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  • 1
    Online Resource
    Online Resource
    Nonmethane hydrocarbon and halocarbon distributions during Atlantic Stratocumulus Transition Experiment/Marine Aerosol and Gas Exchange, June 1992
    American Geophysical Union (AGU) ; 1996
    In:  Journal of Geophysical Research: Atmospheres Vol. 101, No. D2 ( 1996-02-20), p. 4501-4514
    Details
    In: Journal of Geophysical Research: Atmospheres, American Geophysical Union (AGU), Vol. 101, No. D2 ( 1996-02-20), p. 4501-4514
    Abstract: Aircraft measurements of selected nonmethane hydrocarbon and halocarbon species were made in the lower troposphere of the NE Atlantic near the Azores, Portugal, during June 1992 as part of the Atlantic Stratocumulus Transition Experiment/Marine Aerosol and Gas Exchange. In this paper, the impact of continental outflow from both Europe and North America on the study region were assessed. Four main air mass types were characterized from trajectories and trace gas concentrations: clean marine from the Atlantic, and continental air from the Iberian Peninsula, the British Isles and Northern Europe, and North America. Each classification exhibited trace gas concentrations that had been modified en route by photochemical processes and mixing. Comparison with the clean marine boundary layer (MBL) shows that the boundary layer of the predominantly continental air masses were enhanced in hydrocarbons and halocarbons by factors of approximately 2 for ethane, 5 for propane, 2–6 for ethyne and benzene, and 2–3 for C 2 Cl 4 . The same air masses also exhibited large ozone enhancements, with 2 to 3 times higher mixing ratios in the continental boundary layer air compared to the clean MBL. This indicates a primarily anthropogenic photochemical source for a significant fraction of the lower tropospheric ozone in this region. Methyl bromide exhibited on average 10–20% higher concentrations in the boundary layer affected by continental outflow than in the clean MBL, and was seen to be enhanced in individual plumes of air of continental origin. This is consistent with significant anthropogenic sources for methyl bromide. In addition, median MBL concentrations of ethene and methyl iodide showed enhancements of approximately a factor of 2 above free tropospheric values, suggesting primarily coastal/oceanic sources for these species.
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/95JD01370
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 1996
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  • 2
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    Online Resource
    Three‐dimensional distribution of nonmenthane hydrocarbons and halocarbons over the northwestern Pacific during the 1991 Pacific Exploratory Mission (PEM‐West A)
    American Geophysical Union (AGU) ; 1996
    In:  Journal of Geophysical Research: Atmospheres Vol. 101, No. D1 ( 1996-01-20), p. 1763-1778
    Details
    In: Journal of Geophysical Research: Atmospheres, American Geophysical Union (AGU), Vol. 101, No. D1 ( 1996-01-20), p. 1763-1778
    Abstract: A total of 1667 whole air samples were collected onboard the NASA DC‐8 aircraft during the 6‐week Pacific Exploratory Mission over the western Pacific (PEM‐West A) in September and October 1991. The samples were assayed for 15 C 2 ‐C 7 hydrocarbons and six halocarbons. Latitudinal (0.5°S to 59.5°N) and longitudinal (114°E to 122°W) profiles were obtained from samples collected between ground level and 12.7 km. Thirteen of the 18 missions exhibited at least one vertical profile where the hydrocarbon mixing ratios increased with altitude. Longitude‐latitude color patch plots at three altitude levels and three‐dimensional color latitude‐altitude and longitude‐altitude contour plots exhibit a significant number of middle‐upper tropospheric pollution events. These and several lower tropospheric pollution plumes were characterized by comparison with urban data from Tokyo and Hong Kong, as well as with natural gas and the products from incomplete combustion. Elevated levels of nonmethane hydrocarbons (NMHC) and other trace gases in the upper‐middle free troposphere were attributed to deep convection over the Asian continent and to typhoon‐driven convection near the western Pacific coast of Asia. In addition, NMHCs and CH 3 CCl 3 were found to be useful tracers with which to distinguish hydrocarbon and halocarbon augmented plumes emitted from coastal Asian cities into the northwestern Pacific.
