TY - THES A1 - Demory, François T1 - Paleomagnetic dating of climatic events in Late Quaternary sediments of Lake Baikal (Siberia) N2 - Der Baikalsee ist ein ideales Klimaarchiv für die Mitte Eurasiens. In dieser Arbeit wurde gesteinsmagnetische und paleomagnetische Analysen an hemipelagischen Sequenzen von vier Lokationen analysiert. Die Kerne erreichen ein Alter von maximal 300 ky. In Kombination mit TEM, XRD, XRF und geochemischen Analysen zeigt die gesteinsmagnetische Studie, dass detritischer Magnetit das magnetische Signal der glazialen Sedimente dominiert. Die magnetischen Signale der interglazialen Sedimente wurden durch diagenetische Prozesse verändert. Mittels HIRM können Hämatit und Goethit quantifiziert werden. Diese Methode eignet sich, den detritischen Eintrag in den Baikalsee abzuschätzen. Relative Paleointensitäten des Erdmagnetfeldes ergaben reproduizerbare Muster, welche in Korrelation mit gutdatierten Referenzproben die Ableitung eines alternativen Altersmodells für die Datierung der Baikalsedimente ermöglichten. Bei Anwendung des paleomagnetischen Altersmodells beobachtet man, dass die Abkühlung im Baikalgebiet und im Oberflächenwasser des Nordatlantiks wie sie aus den δ18 O-Werten planktonischer Foraminiferen abgeleitet werden kann, zeitgleich ist. Wird das aus benthischen δ18 O-Werten abgeleitete Altermdodell auf den Baikalsee angewandt, ergibt sich eine deutliche Zeitverschiebung. Das benthische Altersmodell repräsentiert die globale Veränderung des Eisvolumens, welche später als die Vänderung der Oberflächenwassertemperatur auftritt. Die Kompilation paleomagnetischer Kurven ergab eine neue relative Paleointensitätskurve “Baikal 200”. Mittels Korngrössenanalyse des Detritus konnten drei Faziestypen mit unterschiedlicher Sedimentationsdynamik unterschieden werden: 1) Glaziale Peroiden werden durch hohe Tongehalte infolge von Windeintrag und durch grobe Sandfraktion mittels Transport durch lokale Winde über das Eis charakterisiert. Dieser Faziestyp deutet auf arides Klima. 2) Während der Glazial/Interglazial-Übergänge steigt die Siltfraktion an. Dies deutet auf erhöhte Feuchtigkeit und damit verbunden erhöhte Sedimentdynamik. Windtransport und in den Schnee der Eisdecke eingetragener Staub sind die vorherrschenden Prozesse, welche den Silt in hemipelagischer Position zur Ablagerung bringen. 3) Während des klimatischen Optimum des Eeemian werden Grösse und Quantität des Silts minimal, was auf eine geschlossene Vegetationsdecke im Hinterland deutet. N2 - Lake Baikal provides an excellent climatic archive for Central Eurasia as global climatic variations are continuously depicted in its sediments. We performed continuous rock magnetic and paleomagnetic analyses on hemipelagic sequences retrieved from 4 underwater highs reaching back 300 ka. The rock magnetic study combined with TEM, XRD, XRF and geochemical analyses evidenced that a magnetite of detrital origin dominates the magnetic signal in glacial sediments whereas interglacial sediments are affected by early diagenesis. HIRM roughly quantifies the hematite and goethite contributions and remains the best proxy for estimating the detrital input in Lake Baikal. Relative paleointensity records of the earth′s magnetic field show a reproducible pattern, which allows for correlation with well-dated reference curves and thus provides an alternative age model for Lake Baikal sediments. Using the paleomagnetic age model we observed that cooling in the Lake Baikal region and cooling of the sea surface water in the North Atlantic, as recorded in planktonic foraminifera δ18 O, are coeval. On the other hand, benthic δ18 O curves record mainly the global ice volume change, which occurs later than the sea surface temperature change. This proves that a dating bias results from an age model based on the correlation of Lake Baikal sedimentary records with benthic δ18 O curves. The compilation of paleomagnetic curves provides a new relative paleointensity curve, “Baikal 200”. With a laser-assisted grain size analysis of the detrital input, three facies types, reflecting different sedimentary dynamics can be distinguished. (1) Glacial periods are characterised by a high clay content mostly due to wind activity and by occurrence of a coarse fraction (sand) transported over the ice by local winds. This fraction gives evidence for aridity in the hinterland. (2) At