TY - GEN A1 - Ascher, Uri M. A1 - Chin, Hongsheng A1 - Reich, Sebastian T1 - Stabilization of DAEs and invariant manifolds N2 - Many methods have been proposed for the stabilization of higher index differential-algebraic equations (DAEs). Such methods often involve constraint differentiation and problem stabilization, thus obtaining a stabilized index reduction. A popular method is Baumgarte stabilization, but the choice of parameters to make it robust is unclear in practice. Here we explain why the Baumgarte method may run into trouble. We then show how to improve it. We further develop a unifying theory for stabilization methods which includes many of the various techniques proposed in the literature. Our approach is to (i) consider stabilization of ODEs with invariants, (ii) discretize the stabilizing term in a simple way, generally different from the ODE discretization, and (iii) use orthogonal projections whenever possible. The best methods thus obtained are related to methods of coordinate projection. We discuss them and make concrete algorithmic suggestions. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 030 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-15625 ER - TY - GEN A1 - Leimkuhler, Benedict A1 - Reich, Sebastian T1 - Symplectic integration of constrained Hamiltonian systems N2 - A Hamiltonian system in potential form (formula in the original abstract) subject to smooth constraints on q can be viewed as a Hamiltonian system on a manifold, but numerical computations must be performed in Rn. In this paper methods which reduce "Hamiltonian differential algebraic equations" to ODEs in Euclidean space are examined. The authors study the construction of canonical parameterizations or local charts as well as methods based on the construction of ODE systems in the space in which the constraint manifold is embedded which preserve the constraint manifold as an invariant manifold. In each case, a Hamiltonian system of ordinary differential equations is produced. The stability of the constraint invariants and the behavior of the original Hamiltonian along solutions are investigated both numerically and analytically. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 032 KW - differential-algebraic equations KW - constrained Hamiltonian systems KW - canonical discretization schemes KW - symplectic methods Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-15653 ER - TY - GEN A1 - Ascher, Uri M. A1 - Chin, Hongsheng A1 - Petzold, Linda R. A1 - Reich, Sebastian T1 - Stabilization of constrained mechanical systems with DAEs and invariant manifolds N2 - Many methods have been proposed for the simulation of constrained mechanical systems. The most obvious of these have mild instabilities and drift problems. Consequently, stabilization techniques have been proposed A popular stabilization method is Baumgarte's technique, but the choice of parameters to make it robust has been unclear in practice. Some of the simulation methods that have been proposed and used in computations are reviewed here, from a stability point of view. This involves concepts of differential-algebraic equation (DAE) and ordinary differential equation (ODE) invariants. An explanation of the difficulties that may be encountered using Baumgarte's method is given, and a discussion of why a further quest for better parameter values for this method will always remain frustrating is presented. It is then shown how Baumgarte's method can be improved. An efficient stabilization technique is proposed, which may employ explicit ODE solvers in case of nonstiff or highly oscillatory problems and which relates to coordinate projection methods. Examples of a two-link planar robotic arm and a squeezing mechanism illustrate the effectiveness of this new stabilization method. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 033 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-15698 ER - TY - GEN A1 - Köberle, Peter A1 - Laschewsky, André T1 - Hybrid materials from organic polymers and inorganic salts N2 - The prepaparation of amorphous, homogeneous blends of zwitterionic polymers and transition metal salts was investigated. Homogeneous miscibility was achieved in many cases up to equimolar amounts of salt, depending on the anion and cation chosen. Various analytical techniques point to a solid state solution of the inorganic ions in the polymer matrix. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 086 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-26884 ER - TY - GEN A1 - Schrader, Lutz T1 - Deutschland und die europäische Sicherheitsagenda Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-28999 ER - TY - GEN A1 - Hopf, Diether T1 - Die Schule und die Ausländerkinder N2 - Inhalt: - Überblick und quantitative Verhältnisse - Die Situation in der DDR - Schul- und Unterrichtsprobleme - Ausländerfeindlichkeit - Rückwanderung T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - paper 096 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-36337 ER - TY - GEN A1 - Hopf, Diether T1 - Kindergarten, Vorschule und Grundschule N2 - Inhalt: - Der Elementarbereich - Die Grundschule - Schüler, Schulen, Klassen - Lehrerinnen und Lehrer - Zur Arbeitsweise der Grundschule - Einschulung, Zeugnisse, «Sitzenbleiben», Schulleistungen und Übergang zur Sekundärschule T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - paper 097 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-36346 ER - TY - GEN A1 - Selting, Margret T1 - Question intonation revisited : the intonation of conversational questions N2 - Content: 1. Introduction 2. Aim and approach of the present analysis 3. Non-restrictive 'open' conversational questions 4. More restrictive "narrower" questions 5. "Deviant cases" 6. Conclusions T3 - Zweitveröffentlichungen der Universität Potsdam : Philosophische Reihe - 66 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-43179 ER - TY - JOUR A1 - Lompscher, Joachim T1 - 5. Europäische Konferenz für Lehr- und Lernforschung JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4472 SN - 0945-294X VL - 7 ER - TY - JOUR A1 - Lompscher, Joachim T1 - Learning strategies BT - an essential component of learning activity JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4506 SN - 0945-294X VL - 7 ER - TY - JOUR A1 - Holzkamp, Klaus T1 - Lernen. Subjektwissenschaftliche Grundlegung - Einführung in die Hauptanliegen des Buches JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4525 SN - 0945-294X VL - 8 ER - TY - JOUR A1 - Weinert, Franz E. A1 - Helmke, Andrea T1 - Wie bereichsspezifisch verläuft eine kognitive Entwicklung JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4568 SN - 0945-294X VL - 9 ER - TY - JOUR A1 - Giest, Hartmut T1 - Rinderherdenaufgaben - ein Beispiel für Problemlöseanforderungen in der Grundschule JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4588 SN - 0945-294X VL - 9 ER - TY - JOUR A1 - Lompscher, Joachim T1 - Lernstrategien BT - Zugänge auf der Reflexions- und Handlungsebene JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4597 SN - 0945-294X VL - 9 ER - TY - JOUR A1 - Lompscher, Joachim T1 - 23. Internationaler Kongreß für Angewandte Psychologie JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4605 SN - 0945-294X VL - 9 ER - TY - GEN A1 - Tomassini, Luciano T1 - Eine postmoderne Sicht der internationalen Beziehungen N2 - The dramatic changes in international relations characterized by the terms "Complex Interdependence" and "Segmentary Globalization" call for new explanation. The author considers the post-modern approaches, a critical analysis of which he presents, to be one possibility to do that. In studies of international policy, these post-modern influences are gaining ground in disputes with realistic and neo-realistic approaches, and they can also clearly be felt in Latin America. Tomassini, based on the historic experiences of Latin America, forcefully calls for an active and constructive incorporation of the region into international developments. For that, Latin-American societies have to establish modern, and open political as well as economic systems which are able to meet those challenges. Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-10985 ER - TY - GEN A1 - Krüger, Joachim T1 - Zu Gast in Peking : die DDR und die VR China in den 80er Jahren T1 - Visiting Peking : the relationship between the GDR and the People's Republic of China in the 1980s N2 - Taking the visit of Erich Honecker to China as an example, the author analyses the bilateral GDR-Chinese relations in the 1980s. Based on extensive original research, the objectives as well as disappointed hopes are presented. The author reveals that not Honecker played the "Chinese Card", but he himself became part of Chinese politics. At the same time, the contradictory reaction to that visit in Moscow are documented when, with the election of Gorbachev, first signs of a change in Soviet policy toward China were indicated. Jahresabo: 40,00 € (ermäßigt: 25,00 €) Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-10999 ER - TY - GEN A1 - Elsenhans, Hartmut T1 - Staat - Wirtschaft - Macht und die Zukunft des internationalen Systems T1 - State, economy, power and the future of the