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/95JD02707
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 1996
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  • 3
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    Hydrocarbon and halocarbon measurements as photochemical and dynamical indicators of atmospheric hydroxyl, atomic chlorine, and vertical mixing obtained during Lagrangian flights
    American Geophysical Union (AGU) ; 1996
    In:  Journal of Geophysical Research: Atmospheres Vol. 101, No. D2 ( 1996-02-20), p. 4331-4340
    Details
    In: Journal of Geophysical Research: Atmospheres, American Geophysical Union (AGU), Vol. 101, No. D2 ( 1996-02-20), p. 4331-4340
    Abstract: Nonmethane hydrocarbons and halocarbons were measured during two Lagrangian experiments conducted in the lower troposphere of the North Atlantic as part of the June 1992, Atlantic Stratosphere Transition Experiment/Marine Aerosol and Gas Exchange (ASTEX/MAGE) expedition. The first experiment was performed in very clean marine air. Meteorological observations indicate that the height of the marine boundary layer rose rapidly, entraining free tropospheric air. However, the free tropospheric and marine boundary layer halocarbon concentrations were too similar to allow this entrainment to be quantified by these measurements. The second Lagrangian experiment took place along the concentration gradient of an aged continental air mass advecting from Europe. The trace gas measurements confirm that the National Center for Atmospheric Research (NCAR) Electra aircraft successfully intercepted the same air mass on consecutive days. Two layers, a surface layer and a mixed layer with chemically distinct compositions, were present within the marine boundary layer. The composition of the free troposphere was very different from that of the mixed layer, making entrainment from the free troposphere evident. Concentrations of the nonmethane hydrocarbons in the Lagrangian surface layer were observed to become depleted relative to the longer‐lived tetrachloroethene. A best fit to the observations was calculated using various combinations of the three parameters, loss by reaction with hydroxyl, loss by reaction with chlorine, and/or dilution from the mixed layer. These calculations provided estimated average concentrations in the surface layer for a 5‐hour period from dawn to 11 UT of 0.3 ± 0.5 × 10 6 molecules cm −3 for HO, and 3.3 ± 1.1 × 10 4 molecules cm −3 for Cl. Noontime concentration estimates were 2.6 ± 0.7 × 10 6 molecules cm −3 for HO and 6.5 ± 1.4 × 10 4 molecules cm −3 for Cl.
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/95JD02457
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 1996
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  • 4
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    Summertime measurements of selected nonmethane hydrocarbons in the Arctic and Subarctic during the 1988 Arctic Boundary Layer Expedition (ABLE 3A)
    American Geophysical Union (AGU) ; 1992
    In:  Journal of Geophysical Research: Atmospheres Vol. 97, No. D15 ( 1992-10-30), p. 16559-16588
    Details
    In: Journal of Geophysical Research: Atmospheres, American Geophysical Union (AGU), Vol. 97, No. D15 ( 1992-10-30), p. 16559-16588
    Abstract: Approximately 1000 whole air samples were collected and assayed for selected C 2 ‐C 5 hydrocarbons during the 6‐week Arctic Boundary Layer Expedition (ABLE 3A). Transit flights enabled latitudinal (40°N to 83°N) and longitudinal (70°W to 155°W) profiles to be obtained for altitudes between 4000 and 6000 m yielding summertime background mixing ratios for ethane, ethyne, propane and n ‐butane of 1050±200, 100±40, 120±80 and 10±8 pptv, respectively. Drilling associated with oil exploration in the Alaskan North Slope area is suggested to be a probable source of the enhanced levels of alkanes observed in the Arctic region within a radius in excess of 300 km from Prudhoe Bay, Alaska. A significant number of pollution plumes were encountered which could be attributed to wildfires. Factors describing the emissions caused by biomass burning relative to ethane for ethyne (0.40) and propane (0.08) were determined. An increase of hydrocarbon mixing ratios with altitude was observed during all but two of the missions. Therefore, the Arctic and sub‐Arctic are significantly influenced by the long‐range transport of pollutants from nonlocal sources. A single vertical profile made in the vicinity of Wallops Island, Virginia, revealed elevated levels of isoprene, numerous hydrocarbons of the types associated with the leakage of natural gas and fossil fuel combustion, and substantial concentrations of nitrogen oxides and ozone. This implies that long‐range transport of various gases from urban areas, combined with local biogenic emissions of isoprene, are significant sources of regional tropospheric ozone.