glacial/interglacial transitions, the quantity of silt increases as the moisture increases, reflecting increased sedimentary dynamics. Wind transport and snow trapping are the dominant process bringing silt to a hemipelagic site (3) During the climatic optimum of the Eemian, the silt size and quantity are minimal due to blanketing of the detrital sources by the vegetal cover. T2 - Paleomagnetic dating of climatic events in Late Quaternary sediments of Lake Baikal (Siberia) KW - Paleomagnetismus KW - Klima KW - Sedimentationsdynamik KW - diagenetische Prozesse KW - Paleomagnetism KW - climate KW - sedimentary dynamics KW - diagenesis Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-0001720 ER - TY - JOUR A1 - Sarsakov, Vladimir A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Woltran, Stefan T1 - A compiler for nested logic programming Y1 - 2004 SN - 3-540- 20721-x ER - TY - JOUR A1 - Linke, Thomas A1 - Tompits, Hans A1 - Woltran, Stefan T1 - On Acyclic and head-cycle free nested logic programs Y1 - 2004 SN - 3-540-22671-01 ER - TY - JOUR A1 - Linke, Thomas A1 - Tompits, Hans A1 - Woltran, Stefan T1 - On acyclic and head-cycle free nested logic programs Y1 - 2004 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Woltran, Stefan T1 - On Computing belief change operations using quantifield boolean formulas N2 - In this paper, we show how an approach to belief revision and belief contraction can be axiomatized by means of quantified Boolean formulas. Specifically, we consider the approach of belief change scenarios, a general framework that has been introduced for expressing different forms of belief change. The essential idea is that for a belief change scenario (K, R, C), the set of formulas K, representing the knowledge base, is modified so that the sets of formulas R and C are respectively true in, and consistent with the result. By restricting the form of a belief change scenario, one obtains specific belief change operators including belief revision, contraction, update, and merging. For both the general approach and for specific operators, we give a quantified Boolean formula such that satisfying truth assignments to the free variables correspond to belief change extensions in the original approach. Hence, we reduce the problem of determining the results of a belief change operation to that of satisfiability. This approach has several benefits. First, it furnishes an axiomatic specification of belief change with respect to belief change scenarios. This then leads to further insight into the belief change framework. Second, this axiomatization allows us to identify strict complexity bounds for the considered reasoning tasks. Third, we have implemented these different forms of belief change by means of existing solvers for quantified Boolean formulas. As well, it appears that this approach may be straightforwardly applied to other specific approaches to belief change Y1 - 2004 SN - 0955-792X ER - TY - JOUR A1 - Lieckfeldt, Elke A1 - Simon-Rosin, Ulrike A1 - Zöller, Daniela A1 - Ebert, Berit A1 - Kehr, Julia A1 - Fisahn, Joachim T1 - Spatio/temporal analysis of gene exression profiles within single cells and specific tissue types of developing Arabidopsis plants Y1 - 2004 SN - 3-00-011587-0 ER - TY - JOUR A1 - Fischer, Florian A1 - Räder, Andy A1 - Wewetzer, Gudrun A1 - Hempel, Luisa A1 - Sack, Beate A1 - Schwill, Andreas A1 - Surrey, Heike A1 - Claussen, Martin A1 - Klein, Oliver A1 - Czempinski, Katrin A1 - Küchmeister, Heike A1 - González, Antonio Martínez A1 - Pecher, Klaus A1 - Resch-Esser, Ursula A1 - Gommert, Natalie T1 - Portal = Unbekanntes Terrain: Die EU-Erweiterung birgt neue Möglichkeiten BT - Die Potsdamer Universitätszeitung N2 - Aus dem Inhalt: - Unbekanntes Terrain: Die EU-Erweiterung birgt neue Möglichkeiten - Zehn Jahre MenschenRechtsZentrum - Wassermangel im Nahen Osten - Karl-Scheel-Preis für Turbulenzforschung T3 - Portal: Das Potsdamer Universitätsmagazin - 06-08/2004 Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-439806 SN - 1618-6893 IS - 06-08/2004 ER - TY - JOUR A1 - Christensen, Lise Bech A1 - Sanchez, Sebastian F. A1 - Jahnke, Knud A1 - Becker, Thomas A1 - Wisotzki, Lutz A1 - Kelz, A. A1 - Popovic, L. C. A1 - Roth, Martin M. T1 - Integral field spectroscopy of extended Ly alpha emission from the DLA galaxy in Q2233+131 N2 - This paper presents observations of an extended Lyman-alpha