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  • 11
    ISSN: 1432-1939
    Keywords: Amino acids ; 15N incorporation ; Nitrate reductase activity ; Nitrogen dioxide ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During spring and autumn 1991, potted 6-yearold spruce trees (Picea abies (L.) Karst.) were fumigated with 60 nl·1−1 15NO2 for 4 days under controlled conditions in constant light. Current and previous flush needles, the bark and the fine roots were analysed for total 15N content and incorporation of 15N into the α-amino nitrogen of free amino acids. In addition, in vitro nitrate reductase activity and stomatal conductance of the needles were measured. Nitrate reductase activity was significantly higher in the needles of fumigated trees compared to control trees exposed to filtered air. With an average of 9.1% 15N, free glutamate was the pool with the most label. Taking into account the time-course of the labelling of this pool, this figure can be taken as an estimate of the minimum contribution of NO2 to the N nutrition of the needles. 15N-labelled amino acids were also detected in the bark and the roots, indicating export from the needles.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Surgical endoscopy and other interventional techniques 11 (1997), S. 1167-1170 
    ISSN: 1432-2218
    Keywords: Key words: VATS — Hand suture — Pacemaker implantation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: In neonates and infants epicardial stimulation may be preferred to endocardial stimulation because of growth-associated lead problems and the risk of vascular complications associated with transvenous electrodes. This study analyzes the feasibility of atrioventricular implantation of a new epicardial lead using the video-assisted thoracic surgical (VATS) technique in an animal model. Methods: Bipolar steroid-eluting epicardial leads were implanted in seven young white pigs. In five animals bipolar atrial and ventricular pacing leads (n= 10) were inserted and fixed by the VATS technique, while two animals served as controls and underwent implantation through anterolateral thoracotomy. Surgical feasibility, pacing, and sensing thresholds of the leads as well as hemodynamic parameters during pacing were studied. Histological changes beneath the electrodes were evaluated 1 week after the implantation. Results: All animals survived the pacemaker lead implantation. One animal which underwent thoracotomy died because of irreversible ventricular fibrillation induced by rapid ventricular pacing. One animal in the VATS group exhibited intraoperative herniation of the heart through the pericardial window. All animals with left-sided VATS implantations demonstrated good individual pacing and sensing threshold values. The mean cardiac output was 1.6 times higher during AAI-mode pacing as compared to VVI-mode pacing at a heart rate of 140/min. One animal died postoperatively due to respiratory failure. No displacements of the pacemaker leads were observed in the survivors. Conclusion: While VATS-guided implantation of epicardial, atrial, and ventricular leads is feasible, technical improvements of the system are mandatory for safe clinical application.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 85 (1995), S. 189-200 
    ISSN: 1573-2932
    Keywords: critical levels ; trees ; crops ; semi-natural vegetation ; level I mapping ; level II mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In recent years, international air pollution effects research has focused on setting critical levels of pollutants, above which adverse effects occur on sensitive receptors. Once established, these levels are used to determine the geographical extent of exceedance for different vegetation categories and ultimately in the development of international protocols for pollution control within the Convention on Long-range Transboundary Air Pollution. Ideally, the critical level for each pollutant and vegetation category should have a relatively simple definition to allow ease of mapping. Nevertheless, the definitions need to be sufficiently robust to apply to sensitive vegetation growing in a diverse range of climates. The restrictions imposed by these criteria have led to complex and delicate negotiations between scientists from the UN/ECE* region. Data for the direct effects of air pollutants on vegetation have been carefully reviewed for applicability to critical levels. To date, critical levels have been set for the effects of SO2, ozone, NOx and NH3 on crops, trees and natural vegetation. The use of effects data to establish these levels is critically assessed in this paper in relation to current and future requirements for mapping.
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1573-2932
    Keywords: ozone ; crops ; critical levels ; visible injury ; yield ; artificial neural networks ; Trifolium subterraneum ; Phaseolus vulgaris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The experiments of the United Nations/Economic Commission for Europe (UN/ECE) International Cooperative Programme on effects of air pollution and other stresses on crops and non-wood plants (ICP-Crops) are designed to investigate the effects of ambient ozone pollution on crops and non-wood plants. Each year, participants from approximately 17 European countries conduct a series of coordinated experiments to determine which species develop visible injury following ozone episodes and whether the biomass or yield of sensitive species is reduced. In 1993, ozone injury was only seen at two thirds of sites but in 1994 injury was detected at almost all sites. This coincides with generally higher ozone concentrations measured in that year. Injury was seen on crops including subterranean clover (Trifolium subterraneum L.), white clover (Trifolium repens L.), bean (Phaseolus vulgaris L.), tomato (Lycopersicon esculentum), soybean (Glycine max), watermelon (Citrullus lanatus) and tobacco (Nicotiana tabacum L.) at experimental sites and in some cases, in commercial fields. The application of ethylenediurea (EDU) to some crop species reduced the level of visible injury. At some sites, the yield of EDU-treated bean plants was greater than that of untreated plants where the critical level of ozone for yield reduction was exceeded. Preliminary analysis of ozone concentrations in the days preceding injury indicated a sequential ozone concentration effect. The results are discussed in relation to Level I and Level II mapping of exceedance of the short- and long-term critical levels for ozone.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 85 (1995), S. 1449-1454 
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The hypothesis that stress ethylene production could determine plant sensitivity to ozone was tested with spring wheat (Triticum aestivum). The mechanism includes formation of radicals which induce peroxidative chain reactions. NO in the low ppb range could induce additional ethylene production. NO was added to three ozone levels in order to investigate its potential in enhancing ozone toxicity. Using malondialdehyde, ethane emission and activity of ascorbate peroxidase as indicators of peroxidation reactions, no indications for the postulated interaction was found. NO at low ozone concentrations induced effects on yield and physiological parameters similar to those of increased ozone concentrations, but this was not due to additional ethylene production. At higher ozone concentrations no adverse effect of NO addition could be detected.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 85 (1995), S. 1355-1360 
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A critical level for ozone has been established under the UN-ECE Convention on Long-Range Transboundary Air Pollutants (LRTAP) on the basis of data for spring wheat which ignores modifying factors. In this study, a correction factor (f[water]) is derived for soil water availability by applying a simple model to predict the mean available soil water content (%FC) from precipitation and potential evapotranspiration, an empirical relationship between %FC and yield, and by assuming that the decrease in grain yield due to reduced soil water is proportional to the reduction in ozone sensitivity. Model inputs were temperature, radiation, and precipitation during June and July. f[water] was tested with data obtained in years with non-limiting and limiting soil water. For a selected Swiss site, f[water] was 1.0 in 1990 to 1993, but in 1989 and 1994, f[water] was 〈1.0. The model was also used to analyze the variability of f[water] across Europe, and to determine the distribution of the potential yield loss in Switzerland on a 0.5km × 0.5km scale. It is concluded that without introducing a correction factor, under dry conditions potential yield losses may be significantly overestimated.
    Type of Medium: Electronic Resource
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