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  • 1
    Keywords: Auroras
    Type of Medium: Book
    Pages: 36 S , Ill
    Series Statement: Geofysiske Publikasjoner 20,9
    Uniform Title: Results of auroral observations at Tromsø and Oslo from the four winters 1953 - 54 to 1956 - 57
    Language: English
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  • 2
    Keywords: Life sciences ; Oncology ; Biochemistry ; Cell biology ; Life Sciences ; Life Sciences ; Oncology ; Biochemistry ; Cytology ; Histone Code ; Gene Therapy methods ; Medical Oncology ; Neoplasms therapy ; Congresses ; Aufsatzsammlung ; Genregulation ; Histone ; Molekulargenetik ; Cytostatikum ; Arzneimittelentwicklung ; Genregulation ; Histone ; Molekulargenetik ; Cytostatikum ; Arzneimittelentwicklung
    Description / Table of Contents: Methylation of DNA at cytosine residues as well as post-translational modifications of histones, including phosphorylation, acetylation, methylation and ubiquitylation, contribute to the epigenetic information carried by chromatin. These changes play an important role in the regulation of gene expression by modulating the access of regulatory factors to the DNA. The use of a combination of biochemical, genetic and structural approaches has allowed demonstration of the role of chromatin structure in transcriptional control. The structure of nucleosomes has been elucidated and enzymes involved in DNA or histone modifications have been extensively characterized. Since deregulation of epigenetic marks has been reported in many cancers, a better understanding of the underlying molecular mechanisms bears the promise that new drug targets may soon be found. The newest developments in this quickly developing field are presented in this book.
    Type of Medium: Online Resource
    Pages: Online-Ressource (XIV, 215 p, online resource)
    ISBN: 9783540376330
    Series Statement: Ernst Schering Research Foundation Workshop 57
    RVK:
    RVK:
    Language: English
    Note: Includes bibliographical references
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  • 3
    Publication Date: 2017-12-14
    Description: Surface melt and subsequent firn air depletion can ultimately lead to disintegration of Antarctic ice shelves1,2 causing grounded glaciers to accelerate3 and sea level to rise. In the Antarctic Peninsula, foehn winds enhance melting near the grounding line4, which in the recent past has led to the disintegration of the most northerly ice shelves5,6. Here, we provide observational and model evidence that this process also occurs over an East Antarctic ice shelf, where meltwaterinduced firn air depletion is found in the grounding zone. Unlike the Antarctic Peninsula, where foehn events originate from episodic interaction of the circumpolar westerlies with the topography, in coastal East Antarctica high temperatures are caused by persistent katabatic winds originating from the ice sheet’s interior. Katabatic winds warm and mix the air as it flows downward and cause widespread snow erosion, explaining 〉3 K higher near-surface temperatures in summer and surface melt doubling in the grounding zone compared with its surroundings. Additionally, these winds expose blue ice and firn with lower surface albedo, further enhancing melt. The in situ observation of supraglacial flow and englacial storage of meltwater suggests that ice-shelf grounding zones in East Antarctica, like their Antarctic Peninsula counterparts, are vulnerable to hydrofracturing7.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 4
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    In:  EPIC3EGU General Assembly 2016, Vienna, Austria, 2016-04-17-2016-04-22
    Publication Date: 2017-10-17
    Description: Ice-shelf channels (along-flow lineations in which ice is thinner) are ubiquitous in Antarctic ice shelves. Although these features are readily visible in satellite imagery, ice-thickness and ice-velocity variations in their surrounding are typically heavily undersampled. Ice-shelf channels focus channelized melting and significantly alter the basal mass balance (and hence ice-shelf stability) on short horizontal scales. Here we use interferometrically-derived TandDEM-X digital elevation models and ice-flow velocities with a horizontal gridding of 125 m illustrating the ice-shelf dynamics of the Roi Baudouin Ice Shelf, Dronning Maud Land (East Antarctica) in unprecedented detail. Using ground-based GPS surface elevation, we demonstrate that TanDEM-X is an ideal sensor to map the channel morphology at the ice-shelf surface. We find velocity anomalies surrounding the channels along the entire ice shelf potentially indicating the presence of locally elevated basal melt rates. Using mass conservation in a Lagrangian framework, we find basal melt rates averaging 0.4 m/a in the middle of the ice shelf and peaking at 12 m/a inside some channels.We illustrate the sensitivity of the method with respect to systematic biases in elevation/velocity and also with respect to lateral variations of the depth-density relationship. With the increased availability of high-resolution radar satellites (such as Sentinel1), the techniques presented here could be applied on an pan-Antarctic scale to map basal melting both in space and time at high-resolution.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 5
    Publication Date: 2017-05-22