international system N2 - Underlying the importance of revenue the author discusses the future of the international order from the perspective of political economy. The international system will not be a capitalist one. Political conflicts will not be removed by nonviolent market regulations. Weakness of labour force and a dominant role of revenue will further more result in political interventions by nation states. The struggle for revenue to maintain comparative advantages in high-tech-development strengthens state intervention in order to protect domestic market. The failure of the "development state" in the third world and the rising of fundamentalistic tendencies supported by a market-oriented middle class will increase conflicts in those regions. Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-11019 ER - TY - GEN A1 - Derichs, Claudia T1 - Japans Neue Linke : die selbsternannte Avantgarde T1 - Japan’s New Left N2 - Although without providing a systematical comparison, it has become clear that the sects or party-factions of Japan’s New Left movement are by no means merely copies of their counterparts in the West. On the other hand their conduct may not be judged as to be a unique Japanese phenomenon. What they embody is, on the whole, a complex symbiosis of universal and particularly Japanese features, which can be observed in the fields of social behavior, organizational structure, and group dynamics. The particularity of the New Left factions is mostly revealed through the higher intensity of specific features rather than through pecularities found only in Japan. Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-11029 ER - TY - GEN A1 - Jacobsen, Hans-Adolf T1 - Geopolitik im Denken und Handeln Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-11035 ER - TY - GEN A1 - Klingebiel, Stephan T1 - Flucht und Vertreibung in Entwicklungsländern T1 - Flight and Expulsion in Less Developed Countries N2 - Flight and expulsion are and will remain important international problems. The existence of refugees is a result of unsolved domestic tasks. Thus, effective solutions require comprehensive and long-term strategies. So far the efforts to reduce the causes of escape have not been sufficient. In the current refugee crises millions of people can survive only with the help of an efficient international system (for example the UNHCR) that guarantees humanitarian aid and protection. However, this system has turned out to be inadequate although the potential of preventive action is sufficient to reach a major progress in diminishing the refugee problem. Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-11048 ER - TY - GEN A1 - Crome, Erhard T1 - Woher und wohin? : Zur Analyse der osteuropäischen Transition T1 - What about the past? What about the future? : towards an analysis of East-European transition N2 - There has never been a theory of transition from really existing Socialism to a democratic and market-oriented system. Different theoretical approaches are taken into consideration by the author. Experiences of other transitional processes are practicable on Eastern Europe in a limited way. The missing of socio-structural differentiation, the socio-cultural consequences of the really existing Socialism and the international conditions did not promote the transition. It seems that the transition in Eastern Europe is obviously not a change from one political system to another one, but for the time being an open process. Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-11007 ER - TY - GEN A1 - Elsenbeer, Helmut A1 - Cassel, Keith A1 - Zuñiga, L. T1 - Throughfall in the terra firme forest of Western Amazonia N2 - Throughfall measurements were made under primary terra firme rainforest in the Rio Pichis valley, in the Upper Amazon Basin of Peru. Based on 214 precipitation events over nearly 18 months, throughfall was estimated to be 83.1±8.8% of gross precipitation. Regression analysis of all events revealed that gross precipitation is the only significant explanatory variable; the use of one-burst events does not significantly improve the regression relationship. Gross precipitation is, however, a poor predictor of throughfall for small rainfall events. The two forest structure parameters, canopy capacity, S, and free throughfall coefficient, p, were determined to be 1.3±0.2 mm and 0.32±0.18 mm. Rainfall intensity was found to influence these parameters. New methods which attempt to minimize the influence of meteorologic variables are used to estimate the potential values of these canopy parameters. