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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Clinical autonomic research 2 (1992), S. 105-111 
    ISSN: 1619-1560
    Schlagwort(e): Asthma ; Heart rate variability ; Spectral analysis ; Respiration ; Autonomic nervous system ; Adrenergic receptors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Sympathetic and parasympathetic activity was evaluated in ten healthy controls, nine asymptomatic, untreated asthmatic subjects and ten asthmatic patients during treatment for acute asthma, by measurement of the variation in resting heart rate using frequency spectrum analysis. Heart rate was recorded by ECG and respiratory rate by impedance plethysmography. Spectral density of the beat-to-beat heart rate was measured within the low frequency band 0.04 to 0.10 Hz (low frequency power) modulated by sympathetic and parasympathetic activity, and within a 0.12 Hz band width at the respiratory frequency mode (respiratory frequency power) modulated by parasympathetic activity. Acute asthmatics had higher heart rates than either of the other two groups; this was probably related to the effects of beta-adrenoceptor agonist medication. Sympathetically mediated heart rate variability (normalized low frequency power) was significantly lower in both asymptomatic (p 〈 0.002) and acute (p 〈 0.02) asthma subjects compared to controls. This is consistent with altered sympathetic/parasympathetic regulation of heart rate in subjects with bronchial asthma.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Clinical autonomic research 3 (1993), S. 5-13 
    ISSN: 1619-1560
    Schlagwort(e): Sepsis syndrome ; Intensive care ; Heart rate variability ; Spectral analysis ; Respiration ; Autonomic nervous system ; Adrenergic receptors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Sympathetic and parasympathetic activity was evaluated on 39 occasions in 17 patients with the sepsis syndrome, by measurement of the variation in resting heart rate using frequency spectrum analysis. Heart rate was recorded by electrocardiography and respiratory rate by impedance plethysmography. The sepsis syndrome was established on the basis of established clinical and physiological criteria. Subjects were studied, whenever possible, during the period of sepsis and during recovery. Spectral density of the beat-to-beat heart rate was measured within the low frequency band 0.04 to 0.10 Hz (low frequency power, LFP) modulated by sympathetic and parasympathetic activity, and within a 0.12 Hz band width at the respiratory frequency mode (respiratory frequency power, RFP) modulated by parasympathetic activity. Results were expressed as the total variability (total area beneath the power spectrum), as the spectral components normalized to the total power (LFPn, RFPn) or as the ratio of LFP/RFP. During the sepsis syndrome, total heart rate variability and the sympathetically mediated component, LFPn were significantly lower than during the following recovery phase (ANOVA,p 〈 0.0001,p 〈 0.01 respectively). Both APACHE II (Acute Physiological and Chronic Health Evaluation) and TISS (Therapeutic Intervention Scoring System) scores showed an inverse correlation with total heart rate variability, logLFP, LFPn and the LFP/RFP ratio (p 〈 0.002 to 0.0001). Sympathetically mediated heart rate variability was significantly lower during the sepsis syndrome and was inversely proportional to disease severity.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 140 (1992), S. 249-254 
    ISSN: 1573-5036
    Schlagwort(e): acid deposition ; hardwood forests ; nutrient leaching ; soil inputs ; stemflow ; succession
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Stemflow and throughfall from a regenerating (8-year-old) southern Appalachian hardwood forest were collected to examine the relative importance of tree bole nutrient leaching in response to acid deposition. Samples from nine (2 m2) stemflow collection plots were analyzed for four dormant season and 11 growing season rainstorm events. Results showed that, relative to throughfall fluxes, stemflow accounted, on average, for approximately 8.5% of total water reaching the forest floor during both dormant and growing season storms. Relative to foliar leaching, K-, SO4-, and PO4 ions appear to be the most easily leached ions from young tree stems. Proportional nitrate and base cation stemflow fluxes increased significantly (p〈0.05) with growing-season storm-event duration, suggesting that the stemsurface nutrient pool is depleted by precipitation more slowly than the foliar pool. On average, proportional stemflow fluxes of SO4 (12%) and K (14%) were consistently higher than reported maximum values for more mature forest stands, which indicates that small-scale stemflow inputs of ions such as these to the forest floor may be important in early successional ecosystems.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1573-515X
    Schlagwort(e): acid deposition ; forest cover ; forest structure ; biogeochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract The Regional Integrated Lake-Watershed Acidification Study (RILWAS) was conducted to identify and to quantify the environmental factors controlling surface water chemistry in forested watersheds of the Adirondack region of New York. The RILWAS vegetation research was designed to: (1) compare the quantitative patterns of forest cover and tree community structure in the study catchments of the Moose River drainage system; and (2) identify important vegetation differences among study watersheds that might help to explain inter-watershed differences in water chemistry and aquatic responses to acidic deposition. Field transect data indicated that the overall drainage system includes 50% mixed forest cover, 38% hardwood forest, 10% coniferous forest, and 2% wetland cover. Major tree species include yellow birch, red spruce, American beech, sugar maple, eastern hemlock, and red maple. Analysis of forest structure indicated that mean weighted basal area estimates ranged two-fold from 24–48 m2ha−1 among watersheds. Likewise, mean weighted estimates for aboveground biomass and aboveground annual productivity ranged among watersheds from 160 to 320 MT ha−1 and from 8 to 18 MT ha−1 yr−1, respectively. Results showed that differences in surface water chemistry were independent of vegetation differences among watersheds.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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