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  • 1
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    Salt diapirs without well defined boundaries – a feasibility study of semi-automatic detection (2011)
    Wiley
    Details
    Publication Date: 2011-04-05
    Description: Prestack depth imaging of seismic data in complex areas such as salt structures requires extensive velocity model updating. In many cases, salt boundaries can be difficult to identify due to lack of seismic reflectivity. Traditional amplitude based segmentation methods do not properly tackle this problem, resulting in extensive manual editing. This paper presents a selection of seismic attributes that can reveal texture differences between the salt diapirs and the surrounding geology as opposed to amplitude-sensitive attributes that are used in case of well defined boundaries. The approach consists of first extracting selected texture attributes, then using these attributes to train a classifier to estimate the probability that each pixel in the data set belongs to one of the following classes: near-horizontal layering, highly-dipping areas and the inside of the salt that appears more like a low amplitude area with small variations in texture. To find the border between the inside of the salt and the highly-dipping surroundings, the posterior probability of the class salt is input to a graph-cut algorithm that produces a smooth, continuous border. An in-line seismic section and a timeslice from a 3D North Sea data set were employed to test the proposed approach. Comparisons between the automatically segmented salt contours and the corresponding contours as provided by an experienced interpreter showed a high degree of similarity.
    Print ISSN: 0016-8025
    Electronic ISSN: 1365-2478
    Topics: Geosciences , Physics
    Published by Wiley
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  • 2
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    Wood density as a screening trait for drought sensitivity in Norway spruce (2014)
    National Research Council Canada (NRC)
    Details
    Publication Date: 2014-02-01
    Description: Canadian Journal of Forest Research, Volume 0, Issue 0, Page 154-161, e-First articles. We linked hydraulic vulnerability in Norway spruce (Picea abies (L.) Karst.) trunkwood with different cambial age to wood density and applied the findings on annual density variations in healthy and declining trees from southern Norway during 1990 to 2010. We hypothesized that drought stress due to the 2003 or 2006 European heat waves were the triggers for tree decline and focused analyses on the structure of wood that was produced after, as well as before, signs of stress, i.e., when decreases in height or diameter growth were visible. In the data set comprising previously published and new measurements, P50, i.e., the pressure potential necessary to induce a 50% loss in hydraulic conductivity, was negatively related to wood density. Declining trees produced wider annual rings with lower density than vigorous trees before their radial and height increment started to decline in 2003 or 2006. Trees that produced low-density wood under favorable water availability were more stressed by a sudden drought event because of higher P50 values in their sapwood. Due to the strong genotypic relationship between wood density and growth, we suggest that spruce trees selected for fast growth might experience limited hydraulic performance under the impact of extreme heat waves.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by National Research Council Canada (NRC)
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  • 3
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    Ecologically implausible carbon response? (2008)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2008-02-15
    Description: Magnani et al. present a very strong correlation between mean lifetime net ecosystem production (NEP, defined as the net rate of carbon (C) accumulation in ecosystems) and wet nitrogen (N) deposition. For their data in the range 4.9-9.8 kg N ha(-1) yr(-1), on which the correlation largely depends, the response is approximately 725 kg C per kg N in wet deposition. According to the authors, the maximum N wet deposition level of 9.8 kg N ha(-1) yr(-1) is equivalent to a total deposition of 15 kg N ha(-1 )yr(-1), implying a net sequestration near 470 kg C per kg N of total deposition. We question the ecological plausibility of the relationship and show, from a multi-factor analysis of European forest measurements, how interactions with site productivity and environment imply a much smaller NEP response to N deposition.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉de Vries, Wim -- Solberg, Svein -- Dobbertin, Matthias -- Sterba, Hubert -- Laubhahn, Daniel -- Reinds, Gert Jan -- Nabuurs, Gert-Jan -- Gundersen, Per -- Sutton, Mark A -- England -- Nature. 2008 Feb 14;451(7180):E1-3; discussion E3-4. doi: 10.1038/nature06579.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Alterra, Wageningen University and Research Centre, PO Box 47, 6700 AA Wageningen, The Netherlands. wim.devries@wur.nl〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18272968" target="_blank"〉PubMed〈/a〉
    Keywords: Carbon/*metabolism ; Ecology ; *Ecosystem ; Europe ; Nitrogen/metabolism ; Trees/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 4
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    Seasonal variations of atmospheric trace gases in the high Arctic at 79° N (1997)
    In:  EPIC3J Geophys Res D11, 102, pp. 12855-12861
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 5
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    Arctic smoke - record high air pollution levels in the European Arctic due to agricultural fires in Eastern Europe (2007)
    In:  EPIC3Atmospheric Chemistry and Physics, 7(2). {www.atmos-chem-phys.net/7/511/2007/}, 511
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 6
    Electronic Resource
    Electronic Resource
    Pigment composition in Norway spruce needles suffering from different types of nutrient deficiency (1998)
    Springer
    Trees 12 (1998), S. 289-292 
    Details
    ISSN: 0931-1890
