ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    No significant increase in long-term CH4 emissions on North Slope of Alaska despite significant increase in air temperature (2016)
    Wiley
    Details
    Publication Date: 2016-06-02
    Description: Continuous measurements of atmospheric methane (CH 4 ) mole fractions measured by NOAA's Global Greenhouse Gas Reference Network in Barrow, AK (BRW), show strong enhancements above background values when winds come from the land sector from July through December from 1986-2014, indicating that emissions from arctic tundra continue through autumn and into early winter. Twenty-nine years of measurements show little change in seasonal mean land-sector CH 4 enhancements, despite an increase in annual mean temperatures of 1.2 ± 0.8 °C/decade (2σ). The record does reveal small increases in CH 4 enhancements in November and December after 2010 due to increased late-season emissions. The lack of significant long-term trends suggests more complex biogeochemical processes are counteracting the observed short-term (monthly) temperature sensitivity of 5.0 ± 3.6 ppb CH 4 /°C. Our results suggest that even the observed short-term temperature sensitivity from the Arctic will have little impact on the global atmospheric CH 4 budget in the long-term if future trajectories evolve with the same temperature sensitivity.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    facet.materialart.
    Unknown
    A multi-year estimate of methane fluxes in Alaska from CARVE atmospheric observations (2016)
    Wiley
    Details
    Publication Date: 2016-09-16
    Description: Methane (CH 4 ) fluxes from Alaska and other arctic regions may be sensitive to thawing permafrost and future climate change, but estimates of both current and future fluxes from the region are uncertain. This study estimates CH 4 fluxes across Alaska for 2012 – 2014 using aircraft observations from the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) and a geostatistical inverse model (GIM). We find that a simple flux model based on a daily soil temperature map and a static map of wetland extent reproduces the atmospheric CH 4 observations at the state-wide, multi-year scale more effectively than global-scale process-based models. This result points to a simple and effective way of representing CH 4 fluxes across Alaska. It further suggests that process-based models can improve their representation of key processes, and that more complex processes included in these models cannot be evaluated given the information content of available atmospheric CH 4 observations. In addition, we find that CH 4 emissions from the North Slope of Alaska account for 24% of the total statewide flux of 1.74  ±  0.26 Tg CH 4 (for May – Oct.). Global-scale process models only attribute an average of 3% of the total flux to this region. This mismatch occurs for two reasons: process models likely underestimate wetland extent in regions without visible surface water, and these models prematurely shut down CH 4 fluxes at soil temperatures near 0° C. Lastly, we find that the seasonality of CH 4 fluxes varied during 2012 – 2014, but that total emissions did not differ significantly among years, despite substantial differences in soil temperature and precipitation.
    Print ISSN: 0886-6236
    Electronic ISSN: 1944-9224
    Topics: Biology , Chemistry and Pharmacology , Geography , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 3
    facet.materialart.
    Unknown
    Relating atmospheric and oceanic DMS levels to particle nucleation events in the Canadian Arctic (2011)
    Wiley
    Details
    Publication Date: 2011-11-01
    Description: Measurements of ocean surface and atmospheric dimethyl sulfide (DMS) and particle size distributions were made in the Canadian Arctic Archipelago during the fall of 2007 and the late summer of 2008 aboard the Canadian Coast Guard Ship Amundsen. Nucleation-mode particles were observed during the 2008 cruise, which took place in the eastern Arctic from August to September when the atmosphere and ocean were more photo-active as compared to the October 2007 transit in the Beaufort Sea during which no nucleation/growth events were observed. The observed nucleation periods in 2008 coincided with high atmospheric and ocean surface DMS concentrations, suggesting that the particles originated from marine biogenic sources. An aerosol microphysics box model was used to simulate nucleation given the measured conditions in the marine boundary layer. Although other sources may have contributed, we find that the newly formed particles can be accounted for by a marine biogenic DMS source for combinations of the following parameters: [OH] ≥ 3 × 105 molecules cm−3, DMS mixing ratio is ≥ 100 pptv, the activation coefficient is ≤ 10−7 and the background particle concentration is ≤ 100 cm−3.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 4
    facet.materialart.
