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342 results on '"Seifert, Wolfgang"'

1. Handbuch Demokratiepädagogik

Author

Wolfgang Beutel, Markus Gloe, Gerhard Himmelmann, Dirk Lange, Volker Reinhardt, Anne Seifert, Wolfgang Beutel, Markus Gloe, Gerhard Himmelmann, Dirk Lange, Volker Reinhardt, Anne Seifert and Wolfgang Beutel, Markus Gloe, Gerhard Himmelmann, Dirk Lange, Volker Reinhardt, Anne Seifert, Wolfgang Beutel, Markus Gloe, Gerhard Himmelmann, Dirk Lange, Volker Reinhardt, Anne Seifert

Published
2022

4. Zircon megacrysts in alkaline lavas of the Lusatian Volcanic field (Central Europe) – petrogenetic implications of U/Pb ages, Hf isotopes and trace element characteristics

Author

Büchner, Jörg, Gerdes, Axel, Viereck, Lothar, Tietz, Olaf, and Seifert, Wolfgang

Abstract

Zirkon-Megakristalle von Edelsteinqualität aus zwei verschiedenen Lokalitäten im Lausitzer Vulkanfeld wurden datiert sowie mineral- und isotopengeochemisch analysiert. Die Zirkone stammen aus einem Schlackenkegel des basanitischen Hofeberg-Vulkanes und einer alluvialen Seife vom Hirschbörnel-Bach flussabwärts des Buchberg-Trachytdoms. Die genetische Interpretation führt im geologischen Kontext zu zwei verschiedenen genetischen Modellen: Im Falle der ersten Lokalität führte die Aufnahme des Zirkons mit primären Verwachsungsphasen in einer basanitischen Schmelze nicht nur zu Resorptions- und Reaktionszonen in der einschließenden Schmelze, sondern auch zu einer Rekristallisation des Zirkons und seiner Verwachsungsphasen. Im Falle der Seifen-Lokalität sind die Zirkonkristalle nicht resorbiert und können aus der anfänglichen explosiven Eruption des hochentwickelten Daches eines trachytischen Schmelzsystems stammen, dessen Relikte durch den flussaufwärts gelegenen trachytischen Lavadom von Buchberg dokumentiert wird. Sowohl das U/Pb-Alter als auch die Hf-Isotopie der Zirkone (30,34 ± 0,10 Ma für Hofeberg; 30,45 ± 0,17 Ma für Buchberg) und εHf (+3,1 bis +6,8 für Hofeberg; εHf +3,4 bis +4,7 für Buchberg) stimmen innerhalb der Fehlergrenzen mit denen ihrer jeweiligen Wirtsgesteine Basanit und Trachyt überein. Dies deutet auf ihre komagmatische Bildung hin. Bei Anwendung des Ti-in-Zirkon-Thermometers und unter Berücksichtigung unterschiedlicher Ti-Aktivitäten, die durch verwachsene Phasen angezeigt werden, können 800–900 °C als Kristallisationstemperaturen für beide Zirkonpopulationen angenommen werden.Die Ausgangsschmelze der Zirkon-Megakristalle vom Hofeberg bleibt jedoch unbestimmt, aber aufgrund der mineralchemischen Eigenschaften ist eine entwickelte, plagioklasfreie Schmelze am wahrscheinlichsten.

Published
2024
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5. Improved Thermoelectric Cooling Based on the Thomson Effect

Author

Snyder, G. Jeffrey, Khanna, Raghav, Toberer, Eric S., Heinz, Nicholas A., and Seifert, Wolfgang

Subjects
Condensed Matter - Materials Science
Abstract

Traditional thermoelectric Peltier coolers exhibit a cooling limit which is primarily determined by the figure of merit, zT. Rather than a fundamental thermodynamic limit, this bound can be traced to the difficulty of maintaining thermoelectric compatibility. Self-compatibility locally maximizes the cooler's coefficient of performance for a given zT and can be achieved by adjusting the relative ratio of the thermoelectric transport properties that make up zT. In this study, we investigate the theoretical performance of thermoelectric coolers that maintain self-compatibility across the device. We find such a device behaves very differently from a Peltier cooler, and term self-compatible coolers "Thomson coolers" when the Fourier heat divergence is dominated by the Thomson, as opposed to the Joule, term. A Thomson cooler requires an exponentially rising Seebeck coefficient with increasing temperature, while traditional Peltier coolers, such as those used commercially, have comparatively minimal change in Seebeck coefficient with temperature. When reasonable material property bounds are placed on the thermoelectric leg, the Thomson cooler is predicted to achieve approximately twice the maximum temperature drop of a traditional Peltier cooler with equivalent figure of merit (zT). We anticipate the development of Thomson coolers will ultimately lead to solid state cooling to cryogenic temperatures., Comment: The Manuscript has been revised for publication in PRB

