502 resultados para 1436


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This paper analyzes the economic impacts of summer drought on Swiss grassland production. We combine field trial data from drought experiments in three different grasslands in Switzerland with site-specific information on economic costs and benefits. The analysis focuses on the economic implications of drought effects on grassland yields as well as grassland composition. In agreement with earlier studies, we found rather heterogeneous yield effects of drought on Swiss grassland systems, with significantly reduced yields as a response to drought at the lowland and sub-alpine sites, but increased yields at the wetter pre-alpine site. Relative yield losses were highest at the sub-alpine site (with annual yield losses of up to 37 %). However, because income from grassland production at extensive sites relies to a large extent on ecological direct payments, even large yield losses had only limited implications in terms of relative profit reductions. In contrast, negative drought impacts at the most productive, intensively managed lowland site were dominant, with average annual drought-induced profit margin reductions of about 28 %. This is furthermore emphasized if analyzing the farm level perspective of drought impacts. Combining site-specific effects at the farm level, we found that in particular farms with high shares of lowland grassland sites suffer from summer droughts in terms of farm-level fodder production and profit margins. Moreover, our results showed that the higher competitiveness of weeds (broad-leaved dock) under drought conditions will require increasing attention on weed control measures in future grassland production systems. Taking into account that the risk of drought occurrence is expected to increase in the coming years, additional instruments to cope with drought risks in fodder production and finally farmers’ income have to be developed.

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In the aquatic environment, fish are exposed to various stimuli at once and have developed different response mechanisms to deal with these multiple stimuli. The current study assessed the combined impacts of estrogens and bacterial infection on the physiological status of fish. Juvenile rainbow trout were exposed to two different concentrations of 17 beta-estradiol (E2) (2 or 20 mg/kg feed) and then infected with three concentrations of Yersinia ruckeri, a bacterial pathogen causing massive losses in wild and farmed salmonid populations. Organism-level endpoints to assess the impact of the single and combined treatments included hepatic vitellogenin transcript expression to evaluate the E2 exposure efficiency and survival rate of pathogen-challenged fish. The two E2 doses increased vitellogenin levels within the physiological range. Infection with Y. ruckeri caused mortality of trout, and this effect was significantly enhanced by a simultaneous exposure to high E2 dose. The hormone reduced survival at intermediate and high (10(4) and 10(6) colony forming units, cfu) bacterial concentrations, but not for a low one (10(2) cfu). Analysis of hepatic gene expression profiles by a salmonid 2 k cDNA microarray chip revealed complex regulations of pathways involved in immune responses, stress responses, and detoxicification pathways. E2 markedly reduced the expression of several genes implicated in xenobiotic metabolism. The results suggest that the interaction between pathogen and E2 interfered with the fish's capability of clearing toxic compounds. The findings of the current study add to our understanding of multiple exposure responses in fish.

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The tropical montane forests of the E Andean cordillera in Ecuador receive episodic Sahara-dust inputs particularly increasing Ca deposition. We added CaCl2 to isolate the effect of Ca deposition by Sahara dust to tropical montane forest from the simultaneously occurring pH effect. We examined components of the Ca cycle at four control plots and four plots with added Ca (2 × 5 kg ha–1 Ca annually as CaCl2) in a random arrangement. Between August 2007 and December 2009 (four applications of Ca), we determined Ca concentrations and fluxes in litter leachate, mineral soil solution (0.15 and 0.30 m depths), throughfall, and fine litterfall and Al concentrations and speciation in soil solutions. After 1 y of Ca addition, we assessed fine-root biomass, leaf area, and tree growth. Only < 3% of the applied Ca leached below the acid organic layer (pH 3.5–4.8). The added CaCl2 did not change electrical conductivity in the root zone after 2 y. In the second year of fertilization, Ca retention in the canopy of the Ca treatment tended to decrease relative to the control. After 2 y, 21% of the applied Ca was recycled to soil with throughfall and litterfall. One year after the first Ca addition, fine-root biomass had decreased significantly. Decreasing fine-root biomass might be attributed to a direct or an indirect beneficial effect of Ca on the soil decomposer community. Because of almost complete association of Al with dissolved organic matter and high free Ca2+ : Al3+ activity ratios in solution of all plots, Al toxicity was unlikely. We conclude that the added Ca was retained in the system and had beneficial effects on some plants.

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Ziel des vorliegenden Beitrages ist es, die Auswirkungen der Arbeitslosigkeit von Eltern und sozio-ökonomischer Deprivation auf das Familienklima zu beschreiben. Dabei stehen die Mechanismen, welche zwischen dem Ereignis Arbeitslosigkeit, dessen Bewältigung, deren Konsequenzen und der Beeinträchtigung des Familienklimas wirken, im Mittelpunkt unseres Interesses. Für die empirischen Analysen verwenden wir Daten einer postalischen Befragung von Dresdner Haushalten, welche im November 1997 durchgeführt wurde. Neben mehrfacher Arbeitslosigkeit und sozio-ökonomischer Deprivation sind vor allem bildungs- und klassenspezifische Bewältigungsressourcen und Beziehungsstrukturen für eine Beeinträchtigung des Familienklimas verantwortlich. Aber auch Aspekte der elterlichen Partnerschaft sowie vor allem die psycho-soziale Verarbeitung der Veränderungen im Familienkontext sind wichtige Mechanismen, welche den Einfluß von Arbeitslosigkeit auf die Qualität der familialen Beziehungen moderieren.

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Dieser Beitrag zeigt auf, welche Möglichkeiten der Einsatz von Web 3.0 Monitoringtechniken im Stakeholder Management bietet. Das Ziel dieses Managements ist es, unternehmerischenVorhaben zu Akzeptanz und Durchsetzungskraft zu verhelfen, indem Ansprüche an Unternehmensentscheide aktiv in den Managementprozess mit eingebunden werden.Stakeholdermaps stellen diese Ansprüche visuell dar. Sie greifen einerseits auf nicht-öffentliche Inhalte zurück und andererseits auf Inhalte, die öffentlich (zumeist im Web) verfügbar sind. Das Semantische Web bietet Möglichkeiten, diese öffentlichen Inhalte nicht nur deskriptiv (was wird argumentiert?) darzustellen, sondern auch Zusammenhänge(z.B. Netzwerke, Kontextualisierungen, Referenzierungen, Gewichtungen) aufzuzeigen. Das vorgestellte Framework kann Grundlage für die öffentlichen Inhalte von Stakeholdermaps sein.