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  • 2010-2014  (67)
  • 2000-2004  (73)
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  • 11
    Publication Date: 2013-02-14
    Description: Recently, indirect evidence was obtained for inhibition of soil net N mineralization by sterols in soil organic matter, which could have been caused by their antioxidant or antimicrobial properties. The objective of this study was to test the effect of potential inhibitors ( i.e., individual compounds with known antioxidant and/or antimicrobial properties) on soil microbial mineralization processes during incubation for 7 and 14 d. A sandy agricultural soil was amended with four substances: two phenolic acids differing in their antioxidant capacity (AOC) (acetovanillone with no AOC, ferulic acid with large AOC), Trolox, an analogue of vitamin E (large AOC), and β-sitosterol (no AOC, but potential antimicrobial properties). The two compounds with large AOC (ferulic acid and Trolox) showed no significant inhibition of C and net N mineralization; and the Trolox amendment actually caused a significant increase in C and net N mineralization after 7 d of incubation. Acetovanillone with no measurable AOC caused a significant increase in C mineralization (109% of substance C added), indicating degradation of the substance, and a very pronounced negative net N mineralization within 7 d (–356%), which was interpreted as N immobilization. Only β-sitosterol showed strong inhibition of net N mineralization after 7 and 14 d (–59% and –26%, respectively) which was not interpreted as N immobilization, since there was no concomitant increase in C mineralization. Thus, an antimicrobial effect of β-sitosterol specificly on microorganisms of the N cycle was suggested, but there was no clear inhibitory effect caused by the antioxidant compounds.
    Print ISSN: 1436-8730
    Electronic ISSN: 1522-2624
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Wiley
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  • 12
    Publication Date: 2012-09-01
    Description: Permian sedimentary sequences exposed in southern Mongolia record final closure of the paleo–Asian Ocean and suturing of the terranes of northern China with the southern margin of a vast accretionary complex (the Altaids) in Mongolia. Detrital zircon U-Pb geochronology results presented here are the first of their kind in southern Mongolia. Geologic mapping, stratigraphic interpretations, and provenance data including U-Pb zircon geochronology suggest that sedimentary strata at two localities in southern Mongolia, Bulgan Uul and Nomgon, were once part of the same closing ocean basin. The Upper Permian sedimentary deposits at Bulgan Uul record an upward-shallowing marine succession that is unconformably overlain by Lower Triassic fluvial and alluvial strata. The Bulgan Uul marine succession is composed of distal turbidite fan deposits in the lowest portion of the section, with interbedded sandstone and limestone interpreted as shallow-marine deposits at the top of the section. Exposures of Permian-aged distal turbidite units at Nomgon are similar in stratigraphic architecture, sandstone provenance, and detrital zircon age distributions to those documented at Bulgan Uul. Paleocurrent measurements, sandstone provenance data, and U-Pb ages from detrital zircons collected from both study locations document southeastern transport directions for sediment derived from extinct Carboniferous and Ordovician–Silurian arcs of the southern Altaids. Results are consistent with depositional models for remnant ocean basins and indicate diachronous west-to-east closure of the paleo–Asian Ocean (a northern segment of Paleotethys) in the Late Permian. Finally, basin reconstructions place the coeval turbidite deposits at Nomgon to the southeast of Bulgan Uul during the Late Permian. These correlative turbidite successions at Nomgon are currently northeast of Bulgan Uul, offset by ~250 km of left-lateral strike-slip faulting across the East Gobi fault zone.
    Print ISSN: 0016-7606
    Electronic ISSN: 1943-2674
    Topics: Geosciences
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  • 13
    Publication Date: 2012-07-14
    Description: The Journal of Physical Chemistry B DOI: 10.1021/jp303448v
    Electronic ISSN: 1520-5207
    Topics: Chemistry and Pharmacology , Physics
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  • 14
    Publication Date: 2011-11-18
    Description: Mangroves provide valuable ecosystem goods and services such as carbon sequestration, habitat for terrestrial and marine fauna, and coastal hazard mitigation. The use of satellite remote sensing to map mangroves has become widespread as it can provide accurate, efficient, and repeatable assessments. Traditional remote sensing approaches have failed to accurately map fringe mangroves and true mangrove species due to relatively coarse spatial resolution and/or spectral confusion with landward vegetation. This study demonstrates the use of the new Worldview-2 sensor, Object-based image analysis (OBIA), and support vector machine (SVM) classification to overcome both of these limitations. An exploratory spectral separability showed that individual mangrove species could not be spectrally separated, but a distinction between true and associate mangrove species could be made. An OBIA classification was used that combined a decision-tree classification with the machine-learning SVM classification. Results showed an overall accuracy greater than 94% (kappa = 0.863) for classifying true mangroves species and other dense coastal vegetation at the object level. There remain serious challenges to accurately mapping fringe mangroves using remote sensing data due to spectral similarity of mangrove and associate species, lack of clear zonation between species, and mixed pixel effects, especially when vegetation is sparse or degraded.
