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  • PANGAEA  (164)
  • Oxford University Press  (9)
  • International Union of Crystallography (IUCr)  (4)
Publikationsart
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Erscheinungszeitraum
  • 1
    Digitale Medien
    Digitale Medien
    X-ray topographic dislocation contrast visible in reflections orthogonal to the Burgers vectors of axial screw dislocations in hexagonal silicon carbide (2001)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 34 (2001), S. 20-26 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Contrast is associated with micropipes in X-ray topographs of SiC crystals obtained with prismatic reflections, representing an apparent violation of the g·b = 0 invisibility criterion. This is explained as a population of basal-plane dislocations with Burgers vectors of the set b = {\textstyle{1 \over 3}}〈11{\bar{2}}0〉 that occur in a high density within a few micrometers of the micropipes, below the resolution of X-ray topography. These basal-plane dislocations could be observed under an electron microscope. The presence of the surfaces of the micropipes influences the dislocation images in the topographs taken with prismatic reflections, often resulting in a band of light contrast along the axes of the micropipes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889800017027
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Harmonic composition of synchrotron white-beam X-ray topographic back-reflection images of basal-cut silicon carbide single-crystal wafers (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 31 (1998), S. 820-822 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Superscrew dislocations are visible in back-reflection synchrotron white-beam X-ray topographs of basal-cut SiC wafers in striking contrast as black rings surrounding white circles, even though such topographs suffer from extensive harmonic contamination. The contributions to the synchrotron white-beam topograph of each member of its series of harmonic reflections, {\bf g}=(0006n), where n=3 to 16, were calculated. Through intensity considerations and comparison with a {\bf g}=00018 topograph taken with Cu Kα1 radiation, the {\bf g}=00024 harmonic was determined to be the most important contributor. The contrast of features lying deep beneath the crystal's surface was attributed to higher harmonics with larger penetration depths.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889898004683
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Superscrew dislocation contrast on synchrotron white-beam topographs: an accurate description of the direct dislocation image (1999)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 32 (1999), S. 516-524 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A kinematic (geometrical) diffraction simulation model has been developed to provide understanding of direct dislocation images on synchrotron white-beam X-ray topographs, and has been successfully applied to illustrate the contrast formation mechanisms involved in images of micropipe-related superscrew dislocations in silicon carbide crystals. The coincidence of the simulations with the contrast features of the superscrew dislocation images, recorded using a series of synchrotron topography techniques, shows that this model is capable of revealing the detailed diffraction behavior of the highly distorted region around the dislocation core and determining the quantitative characteristics of the dislocations. The simulation technique is thus demonstrated to be a simple but efficient method for interpretation of synchrotron topographs, and may be applied to explain the topographic contrast characters of general crystal defects.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889899002939
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Crystallization and preliminary X-ray analysis of human RCC1, the regulator of chromosome condensation (1999)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 55 (1999), S. 272-275 
    Details
    ISSN: 1399-0047
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: RCC1, the regulator of chromosome condensation, is the guanine nucleotide-exchange factor (GEF) of the GTP-binding protein Ran. Its GEF activity on Ran makes it a key element in nucleo-cytoplasmic transport and cell-cycle regulation. Crystals of human RCC1 suitable for X-ray analysis have been obtained using the seeding technique in hanging drops with sodium citrate as a precipitant. The crystals diffract to 1.7 Å at 100 K and belong to the space group P1, with unit-cell parameters a = 49.5, b = 84.3, c = 84.9 Å, α = 113.0, β = 103.9,γ = 103.3°. The Matthews parameter (Vm) and the self-rotation function are consistent with three molecules in the unit cell, which is confirmed by the averaged single isomorphous replacement (SIR) electron-density map.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0907444998007768
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  • 5
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    Signal integration by the CYP1A1 promoter -- a quantitative study (2015)
    Oxford University Press
    Details
    Publikationsdatum: 2015-06-24
    Beschreibung: Genes involved in detoxification of foreign compounds exhibit complex spatiotemporal expression patterns in liver. Cytochrome P450 1A1 ( CYP1A1 ), for example, is restricted to the pericentral region of liver lobules in response to the interplay between aryl hydrocarbon receptor (AhR) and Wnt/β-catenin signaling pathways. However, the mechanisms by which the two pathways orchestrate gene expression are still poorly understood. With the help of 29 mutant constructs of the human CYP1A1 promoter and a mathematical model that combines Wnt/β-catenin and AhR signaling with the statistical mechanics of the promoter, we systematically quantified the regulatory influence of different transcription factor binding sites on gene induction within the promoter. The model unveils how different binding sites cooperate and how they establish the promoter logic; it quantitatively predicts two-dimensional stimulus-response curves. Furthermore, it shows that crosstalk between Wnt/β-catenin and AhR signaling is crucial to understand the complex zonated expression patterns found in liver lobules. This study exemplifies how statistical mechanical modeling together with combinatorial reporter assays has the capacity to disentangle the promoter logic that establishes physiological gene expression patterns.