    Unknown
    Annual distributions and sources of Arctic aerosol components, aerosol optical depth, and aerosol absorption (2014)
    Wiley
    Details
    Publication Date: 2014-03-13
    Description: Radiative forcing by aerosols and tropospheric ozone could play a significant role in recent Arctic warming. These species are in general poorly accounted for in climate models. We use the GEOS-Chem global chemical transport model to construct a 3-D representation of Arctic aerosols and ozone that is consistent with observations and can be used in climate simulations. We focus on 2008, when extensive observations were made from different platforms as part of the International Polar Year. Comparison to aircraft (ARCTAS), surface, and ship cruise (ICEALOT, ASCOS) observations suggests that GEOS-Chem provides in general a successful year-round simulation of Arctic black carbon (BC), organic carbon (OC), sulfate, and dust aerosol. BC has major fuel combustion and boreal fire sources, OC is mainly from fires, sulfate has a mix of anthropogenic and natural sources, and dust is mostly from the Sahara. The model is successful in simulating aerosol optical depth (AOD) observations from AERONET stations in the Arctic; the sharp drop from spring to summer appears driven in part by the smaller size of sulfate aerosol in summer. The anthropogenic contribution to Arctic AOD is a factor of 4 larger in spring than summer and is mainly sulfate. Simulation of absorbing aerosol optical depth (AAOD) indicates that non-BC aerosol (OC and dust) contributed 24% of Arctic AAOD at 550 nm and 37% of absorbing mass deposited to the snow pack in 2008. Open fires contributed half of AAOD at 550 nm and half of deposition to the snowpack.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 5
    facet.materialart.
    Unknown
    Application of a modified manifold-based exponentially convergent algorithm to solve elliptic boundary-value problems (2014)
    Oxford University Press
    Details
    Publication Date: 2014-01-25
    Description: In this paper, we combine a novel finite difference method (FDM) with a manifold-based exponentially convergent algorithm (MBECA) to solve a nonlinear elliptic boundary-value problem defined in an arbitrary plane domain. It is very difficult to solve nonlinear and geometric complexity problems by conventional FDM. To overcome these problems, the concepts of internal residual and boundary residual in a fictitious rectangular domain are introduced. Besides, by adding a fictitious time coordinate, we avoid the need to treat complex boundary conditions but only use shape functions. Also, it is not necessary to solve an inverse matrix of algebraic equations when by using the MBECA. Moreover, in order to increase the numerical stability of the MBECA, we introduce a group-preserving scheme (GPS) to address fictitious time integration. Given the cone structure of the GPS and MBECA and their manifold properties, we can preserve the manifold path on the cone structure by a weighting factor such that the MBECA must also exhibit a cone construction, Lie algebra and group properties at each fictitious time step. Finally, the accuracy and convergence behaviour of this present method are demonstrated in several examples.
    Print ISSN: 0272-4979
    Electronic ISSN: 1464-3642
    Topics: Mathematics
    Published by Oxford University Press
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 6
    facet.materialart.
    Unknown
    Architecture of the type IVa pilus machine (2016)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2016-03-12
    Description: Type IVa pili are filamentous cell surface structures observed in many bacteria. They pull cells forward by extending, adhering to surfaces, and then retracting. We used cryo-electron tomography of intact Myxococcus xanthus cells to visualize type IVa pili and the protein machine that assembles and retracts them (the type IVa pilus machine, or T4PM) in situ, in both the piliated and nonpiliated states, at a resolution of 3 to 4 nanometers. We found that T4PM comprises an outer membrane pore, four interconnected ring structures in the periplasm and cytoplasm, a cytoplasmic disc and dome, and a periplasmic stem. By systematically imaging mutants lacking defined T4PM proteins or with individual proteins fused to tags, we mapped the locations of all 10 T4PM core components and the minor pilins, thereby providing insights into pilus assembly, structure, and function.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chang, Yi-Wei -- Rettberg, Lee A -- Treuner-Lange, Anke -- Iwasa, Janet -- Sogaard-Andersen, Lotte -- Jensen, Grant J -- R01 GM094800B/GM/NIGMS NIH HHS/ -- Howard Hughes Medical Institute/ -- New York, N.Y. -- Science. 2016 Mar 11;351(6278):aad2001. doi: 10.1126/science.aad2001. Epub 2016 Mar 10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉California Institute of Technology, Pasadena, CA 91125, USA. Howard Hughes Medical Institute, Pasadena, CA 91125, USA. ; Howard Hughes Medical Institute, Pasadena, CA 91125, USA. ; Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany. ; University of Utah, Salt Lake City, UT 84112, USA. ; California Institute of Technology, Pasadena, CA 91125, USA. Howard Hughes Medical Institute, Pasadena, CA 91125, USA. jensen@caltech.edu.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26965631" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Adhesion ; Cryoelectron Microscopy ; Fimbriae, Bacterial/genetics/*ultrastructure ; Microscopy, Electron, Transmission ; Models, Molecular ; Mutation ; Myxococcus xanthus/genetics/physiology/*ultrastructure
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 7
    facet.materialart.
