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991.
Jean-Yannick Pailler Cédric Guignard Berenike Meyer Jean-François Iffly Laurent Pfister Lucien Hoffmann Andreas Krein 《Water, air, and soil pollution》2009,203(1-4):79-98
The objective of this investigation is to analyse the variations of xenobiotic concentrations and the fluxes of dissolved xenobiotics during runoff events in the small rural Mess catchment (35 km2) in the Southwestern part of Luxembourg. Sulfonamides, tetracyclines, analgesics and hormones, dissolved nutrients, sulphate and chloride were measured to gather information about runoff generation. Typically, the highest values can be found during the first flush mainly in the rising limb of the flood hydrographs. The highest concentrations in eleven flood events are measured for ibuprofen (2,383 ng l-1), estrone (27 ng l-1) and diclofenac (20 ng l-1). From the tetracycline group tetracycline (9 ng l-1) itself is of relevance, while the sulfonamides are mainly represented by sulfamethoxazole (5 ng l-1). The variable patterns of chemographs are attributed to the heterogeneous runoff generation characterised by different reactions of storm overflows from the combined sewer systems. During single flood events, the fluxes of ibuprofen (maximum 24,000 mg), 17α-ethinylestradiol (122 mg), 17β-estradiol (32 mg) or estrone (274 mg) are rather low. 相似文献
992.
Christoph Schleip Andreas Rais Annette Menzel 《Agricultural and Forest Meteorology》2009,149(10):1699-1708
The temperature sensitivity of 43 phenological phases was analysed in Germany within the period 1951–2006 with the help of a Bayesian approach. First a Bayesian model comparison of monthly temperatures and phenological phases throughout the year was conducted. We analysed the data as constant (mean onset date), as linear (constant trend over time) and as change point model (time varying change). The change point model involves the selection of two linear segments which match at a particular time. The matching point is estimated by an examination of all possible breaks weighted by their respective change point probability. Secondly a Bayesian coherence analysis was applied to investigate the relationship between phenological onset dates and an effective temperature generated as a weighted average of monthly means. Temperature weight coefficients were obtained from an optimization of a coherence factor by simulated annealing.Results reveal that late spring, summer and early autumn temperature months exhibit a clear preference for the change point model (>50%) indicating nonlinear change. The temperature development of April and August shows exceptionally high nonlinearities compared to the other months with change point model probabilities of 78% and 81% over the last five decades.For all phenophases a strong dependence of phenology on temperature is determined. We can classify two main temperature response patterns of the studied phenological phases: on the one hand spring phenophases are particularly sensitive to temperatures in April, exhibiting a prompt response. On the other hand summer phenophases are less influenced by temperature during or right before the month of the onset. They reveal a delayed response to nonlinear temperature changes mainly of April. Especially abrupt changes during the temperature sensitive stage of species cause a pronounced change in plant phenology regardless of the time of onset. 相似文献
993.
Sören-Nils Haubrock Matthias Kuhnert Sabine Chabrillat Andreas Güntner Hermann Kaufmann 《CATENA》2009
Microtopography and roughness are highly dynamic properties of the soil surface and important factors governing surface runoff and erosion processes. While various remote sensing technologies were successfully applied for topography measurements at different spatial scales, there is a lack of field studies that collected systematically microtopography data over long observation periods. In this paper an approach to measure and quantify surface roughness in the field based on laser scanning technologies is presented. Between June 2004 and November 2005 97 in-situ measurements were conducted in a test site with two different sandy substrates in vegetation-free conditions. Two-dimensional high-resolution (1 mm) datasets where generated for eight micro erosion plots of 0.25 to 2.9 m2 in size. Dynamics and pattern formation were quantified for surface roughness and surface height changes. Roughness patterns at different scales were analyzed by local roughness indices using sliding windows of 3 to 55 mm in size. Results show strong spatial and temporal dynamics in surface roughness as well as substrate-specific variations. Temporal roughness variations could be detected and were linked to precipitation patterns. The methods presented in this paper are considered suitable to generate high-resolution datasets on spatiotemporal and multi-scale microtopography patterns and to advance the understanding of surface processes at small scales in natural environments. 相似文献
994.