emission nebula surrounding the galaxy responsible for the Damped Lyman-alpha Absorption (DLA) line in the spectrum of the quasar Q2233+131. With the Potsdam Multi Aperture Spectrophotometer (PMAS) we measure the properties of the extended Lyalpha emission in an area of 3" x 5" having a total line flux of (2.8 +/- 0.3) x 10(-16) erg cm(-2) s(-1), which at redshift z = 3.15 corresponds to a luminosity of (2.4(-0.2)(+0.3)) x 10(43) erg s(-1) and a size of 23 x 38 kpc. The location of the emission is spatially coincident with the previously detected DLA galaxy, but extends significantly beyond its limb. We argue that the Lya emission is likely to be caused by an outflow from the DLA galaxy, presumably powered by star formation. In the case of negligible dust extinction, the Lya luminosity indicates a star-formation rate of 19 +/- 10 M-. yr(-1) consistent with that derived from the UV continuum flux from the parent galaxy. The wind velocity indicated by the integral field spectra is of the order of several hundred km s(-1). We find no indication of emission originating in a rotating disk Y1 - 2004 ER - TY - JOUR A1 - Wisotzki, Lutz A1 - Becker, Thomas A1 - Christensen, Lise Bech A1 - Jahnke, Knud A1 - Helms, Andreas A1 - Kelz, A. A1 - Roth, Martin M. A1 - Sanchez, Sebastian F. T1 - Integral field spectrophotometry of gravitationally lensed QSOs with PMAS N2 - We present spatially resolved spectrophotometric observations of multiply imaged QSOs, using the Potsdam Multi- Aperture Spectrophotometer (PMAS), with the intention to search for spectral differences between components indicative of either microlensing or dust extinction. For the quadruple QSO HE 0435-1223 we find that the continuum shapes are indistinguishable, therefore differential extinction is negligible. The equivalent widths of the broad emission lines are however significantly different, and we argue that this is most likely due to microlensing. Contrariwise, the two components of the well-known object UM 673 have virtually identical emission line properties, but the continuum slopes differ significantly and indicate different dust extinction along both lines of sight Y1 - 2004 SN - 0004-6337 ER - TY - JOUR A1 - Christensen, Lise Bech A1 - Sanchez, Sebastian F. A1 - Jahnke, Knud A1 - Becker, Thomas A1 - Kelz, A. A1 - Wisotzki, Lutz A1 - Roth, Martin M. T1 - Integral field observations of damped Lyman-alpha galaxies N2 - We report preliminary results from a targeted investigation on quasars containing damped Lyman-alpha absorption (DLA) lines as well strong metal absorption lines, carried out with the Potsdam Multi Aperture Spectrophotometer (PMAS). We search for line-emitting objects at the same redshift as the absorption lines and close to the line of sight of the QSOs. We have observed and detected the already confirmed absorbing galaxies in Q2233+131 (Z(abs) = 3.15) and Q0151+045 (Z(abs),= 0.168), while failing to find spectral signatures for the z = 0.091 absorber in Q0738+313. From the Q2233+131 DLA galaxy, we have detected extended Lyalpha emission from an area of 3" x 5" Y1 - 2004 ER - TY - JOUR A1 - Jahnke, Knud A1 - Wisotzki, Lutz A1 - Sanchez, Sebastian F. A1 - Christensen, Lise Bech A1 - Becker, Thomas A1 - Kelz, A. A1 - Roth, Martin M. T1 - Integral field spectroscopy of QSO host galaxies N2 - We describe a project to study the state of the ISM in similar to20 low redshift (z < 0.3) QSO host galaxies observed with the PMAS integral field spectrograph. We describe the development of the method to access the stellar and gas components of the spectrum without the strong nuclear emission, in order to access the host galaxy properties in the central region. It shows that integral field spectroscopy promises to be very efficient in studying the gas distribution and its velocity field, and also the spatially resolved stellar population in the host galaxies of luminous AGN Y1 - 2004 ER - TY - JOUR A1 - Grözinger, Karl Erich T1 - פרשנותו של מרטין בובר לתולדות עם ישראל כניסיון למודרניזציה של היהדות, או: אי-ההבנה הכפולה JF - ההיסטוריה הגרמנית-יהודית שירשנו Y1 - 2004 SN - 9654931451 SP - 36 EP - 50 PB - Leo-Baeck-Institute CY - Jerusalem ER - TY - JOUR A1 - Schneider, Hans Julius T1 - Das Prinzip der Ausdrückbarkeit, die Grenzen des Sagbaren und die Rolle der Metapher Y1 - 2004 SN - 3-937262-14-8 ER - TY - JOUR A1 - Schneider, Hans Julius T1 - Die Sprache : trübes Medium oder Lebenselement der Kommunikation? Y1 - 2004 ER - TY - JOUR A1 - Schneider, Hans Julius T1 - Das Unsagbare und das Unsägliche : Grenzen im Bereich der Wissensformen Y1 - 2004 ER - TY - JOUR A1 - Schneider, Hans Julius T1 - Erfahrung und Erlebnis : ein Plädoyer für die Legitimität interaktiver Erfahrungen in den Naturwissenschaften Y1 - 2004 ER - TY - JOUR A1 - Schneider, Hans Julius T1 - Anliegen und Ambivalenzen postmodernen Denkens Y1 - 2004 SN - 1437-0956 ER - TY - JOUR A1 - Zimmermann, P. A1 - Regierer, Babette A1 - Kossmann, Jens A1 - Frossard, Emmanuel A1 - Amrhein, Nikolaus A1 - Bucher, Matthias T1 - Differential expression of three purple acid phosphatases from potato N2 - Three cDNAs encoding purple acid phosphatase (PAP) were cloned from potato (Solanum tuberosum L. cv. Desiree) and expression of the corresponding genes was characterised. StPAP1 encodes a low-molecular weight PAP clustering with mammalian, cyanobacterial, and other plant PAPs. It was highly expressed in stem and root and its expression did not change in response to phosphorus (P) deprivation. StIPAP2 and StPAP3 code for high-molecular weight PAPs typical for plants. Corresponding gene expression was shown to be responsive to the level of P supply, with transcripts of StPAP2 and StPAP3 being most abundant in P-deprived roots or both stem and roots, respectively. Root colonisation by arbuscular mycorrhizal fungi had no effect on the expression of any of the three PAP genes. StIPAP1 mRNA is easily detectable along the root axis, including root hairs, but is barely detectable in root tips. In contrast, both StPAP2 and StPAP3 transcripts are abundant along the root axis, but absent in root hairs, and are most abundant in the root tip. All three PAPs described contain a predicted N-terminal secretion signal and could play a role in extracellular P scavenging, P mobilisation from the rhizosphere, or cell wall regeneration Y1 - 2004 SN - 1435-8603 ER - TY - BOOK A1 - Saposhnikov, V. V. A1 - Saposhnikov, Vl. V. A1 - Morozov, Alexei A1 - Gössel, Michael T1 - Necessary and Sufficient Conditions for the Existence of Self-Checking Circuits ba Use of Complementary Circuits T3 - Preprint / Universität Potsdam, Institut für Informatik Y1 - 2004 SN - 0946-7580 VL - 2004, 1 PB - Univ. CY - Potsdam ER - TY - JOUR A1 - Tiedemann, Ralph A1 - Paulus, Kirsten B. A1 - Scheer, M. A1 - Von Kistowski, K. G. A1 - Skirnisson, K. A1 - Bloch, D. A1 - Dam, M. T1 - Mitochondrial DNA and microsatellite variation in the eider duck (Somateria mollissima) indicate stepwise postglacial colonization of Europe and limited current long-distance dispersal N2 - To unravel the postglacial colonization history and the current intercolony dispersal in the common eider, Somateria mollissima, we analysed genetic variation at a part of the mitochondrial control region and five unlinked autosomal microsatellite loci in 175 eiders from 11 breeding colonies, covering the entire European distribution range of this species. As a result of extreme female philopatry, mitochondrial DNA differentiation is substantial both among local colonies and among distant geographical regions. Our study further corroborates the previous hypothesis of a single Pleistocene refugium for European eiders. A nested clade analysis on mitochondrial haplotypes suggests that (i) the Baltic Sea eider population is genetically closest to a presumably ancestral population and that (ii) the postglacial recolonization progressed in a stepwise fashion via the North Sea region and the Faroe Islands to Iceland. Current long-distance dispersal is limited. Differentiation among colonies is much less pronounced at microsatellite loci. The geographical pattern of this nuclear genetic variation is to a large extent explained by isolation by distance. As female dispersal is very limited, the geographical pattern of nuclear variation is probably explained by male-mediated gene flow among breeding colonies. Our study provides genetic evidence for the assumed prominent postglacial colonization route shaping the present terrestrial fauna of the North Atlantic islands Iceland and the Faroes. It suggests that this colonization had been a stepwise process originating in continental Europe. It is the first molecular study on eider duck populations covering their entire European distribution range Y1 - 2004 SN - 0962-1083 ER -