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 049 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16955 ER - TY - GEN A1 - Anton, Peter A1 - Laschewsky, André T1 - Solubilization by polysoaps N2 - The aqueous solubilization power of several series of micellar homopolymers and copolymers (polysoaps) is investigated. Using five insoluble or poorly water-soluble dyes, comparisons of the capacities are made with respect ot the influence of structural variables such as the polymer backbone, the polymer geometry, the comonomer content, and the charge of the hydrophilic group. Some guidelines for polysoap structures suited for efficient solubilization are established. Noteworthy is that the solubilization capacities of the polysoaps are neither linked to the ability to reduce the surface tension of water, nor to the polarity of the solubilization sites deduced from spectroscopic probes. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 083 KW - Micellar polymers KW - polysoaps KW - solubilization Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17327 ER - TY - GEN A1 - Partenheimer, Lutz T1 - Albrecht der Bär, Jaxa von Köpenick und der Kampf um die Brandenburg in der Mitte des 12. Jahrhunderts N2 - Die ehemalige Brandenburg auf der Brandenburger Dominsel, der alte Fürstensitz der slawischen Heveller, gab der Mark Brandenburg ihren Namen. 1150 konnte der Markgraf der sächsischen Nordmark, Albrecht der Bär aus dem Geschlecht der am Ostharz begüterten Askanier, die Havelfeste nach dem Tod des letzten Hevellerherrschers besetzen. Zu den bis heute ungeklärten Problemen im Zusammenhang mit der Entstehung der Mark Brandenburg gehört die Frage, wann Albrecht die Burg wieder verlor, so daß er gezwungen war, sie durch eine Belagerung zum zweiten Male in seine Gewalt zu bringen, was am 11. Juni 1157 geschah. In der folgenden Untersuchung soll erneut der Frage nachgegangen werden, zu welchem Zeitpunkt dem Markgrafen die Brandenburg noch einmal entrissen worden war. T3 - Zweitveröffentlichungen der Universität Potsdam : Philosophische Reihe - 33 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-40882 ER - TY - JOUR A1 - Rückriem, Georg T1 - Sinnkrise des Wissens JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4513 SN - 0945-294X VL - 8 ER - TY - JOUR A1 - Adey, Philip T1 - Cognitive acceleration BT - science and other entrances to formal operations JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4483 SN - 0945-294X VL - 7 ER - TY - JOUR A1 - Kreisel, Marina T1 - Der Tätigkeitsbegriff - (k)eine Leerformel? BT - Überlegungen zu sprachdidaktischen Lösungen (unter Nutzung von Ergebnissen der "Ostberliner Aufsatzstudie") JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4461 SN - 0945-294X VL - 7 ER - TY - JOUR A1 - Grob, Karl T1 - Cognitive abilities, motives, learning strategies and social interactions as components of long-term-learning in basic electricity JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4498 SN - 0945-294X VL - 7 ER - TY - JOUR A1 - Lompscher, Joachim T1 - Was ist und was will Psychologische Didaktik? JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4459 SN - 0945-294X VL - 7 ER - TY - JOUR A1 - Giest, Hartmut T1 - Schulansichten - Beobachtungen aus einer Lerntherapeutischen Beratungsstelle JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4536 SN - 0945-294X VL - 8 ER - TY - JOUR A1 - Wyschkon, Uwe T1 - Zur Gestaltung der Lerntätigkeit unter dem Aspekt der Befähigung zum wissenschaftlichen Arbeiten und Studieren in der gymnasialen Oberstufe JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4545 SN - 0945-294X VL - 8 ER - TY - JOUR A1 - Mikelskis, Helmut T1 - Inszenierung von Gelegenheiten des Naturverstehens BT - konzeptionelle Betrachtungen zu einer empirischen Studie über ganzheitliches Lernen im Physikunterricht JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4578 SN - 0945-294X VL - 9 ER - TY - JOUR A1 - Edelstein, Wolfgang T1 - Eine Medidation zum Problem der entwicklungsorientierten Didaktik JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4557 SN - 0945-294X VL - 9 ER - TY - GEN A1 - Reich, Sebastian T1 - Momentum conserving symplectic integrators N2 - In this paper, we show that symplectic partitioned Runge-Kutta methods conserve momentum maps corresponding to linear symmetry groups acting on the phase space of Hamiltonian differential equations by extended point transformation. We also generalize this result to constrained systems and show how this conservation property relates to the symplectic integration of Lie-Poisson systems on certain submanifolds of the general matrix group