Kurth A Evermann JF Skilling DE Matson DO Smith AW 《American journal of veterinary research》2006,67(1):114-119
OBJECTIVE: To examine sera obtained from dairy and beef cattle to detect antibodies against vesivirus and compare seroprevalence among cattle within the sample population. SAMPLE POPULATION: Cattle sera from 8 western states and Maryland submitted to the Washington Animal Disease Diagnostic Laboratory during 1999 and 2000. PROCEDURE: Sera were analyzed for vesivirus-specific antibodies by use of a recombinant vesivirus-San Miguel sea lion virus serotype 5-capsid peptide antigen in an indirect ELISA. RESULTS: Overall, 693 sera were tested and 105 (15.2%) had positive results. Seropositive cattle were from 7 states (all cattle from Montana and Maryland 10 and 4, respectively were seronegative). Overall seroprevalence for antivesivirus antibody in herds ranged between 0% and 80% (median, 14%). Higher antibody prevalence was significantly associated with older age, dairy rather than beef cattle, and reasons for submission. Logistic regression of factors (abortion, respiratory tract disease, and all other reasons for sample submission) revealed that older age and other reasons were independently associated with higher seroprevalence. Higher seropositive optical density values for the ELISA were observed among older cattle and cattle that aborted, compared with values for cattle with respiratory tract disease or other reasons for submission. CONCLUSIONS AND CLINICAL RELEVANCE: This laboratory-based surveillance sample provided a point estimate of seroprevalence against vesivirus among cattle in 9 US states. This suggests that vesivirus infection is widespread with high prevalence in some herds. Risk factors associated with vesivirus seroprevalence in beef and dairy cattle should be confirmed in population-based studies. 相似文献
995.
Humans and animals can nonverbally enumerate visual items across time in a sequence or rapidly estimate the set size of spatial dot patterns at a single glance. We found that temporal and spatial enumeration processes engaged different populations of neurons in the intraparietal sulcus of behaving monkeys. Once the enumeration process was completed, however, another neuronal population represented the cardinality of a set irrespective of whether it had been cued in a spatial layout or across time. These data suggest distinct neural processing stages for different numerical formats, but also a final convergence of the segregated information to form most abstract quantity representations. 相似文献
996.
Ibrom A Jarvis PG Clement R Morgenstern K Oltchev A Medlyn BE Wang YP Wingate L Moncrieff JB Gravenhorst G 《Tree physiology》2006,26(7):845-864
Gross canopy photosynthesis (P(g)) can be simulated with canopy models or retrieved from turbulent carbon dioxide (CO2) flux measurements above the forest canopy. We compare the two estimates and illustrate our findings with two case studies. We used the three-dimensional canopy model MAESTRA to simulate P(g) of two spruce forests differing in age and structure. Model parameter acquisition and model sensitivity to selected model parameters are described, and modeled results are compared with independent flux estimates. Despite higher photon fluxes at the site, an older German Norway spruce (Picea abies L. (Karst.)) canopy took up 25% less CO2 from the atmosphere than a young Scottish Sitka spruce (Picea sitchensis (Bong.) Carr.) plantation. The average magnitudes of P(g) and the differences between the two canopies were satisfactorily represented by the model. The main reasons for the different uptake rates were a slightly smaller quantum yield and lower absorptance of the Norway spruce stand because of a more clumped canopy structure. The model did not represent the scatter in the turbulent CO2 flux densities, which was of the same order of magnitude as the non-photosynthetically-active-radiation-induced biophysical variability in the simulated P(g). Analysis of residuals identified only small systematic differences between the modeled flux estimates and turbulent flux measurements at high vapor pressure saturation deficits. The merits and limitations of comparative analysis for quality evaluation of both methods are discussed. From this analysis, we recommend use of both parameter sets and model structure as a basis for future applications and model development. 相似文献
997.