    Electronic ISSN: 2072-4292
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by MDPI Publishing
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  • 15
    Publication Date: 2011-02-02
    Description: Mangroves are salt tolerant woody plants that form highly productive intertidal ecosystems in tropical and subtropical regions. Despite the established importance of mangroves to the coastal environment, including fisheries, deforestation continues to be a major threat due to pressures for wood and forest products, land conversion to aquaculture, and coastal urban development. Over the past 15 years, remote sensing has played a crucial role in mapping and understanding changes in the areal extent and spatial pattern of mangrove forests related to natural disasters and anthropogenic forces. This paper reviews recent advancements in remote-sensed data and techniques and describes future opportunities for integration or fusion of these data and techniques for large-scale monitoring in mangroves as a consequence of anthropogenic and climatic forces. While traditional pixel-based classification of Landsat, SPOT, and ASTER imagery has been widely applied for mapping mangrove forest, more recent types of imagery such as very high resolution (VHR), Polarmetric Synthetic Aperture Radar (PolSAR), hyperspectral, and LiDAR systems and the development of techniques such as Object Based Image Analysis (OBIA), spatial image analysis (e.g. image texture), Synthetic Aperture Radar Interferometry (InSAR), and machine-learning algorithms have demonstrated the potential for reliable and detailed characterization of mangrove forests including species, leaf area, canopy height, and stand biomass. Future opportunities include the application of existing sensors such as the hyperspectral HYPERION, the application of existing methods from terrestrial forest remote sensing, investigation of new sensors such as ALOS PRISM and PALSAR, and overcoming challenges to the global monitoring of mangrove forests such as wide-scale data availability, robust and consistent methods, and capacity-building with scientists and organizations in developing countries.
    Print ISSN: 0309-1333
    Electronic ISSN: 1477-0296
    Topics: Geography
    Published by Sage
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  • 16
    Publication Date: 2011-03-22
    Description: Unusually low net N mineralization in soils relatively rich in total organic C and N was repeatedly reported for sandy arable soils in NW Europe. In order to adequately account for it in simulation models, it is necessary to know the involved substances and processes. Therefore, 9 arable top soils (〈 6% clay) with a wide range of total organic C (1.1%–5.2%) and C : N ratios (12–35) were studied. The soils varied strongly in the mineralizability of soil organic N which was determined via long-term laboratory incubations (〉 200 d). It was hypothesized that mineralization was controlled by antioxidants, and the Trolox equivalent antioxidant capacity (TEAC) of the soils was measured. In addition, pyrolysis–field ionization mass spectrometry (Py-FIMS) was applied to investigate the influence of the molecular-chemical composition of soil organic matter. In these soils, the compound class of sterols from Py-FIMS analysis was most closely, negatively correlated with the mineralizability of soil organic N ( r 〈?h.3〉 2 = 0.75, p = 0.003). This was probably not an antioxidative effect, because the TEAC values did not correlate sufficiently with the mineralizability and the sterol intensities. However, the negative relation with sterols could be causal, since the correlation was about as close with other components of the compound class of sterols and even closer with the main plant sterol beta-sitosterol ( r 〈?h.3〉 2 = 0.84, p = 0.001). In addition, the variability among samples was strongly governed by the proportions of sterols, and sterols also had a high discriminating power in discriminant analysis. Furthermore, the proportions of sterols were extraordinary in those arable podzol soils that developed under previous heath- or woodland (up to 10.2% of total ion intensity from Py-FIMS). In conclusion, the inhibitory effect of these compounds needs to be investigated in more detail in order to optimize parameterization of N as well as C simulation models especially for podzolized, sandy arable soils with former heath- or woodland vegetation.
    Print ISSN: 1436-8730
    Electronic ISSN: 1522-2624
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Wiley
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  • 17
    Publication Date: 2014-01-15
    Description: We demonstrate that membrane proteins and phospholipids can self-assemble into polyhedral arrangements suitable for structural analysis. Using the Escherichia coli mechanosensitive channel of small conductance (MscS) as a model protein, we prepared membrane protein polyhedral nanoparticles (MPPNs) with uniform radii of ∼20 nm. Electron cryotomographic analysis established that these MPPNs...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 18
    Publication Date: 2013-07-17
    Description: Highly active antiretroviral therapy (HAART) decreases plasma viremia below the limits of detection in the majority of HIV-infected individuals, thus serving to slow disease progression. However, HAART targets only actively replicating virus and is unable to eliminate latently infected, resting CD4+ T cells. Such infected cells are potentially capable of...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 19
    Publication Date: 2012-05-03
    Description: Mangroves provide valuable ecosystem goods and services such as carbon sequestration, habitat for terrestrial and marine fauna, and coastal hazard mitigation. The use of satellite remote sensing to map mangroves has become widespread as it can provide accurate, efficient, and repeatable assessments. Traditional remote sensing approaches have failed to accurately map fringe mangroves and true mangrove species due to relatively coarse spatial resolution and/or spectral confusion with landward vegetation. This study demonstrates the use of the new Worldview-2 sensor, Object-based image analysis (OBIA), and support vector machine (SVM) classification to overcome both of these limitations. An exploratory spectral separability showed that individual mangrove species could not be spectrally separated, but a distinction between true and associate mangrove species could be made. An OBIA classification was used that combined a decision-tree classification with the machine-learning SVM classification. Results showed an overall accuracy greater than 94% (kappa = 0.863) for classifying true mangroves species and other dense coastal vegetation at the object level. There remain serious challenges to accurately mapping fringe mangroves using remote sensing data due to spectral similarity of mangrove and associate species, lack of clear zonation between species, and mixed pixel effects, especially when vegetation is sparse or degraded.
    Electronic ISSN: 2072-4292
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by MDPI Publishing
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  • 20
    Publication Date: 2013-11-24
    Description: Journal of Medicinal Chemistry DOI: 10.1021/jm401291q
    Topics: Chemistry and Pharmacology
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