GL(n). T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 044 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16824 ER - TY - JOUR A1 - Kreisel, Marina T1 - Berichtigung zu : "Der Tätigkeitsbegriff - (k)eine Leerformel? BT - Überlegungen zu sprachdidaktischen Lösungen ( unter Nutzung von Ergebnissen der "Ostberliner Aufsatzstudie") JF - LLF-Berichte / Universität Potsdam, Zentrum für Lehrerbildung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-5166 SN - 0945-294X VL - 8 ER - TY - GEN A1 - Bohlen, Andreas T1 - Die sanfte Offensive : Untersuchungen zur Verwendung politischer Euphemismen in britischen und amerikanischen Printmedien bei der Berichterstattung über den Golfkrieg im Spannungsfeld zwischen Verwendung und Mißbrauch der Sprache N2 - Inhalt: 1. Vorbemerkungen 2. Zu einigen philosophischen und theoretisch-linguistischen Grundlagen einer kommunikativ orientierten Betrachtung der Sprache 3. Sprache und menschliche Gesellschaft 4. Der Euphemismus 5. Euphemismen im Golfkrieg - Zur Analyse der Untersuchungsergebnisse 6. Zusammenfassung und Schlußfolgerungen 7. Perspektiven der kommunikativen Sprachforschung bezüglich 215der Untersuchung des politischen Euphemismus - Forschungsausblick und Schlußbemerkungen T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - paper 130 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-39213 ER - TY - BOOK A1 - Barsch, Heiner A1 - Saupe, Gabriele A1 - Bierwagen, Charlotte A1 - Ebert, Beatrix A1 - Goltz, Elke A1 - Halfmann, Jochen A1 - Itzerott, Sibylle A1 - Kaden, Klaus A1 - Knothe, Dieter A1 - Krüger, Wolfgang A1 - Syrbe, Ralf-Uwe A1 - Steinhardt, Uta A1 - Thieme, Siegfried A1 - Ziener, Karen ED - Barsch, Heiner ED - Saupe, Gabriele T1 - Bewertung und Gestaltung der naturnahen Landschaft in Schutzgebieten, Erholungs- und Freizeitgebieten. Anhang T3 - Potsdamer Geographische Forschungen - 8, Anhang Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-52928 ER - TY - GEN A1 - Püschel, Gerhard Paul A1 - Christ, Bruno T1 - Inhibition by PGE₂ of glucagon-induced increase in phosphoenolpyruvate carboxykinase mRNA and acceleration of mRNA degradation in cultured rat hepatocytes N2 - In cultured rat hepatocytes the key gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PCK) is known to be induced by glucagon via an elevation of cAMP. Prostaglandin E₂ has been shown to antagonize the glucagon-activated cAMP formation, glycogen phosphorylase activity and glucose output in hepatocytes. It was the purpose of the current investigation to study the potential of PGE₂ to inhibit the glucagon-induced expression of PCK on the level of mRNA and enzyme activity. PCK mRNA and enzyme activity were increased by 0.1 nM glucagon to a maximum after 2 h and 4 h, respectively. This increase was completely inhibited if 10 μM PGE2 was added concomitantly with glucagon. This inhibition by PGE₂ of glucagon-induced PCK activity was abolished by pertussis toxin treatment. When added at the maximum of PCK mRNA at 2 h, PGE₂ accelerated the decay of mRNA and reduced enzyme activity. This effect was not reversed by pertussis toxin treatment. Since in liver PGE₂ is derived from Kupffer cells, which play a key role in the local inflammatory response, the present data imply that during inflammation PGE₂ may reduce the hepatic gluconeogenic capacity via a Gᵢ-linked signal chain. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 045 KW - Prostaglandin E₂ KW - Glucagon KW - Phosphoenolpyruvate carboxykinase KW - Inflammation KW - mRNA degradation Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-45792 ER - TY - GEN A1 - Neuschäfer-Rube, Frank A1 - DeVries, Christa A1 - Hänecke, Kristina A1 - Jungermann, Kurt A1 - Püschel, Gerhard Paul T1 - Molecular cloning and expression of a prostaglandin E₂ receptor of the EP₃ϐ subtype from rat hepatocytes N2 - Rat hepatocytes have previously been reported to possess prostaglandin E₂ receptors of the EP₃-type (EP₃-receptors) that inhibit glucagonstimulated glycogenolysis by decreasing cAMP. Here, the isolation of a functional EP₃ϐ receptor cDNA clone from a rat hepatocyte cDNA library is reported. This clone can be translated into a 362-amino-acid protein, that displays over 95% homology to the EP₃ϐ receptor from mouse mastocytoma. The amino- and carboxy-terminal region of the protein are least conserved. Transiently transfected HEK 293 cells expressed a single binding site for PGE₂ with an apparent Kd of 15 nM. PGE₂ > PGF₂α > PGD₂ competed for [³H]PGE₂ binding sites as did the EP₃ receptor agonists M&B 28767 = sulprostone > misoprostol but not the EP₁ receptor antagonist SC 19220. In stably transfected CHO cells M&B 28767 > sulprostone = PGE₂ > misoprostol > PGF₂α inhibited the forskolin-elicited cAMP formation. Thus, the characteristics of the EP₃ϐ receptor of rat hepatocytes closely resemble those of the EP₃ϐ receptor of mouse mastocytoma. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 108 KW - Prostaglandin receptor KW - Hepatocyte (rat) KW - Molecular cloning and expression Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-45830 ER - TY - GEN A1 - Selting, Margret A1 - Sandig, Barbara T1 - [Bericht der] Sektion Textlinguistik und Stilistik : Schwerpunkt 'Sprech- und Gesprächsstile'; Beitrag im Rahmen der 24. Jahrestagung der Gesellschaft für Angewandte Linguistik GAL e.V. T3 - Zweitveröffentlichungen der Universität Potsdam : Philosophische Reihe - 68 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-43010 ER - TY - GEN A1 - Watanabe, Yuji A1 - Püschel, Gerhard Paul A1 - Gardemann, Andreas A1 - Jungermann, Kurt T1 - Presinusoidal and proximal intrasinusoidal confluence of hepatic artery and portal vein in rat liver : functional evidence by orthograde and retrograde bivascular perfusion N2 - The site of confluence of the artery and the portal vein in the liver still appears to be controversial. Anatomical studies suggested a presinusoidal or an intrasinusoidal confluence in the first, second or even final third of the sinusoids. The objective of this investigation was to study the problem with functional biochemical techniques. Rat livers were perfused through the hepatic artery and simultaneously either in the orthograde direction from the portal vein to the hepatic vein or in the retrograde direction from the hepatic vein to the portal vein. Arterial how was linearly dependent on arterial pressure between 70 cm H2O and 120 cm H2O at a constant portal or hepatovenous pressure of 18 cm H2O. An arterial pressure of 100 cm H2O was required for the maintenance of a homogeneous orthograde perfusion of the whole parenchyma and of a physiologic ratio of arterial to portal how of about 1:3. Glucagon was infused either through the artery or the portal vein and hepatic vein, respectively, to a submaximally effective ''calculated'' sinusoidal concentration after mixing of 0.1 nmol/L. During orthograde perfusions, arterial and portal glucagon caused the same increases in glucose output. Yet during retrograde perfusions, hepatovenous glucagon elicited metabolic alterations equal to those in orthograde perfusions, whereas arterial glucagon effected changes strongly reduced to between 10% and 50%. Arterially infused trypan blue was distributed homogeneously in the parenchyma during orthograde perfusions, whereas it reached clearly smaller areas of parenchyma during retrograde perfusions. Finally, arterially applied acridine orange was taken up by all periportal hepatocytes in the proximal half of the acinus during orthograde perfusions but only by a much smaller portion of periportal cells in the proximal third of the acinus during retrograde perfusions. These findings suggest that in rat liver, the hepatic artery and the portal vein mix before and within the first third of the sinusoids, rather than in the middle or even last third. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 067 KW - Hepatic artery KW - Portal vein KW - Confluence KW - Rat KW - Animal KW - Experimental study KW - Anatomy KW - Biochemical analysis KW - Technique KW - Perfusion KW - Exploration Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16702 ER - TY - GEN A1 - Jacobi, Juliane T1 - Zwischen Erwerbsfleiss und Bildungsreligion : Mädchenbildung in Deutschland N2 - Inhalt: - "Das Recht der Frauen auf Erwerb". Weibliche Bildung zwischen Allgemein- und Berufsbildung - Höhere Mädchenbildung zwischen 1889-1914 - der Kampf um gleihberechtigte Teilhabe an Wissenschaft, Staat und Kultur T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - paper 136 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-39306 ER - TY - GEN A1 - Assing, Helmut A1 - Partenheimer, Lutz T1 - Alte Kulturen in Mitteleuropa [Begleitmaterial zur Sendereihe des Ostdeutschen Rundfunks Brandenburg] N2 - Inhalt: 1. Kritische Erläuterung der Bilder und Texte jeder Folge - 1. Folge: Funde der Bronzezeit (Ein Film von Uschi Demitter) - 2. Folge: Germanische Stämme (Ein Film von Uschi Demitter) - 3. Folge: Siedlung der Slawen (Ein Film von Kurt Barthel - 4. Folge: Das verschwundene Heiligtum (Ein Film von Kurt Barthel) - 5. Folge: Von der Kaiserpfalz zur Stadt (Ein Film von Uschi Demitter und Richard Krause) 2. Einordnung der historischen Details der Folgen in den Geschichtsprozeß - 1. Folge: Funde der Bronzezeit - 2. Folge: Germanische Stämme - 3. Folge: Siedlung der Slawen - 4. Folge: Das verschwundene Heiligtum - 5. Folge: Von der Kaiserpfalz zur Stadt 3. Didaktisch-methodische Empfehlungen zum Einsatz der Sendereihe 3.1 Zuordnung der Sendefolgen zu den Rahmenplänen 3.2 Hinweise für die Unterrichtsarbeit des Lehrers 4. Ergänzende Medien zu den Themenbereichen in der Sammlung des MPZ T3 - Zweitveröffentlichungen der Universität Potsdam : Philosophische Reihe - 34 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-40897 ER - TY - GEN A1 - Elsenbeer, Helmut A1 - West, Adam A1 - Bonell, Mike T1 - Hydrologic pathways and stormflow hydrochemistry at South Creek, northeast Queensland N2 - Earlier investigations at South Creek in northeastern Queensland established the importance of overland flow as a hydrologic pathway in this tropical rainforest environment. Since this pathway is ‘fast’, transmitting presumably ‘new’ water, its importance should be reflected in the stormflow chemistry of South Creek: the greater the volumentric contribution to the stormflow hydrograph, the more similarity between the chemical composition of streamwater and of overland flow is to be expected. Water samples were taken during two storm events in an ephemeral gully (gully A), an intermittent gully (gully B) and at the South Creek catchment outlet; additional spot checks were made in several poorly defined rills. The chemical composition of ‘old’ water was determined from 45 baseflow samples collected throughout February. The two events differed considerably in their magnitudes, intensities and antecedent moisture conditions. In both events, the stormflow chemistry in South Creek was characterized by a sharp decrease in Ca, Mg, Na, Si, Cl, EC, ANC, alkalinity and total inorganic carbon. pH remained nearly constant with discharge, whereas K increased sharply, as did sulfate in an ill-defined manner. In event 1, this South Creek stormflow pattern was closely matched by the pattern in gully A, implying a dominant contribution of ‘new’ water. This match was confirmed by the spot samples from rills. Gully B behaved like South Creek itself, but with a dampened ‘new’ water signal, indicating less overland flow generation in its subcatchment. In event 2, which occurred five days later, the initial ‘new’ water signal in gully A was rapidly overwhelmed by a different signal which is attributed to rapid drainage from a perched water table. This study shows that stormflow in this rainforest catchment consists predominantly of ‘new’ water which reaches the stream channel via ‘fast’ pathways. Where the ephemeral gullies delivering overland flow are incised deeply enough to intersect a perched water table, a delayed, ‘old’ water-like signal may be transmitted. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 046 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16904 ER - TY - GEN A1 - Selting, Margret T1 - Emphatic speech style : with special focus on the prosodic signalling of heightened emotive involvement in conservation N2 - After a review of previous work on the prosody of emotional involvement, data extracts from natural conversations are analyzed in order to argue for the constitution of an 'emphatic (speech) style', which linguistic devices are used to signal heightened emotive involvement. Participants use prosodic cues, in co-occurrence with syntactic and lexical cues, to contextualize turn-constructional units as 'emphatic'. Only realizations of prosodic categories that are marked in relation to surrounding uses of these categories have the power to contextualize units as displaying 'more-than-normal involvement'. In the appropriate context, and in cooccurrence with syntactic and lexical cues and sequential position, the context-sensitive interpretation of this involvement is 'emphasis'. Prosodic marking is used in addition to various unmarked cues that signal and constitute different activity types in conversation. Emphatic style highlights and reinforms particular conversational activities, and makes certain types of recipient responses locally relevant. In particular, switches from non-emphatic to emphatic style are used to contextualize 'peaks of involvement' or 'climaxes' in story-telling. These are shown in the paper to be 'staged' by speakers and treated by recipients as marked activities calling for displays of alignment with respect to the matter at hand. Signals of emphasis are deployable as techniques for locally organizing demonstrations of shared understanding and participant reciprocity in conversational interaction. T3 - Zweitveröffentlichungen der Universität Potsdam : Philosophische Reihe - 41 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-37933 ER - TY - GEN A1 - Hopf, Diether A1 - Hatzichristou, Chryse T1 - Rückkehr in die Heimat : zur schulischen und sozialpsychologischen Situation griechischer Schüler nach der Remigration N2 - Dieser Aufsatz berichtet über die Ergebnisse einer umfassenden empirischen Untersuchung zur Schulsituation griechischer Kinder und Jugendlicher, die aus der BRD in ihre Heimat zurückgewandert sind. An Stichproben aus Grundschulen und Sekundarstufen wird überprüft, welche Probleme in den Schulleistungen und im psychosozialen Befinden bei Rückkehrern im Vergleich zu Einheimischen auftreten. Die Informationen über jeden Schüler enthalten mehrere Perspektiven: Lehrerurteil, Einschätzung durch die Mitschüler, Selbstkonzept sowie Schulleistungsindikatoren. Es zeigt sich, daß die Rückkehrerkinder schulisch im Rückstand liegen sowie eine Reihe psychosozialer Belastungen aufweisen, die je nach Remigrationszeitpunkt, Geschlecht etc. unterschiedlich ausgeprägt sind. Unproblematisch verläuft die Rückkehr in die Heimat und die schulische Integration nur, wenn sie vor dem 8. Lebensjahr erfolgt. N2 - The authors report the results of a comprehensive empirical study on the school situation of Greek children and adolescents who remigrated from Germany into their home country. On the basis of random samples taken in primary and secondary schools, they inquire into the problems regarding school achievement and the psychosocial condition of remigrants compared to locals. The information on each student comprises several dimensions: teacher judgement, assessment by schoolmates, self-concept, and indicators of school-achievement. It is shown that the children of remigrants lag behind as regards school achievement and manifest psychosocial strain which differs according to the date of remigration, the gender etc. The return to the home country and integration into the school takes an unproblematic course only if remigration takes place before the age of eight. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - paper 095 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-36323 ER - TY - GEN A1 - Selting, Margret T1 - Konstruktionen am Satzrand als interaktive Ressource in natürlichen Gesprächen T3 - Zweitveröffentlichungen der Universität Potsdam : Philosophische Reihe - 48 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41932 ER - TY - GEN A1 - Henkel, Carsten A1 - Steane, Andrew M. A1 - Kaiser, Robin A1 - Dalibard, Jean T1 - A modulated mirror for atomic interferometry N2 - A novel atomic beam splitter, using reflection of atoms off an evanescent light wave, is investigated theoretically. The intensity or frequency of the light is modulated in order to create sidebands on the reflected de Broglie wave. The weights and phases of the various sidevands are calculated using three different approaches: the Born approximation, a semiclassical path integral approach, and a numerical solution of the time-dependent Schrdinger equation. We show how this modulated mirror could be used to build practical atomic interferometers. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 102 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-42279 ER - TY - GEN A1 - Henkel, Carsten A1 - Courtois, Jean-Yves A1 - Aspect, Alain T1 - Atomic diffraction by a thin phase grating N2 - We present a semiclassical perturbation method for the description of atomic diffraction by a weakly modulated potential. It proceeds in a way similar to the treatment of light diffraction by a thin phase grating, and consists in calculating the atomic wavefunction by means of action integrals along the classical trajectories of the atoms in the absence of the modulated part of the potential. The capabilities and the validity condition of the method are illustrated on the well-known case of atomic diffraction by a Gaussian standing wave. We prove that in this situation the perturbation method is equivalent to the Raman-Nath approximation, and we point out that the usually-considered Raman-Nath validity condition can lead to inaccuracies in the evaluation of the phases of the diffraction amplitudes. The method is also applied to the case of an evanescent wave reflection grating, and an analytical expression for the diffraction pattern at any incidence angle is obtained for the first time. Finally, the application of the method to other situations is briefly discussed. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 101 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-42269 ER -