Stéphanie Schmid Andreas Zingg Peter Biber Harald Bugmann 《European Journal of Forest Research》2006,125(1):43-55
The semi-empirical single-tree model SILVA 2.2 has been developed and parameterised using forest research and inventory data
from Germany that range from the colline to the montane zone. The focus of the model evaluation presented in this study was
to test the applicability of the model for the main Swiss forest types and at elevations ranging from the colline to the upper
subalpine zone. To this end, SILVA was initialized using data from long-term forest yield research plots. The results at the
end of the 30-year simulation were compared with observed data. The analysis of the results at each test site showed that
there were no significant differences in model performance between forest types. However, the deviation between simulated
and observed growth depended strongly on the elevational zone, i.e., on climate. As expected, the best results were found
in the colline zone, for which the model had been calibrated, whereas the upper subalpine sites revealed the strongest differences.
The quality of the data regarding forest structure that were available for model initialization had a strong impact on the
simulation results, mainly at high-elevation zones (i.e., supalpine and upper subalpine). We conclude that SILVA 2.2 is a
suitable tool to estimate the development of single trees and standing volume for a large fraction of the forests in Switzerland.
However, extreme climate conditions should be avoided with the model, and the availability of detailed stand structure information
is a key priority that has a strong effect on the quality of the simulation results.
相似文献
Harald BugmannEmail: |
998.
Dittrich R Hoffmann I Stahl P Müller A Beckmann MW Pischetsrieder M 《Journal of agricultural and food chemistry》2006,54(18):6924-6928
Maillard products, such as Nepsilon-carboxymethyllysine (CML), are readily formed during the manufacturing of infant formulas. Little has been known, however, about the presence of CML in human breast milk and about the uptake of CML by infants. In this study, CML was measured in the serum and breast milk of 32 healthy mothers by ELISA. CML concentrations in breast milk (137 +/- 82.7 ng/mL) were significantly lower than in the serum (399 +/- 67.8 ng/mL, p < 0.001) and on average 35-fold lower than in infant formulas (4754 +/- 4299.5 ng/mL). CML was also measured in the urine of 21 infants, which were fed with breast milk or formulas. Although there was a tendency toward higher urinary CML excretion in infants fed with hypoallergenic formulas compared to breast-fed ones, the differences were not significant. Neonates that were delivered by vaginal birth had significantly higher concentrations of CML compared to those delivered by caesarean section (1306 +/- 653 vs 601 +/- 220 ng/mL, p = 0.012). It is concluded that CML passes from the serum into the breast milk, but the levels are by far lower than in infant formulas. In very young neonates (< or =3 days), the mode of delivery has a greater influence on urinary CML excretion than the nutrition. 相似文献
999.
Zaugg J Potterat O Plescher A Honermeier B Hamburger M 《Journal of agricultural and food chemistry》2006,54(18):6623-6628
Lipophilic triterpenoidal esters with radical scavenging and cyclooxygenase inhibitory properties were recently found in cold-pressed, nonraffinated evening primrose oil (EPO). A quantitative assay for the analysis of 3-O-trans-caffeoyl derivatives of betulinic, morolic, and oleanolic acid in evening primrose seeds was developed and validated. Extraction efficiency >99% was achieved by means of pressurized liquid extraction with two extraction cycles and 80% (v/v) ethanol at 120 degrees C. Analysis of esters was by normal-phase high-performance liquid chromatography on a Diol column and hexane/ethyl acetate (containing 0.1% formic acid) (65:35) as the eluent. The analytes were determined without further prepurification. Seeds from defined cultures of Oenothera biennis, Oenothera lamarckiana, and Oenothera ammophila, grown under identical conditions, were analyzed. The cultures originated from seeds from eight collections in the wild and from selections from five cultivars. The content of total triterpenoidal esters in seeds varied between 1.34 and 2.78 mg/g. Three types of qualitative patterns were observed for the triterpenoidal esters. The influence of different harvest times and plant treatments was studied with the cultivar Anothera. Variations between 1.5 and 2.3 mg/g were found. 相似文献