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  • 1
    Digitale Medien
    Digitale Medien
    Defect dominated charge transport in amorphous Ta2O5 thin films (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 850-862 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Ta2O5 is a candidate for use in metal–oxide–metal (MOM) capacitors in several areas of silicon device technology. Understanding and controlling leakage current is critical for successful implementation of this material. We have studied thermal and photoconductive charge transport processes in Ta2O5 MOM capacitors fabricated by anodization, reactive sputtering, and chemical vapor deposition. We find that the results from each of these three methods are similar if one compares films that have the same thickness and electrodes. Two types of leakage current are identified: (a) a transient current that charges the bulk states of the films and (b) a steady state activated process involving electron transport via a defect band. The transient process involves either tunneling conductivity into states near the Fermi energy or ion motion. The steady state process, seen most commonly in films 〈300 Å thick, is dominated by a large number of defects, ∼1019–1020 cm−3, located near the metal–oxide interfaces. The interior of thick Ta2O5 films has a substantially reduced number of defects. Modest heating (300–400 °C) of Ta2O5 in contact with a reactive metal electrode such as Al, Ti, or Ta results in interfacial reactions and the diffusion of defects across the thickness of the film. These experiments show that successful integration of Ta2O5 into semiconductor processing requires a better understanding of the impact of defects on the electrical characteristics and a better control of the metal–Ta2O5 interface. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.373747
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  • 2
    Digitale Medien
    Digitale Medien
    High electric fields from industrial stack plumes (1976)
    [s.l.] : Nature Publishing Group
    Nature 264 (1976), S. 236-237 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Measurements were carried out from July 6 to July 10, 1976 of the vertical component of the electric field downwind of a 110-m chimney stack of a cement works at Eastgate, Co. Durham, using a series of conventional field mills1. Eastgate, 33 km W of Durham City, is sited in a broad valley, 235 m ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/264236a0
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  • 3
    Digitale Medien
    Digitale Medien
    Measuring wood preference in termites (1990)
    Springer
    Entomologia experimentalis et applicata 56 (1990), S. 117-123 
    Details
    ISSN: 1570-7458
    Schlagwort(e): Rhinotermitidae ; termites ; Coptotermes formosanus ; wood density
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé Les préférences alimentaires des termites xylophages ont été mesurées en comparant les différentes biomasses de bois prélevées, les pourcentages de bois consommé et l'importance des dégâts en fonction de catégories arbitrairement définies. Quand les caractéristiques des bois examinés différent, par exemple la densité, ces comparaisons ne sont plus possibles. Nous avons examiné les réactions de Coptotermes formosanus Shiraki (Iso., Rhinitermitidae) en présence de bois différant par leurs caractéristiques physiques, par compression du bois jusqu'à une densité dépassant de 40% la densité naturelle. Les termites consomment alors significativement moins en pourcentage, mais les biomasses consommées sont voisines de celles que l'on observe avec du bois du pin normal. Par contre, elles consomment significativement plus de biomasse, mais les mêmes pourcentages d'acajou compressé ou normal. Savoir quel critère doit être préférentiellement utilisé: le pourcentage ou la fraction de biomasse prélevé, dépend de la nature des facteurs de régulation de la taille du repas chez les termites. Si les termites consomment des repas de biomasse déterminée, alors la biomasse consommée est un bon critère: s'ils consomment un repas de volume déterminé, alors le pourcentage prélevé est un critère satisfaisant.