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/92JD00892
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 1992
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  • 5
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    Comprehensive analysis of epigenetic clocks reveals associations between disproportionate biological ageing and hippocampal volume
    Springer Science and Business Media LLC ; 2022
    In:  GeroScience Vol. 44, No. 3 ( 2022-06), p. 1807-1823
    Details
    In: GeroScience, Springer Science and Business Media LLC, Vol. 44, No. 3 ( 2022-06), p. 1807-1823
    Abstract: The concept of age acceleration, the difference between biological age and chronological age, is of growing interest, particularly with respect to age-related disorders, such as Alzheimer’s Disease (AD). Whilst studies have reported associations with AD risk and related phenotypes, there remains a lack of consensus on these associations. Here we aimed to comprehensively investigate the relationship between five recognised measures of age acceleration, based on DNA methylation patterns (DNAm age), and cross-sectional and longitudinal cognition and AD-related neuroimaging phenotypes (volumetric MRI and Amyloid-β PET) in the Australian Imaging, Biomarkers and Lifestyle (AIBL) and the Alzheimer’s Disease Neuroimaging Initiative (ADNI). Significant associations were observed between age acceleration using the Hannum epigenetic clock and cross-sectional hippocampal volume in AIBL and replicated in ADNI. In AIBL, several other findings were observed cross-sectionally, including a significant association between hippocampal volume and the Hannum and Phenoage epigenetic clocks. Further, significant associations were also observed between hippocampal volume and the Zhang and Phenoage epigenetic clocks within Amyloid-β positive individuals. However, these were not validated within the ADNI cohort. No associations between age acceleration and other Alzheimer’s disease-related phenotypes, including measures of cognition or brain Amyloid-β burden, were observed, and there was no association with longitudinal change in any phenotype. This study presents a link between age acceleration, as determined using DNA methylation, and hippocampal volume that was statistically significant across two highly characterised cohorts. The results presented in this study contribute to a growing literature that supports the role of epigenetic modifications in ageing and AD-related phenotypes.
    Type of Medium: Online Resource
    ISSN: 2509-2715 , 2509-2723
    URL: Article
    DOI: 10.1007/s11357-022-00558-8
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
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  • 6
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    Intranasal chalcone, Ro 09–0410, as prophylaxis against rhinovirus infection in human volunteers
    Oxford University Press (OUP) ; 1987
    In:  Journal of Antimicrobial Chemotherapy Vol. 20, No. 6 ( 1987), p. 887-892
    Details
    In: Journal of Antimicrobial Chemotherapy, Oxford University Press (OUP), Vol. 20, No. 6 ( 1987), p. 887-892
    Type of Medium: Online Resource
    ISSN: 0305-7453 , 1460-2091
    URL: Article
    DOI: 10.1093/jac/20.6.887
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 1987
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  • 7
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    Vertical profiling and determination of landscape fluxes of biogenic nonmethane hydrocarbons within the planetary boundary layer in the Peruvian Amazon
    American Geophysical Union (AGU) ; 1998
    In:  Journal of Geophysical Research: Atmospheres Vol. 103, No. D19 ( 1998-10-20), p. 25519-25532
    Details
    In: Journal of Geophysical Research: Atmospheres, American Geophysical Union (AGU), Vol. 103, No. D19 ( 1998-10-20), p. 25519-25532
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/98JD01023
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 1998
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