    Keywords: Key words Pigments ; Carbohydrates ; Yellowing ; Nutrient deficiency ; Norway spruce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Concentrations of pigments in needles of yellowish Norway spruce [Picea abies (L.) Karst] trees suffering from either N, Mg or K deficiency in field sites in southeast Norway are reported. The yellowish trees had a considerably lower (roughly 50%) pigment concentration, as well as a lower chlorophyll/carotenoid ratio, compared to green trees within the same sites. Yellowing was interpreted as a general bleaching of colour, as well as a slight turn from the green (chlorophylls) towards yellow (lutein). Concentrations of pigments were highly intercorrelated. N deficiency was especially associated with low α-carotene concentrations. This was interpreted as α-carotene being the most sensitive pigment to stress. However, this pigment might be specifically sensitive to N deficiency. Carbohydrate concentrations were slightly higher in yellowish trees.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004680050153
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  • 7
    Electronic Resource
    Electronic Resource
    Crown density changes of Norway spruce and the influence from increased age on permanent monitoring plots in Norway during 1988–1997 (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Forest pathology 29 (1999), S. 0 
    Details
    ISSN: 1439-0329
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: On the ‘local county monitoring plots’ located throughout Norway a reduction of crown density has been noted during the period 1988–1997. The aim of this study was to determine whether this change could be attributed to normal effects due to the increased age of trees in the plots. The dataset comprised around 580 plots and 27 000 single trees of Norway spruce (Picea abies), with 10 years of crown density measurements available for each tree. A two-step approach was used, first to search for an expectancy for normal reduction of crown density by age derived from the dataset, and then to compare this with the actual reduction. The interpretation was somewhat complicated as the various results were dependent upon each other. Highly significant correlations were found between crown density and age. The relationship indicated an annual reduction of crown density of around 0.12%. However, the relationship varied both between years and between regions, and it was not possible to definitely determine whether the relationship was best described by linear or nonlinear models. Of major importance here is that the relationship appeared to be influenced by the presence of stresses, whose effects tended to be more severe in old stands. On this basis it seems questionable whether an expectancy for normal ageing can be properly defined. In the present study, however, it could still be definitely determined that the mean crown density change of—0.41% annually was too negative to be attributed to normal ageing, as it was clearly below all the suggested expectancies from the various models. This suggests that the amount of stress in the period under study has been higher than normal, and this encourages the search for causal agents in further studies. Changes in silviculture may have had some influence. The results were valid for most of Norway, with the exception of western and northern regions. Crown density assessments are subjective, which may possibly give erroneous time trends. However, it is argued that this is less likely to be of major importance in the present data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1439-0329.1999.00150.x
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  • 8
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    LEE, "Asian American Experience in the United States: Oral Histories of First to Fourth Generation Americans from China, the Philippines, Japan, India, the Pacific Islands, Vietnam and Cambodia" (Book Review) (1992)
    Ann Arbor, Mich., etc., : Periodicals Archive Online (PAO)
    Journal of Asian Studies. 51:1 (1992:Feb.) 125 
    Details
    ISSN: 0021-9118
    Topics: Political Science , Economics
    Description / Table of Contents: Asia General
    Notes: Book Reviews
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:1113-1992-051-01-000012
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  • 9
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    LEE (trans.), "The Wind and the Waves: Four Modern Korean Poets" (Book Review) (1990)
    Ann Arbor, Mich., etc., : Periodicals Archive Online (PAO)
    Journal of Asian Studies. 49:4 (1990:Nov.) 949 
    Details
    ISSN: 0021-9118
    Topics: Political Science , Economics
    Description / Table of Contents: Korea
    Notes: Book Reviews
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:1113-1990-049-04-000071
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  • 10
    Electronic Resource
    Electronic Resource
    Reactive Nitrogen Compounds at Spitsbergen in the Norwegian Arctic (1997)
    Springer
    Journal of atmospheric chemistry 28 (1997), S. 209-225 
    Details
    ISSN: 1573-0662
    Keywords: PAN ; NOy ; Arctic measurements ; nitrogen oxides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Simultaneousindependent measurements of NOy and NOx(NOx= NO + NO2) by high-sensitivitychemiluminescence systems and of PAN (peroxyacetylnitrate) and PPN (peroxypropionyl nitrate) by GC-ECDwere made at Spitsbergen in the Norwegian Arcticduring the first half year of 1994. The average mixingratio of the sum of PAN and PPN (denoted PANs)increased from around 150 pptv in early winter to amaximum of around 500 pptv in late March, whereasepisodic peak values reached 800 pptv. This occurredsimultaneously with a maximum in ozone which increasedto 45–50 ppbv in March–April. The average NOxmixing ratio was 27 pptv and did not show any cyclethrough the period. The NOy mixing ratio showeda maximum in late March, while the difference betweenNOy and PAN decreased during spring. This is anindication of the dominance of PAN in the NOybudget in the Arctic, but possible changes in theefficiency of the NOy converter could alsocontribute to this. Although most PAN in theArctic is believed to be due to long range transport,the observations indicate local loss and formationrates of up to 1–2 pptv h-1 in April–May.Measurements of carbonyl compounds suggest thatacetaldehyde was the dominant, local precursor ofPAN.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005883323285
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