    Notizen: Abstract Feeding preferences of xylophagous termites have been determined by comparing differences in wood biomass removed, percentage of wood consumed or degree of damage rated in arbitrary categories. When test woods differ in physical characteristics such as density, these measures are not comparable. We examined the response of the Formosan termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae) to wood that differed in physical characteristics by compressing blocks to 40% greater than the natural density. Termites ate significantly greater percentages, but similar amounts of biomass, of uncompressed over compressed natural pine. In contrast, they ate significantly greater amounts of biomass, but similar percentages, of compressed over uncompressed mahogany. Whether percentage or amount of biomass removed should be used as a measure of preference depends on what regulates insect meal size. If termites consume meals of fixed biomass, then biomass consumed is the correct measure; percentage removed is appropriate if they consume meals of fixed volume.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00163453
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  • 4
    Digitale Medien
    Digitale Medien
    Computed tomographic evaluation and guided correction of malpositioned nephrostomy catheters (1999)
    Springer
    Abdominal imaging 24 (1999), S. 422-425 
    Details
    ISSN: 1432-0509
    Schlagwort(e): Key words: Nephrostomy catheters—Computed tomography—CT guided—Dislodged nephrostomy.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Background: To determine the utility of computed tomography (CT) in the detection and correction of malpositioned nephrostomy catheters after contrast spillage during nephrostograms. Methods: CT was performed in nine patients after an abnormal (contrast spillage) tube nephrostogram performed during or after nephrostomy tube placement. CT was used to locate the nephrostomy catheter position in relation to the renal collecting system. If possible, CT was also used for guidance and repositioning of the nephrostomy catheters into the intrarenal collecting system. Results: In all nine cases, CT was successful in detecting the position of the suspected malpositioned catheter. In seven of nine cases, CT demonstrated the catheter outside the renal collecting system and effectively helped reposition the catheters into the intrarenal collecting system. In one case, the malpositioned nephrostomy catheter was within the intraperitoneal cavity and required surgical correction. Another case required fluoroscopic-guided repositioning for the initial nephrostomy catheter, which was partly posterior to the kidney and partly within the kidney. The catheter in this latter case was successfully advanced over a guidewire into the collecting system. Conclusions: CT may be used to detect possible catheter malposition associated with nephrostomy tube placement. CT may also be used to successfully guide catheter repositioning in the renal collecting system.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002619900529
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  • 5
    Digitale Medien
    Digitale Medien
    Tabulated statistics for some ion dispersion experiments in turbulent air (1984)
    Springer
    Boundary layer meteorology 28 (1984), S. 89-105 
    Details
    ISSN: 1573-1472
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract In July 1977 dispersion experiments with air ions as tracer were carried out at Porton in southern England. Each trial lasted about 40 min. The source height was 5 m. Continuous ion production took place in eight trials for source-sensor distances between 10 and 100m. Ion production in 1 s pulses took place in another four trials for source-sensor distances between 10 and 50 m. Two sensors were positioned at a height of 5 m and one sensor at 4 m. The experimental set-up and the weather conditions are described. Tabulated results comprise concentration frequency distributions, as well as auto- and cross-correlations, both for 0.01 and 0.1 s resolution.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00119458
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  • 6
    Digitale Medien
    Digitale Medien
    Tracer experiments with turbulently dispersed air ions (1983)
    Springer
    Boundary layer meteorology 26 (1983), S. 127-139 
    Details
    ISSN: 1573-1472
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Unipolar air ions released into the wind constitute a tracer which can be measured with high resolution. An ion source produces a cloud with homogeneous charge density, insensitive to source strength, dependent on time since formation only. It is well suited for tracing concentration changes due to turbulence, less suited for cloud size tracing. A tight array of 8 sensors has been used to examine turbulently dispersed ions. High-resolution records are presented and discussed. The highest concentrations measured could be undiluted source material. The frequency distribution within a plume did not differ from that in a multitude of puffs. The distribution seems to be log-normal with a geometric standard deviation of about 2.45. The time resolution used corresponds to volume resolutions of 40, 225, and 650 cm3. Sample size had no apparent effect.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00121538
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  • 7
    Digitale Medien
    Digitale Medien
    Concentration fluctuation data from dispersion experiments carried out in stable and unstable conditions (1994)
    Springer
    Boundary layer meteorology 67 (1994), S. 41-74 
    Details
    ISSN: 1573-1472
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Experiments have been carried out to investigate the dispersion of plumes at short range in the atmospheric boundary layer during stable and unstable conditions. The experiments and measurement system are described, and the results are compared with those of previous experiments. The slow meandering under stable conditions found by Mylne (1992) is not present here (probably because of topographic effects), so the plume is present on the mean centreline more often, and timescales are shorter, under stable conditions. Associated with this, statistics during stable conditions exhibit greater stability to changes in total sampling time. Intensity is found to be greater under unstable conditions, but there do not appear to be large differences in the shape of the probability density function between stable and unstable conditions. The intermittency is calculated using several variations on the conventional definition. The values obtained vary substantially according to which definition is used (although they are always higher in the stable than in the unstable experiments), demonstrating the sensitivity to both the precise definition and to measurement system characteristics. It is shown that even at very short range the mean and variance of concentration are determined almost entirely by the fluid not emanating from the source. Thus the partition between source and non-source fluid suggested by Chatwin and Sullivan (1989), while providing a more scientifically sound definition of intermittency, does not have an obvious direct practical application.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00705507
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  • 8
    facet.materialart.
