Helen M. and Sch{\"a}bitz, Frank and Trauth, Martin H. and Beck, Catherine C. and Feibel, Craig S. and Cohen, Andrew S.}, title = {Orbital controls on eastern African hydroclimate in the Pleistocene}, series = {Scientific reports}, volume = {12}, journal = {Scientific reports}, number = {1}, publisher = {Macmillan Publishers Limited}, address = {London}, issn = {2045-2322}, doi = {10.1038/s41598-022-06826-z}, pages = {10}, year = {2022}, abstract = {Understanding eastern African paleoclimate is critical for contextualizing early human evolution, adaptation, and dispersal, yet Pleistocene climate of this region and its governing mechanisms remain poorly understood due to the lack of long, orbitally-resolved, terrestrial paleoclimate records. Here we present leaf wax hydrogen isotope records of rainfall from paleolake sediment cores from key time windows that resolve long-term trends, variations, and high-latitude effects on tropical African precipitation. Eastern African rainfall was dominantly controlled by variations in low-latitude summer insolation during most of the early and middle Pleistocene, with little evidence that glacial-interglacial cycles impacted rainfall until the late Pleistocene. We observe the influence of high-latitude-driven climate processes emerging from the last interglacial (Marine Isotope Stage 5) to the present, an interval when glacial-interglacial cycles were strong and insolation forcing was weak. Our results demonstrate a variable response of eastern African rainfall to low-latitude insolation forcing and high-latitude-driven climate change, likely related to the relative strengths of these forcings through time and a threshold in monsoon sensitivity. We observe little difference in mean rainfall between the early, middle, and late Pleistocene, which suggests that orbitally-driven climate variations likely played a more significant role than gradual change in the relationship between early humans and their environment.}, language = {en} } @misc{CohenCampisanoArrowsmithetal.2016, author = {Cohen, Abby and Campisano, Christopher and Arrowsmith, J. Ramon and Asrat, Asfawossen and Behrensmeyer, A. K. and Deino, A. and Feibel, C. and Hill, A. and Johnson, R. and Kingston, J. and Lamb, Henry F. and Lowenstein, T. and Noren, A. and Olago, D. and Owen, Richard Bernhart and Potts, R. and Reed, Kate and Renaut, R. and Sch{\"a}bitz, Frank and Tiercelin, J.-J. and Trauth, Martin H. and Wynn, J. and Ivory, S. and Brady, K. and O'Grady, R. and Rodysill, J. and Githiri, J. and Russell, Joellen and Foerster, Verena and Dommain, Ren{\´e} and Rucina, J. S. and Deocampo, D. and Russell, J. and Billingsley, A. and Beck, C. and Dorenbeck, G. and Dullo, L. and Feary, D. and Garello, D. and Gromig, R. and Johnson, T. and Junginger, Annett and Karanja, M. and Kimburi, E. and Mbuthia, A. and McCartney, Tannis and McNulty, E. and Muiruri, V. and Nambiro, E. and Negash, E. W. and Njagi, D. and Wilson, J. N. and Rabideaux, N. and Raub, Timothy and Sier, Mark Jan and Smith, P. and Urban, J. and Warren, M. and Yadeta, M. and Yost, Chad and Zinaye, B.}, title = {The Hominin Sites and Paleolakes Drilling Project}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {611}, doi = {10.25932/publishup-41249}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-412498}, pages = {16}, year = {2016}, abstract = {The role that climate and environmental history may have played in influencing human evolution has been the focus of considerable interest and controversy among paleoanthropologists for decades. Prior attempts to understand the environmental history side of this equation have centered around the study of outcrop sediments and fossils adjacent to where fossil hominins (ancestors or close relatives of modern humans) are found, or from the study of deep sea drill cores. However, outcrop sediments are often highly weathered and thus are unsuitable for some types of paleoclimatic records, and deep sea core records come from long distances away from the actual fossil and stone tool remains. The Hominin Sites and Paleolakes Drilling Project (HSPDP) was developed to address these issues. The project has focused its efforts on the eastern African Rift Valley, where much of the evidence for early hominins has been recovered. We have collected about 2 km of sediment drill core from six basins in Kenya and Ethiopia, in lake deposits immediately adjacent to important fossil hominin and archaeological sites. Collectively these cores cover in time many of the key transitions and critical intervals in human evolutionary history over the last 4 Ma, such as the earliest stone tools, the origin of our own genus Homo, and the earliest anatomically modern Homo sapiens. Here we document the initial field, physical property, and core description results of the 2012-2014 HSPDP coring campaign.}, language = {en} } @article{CohenCampisanoArrowsmithetal.2016, author = {Cohen, Andrew and Campisano, C. and Arrowsmith, J. Ram{\´o}n and Asrat, Asfawossen and Behrensmeyer, A. K. and Deino, A. and Feibel, C. and Hill, A. and Johnson, R. and Kingston, J. and Lamb, Henry F. and Lowenstein, T. and Noren, A. and Olago, D. and Owen, R. B. and Potts, R. and Reed, Kate and Renaut, R. and Sch{\"a}bitz, Frank and Tiercelin, J. -J. and Trauth, Martin H. and Wynn, J. and Ivory, S. and Brady, K. and Rodysill, J. and Githiri, J. and Russell, J. and F{\"o}rster, Verena and Dommain, Ren{\´e} and Rucina, S. and Deocampo, D. and Russell, J. and Billingsley, A. and Beck, C. and Dorenbeck, G. and Dullo, L. and Feary, D. and Garello, D. and Gromig, R. and Johnson, T. and Junginger, A. and Karanja, M. and Kimburi, E. and Mbuthia, A. and McCartney, T. and McNulty, E. and Muiruri, V. and Nambiro, E. and Negash, E. W. and Njagi, D. and Wilson, J. N. and Rabideaux, N. and Raub, T. and Sier, M. J. and Smith, P. and Urban, J. and Warren, M. and Yadeta, M. and Yost, C. and Zinaye, B.}, title = {The Hominin Sites and Paleolakes Drilling Project: inferring the environmental context of human evolution from eastern African rift lake deposits}, series = {Scientific Drilling}, volume = {21}, journal = {Scientific Drilling}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1816-8957}, doi = {10.5194/sd-21-1-2016}, pages = {1 -- 16}, year = {2016}, abstract = {The role that climate and environmental history may have played in influencing human evolution has been the focus of considerable interest and controversy among paleoanthropologists for decades. Prior attempts to understand the environmental history side of this equation have centered around the study of outcrop sediments and fossils adjacent to where fossil hominins (ancestors or close relatives of modern humans) are found, or from the study of deep sea drill cores. However, outcrop sediments are often highly weathered and thus are unsuitable for some types of paleoclimatic records, and deep sea core records come from long distances away from the actual fossil and stone tool remains. The Hominin Sites and Paleolakes Drilling Project (HSPDP) was developed to address these issues. The project has focused its efforts on the eastern African Rift Valley, where much of the evidence for early hominins has been recovered. We have collected about 2 km of sediment drill core from six basins in Kenya and Ethiopia, in lake deposits immediately adjacent to important fossil hominin and archaeological sites. Collectively these cores cover in time many of the key transitions and critical intervals in human evolutionary history over the last 4 Ma, such as the earliest stone tools, the origin of our own genus Homo, and the earliest anatomically modern Homo sapiens. Here we document the initial field, physical property, and core description results of the 2012-2014 HSPDP coring campaign.}, language = {en} }