Published
2011
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16. Long-Term Geological Evolution and Mass-Flow Balance of the South-Central Andes

Author

Glodny, Johannes, Echtler, Helmut, Figueroa, Oscar, Franz, Gerhard, Gräfe, Kirsten, Kemnitz, Helga, Kramer, Wolfgang, Krawczyk, Charlotte, Lohrmann, Jo, Lucassen, Friedrich, Melnick, Daniel, Rosenau, Matthias, Seifert, Wolfgang, Brun, J. P., editor, Oncken, O., editor, Weissert, H., editor, Dullo, C., editor, Oncken, Onno, editor, Chong, Guillermo, editor, Franz, Gerhard, editor, Giese, Peter, editor, Götze, Hans-Jürgen, editor, Ramos, Victor A., editor, Strecker, Manfred R., editor, and Wigger, Peter, editor

Published
2006
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22. P

Author

Seifert, Wolfgang, Alt, Rainer, Delfmann, Werner, Pawellek, Günther, Göpfert, Ingrid, Klaus, Peter, editor, and Krieger, Winfried, editor

Published
2000
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23. K

Author

Wildemann, Horst, Weber, Jürgen, Seifert, Wolfgang, Pawellek, Günther, Delfmann, Werner, Stein, Andreas, Klaus, Peter, editor, and Krieger, Winfried, editor

Published
2000
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27. EXPERTS’ PERCEIVED PATIENT BURDEN AND OUTCOMES OF KNEE-ANKLE-FOOT-ORTHOSES (KAFOs) VS. MICROPROCESSOR-STANCE-AND-SWING-PHASE-CONTROLLED-KNEE-ANKLE-FOOT ORTHOSES (MP-SSCOs)

Author

Brüggenjürgen, Bernd, primary, Braatz, Frank, additional, Greitemann, Bernhard, additional, Drewitz, Heiko, additional, Ruetz, Axel, additional, Schäfer, Michael, additional, Seifert, Wolfgang, additional, Steinfeldt, Friedemann, additional, Weichold, Claudia, additional, Yao, Daiwei, additional, and Stukenborg-Colsman, Christina, additional

Published
2022
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28. P

Author

Delfmann, Werner, Seifert, Wolfgang, Pawellek, Günther, Göpfert, Ingrid, Klaus, Peter, editor, and Krieger, Winfried, editor

Published
1998
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29. K

Author

Wildemann, Horst, Seifert, Wolfgang, Stein, Andreas, Delfmann, Werner, Pawellek, Günther, Klaus, Peter, editor, and Krieger, Winfried, editor

Published
1998
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50. Abandonment of the South Penninic-Austroalpine palaeosubduction zone, Central Alps, and shift from subduction erosion to accretion: constraints from Rb/Sr geochronology

Author

Bachmann, Raik, Glodny, Johannes, Oncken, Onno, and Seifert, Wolfgang

Subjects
Alps -- Natural history, Subduction zones (Geology) -- Natural history, Subduction zones (Geology) -- Properties, Erosion -- Research, Geochronology -- Research, Earth sciences
Abstract

We present new age data for the evolution of the suture zone between lower plate South Penninic and upper plate Austroalpine units in the Central European Alps. Rb/Sr deformation ages for mylonitized rocks of the South Penninic palaeosubduction melange and for deformed Austroalpine basement (Eastern Switzerland) shed light on the pre-Alpine and Alpine deformation history along the suture, as well as on synsubduction interplate mass transfer. Rb/Sr age data define two age groups. The first group reflects pre-Alpine events within the upper plate basement, with varying degree of resetting by subsequent Alpine overprints. The second group marks the waning of subduction-related deformation along the South Penninic Austroalpine suture zone, at around 50 Ma, and termination at c. 47 Ma. Identical Rb/Sr ages for pervasively deformed Austroalpine and South Penninic lithologies point to tectonic erosion of the upper plate during subduction. We propose that underplating of the Middle Penninic micro-continent at c. 50 Ma led to the cessation of deformation within the South Penninic melange, and shifted the zone of active deformation into the footwall. This also caused a contemporaneous upper plate surface uplift and shutoff of sedimentation in Alpine Gosau-type forearc basins.

Published
2009

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