    Print ISSN: 0305-1048
    Digitale ISSN: 1362-4962
    Thema: Biologie
    Publiziert von Oxford University Press
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
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    The oncogenic triangle of HMGA2, LIN28B and IGF2BP1 antagonizes tumor-suppressive actions of the let-7 family (2016)
    Oxford University Press
    Details
    Publikationsdatum: 2016-05-06
    Beschreibung: The tumor-suppressive let-7 microRNA family targets various oncogene-encoding mRNAs. We identify the let-7 targets HMGA2, LIN28B and IGF2BP1 to form a let-7 antagonizing self-promoting oncogenic triangle. Surprisingly, 3'-end processing of IGF2BP1 mRNAs is unaltered in aggressive cancers and tumor-derived cells although IGF2BP1 synthesis was proposed to escape let-7 attack by APA-dependent (alternative polyadenylation) 3' UTR shortening. However, the expression of the triangle factors is inversely correlated with let-7 levels and promoted by LIN28B impairing let-7 biogenesis. Moreover, IGF2BP1 enhances the expression of all triangle factors by recruiting the respective mRNAs in mRNPs lacking AGO proteins and let-7 miRNAs. This indicates that the downregulation of let-7, largely facilitated by LIN28B upregulation, and the protection of let-7 target mRNAs by IGF2BP1-directed shielding in mRNPs synergize in enhancing the expression of triangle factors. The oncogenic potential of this triangle was confirmed in ovarian cancer (OC)-derived ES-2 cells transduced with let-7 targeting decoys. In these, the depletion of HMGA2 only diminishes tumor cell growth under permissive conditions. The depletion of LIN28B and more prominently IGF2BP1 severely impairs tumor cell viability, self-renewal and 2D as well as 3D migration. In conclusion, this suggests the targeting of the HMGA2-LIN28B-IGF2BP1 triangle as a promising strategy in cancer treatment.
    Print ISSN: 0305-1048
    Digitale ISSN: 1362-4962
    Thema: Biologie
    Publiziert von Oxford University Press
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    facet.materialart.
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    Solving or resolving global tomographic models with spherical wavelets, and the scale and sparsity of seismic heterogeneity (2011)
    Oxford University Press
    Details
    Publikationsdatum: 2011-09-29
    Beschreibung: SUMMARY We propose a class of spherical wavelet bases for the analysis of geophysical models and for the tomographic inversion of global seismic data. Its multiresolution character allows for modelling with an effective spatial resolution that varies with position within the Earth. Our procedure is numerically efficient and can be implemented with parallel computing. We discuss two possible types of discrete wavelet transforms in the angular dimension of the cubed sphere. We describe benefits and drawbacks of these constructions and apply them to analyse the information in two published seismic wave speed models of the mantle, using the statistics of wavelet coefficients across scales. The localization and sparsity properties of wavelet bases allow finding a sparse solution to inverse problems by iterative minimization of a combination of the ℓ 2 norm of the data residuals and the ℓ 1 norm of the model wavelet coefficients. By validation with realistic synthetic experiments we illustrate the likely gains from our new approach in future inversions of finite-frequency seismic data.
