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  • 2015-2019  (64)
  • 1
    Publication Date: 2018-11-09
    Description: The Canadian Sea Ice and Snow Evolution (CanSISE) Network is a climate research network focused on developing and applying state-of-the-art observational data to advance dynamical prediction, projections, and understanding of seasonal snow cover and sea ice in Canada and the circumpolar Arctic. This study presents an assessment from the CanSISE Network of the ability of the second-generation Canadian Earth System Model (CanESM2) and the Canadian Seasonal to Interannual Prediction System (CanSIPS) to simulate and predict snow and sea ice from seasonal to multi-decadal timescales, with a focus on the Canadian sector. To account for observational uncertainty, model structural uncertainty, and internal climate variability, the analysis uses multi-source observations, multiple Earth system models (ESMs) in Phase 5 of the Coupled Model Intercomparison Project (CMIP5), and large initial-condition ensembles of CanESM2 and other models. It is found that the ability of the CanESM2 simulation to capture snow-related climate parameters, such as cold-region surface temperature and precipitation, lies within the range of currently available international models. Accounting for the considerable disagreement among satellite-era observational datasets on the distribution of snow water equivalent, CanESM2 has too much springtime snow mass over Canada, reflecting a broader northern hemispheric positive bias. Biases in seasonal snow cover extent are generally less pronounced. CanESM2 also exhibits retreat of springtime snow generally greater than observational estimates, after accounting for observational uncertainty and internal variability. Sea ice is biased low in the Canadian Arctic, which makes it difficult to assess the realism of long-term sea ice trends there. The strengths and weaknesses of the modelling system need to be understood as a practical tradeoff: the Canadian models are relatively inexpensive computationally because of their moderate resolution, thus enabling their use in operational seasonal prediction and for generating large ensembles of multidecadal simulations. Improvements in climate-prediction systems like CanSIPS rely not just on simulation quality but also on using novel observational constraints and the ready transfer of research to an operational setting. Improvements in seasonal forecasting practice arising from recent research include accurate initialization of snow and frozen soil, accounting for observational uncertainty in forecast verification, and sea ice thickness initialization using statistical predictors available in real time.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
    Format: application/pdf
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  • 2
    Publication Date: 2018-12-05
    Description: Recently, second-generation (non-vegetable oil) feedstocks for biodiesel production are receiving significant attention due to the cost and social effects connected with utilising food products for the production of energy products. The Beauty leaf tree (Calophyllum inophyllum) is a potential source of non-edible oil for producing second-generation biodiesel because of its suitability for production in an extensive variety of atmospheric condition, easy cultivation, high fruit production rate, and the high oil content in the seed. In this study, oil was extracted from Beauty leaf tree seeds through three different oil extraction methods. The important physical and chemical properties of these extracted Beauty leaf oils were experimentally analysed and compared with other commercially available vegetable oils. Biodiesel was produced using a two-stage esterification process combining of an acid catalysed pre-esterification process and an alkali catalysed transesterification process. Fatty acid methyl ester (FAME) profiles and important physicochemical properties were experimentally measured and estimated using equations based on the FAME analysis. The quality of Beauty leaf biodiesels was assessed and compared with commercially available biodiesels through multivariate data analysis using PROMETHEE-GAIA software. The results show that mechanical extraction using a screw press produces oil at a low cost, however, results in low oil yields compared with chemical oil extraction. High pressure and temperature in the extraction process increase oil extraction performance. On the contrary, this process increases the free fatty acid content in the oil. A clear difference was found in the physical properties of Beauty leaf oils, which eventually affected the oil to biodiesel conversion process. However, Beauty leaf oils methyl esters (biodiesel) were very consistent physicochemical properties and able to meet almost all indicators of biodiesel standards. Overall this study found that Beauty leaf is a suitable feedstock for producing second-generation biodiesel in commercial scale. Therefore, the findings of this study are expected to serve as the basis for further development of Beauty leaf as a feedstock for industrial scale second-generation biodiesel production.