    Unknown
    Sedimentological and geochemical characteristics of a fluvial travertine: A case from the eastern Mediterranean region (2013)
    Wiley
    Details
    Publication Date: 2013-11-19
    Description: A sedimentological and geochemical study was performed on the travertines in the southern part of the Uşak geothermal field, western Turkey, to assess the applicability of a fluvial tufa facies model in interpreting late Quaternary travertine deposits developed along the stream valleys that follow fault and fracture systems. Modern thermal (31 to 38ºC) springs are found on the floor of the valley between 480 m and 520 m above sea-level. The distribution and nature of travertine facies were determined from natural outcrops. Samples of the travertines and spring water were characterized using a range of geochemical and petrographic methods. Waterfall, slope and pool facies associations consist of various combinations of travertine facies and subordinate detrital facies. Waterfall and slope facies associations of the older deposits occur where the springs emerged onto a hillslope or topographic break. In contrast, the pool facies association developed in depressions or flat areas that were fed by thermal springs. The youngest generation (1.85 ka) precipitated at lower elevations than the older ones (147 to 153 ka). Stable carbon and oxygen isotope values of the Aksaz travertines range between +4.3‰ and +6.3‰ (Vienna Pee Dee Belemnite) and -12.6‰ and -7.2‰ (Vienna Pee Dee Belemnite), respectively. The high δ 13 C values suggest that the thermal waters were charged with isotopically heavy CO 2 of deep origin. Based on palaeotemperature calculations, the temperatures of the palaeosprings are slightly higher (up to 44ºC) than the present equivalents, but sometimes the temperature is lower, probably due to mixing with the stream water. Although the thermal waters occasionally are impeded by fluvial activity, travertine precipitation occurs in the protected parts of the Aksaz Stream valley. This contribution highlights the applicability of the fluvial facies model for tufa for the interpretation of travertine deposits worldwide. This article is protected by copyright. All rights reserved.
    Print ISSN: 0037-0746
    Electronic ISSN: 1365-3091
    Topics: Geosciences
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    Marine Aerosol Production via Detrainment of Bubble Plumes Generated in Natural Seawater with a Forced‐Air Venturi (2019)
    Wiley
    Details
    Publication Date: 2019
    Description: Abstract During September‐October 2016, a marine aerosol generator configured with forced‐air Venturis was deployed at two biologically productive and two oligotrophic regions of the western North Atlantic Ocean to investigate factors that modulate primary marine aerosol (PMA) production. The generator produced representative bubble size distributions with Hinze scales (0.32 to 0.95 mm radii) and void fractions (0.011 to 0.019 Lair Lsw‐1) that overlapped those of plumes produced in the surface ocean by breaking wind waves. Hinze scales and void fractions of bubble plumes varied among seawater hydrographic regions, whereas corresponding peaks and widths of bubble size distributions did not, suggesting that variability in seawater surfactants drove variability in plume dynamics. Peaks in size‐resolved number production efficiencies for model PMA (mPMA) emitted via bubble bursting in the generator were within a narrow range (0.059 to 0.069 μm geometric mean diameter) over wide ranges in subsurface bubble characteristics, suggesting that subsurface bubble size distributions were not the primary controlling factors as was suggested by previous work. Total mass production efficiencies for mPMA decreased with increasing air detrainment rates, supporting the hypothesis that surface bubble rafts attenuate mPMA mass production. Total mass and Na+ production efficiencies for mPMA from biologically productive seawater were significantly greater than those from oligotrophic seawater. Corresponding mPMA number distributions peaked at smaller sizes during daytime, suggesting that short‐lived surfactants of biological and/or photochemical origin modulated diel variability in marine aerosol production.
    Print ISSN: 2169-897X
    Electronic ISSN: 2169-8996
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 9
    Electronic Resource
    Electronic Resource
    The Chromic Acid Oxidation of Diisopropyl Ether1,2 (1960)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 82 (1960), S. 406-410 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01487a039
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    The Chromic Acid Oxidation of Pinacol1 (1960)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 82 (1960), S. 1401-1405 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01491a030
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...