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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 67-68 (Apr. 1999), p. 571-576 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A series of laboratory (short-term exposure in small beakers) studies and a 19 d mesocosm (6 m3 polyethylene bags filled with fjord water) study were conducted on blue mussel, Mytilus edulis, larvae and plantigrades exposed to a concentration gradient of the detergent linear alkylbenzene sulphonate (LAS, 0 to 39 mg l−1). LAS is increasingly found in nearshore environments receiving wastewater from urban treatment plants. The aims were to observe physiological effects on swimming, grazing and growth in the laboratory and effects on settling and population development at in situ conditions (in field mesocosms) in order to evaluate the damages on ciliated meroplankton caused by LAS. In the laboratory the larvae showed a 50% mortality at 3.8 mg LAS l−1 after 96 h exposure whether or not food was provided. Additionally the swimming behaviour was affected at 0.8 mg LAS l−1 (i.e. a more compact swimming track, a smaller diameter of the swimming tracks, and reduced swimming speed). The larval particle grazing was reduced 50% at 1.4 mg LAS l−1. The specific growth rate of the larvae was reduced to half at 0.82 mg LAS l−1 over 9 d. During the mesocosm experiment, the larval population showed a dramatic decrease in abundance within 2 d at concentrations as low as 0.08 mg LAS l−1, both due to a significantly increased mortality, but also due to settling. The settling success was reduced at the same LAS concentration as that at which mortality was observed to increase significantly. In addition to reduced settling rate, the larvae showed delayed metamorphosis and reduced shell growth as a response to LAS. Our hypothesis that the larval ciliary apparatus, crucial for normal swimming, orientation, and settling behaviours and for particle uptake, was damaged due to LAS exposure is supported by our results. This is confirmed by the physiological data (grazing, growth) and in the direct video-based observations of larval performance (swimming) and provides a reasonable explanation for what was observed in the bags (abundance, settling, mortality). These physiological effects on blue mussel larvae/plantigrades occurred at LAS concentrations reported to occur in estuarine waters.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Annales geophysicae 14 (1996), S. 574-583 
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The observational systems utilised during the TRACT experimental campaign (September 1992) can roughly be divided into: existing climate stations and towers: background chemical monitoring stations; aerological measurements; instrumented aircraft; and special micrometeorological stations operated only during the experimental period. Database 4, which contains the latter surface measurements, includes station descriptions and data from 21 sites operated by nine different groups during the campaign period. These data will be described briefly. There are a number of advantages in using a relational database for analysis of this data. Without creating an unnecessarily large database which is awkward to view and slow to process, specific measurements can be selected easily since data from each site have been standardized using a common time index. This allows comparison of the same or different variables from one or more sites for investigating data quality or the effects of site location. Data can readily be combined into hourly or daily averages or time series for comparison with other data sets (e.g. model or aircraft data). Spatial analysis is also straightforward, although the clustering of the sites in the centre of the investigation area means that care must be taken. Some preliminary comparisons are made here in order to demonstrate the availability and reliability of the data.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 67-68 (Apr. 1999), p. 459-464 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 2996-2998 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ion-assisted deposition is suitable for the formation of epitaxial Si films at high deposition rate and low substrate temperature. We demonstrate epitaxial deposition of Si films on (100)-oriented Si wafers using deposition rates up to 0.3 μm/min at deposition temperatures in the range of 500–650 °C. Hall-effect measurements show a majority carrier mobility of 200 cm2/V s at a hole concentration of 1.4×1017 cm−3 in our films. A minority carrier diffusion length of 4.5 μm is determined from quantum efficiency measurements in the epitaxially grown Si films. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0827
    Keywords: Key words: Trabecular bone strength — Bone mineral density — Proximal tibia.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. The feasibility of two noninvasive methods [dual photon absorptiometry (DPA) and dual energy X-ray absorptiometry (DXA)] for prediction in vivo of local variations of trabecular bone strength within the proximal tibia was evaluated in 14 cadaveric knees. Trabecular bone strength was measured using an osteopenetrometer and from destructive compression tests performed on bone cylinders, thus measuring the penetration strength and ultimate strength in the medial, lateral, and central part of the tibial bone specimens. Linear regression analysis showed significant relations between BMD measured by DPA (r2= 72%) or DXA (r2= 73%) and ultimate strength. Even closer relations between BMD (DPA: r2= 80%, DXA r2= 81%) and penetration strength of trabecular bone were found. We conclude that DPA and DXA are suitable methods for evaluation in vivo of local variations in trabecular bone strength within the proximal tibia, and could easily be performed preoperatively before insertion of total knee arthroplasty.