    Keywords: ddc:330 ; Beauty leaf ; Oil extraction ; Physiochemical properties ; PROMETHEE-GAIA ; Second-generation biodiesel
    Repository Name: EconStor: OA server of the German National Library of Economics - Leibniz Information Centre for Economics
    Language: English
    Type: doc-type:article
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  • 3
    Publication Date: 2016-10-14
    Keywords: natural gas engine, lean-burn, combustion instabilities, gas injection timing (GIT), recurrence plots (RPs), recurrence qualification analysis (RQA)
    Type: paper
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  • 4
    Publication Date: 2019-06-11
    Type: paper
    Format: application/pdf
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  • 5
    Publication Date: 2019-07-13
    Description: The Systems Engineering Project Management Advancement Program (SEPMAP) at NASA Johnson Space Center (JSC) is an employee development program designed to provide graduate level training in project management and systems engineering. The program includes an applied learning project with engineering and integrated science goals requirements. The teams were presented with a task: Collect a representative sample set from a field site using a hexacopter platform, as if performing a scientific reconnaissance to assess whether the site is of sufficient scientific interest to justify exploration by astronauts. Four teams worked through the eighteen-month course to design customized sampling payloads integrated with the hexacopter, and then operate the aircraft to meet sampling requirements of number ( 5) and mass ( 5g each). The "Mars Yard" at JSC was utilized for this purpose. This project activity closely parallels NASA plans for the future exploration of Mars, where remote sites will be reconnoitered ahead of crewed exploration.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-38465 , Lunar and Planetary Science Conference; 20-24 Mar. 2017; The Woodlands, TX; United States
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  • 6
    Publication Date: 2016-07-06
    Description: Familial medullary thyroid cancer (MTC) and its precursor, C cell hyperplasia (CCH), is associated with germline RET mutations causing multiple endocrine neoplasia type 2. However, some rare families with apparent MTC/CCH predisposition do not have a detectable RET mutation. To identify novel MTC/CCH predisposition genes we undertook exome resequencing studies in a family with apparent predisposition to MTC/CCH and no identifiable RET mutation. We identified a novel ESR2 frameshift mutation, c.948delT, which segregated with histological diagnosis following thyroid surgery in family members and demonstrated loss of ESR2 -encoded ERβ expression in the MTC tumour. ERα and ERβ form heterodimers binding DNA at specific oestrogen-responsive elements (EREs) to regulate gene transcription. ERβ represses ERα-mediated activation of the ERE and the RET promoter contains three EREs . In vitro , we showed that ESR2 c.948delT results in unopposed ERα mediated increased cellular proliferation, activation of the ERE and increased RET expression. In vivo , immunostaining of CCH and MTC using an anti-RET antibody demonstrated increased RET expression. Together these findings identify germline ESR2 mutation as a novel cause of familial MTC/CCH and provide important insights into a novel mechanism causing increased RET expression in tumourigenesis.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
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  • 7
    Publication Date: 2015-12-25
    Description: Current theories cannot explain how trans-Neptunian objects (TNOs) either formed in situ or how ultrawide trans-Neptunian binaries (TNBs) exist if they were formed closer to the Sun and were later dispersed during Neptune's migration. Furthermore, no theory can adequately explain the documented clustering of near 0° for TNOs with a  〉 150 au. Here, we show that not only is clustered for the nine long-period TNOs (LPTNOs) with a  〉 200 au, but is also grouped almost as closely. Neither of these orbital elements is randomly distributed for any collection of TNOs investigated, including those that are not in resonance with Neptune, those with q  〉 30 au, q  〉 44 au, and LPTNOs. Every frequency distribution of and indicates that many TNOs were recently affected by Neptune. Based on this study, we propose that TNOs were inside Neptune's orbit in the last few Myr. The TNOs then migrated outwards in a relatively short time period. Ultrawide TNBs never came close to Neptune during this migration, allowing these fragile pairs to remain intact. However, many other TNOs were perturbed as they passed Neptune, resulting in the distribution of orbital elements we see today for all TNOs, including those in the Kuiper belt and the LPTNOs.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 8
    Publication Date: 2015-10-30
    Description: Filtered x-ray diode (XRD) arrays are often used to measure x-ray spectra vs. time from spectrally continuous x-ray sources such as hohlraums. A priori models of the incident x-ray spectrum enable a more accurate unfolding of the x-ray flux as compared to the standard technique of modifying a thermal Planckian with spectral peaks or dips at the response energy of each filtered XRD channel. A model x-ray spectrum consisting of a thermal Planckian, a Gaussian at higher energy, and (in some cases) a high energy background provides an excellent fit to XRD-array measurements of x-ray emission from laser heated hohlraums. If high-resolution measurements of part of the x-ray emission spectrum are available, that information can be included in the a priori model. In cases where the x-ray emission spectrum is not Planckian, candidate x-ray spectra can be allowed or excluded by fitting them to measured XRD voltages. Examples are presented from the filtered XRD arrays, named Dante, at the National Ignition Facility and the Laboratory for Laser Energetics.
    Print ISSN: 0034-6748
    Electronic ISSN: 1089-7623
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
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  • 9
    Publication Date: 2015-11-21
    Description: The conditions under which metal cores formed in silicate-metal planetary bodies in the early Solar System are poorly known. We studied the Buck Mountains 005 (L6) chondrite with serial sectioning, X-ray computed microtomography, and optical and electron microscopy to better understand how metal and troilite were redistributed as a result of a moderately strong (shock stage S4) shock event, as an example of how collisional processes could have contributed to differentiation. The chondrite was recovered on Earth in multiple small pieces, some of which have a prominent, 1.5–3 mm wide holocrystalline shock melt dike that forms a jointed, sheet-like structure, as well as an associated shock vein network. The data suggest that metal and troilite within the dike were melted, sheared, and transported as small parcels of melt, with metal moving out of the dike and along branching veins to become deposited as coarser nodules and veins within largely unmelted host. Troilite also mobilized but partly separated from metal to become embedded as finer-grained particles, vein networks, and emulsions intimately intergrown with silicates. Rock textures and metal compositions imply that shock melts cooled rapidly against relatively cool parent body materials, but that low-temperature annealing occurred by deep burial within the parent body. Our results demonstrate the ability of shock processes to create larger metal accumulations in substantially unmelted meteorite parent bodies, and they have implications for the formation of iron meteorites and for core formation within colliding planetesimals.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
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  • 10
    Publication Date: 2015-02-04
    Description: The large discharge of radioactivity into the northwest Pacific Ocean from the 2011 Fukushima Dai-ichi nuclear reactor accident has generated considerable concern about the spread of this material across the ocean to North America. We report here the first systematic study to our knowledge of the transport of the Fukushima...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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