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Friedland
(2000)
Lübbenau
(2000)
Lübben
(2000)
Ludwigsfelde
(2000)
Das Ende Preußens
(2000)
Estimating production in plankton food webs from biomass size spectra and allometric relationships
(2000)
Im Rahmen der Forschungen zur Landschaftsentwicklung des Pazifischen Nordwestens der USA wurde die Entwicklung eines Schluchtensystems im südlichen Teil des North Fork Cottonwood Creek bei Monument, Zentral-Oregon, untersucht. Die ackerbauliche Nutzung begann hier um 1870. Während des späten 19. Jahrhunderts überwog hier die Hangerosion. Bis zum frühen 20. Jahrhundert wurden Oberböden der Oberhänge erodiert und Sedimente mit sehr geringer Infiltrationskapazität freigelegt. Dieses bewog die Farmer zur Umstellung der Landnutzung auf extensives Weideland. Die dadurch eintretende Verringerung der Sedimentkonzentration im Oberflächenabfluß verursachte seitdem ausgedehnte Einkerbungen. Ein vor etwa 110 Jahren angelegter Brunnen im Süden der Talaue wurde dabei angeschnitten. Heute hat die Hauptschlucht eine Tiefe von mehr als 15m und eine Länge von mehr als einem Kilometer. Eine Terrasse im breiten Talboden der Schlucht enthielt Teile eines alten Autos. Durch das Hineinwerfen von Schrottautos in den oberen Teil der Schlucht konnten die Farmer deren weitere Ausbreitung verhindern.
L'objectif principal de cet article est de déterminer les temps verbaux, les modes et les voix qui devraient figurer parmi les contenus linguistiques d'un cours de français 2e ou 3e langue étrangère obligatoire dans le cadre de l'enseignement général en Allemagne. Mes propositions s'adressent en premier lieu aux auteurs des futurs programmes de lycées et aux auteurs des manuels utilisés dans ces établissements. Mes conclusions sont valables également pour l'enseignement du français dans d'autres pays.
Forschung in ungelüfteten Räumen : Anmerkungen zur Militärgeschichtsschreibung in der ehemaligen DDR
(2000)
Stationen des öffentlichen und historiographischen Umgangs in Deutschland mit der Zäsur von 1945
(2000)
Prostanoids, that are released from nonparenchymal liver cells in response to proinflammatory stimuli, are involved in the regulation of hepatic functions during inflammation. They exert their effects on their target cells via heptahelical receptors in the plasma membrane. For the 5 prostanoids prostaglandin E(2) (PGE(2)), prostaglandin F(2alpha), prostaglandin D(2) (PGD(2)), prostacyclin, and thromboxane A(2) there exist 8 receptors that are coupled to different heterotrimeric G proteins. These receptors are expressed differentially in the 4 principal liver cell types, i.e., hepatocytes, Kupffer cells, sinusoidal endothelial cells, and hepatic stellate cells. It was intriguing, that the messenger RNA (mRNA) of none of the G(s)-coupled prostanoid receptors (DP-R, EP2-R, EP4-R, and IP-R) that can attenuate the inflammatory reaction were present in hepatocytes. The current study shows that the expression of the G(s)-coupled prostanoid receptors EP2-R, EP4-R, and DP-R, but not the IP-R, was efficiently and rapidly up-regulated by treatment of hepatocytes in vitro or rats in vivo with the key acute phase cytokine interleukin 6 (IL-6). In IL-6-treated hepatocytes PGE(2) in turn attenuated the IL-6-induced alpha(2)-macroglobulin formation via a cyclic adenosine monophosphate (cAMP)- dependent signal chain. The data indicate that an IL-6-mediated induction of the previously not expressed EP2-R and EP4- R on hepatocytes might establish a prostanoid-mediated feedback inhibition loop for the attenuation of the acute phase response.
Rieselfelder
(2000)
Water column mixing is known to have a decisive impact on plankton communities. The underlying mechanisms depend on the size and depth of the water body, the nutrient status, and the plankton community structure and they are well understood for shallow polymictic and deep stratified lakes. Two consecutive mixing events of similar intensity under different levels of herbivory were performed in enclosures in a shallow, but periodically stratified, eutrophic lake, in order to investigate the effects of water column mixing on bacteria abundance, phytoplankton abundance and diversity, and rotifer abundance and fecundity. When herbivory by filter-feeding zooplankton was low, water column mixing provoking a substantial nutrient input into the euphotic zone, led to an intense net increase of bacteria and phytoplankton biomass. Phytoplankton diversity was lower in the mixed enclosures than in the undisturbed ones owing to the larger contribution of a few fast-growing species. After the second mixing event at high biomass of filter-feeding crustaceans, the increase of phytoplankton biomass was lower than after the first mixing, and diversity remained unchanged as the enhanced growth of small fast-growing was prevented by zooplankton grazing. Bacteria abundance did not increase after the second mixing, when cladoceran biomass was high. Rotifer fecundity indicated a transmission of the phytoplankton response to the next trophic level. Our results suggest that water column mixing in shallow eutrophic lakes with periodic stratification has a strong effect on the plankton community by enhanced nutrient availability rather than resuspension or reduced light availability. This fuels the basis of the classic and microbial food chain via enhanced phytoplankton and bacteria growth, but the effects on biomass may be dampened by high levels of herbivory.