234 research outputs found
Fallout radionuclides in cryoconite and proglacial sediments
No full textThese data describe fallout radionuclide (FRN) activity concentrations for glacial sites around the global cryosphere, including 137Cs, 241Am, and excess 210Pb. Mean, maximum, and minimum FRN activity concentrations are provided for cryoconite at each glacier site, and minimum and maximum FRN activity concentrations are provided for proglacial sediment samples at sites where this data is available. Loss-on-ignition and FRN data are also provided for a selection of individual cryoconite samples. FRN activity concentrations (all in Bq kg-1) are based on gamma and alpha spectrometry, and the methodological approach is described in detail in Clason et al. (in prep.), in addition to original data sources where applicable
Modelling the transfer of supraglacial meltwater to the bed of Leverett Glacier, Southwest Greenland
No full text© Author(s) 2015. This work is distributed under the Creative Commons Attribution 3.0 License. Acknowledgements. We acknowledge the College of Physical Sciences, University of Aberdeen, the Leverhulme Trust through a Study Abroad Studentship and the Swedish Radiation Safety Authority, for funding awarded to C. Clason. Data collection was supported by the UK Natural Environment Research Council (through a studentship to I. Bartholomew and grants to P. Nienow and D. Mair) and the Edinburgh University Moss Centenary Scholarship (I. Bartholomew). We acknowledge I. Joughin for providing InSAR velocity data, and the National Snow and Ice Data Centre, University of Colorado, and J. Bamber for ice thickness data. We thank two anonymous reviewers for their comments which helped to improve the paper.Peer reviewe
Cubature on C^1 space
No full textWe explore in this paper cubature formulas over the space of functions having a first continuous derivative, i.e., C^1. We show that known cubature formulas are not optimal in this case and explain what is the origin of the loss of optimality and how to construct optimal ones; to illustrate we give cubature formulas up to (including) order 9
Fallout radionuclides in cryoconite and proglacial sediments
No full textThese data describe fallout radionuclide (FRN) activity concentrations for glacial sites around the global cryosphere, including 137Cs, 241Am, and excess 210Pb. Mean, maximum, and minimum FRN activity concentrations are provided for cryoconite at each glacier site, and minimum and maximum FRN activity concentrations are provided for proglacial sediment samples at sites where this data is available. Loss-on-ignition and FRN data are also provided for a selection of individual cryoconite samples. FRN activity concentrations (all in Bq kg-1) are based on gamma and alpha spectrometry, and the methodological approach is described in detail in Clason et al. (in prep.), in addition to original data sources where applicable.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV
Accumulation of Environmental Radioactivity on the Surface of a High Arctic Ice Cap (Flade Isblink, NE Greenland)
No full textUnder climatic warming, glaciers are becoming a secondary source of atmospheric contaminants originally released into the environment decades ago. This phenomenon has been well-documented for glaciers near emission sources. However, less is known about polar ice sheets and ice caps. Radionuclides are one of the contaminants that can be remobilised through ice melting and accumulate in cryoconite material on the surface of glaciers. To understand the cycling of radionuclides in polar glacial contexts, we evaluate the radioactivity of cryoconite samples from Flade Isblink, a High Arctic ice cap in northeast Greenland. The measured radioactivity is among the highest reported across the High Arctic and the highest from Greenland. The high variability observed among the samples is explained by considering the different macroscopic features of single cryoconite deposits. The radioactivity source is compatible with the stratospheric reservoir established during atmospheric nuclear tests and with weapons-grade fissile fuel, likely originating from Novaya Zemlya proving grounds. This study shows that the ability of cryoconite to accumulate radioactivity in remote areas is undisputed, highlighting the need for a deeper understanding of the remobilisation of radioactive species in polar glacial contexts
Parallel imaging with nonlinear reconstruction using variational penalties.
No full textA new approach based on nonlinear inversion for autocalibrated parallel imaging with arbitrary sampling patterns is presented. By extending the iteratively regularized GaussNewton method with variational penalties, the improved reconstruction quality obtained from joint estimation of image and coil sensitivities is combined with the superior noise suppression of total variation and total generalized variation regularization. In addition, the proposed approach can lead to enhanced removal of sampling artifacts arising from pseudorandom and radial sampling patterns. This is demonstrated for phantom and in vivo measurements. Magn Reson Med 67:3441, 2012. (C) 2011 Wiley Periodicals, Inc
Accumulation of legacy fallout radionuclides in cryoconite on Isfallsglaciären (Arctic Sweden) and their downstream spatial distribution
No full textThe release of legacy contaminants such as fallout radionuclides (FRNs) in response to glacier retreat is a
process that has received relatively little attention to date, yet may have consequences as a source of secondary contamination as glaciers melt and down-waste in response to a warming climate. The presence of FRNs in glacier-fed catchments is poorly understood in comparison to other contaminants, yet there is now emerging evidence from multiple regions of the global cryosphere for substantially augmented FRN activities in cryoconite. Here we report concentrated FRNs in both cryoconite and proglacial sediments from the Isfallsglaciären catchment in Arctic Sweden. Activities of some FRNs in cryoconite are 2 orders of magnitude above those found elsewhere in the catchment, and above the activities found in other environmental matrices outside of nuclear exclusion zones. We also describe the presence of the shortlived cosmogenic radionuclide 7Be in cryoconite samples, highlighting the importance of meltwater–sediment interactions in radionuclide accumulation in the ice surface environment. It is currently unknown whether high accumulations of fallout radionuclides in glaciers have the potential to impact local environmental quality through down-wasting and
downstream transport of contaminants to the proglacial environment through interaction with sediments and meltwater. We thus recommend that future research in this field focusses on processes of accumulation of FRNs and other environmental contaminants in cryoconite and whether these contaminants are present in quantities harmful for downstream ecosystems
Valve resizing kit product
No full textIndustrial Products. Advertising. Valve resizing kit manufactured by George Olcott Company, Allegan. Client: Earl Clason Advertising (Photographic Negative
BIM : value for real estate developers and owners
No full textThesis (S.M. in Real Estate Development)--Massachusetts Institute of Technology, Dept. of Architecture, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 52-55).The Architecture, Engineering, and Construction industry severely lags behind the manufacturing industry in terms of efficiency and productivity growth. This lag is a result of the fragmented nature of the industry and its resistance to adopting innovative technologies and processes that enable collaboration and efficiency. Building Information Modeling (BIM) is one of these innovations. Since building owners ultimately absorb every cost associated with a building project, they are in the best position to lead the AEC industry into an era of increased productivity through the adoption of collaborative practices and technologies such as BIM. However, owners cannot be expected to venture down this path unless they are aware of the potential value that the proper use of BIM can create for them. Therefore, this paper provides evidence of the value created for owners and developers by the use of BIM, and conveys that evidence in a framework that follows the actual phases and tasks of a real development project. Those phases are as follows: Market Research, Feasibility Analysis, Design, Construction, and Operations. In addition to actual examples of value creation, theoretical examples of future applications are discussed. The value created for owners and developers by implementing BIM on their projects is manifested primarily in the form of improved design quality and savings in time and money.by John C. Clason.S.M.in Real Estate Developmen
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