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 37 (1999), S. 415-423 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. The objective of the study was to corroborate or refute the hypothesis that farmers having a high intake of organic grown commodities have a high semen quality due to their expected lower level of dietary pesticides intake. Food frequency data and semen were collected from 256 farmers (171 traditional farmers and 85 organic farmers, overall participation rate: 32%) who were selected from central registers. Each farmer delivered one semen sample before the spraying season started. The farmers were divided into three groups where the commodities from organic production contributed no (N, 0%), medium (M, 1–49%), or a high (H, 50–100%) proportion of the fruit and vegetables consumed. Farmers having a high relative intake of organically grown fruit and vegetables also had a high relative consumption of organically produced meat, milk, and bread, and differences were observed comparing the actual mean intake of single commodities, such as rice, potato, and pork meat. The current individual dietary intake of 40 pesticides was estimated using food frequencies and generalized serving size data in combination with data on pesticide concentrations in food commodities as obtained from the National Danish Food Monitoring Program. The estimated pesticide intake was significantly lower among farmers of group H, but for all three groups of farmers the average dietary intake of 40 pesticides was at or below 1% of the acceptable daily intake (ADI) except for the dithiocarbamates (max = 0.21 μg/kg day = 2.2% ADI), methidathion, (max = 0.01 μg/kg day = 1.4% ADI), and 2-phenylphenol (max = 0.21 μg/kg day = 1.1% ADI). The median sperm concentration for the three groups of farmers was not significantly different (p = 0.40, median sperm concentration was N = 62, M = 44, and H = 75 million/ml). The group of men without organic food intake had a significant lower proportion of morphologically normal spermatozoa, but in relation to 14 other semen parameters no significant differences were found between the groups. Intake of 40 individual pesticides was correlated with four semen parameters (concentration, percentage dead spermatozoa, percentage normal sperm heads, and motility [VCL]). Five significant correlations (p value 0.01) were found among the 160 comparisons in relation to percentage dead spermatozoa: azinphos-methyl, carbaryl, chlorfenson, fenitrothion, and tetradifon. For all of them a lower percentage of dead spermatozoa were found in the groups with a high dietary intake of the specific pesticide. In contrast, for all pesticides evaluated only minor differences were found between the groups when considering spermatozoa concentration, morphology, and motility. In conclusion, the estimated dietary intake of 40 pesticides did not entail a risk of impaired semen quality, but precautions should be taken when generalizing this negative result to populations with a higher dietary exposure level or an intake of other groups of pesticides.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1434-6036
    Keywords: PACS. 05.40.+j Fluctuation phenomena, random processes, and Brownian motion - 75.10.Hk Classical spin models - 75.30.-m Intrinsic properties of magnetically ordered materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: We study the effects of finite temperature on the dynamics of non-planar vortices in the classical, two-dimensional anisotropic Heisenberg model with XY- or easy-plane symmetry. To this end, we analyze a generalized Landau-Lifshitz equation including additive white noise and Gilbert damping. Using a collective variable theory with no adjustable parameters we derive an equation of motion for the vortices with stochastic forces which are shown to represent white noise with an effective diffusion constant linearly dependent on temperature. We solve these stochastic equations of motion by means of a Green's function formalism and obtain the mean vortex trajectory and its variance. We find a non-standard time dependence for the variance of the components perpendicular to the driving force. We compare the analytical results with Langevin dynamics simulations and find a good agreement up to temperatures of the order of 25% of the Kosterlitz-Thouless transition temperature. Finally, we discuss the reasons why our approach is not appropriate for higher temperatures as well as the discreteness effects observed in the numerical simulations.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-0662
    Keywords: DMS oxidation ; sulphur dioxide ; methane sulphonic acid ; non-sea-salt sulphate ; multi-phase atmospheric chemistry ; temperature dependency analysis ; uncertainty analysis ; sensitivity analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A kinetic model for the OH-initiated homogeneous gas phase oxidation of dimethylsulfide (DMS) in the atmosphere (Saltelli and Hjorth, 1995), has been extended here to include the liquid phase chemistry. The updated model has then been employed to predict the temperature dependency of the MSA/nss-SO42- ratio. Model predictions have been compared with observational data reported in Bates et al. (1992). Sensitivity and uncertainty analysis has been performed in a Monte Carlo fashion to identify which are the important uncertainties on the input parameters and which are the possible combinations of parameter values that could explain the field observations. Results of the analysis have indicated that the temperature dependencies of the interactions between gas phase and liquid phase chemistry may to a large extent explain the observed T-dependence of the MSA/nss- SO42- ratio. The potential role of multi-phase atmospheric chemistry, not only in the case of SO2 but also of other oxidation products of DMS and, particularly, of DMS itself, has been highlighted.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 85 (1995), S. 2223-2228 
    ISSN: 1573-2932
    Keywords: Ozone ; flux ; deposition velocity ; surface resistance ; canopy stomatal resistance ; water vapour flux ; Norway spruce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The flux of O3 was measured by the eddy-correlation method over Norway spruce in periods when the trees had a very low activity, periods with optimum growth, and periods with water stress. The aerodynamic resistance (r a ), viscous sub-layer resistance (r b ) and surface resistance (r c ) to O3 were calculated from meteorological parameters and the deposition velocity. The canopy stomatal resistance to O3 was calculated from measurements of the water vapour flux. The deposition velocities showed a diurnal pattern with night-time values of 3.5 mm s−1 and day-time values of 7 mm s−1, when the trees had optimal growth conditions. The surface resistance was highly dominating in day-time and the influence of meteorology low. In night-time the surface resistance to 03 was lower than the canopy stomatal resistance. A low surface resistance was also found in winter-time, when the activity of the trees was low. The surface resistance increased when the trees were subject to water stress. It is concluded that stomatal uptake is an important parameter for the deposition of O3. However, other processes such as destruction of O3 at surfaces, reaction with NO emitted from the soil, and reactions with radicals produced from VOC's emitted from the forest, should also be taken into consideration.
    Type of Medium: Electronic Resource
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