    Unbekannt
    The mechanisms of North Atlantic CO〈sub〉2〈/sub〉 uptake in a large Earth System Model ensemble (2015)
    In:  EPIC3Biogeosciences, 12(14), pp. 4497-4508, ISSN: 1726-4189
    Details
    Publikationsdatum: 2015-08-07
    Beschreibung: The oceans currently take up around a quarter of the carbon dioxide (CO2) emitted by human activity. While stored in the ocean, this CO2 is not influencing Earth's radiation budget; the ocean CO2 sink therefore plays an important role in mitigating global warming. CO2 uptake by the oceans is heterogeneous, with the subpolar North Atlantic being the strongest CO2 sink region. Observations over the last 2 decades have indicated that CO2 uptake by the subpolar North Atlantic sink can vary rapidly. Given the importance of this sink and its apparent variability, it is critical that we understand the mechanisms behind its operation. Here we explore the combined natural and anthropogenic subpolar North Atlantic CO2 uptake across a large ensemble of Earth System Model simulations, and find that models show a peak in sink strength around the middle of the century after which CO2 uptake begins to decline. We identify different drivers of change on interannual and multidecadal timescales. Short-term variability appears to be driven by fluctuations in regional seawater temperature and alkalinity, whereas the longer-term evolution throughout the coming century is largely occurring through a counterintuitive response to rising atmospheric CO2 concentrations. At high atmospheric CO2 concentrations the contrasting Revelle factors between the low latitude water and the subpolar gyre, combined with the transport of surface waters from the low latitudes to the subpolar gyre, means that the subpolar CO2 uptake capacity is largely satisfied from its southern boundary rather than through air–sea CO2 flux. Our findings indicate that: (i) we can explain the mechanisms of subpolar North Atlantic CO2 uptake variability across a broad range of Earth System Models; (ii) a focus on understanding the mechanisms behind contemporary variability may not directly tell us about how the sink will change in the future; (iii) to identify long-term change in the North Atlantic CO2 sink we should focus observational resources on monitoring lower latitude as well as the subpolar seawater CO2; (iv) recent observations of a weakening subpolar North Atlantic CO2 sink may suggest that the sink strength has peaked and is in long-term decline.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev , info:eu-repo/semantics/article
    Format: application/pdf
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  • 9
    facet.materialart.
    Unbekannt
    Diet of two icefish species from the South Shetland Islands and Elephant Island, Champsocephalus gunnari and Chaenocephalus aceratus (2004)
    In:  EPIC3Polar Biology, 27(2), pp. 119-129, ISSN: 0722-4060
    Details
    Publikationsdatum: 2019-07-17
    Beschreibung: The summer diet of two species of icefishes (Channichthyidae) from the South Shetland Islands and Elephant Island, Champsocephalus gunnari and Chaenocephalus aceratus, was investigated from 2001 to 2003. Champsocephalus gunnari fed almost exclusively on krill (Euphausia superba) in all years. The importance of other taxa (Themisto gaudichaudii, mysids, myctophids) in the diet was negligible. The average feeding rate of Champsocephalus gunnari inferred from an exponential gastric evacuation model was between 1.0 and 1.5% body weight per day. Most of the stomachs of Chaenocephalus aceratus were empty. Stomachs with food contained mainly krill, mysids and fish. Among the fish taken, locally abundant species formed the bulk of the diet: Gobionotothen gibberifrons in 2001, Lepidonotothen larseni and Champsocephalus gunnari in 2002 and L. larseni in 2003. An ontogenetic shift in feeding preference of Chaenocephalus aceratus was observed: fish smaller than 30 cm fed on krill and mysids, while larger animals relied primarily on fish.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
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  • 10
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    Climate-carbon cycle feedback analysis : results from the C4MIP model intercomparison (2010)
    American Meteorological Society
    Details
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Meteorological Society 2006. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 19 (2006): 3337–3353, doi:10.1175/JCLI3800.1.
    Beschreibung: Eleven coupled climate–carbon cycle models used a common protocol to study the coupling between climate change and the carbon cycle. The models were forced by historical emissions and the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A2 anthropogenic emissions of CO2 for the 1850–2100 time period. For each model, two simulations were performed in order to isolate the impact of climate change on the land and ocean carbon cycle, and therefore the climate feedback on the atmospheric CO2 concentration growth rate. There was unanimous agreement among the models that future climate change will reduce the efficiency of the earth system to absorb the anthropogenic carbon perturbation. A larger fraction of anthropogenic CO2 will stay airborne if climate change is accounted for. By the end of the twenty-first century, this additional CO2 varied between 20 and 200 ppm for the two extreme models, the majority of the models lying between 50 and 100 ppm. The higher CO2 levels led to an additional climate warming ranging between 0.1° and 1.5°C. All models simulated a negative sensitivity for both the land and the ocean carbon cycle to future climate. However, there was still a large uncertainty on the magnitude of these sensitivities. Eight models attributed most of the changes to the land, while three attributed it to the ocean. Also, a majority of the models located the reduction of land carbon uptake in the Tropics. However, the attribution of the land sensitivity to changes in net primary productivity versus changes in respiration is still subject to debate; no consensus emerged among the models.
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: application/pdf
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