    Description: Ice-shelf channels are long curvilinear tracts of thin ice found on Antarctic ice shelves. Many of them originate near the grounding line, but their formation mechanisms remain poorly understood. Here we use ice-penetrating radar data from Roi Baudouin Ice Shelf, East Antarctica, to infer that the morphology of several ice-shelf channels is seeded upstream of the grounding line by large basal obstacles indenting the ice from below. We interpret each obstacle as an esker ridge formed from sediments deposited by subglacial water conduits, and calculate that the eskers’ size grows towards the grounding line where deposition rates are maximum. Relict features on the shelf indicate that these linked systems of subglacial conduits and ice-shelf channels have been changing over the past few centuries. Because ice-shelf channels are loci where intense melting occurs to thin an ice shelf, these findings expose a novel link between subglacial drainage, sedimentation and ice-shelf stability.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 4341-4343 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of heat treatments on the structure and composition of a system consisting of a conductive outer layer made of Al(0.8% Si) thin film, TiW(30:70 at. %) thin film as a diffusion barrier, and a polycrystalline Si substrate was studied. It was established that heat treatments at temperatures ranging between 400 and 500 °C led to the diffusion of Si and Al through the TiW layer, following which Al diffused into the polycrystalline Si, while Si diffused into the Al film. The silicides of TiSi, TiSi2, and intermetallic compounds of Al3Ti and WAl12 were formed at the Al/TiW interface as a result of the 30-min heat treatment at temperatures ranging between 450 and 500 °C.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 6888-6902 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Image blurring as a result of stochastic particle–particle interactions has been investigated for projection electron- and ion-beam lithography systems. A comparative analysis of the currently available analytical theories is presented. The results from these theories are also compared with Monte Carlo simulation results and experimental data. Large variations in results and serious disagreements between the different theoretical approaches are found. We have formulated a new theory on the basis of a simple, analytical approach that overcomes most of the difficulties experienced by earlier theories with two key concepts: consideration of nearest-neighbor interactions only, and a randomization length, over which the interactions are correlated. Our model displays satisfactory functional and numerical agreement with Monte Carlo simulation results over a large range of beam currents, as well as with the only available experimental data. The physical basis of our model also enables us to understand the origins of the discrepancies arising from earlier theories. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 153-155 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a new approach to projection-electron lithography which allows sub-0.1 μm resolution to be achieved with short exposure times and a parallel illumination system. We have printed a grating pattern into PMMA with 0.1 μm linewidths. Our new technique consists of using an angularly limiting filter which differentiates electrons that have traversed a transparent mask in terms of the degree of scattering between the patterned and unpatterned regions.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— A total of 25 human brain tumors and 4 specimens of human brain were rapidly frozen at the time of operation and analyzed for ATP, ADP, AMP, UTP, total nucleoside triphosphates, P-creatine, creatine, inorganic P, creatine kinase, lipid and glycogen. Analyses were made on submicrogram samples dissected from frozen dried sections in order to obtain material as free as possible from admixture with brain, necrotic tissue, blood, etc. A method was developed to estimate the original water content of the frozen dried samples. The brain specimens contained five times as much glycogen as small mammal brains, otherwise the values were similar. The tumors were in fair to excellent energy status. Within the areas chosen for assay, most of ATP and total adenylate were substantially higher than in brain in the case of 5 out of 15 gliomas, 3 of 5 meningiomas, and 1 of 4 schwannomas. UTP was almost invariably higher and other nucleotide triphosphates (besides ATP and UTP) lower than in brain. Glycogen was extremely variable, ranging among the gliomas from 0.05% to 6% of dry wt (4 times the level in the human brains). Creatine plus P-creatine, compared to cerebral cortex levels, ranged from 15 to 85% in gliomas, was about 25% in meningiomas and the only medulloblastoma, and varied between 6 and 8% in the schwannomas. P-Creatine varied more or less in keeping with the energy status. Creatine kinase was exceedingly variable. It was almost zero in the schwannomas, the medulloblastomas, 3 of 5 meningiomas, and 2 of 15 gliomas, whereas in some of the gliomas the activity approached that found in brain.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 32 (2000), S. 347-382 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The relationship between flow in the arteries, particularly the wall shear stresses, and the sites where atherosclerosis develops has motivated much of the research on arterial flow in recent decades. It is now well accepted that it is sites where shear stresses are low, or change rapidly in time or space, that are most vulnerable. These conditions are likely to prevail at places where the vessel is curved; bifurcates; has a junction, a side branch, or other sudden change in flow geometry; and when the flow is unsteady. These flows, often but not always involving flow separation or secondary motions, are also the most difficult ones in fluid mechanics to analyze or compute. In this article we review the modeling studies and experiments on steady and unsteady, two-and three-dimensional flows in arteries, and in arterial geometries most relevant in the context of atherosclerosis. These include studies of normal vessels-to identify, on the basis of the fluid mechanics, lesion foci-and stenotic vessels, to model and measure flow in vessels after the lesions have evolved into plaques sufficiently large to significantly modify the flow. We also discuss recent work that elucidates many of the pathways by which mechanical forces, primarily the wall shear stresses, are transduced to effect changes in the arterial wall at the cellular, subcellular, and genetic level.
    Type of Medium: Electronic Resource
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