979 resultados para gross nitrification


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Effects of soil freezing on nitrogen (N) mineralization have been the subject of increased attention in the ecological literature, though fewer studies have examined N mineralization responses to successive mild freezing, severe freezing and cyclic freeze–thaw events. Even less is known about relationships of responses to soil N status. This study measured soil N mineralization and nitrification in the field along an experimental N gradient in a grassland of northern China during the dormant season (October 2005–April 2006), a period in which freezing naturally occurs. Net N mineralization exhibited great temporal variability, with nitrification being the predominant N transformation process. Soil microbial biomass C and N and extractable NH4 + pools declined by 40, 52, and 56%, respectively, in April 2006, compared with their initial concentrations in October 2005; soil NO3– pools increased by 84%. Temporal patterns of N mineralization were correlated with soil microbial biomass C and N. N mineralization and nitrification increased linearly with added N. Microbial biomass C in treated soils increased by 10% relative to controls, whereas microbial N declined by 9%. Results further suggest that freezing events greatly alter soil N dynamics in the dormant season at this site, with considerable available N accumulating during this period.

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Das "Zeytregister" des Ulmer Bauern und Landhandwerkers Hans Heberle ist in seiner Art eine einzigartige Hinterlassenschaft eines bäuerlichern Schriftstellers des 17. Jahrhunderts. Der Gesichtskreis Heberles geht weit über den engen Horizont der Wirtschaftsführung hinaus, indem er persönliche Erfahrungen mit der Schilderung der Kriegsereignisse seiner Zeit verbindet. Unter Berücksichtigung von Schreibintention und -praxis relativieren sich indes die Möglichkeiten einer persönlichkeitsnahen Ausschöpfung der Quelle im Sinne eines 'Ego-Dokuments'. So sind den im wesentlichen auf Geburt und Tod beschränkten Notaten über die eigene Familie, über persönliche Erlebnisse und Beobachtungen aus näherer Anschauung durch die absorbierende Kriegsschilderung Grenzen auferlegt. Die selektive Auswahl der Themenpunkte und das weitestgehende Zurücktreten affektiver Momente erklärt sich auch durch die technische Verfahrensweise Heberles, der nach Ausweis inhaltlicher und formaler Aspekte der Handschrift in deutlichem zeitlichem Ereignisabstand an seiner Chronik arbeitete.

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bearb. von [R.] Berndt

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von J. Berberich

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Schizophrenia is associated with heterogeneous course of positive and negative symptoms. In addition, reduced motor activity as measured by wrist actigraphy has been reported. However, longitudinal studies of spontaneous motor activity are missing. We aimed to explore whether activity levels were stable within and between psychotic episodes. Furthermore, we investigated the association with the course of negative symptoms. In 45 medicated patients, we investigated motor behavior within a psychotic episode. In addition, we followed 18 medicated patients across 2 episodes. Wrist actigraphy and psychopathological ratings were applied. Within an episode symptoms changed but activity levels did not vary systematically. Activity at baseline predicted the course of negative symptoms. Between two episodes activity recordings were much more stable. Again, activity at the index episode predicted the outcome of negative symptoms. In sum, spontaneous motor activity shares trait and state characteristics, the latter are associated with negative symptom course. Actigraphy may therefore become an important ambulatory instrument to monitor negative symptoms and treatment outcome in schizophrenia.

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von Morus [[Elektronische Ressource]]

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Selig Eugen Soskin

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Selig Eugen Soskin