    Print ISSN: 0956-540X
    Digitale ISSN: 1365-246X
    Thema: Geologie und Paläontologie
    Publiziert von Oxford University Press im Namen von The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 8
    facet.materialart.
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    Developmental regulation of N-terminal H2B methylation in Drosophila melanogaster (2012)
    Oxford University Press
    Details
    Publikationsdatum: 2012-02-28
    Beschreibung: Histone post-translational modifications play an important role in regulating chromatin structure and gene expression in vivo . Extensive studies investigated the post-translational modifications of the core histones H3 and H4 or the linker histone H1. Much less is known on the regulation of H2A and H2B modifications. Here, we show that a major modification of H2B in Drosophila melanogaster is the methylation of the N-terminal proline, which increases during fly development. Experiments performed in cultured cells revealed higher levels of H2B methylation when cells are dense, regardless of their cell cycle distribution. We identified dNTMT (CG1675) as the enzyme responsible for H2B methylation. We also found that the level of N-terminal methylation is regulated by dART8, an arginine methyltransferase that physically interacts with dNTMT and asymmetrically methylates H3R2. Our results demonstrate the existence of a complex containing two methyltransferases enzymes, which negatively influence each other’s activity.
    Print ISSN: 0305-1048
    Digitale ISSN: 1362-4962
    Thema: Biologie
    Publiziert von Oxford University Press
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
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    Staging for distant metastases in operable breast cancer: a suggested expansion of the ESMO guideline recommendation for staging imaging of node-negative, hormonal receptor-negative disease (2013)
    Oxford University Press
    Details
    Publikationsdatum: 2013-01-23
    Beschreibung: We evaluated the impact of staging procedures to detect asymptomatic distant metastases (DM) in the management of women with operable invasive breast cancer (BC, entire cohort: n = 866). Out of 472 patients with lymph node (LN)-negative disease (pN0), DM were found in four cases (detection rate: 0.8%). All four patients presented with established risk factors: hormone receptor (HR)-negative status, HER2-positive status, n = 3; ‘triple-negative’ disease, n = 1. Considering the subgroup of LN-negative patients whose tumors showed the risk factor ‘negative HR status’ ( n = 66), the detection rate of DM was 6%. The detection rates of DM in higher pN categories were as follows: pN1:1.7%; pN2:9.5%; pN3:13.5%. We generally support the international guidelines, including those published by the European Society for Medical Oncology (ESMO) which emphasize that patients with early-stage BC do not profit from radiological staging for the detection of DM and recommend refraining from this. However, we would expand these guidelines and propose that screening should be carried out in node-negative patients whose tumors show established tumor-related risk factors (e.g. HR-negative and HER2-positive status), since in this particular subcohort, the detection rate of DM is with 6% similarly high as that of patients with four to nine positive LNs.
    Print ISSN: 0923-7534
    Digitale ISSN: 1569-8041
    Thema: Medizin
    Publiziert von Oxford University Press
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
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    Recommended Patient-Reported Core Set of Symptoms to Measure in Prostate Cancer Treatment Trials (2014)
    Oxford University Press
    Details
    Publikationsdatum: 2014-07-10
    Beschreibung: The National Cancer Institute (NCI) Symptom Management and Health-Related Quality of Life Steering Committee convened four working groups to recommend core sets of patient-reported outcomes to be routinely incorporated in clinical trials. The Prostate Cancer Working Group included physicians, researchers, and a patient advocate. The group’s process included 1) a systematic literature review to determine the prevalence and severity of symptoms, 2) a multistakeholder meeting sponsored by the NCI to review the evidence and build consensus, and 3) a postmeeting expert panel synthesis of findings to finalize recommendations. Five domains were recommended for localized prostate cancer: urinary incontinence, urinary obstruction and irritation, bowel-related symptoms, sexual dysfunction, and hormonal symptoms. Four domains were recommended for advanced prostate cancer: pain, fatigue, mental well-being, and physical well-being. Additional domains for consideration include decisional regret, satisfaction with care, and anxiety related to prostate cancer. These recommendations have been endorsed by the NCI for implementation.
    Digitale ISSN: 1460-2105
    Thema: Medizin
    Publiziert von Oxford University Press
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