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  • 1
    Publication Date: 2010-09-28
    Description: The North China craton (NCC) is one of oldest cratons in the world, with crust up to c. 3.8 Ga old, and has a complicated evolution. The main Early Precambrian geological events and key tectonic issues are as follows. (1) Old continental nuclei have been recognized in the NCC, and the oldest remnants of granitic gneiss and supracrustal rocks are 3.8 Ga old. The main crustal growth in the NCC took place at 2.9-2.7 Ga. The NCC can be divided into several microblocks, which are separated by Archaean greenstone belts that represent continental accretion surrounding the old continental nuclei. (2) By 2.5 Ga, the microblocks amalgamated to form a coherent craton by continent-continent, arc-continent or arc-arc collisions. The tectonic processes in Neoarchaean and modern times appear to differ more in degree than in principle. Extensive intrusion of K-granite sills and mafic dykes and regional upper amphibolite- to granulite-facies metamorphism occurred, and marked the beginning of cratonization in the NCC. Coeval ultramafic-mafic and syenitic dykes of c. 2500 Ma in Eastern Hebei indicate that the NCC became a stable, thick and huge continent at the end of the Archaean, and probably was a part of the Neoarchaean supercontinent that has been suggested by previous studies. (3) In the period between 2500 and 2350 Ma, the NCC was tectonically inactive, but the development of a Palaeoproterozoic volcanic and granitic rocks occurred between 2300 and 1950 Ma. The volcanic-sedimentary rocks are termed Palaeoproterozoic mobile belts; these have a linear distribution, and were affected by strong folding and metamorphism at 1900-1850 Ma, and intruded by granites and pegmatites at 1850-1800 Ma. The Palaeoproterozoic mobile belts formed and evolved within the craton or continental margin (epicontinental geosyncline). Some 2.30-1.95 Ga rift-margin, passive continental margin deposits, analogous arc or back-arc assemblages, as well as HP and HT-UHT metamorphic complexes seem to be comparable with many in the late Phanerozoic orogenic belts. Regarding Palaeoproterozoic orogeny in other cratons, it is possible that a global Palaeoproterozoic orogenic event occurred, existed and resulted in the formation of a pre-Rodinian supercontinent at c. 2.0-1.85 Ga. (4) In contrast, the c. 1800 Ma event is an extension-migmatization event, which includes uplift of the lower crust of the NCC as a whole, the emplacement of mafic dyke swarms, continental rifting, and intrusion of an orogenic magmatic association. This event has been considered to be related to the break-up of the pre-Rodinian supercontinent at 1.8 Ga, attributed to a Palaeoproterozoic plume. (5) As HP and HT-UHT metamorphic rocks occur widely in the NCC, their high pressure of 10-14 kbar has attracted attention from researchers, and several continental collisional models have been proposed. However, it is argued that these rocks have much higher geothermal gradient and much slower uplift rate than those in Phanerozoic orogenic belts. Moreover, HP and HT-UHT rocks commonly occur together and are not distributed in linear zones, suggesting that the geological and tectonic implications of these data should be reassessed.
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  • 2
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    In:  Geophysical Research Letters ; Year: 2013 ; Volume: 40 ; Pages: 2125-2130
    Publication Date: 2015-04-01
    Keywords: ddc:550
    Type: http://purl.org/escidoc/metadata/ves/publication-types/article
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  • 3
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    In:  Geophysical Research Letters ; Year: 2013 ; Volume: 40 ; Pages: 2125-2130
    Publication Date: 2015-04-01
    Type: http://purl.org/escidoc/metadata/ves/publication-types/article
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  • 4
    Publication Date: 2014-03-28
    Description: The goal of this paper is to study an initial boundary value problem of stochastic viscoelastic wave equation with nonlinear damping and source terms. Under certain conditions on the initial data: the relaxation function, the indices of nonlinear damping, and source terms and the random force, we prove the local existence and uniqueness of solution by the Galerkin approximation method. Then, considering the relationship between the indices of nonlinear damping and nonlinear source, we give the necessary conditions of global existence and explosion in finite time in some sense of solutions, respectively.
    Print ISSN: 1110-757X
    Electronic ISSN: 1687-0042
    Topics: Mathematics
    Published by Hindawi
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  • 5
    Publication Date: 2014-04-02
    Description: Angiotensin II (Ang II), a biologically active peptide of the renin–angiotensin system (RAS), plays an important role in promoting cell migration via Angiotensin II type 1 receptor (AT1R). In this study, we examined the mechanisms by which Ang II affected cell migration in AT1R-positive MDA-MB-231 human breast cancer cells. Ang II increased cell migration and expression of matrix metalloproteinase (MMP)-2,-9 in a dose-dependent manner. Ang II-mediated cell migration was reduced by specific blocking of MMP-2 and MMP-9, as well as with pretreatment with inhibitors of AT1R, phosphatidylinositol 3-kinase (PI3K), Akt, and NF-κB. Similarly, Ang II-mediated expression of MMP-2,-9 was downregulated by pretreatment with inhibitors of AT1R and PI3K. In addition, Ang II treatment significantly induced phosphorylation of PI3K, Akt, and resulted in increased NF-κB activity. These findings suggest that Ang II activates the AT1R/PI3K/Akt pathway, which further activates IKKα/β and NF-κB, resulting in enhanced expression of MMP-2,-9 and migration in human breast cancer cells. Therefore, targeting Ang II/AT1R/PI3K/Akt/NF-κB signaling could be a novel anti-metastatic therapy for breast cancer. J. Cell. Physiol. © 2014 Wiley Periodicals, Inc.
    Electronic ISSN: 1097-4652
    Topics: Biology , Medicine
    Published by Wiley
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  • 6
    Publication Date: 2014-07-01
    Description: As the world's highest and largest plateau, the Qinghai–Xizang Plateau has experienced a greater warming than the Northern Hemisphere and global averages. This warming has been reported to exhibit an elevation-dependent pattern. However, the finding involved plenty of uncertainties caused by the spatially limited datasets and complex topography. Here, we explored an approach integrating satellite-derived LST data and ground records to generate a spatially continuous air temperature dataset for the plateau grasslands from 2003 to 2012, and then examined influences of elevation/topography on temperature change trends. The derived temperature dataset was validated to be closely correlated with field-station records. Based on the derived spatially continuous temperature datasets, we found an opposite change trend of annually average temperature between Qinghai and Xizang Province. The contrasted trend was obvious in daytime and more so in summer season. By analyzing the temperature trend in relation to elevation, we found an enhanced temperature change trend in higher elevation than in lower elevation for autumn nights and winter temperatures, while the temperature change trends for other seasons were more evident in lower elevation areas. The varying temperature change trends as regulated by elevation implies that temperate grasslands have experienced a more rapid temperature change than alpine grasslands during the past decade. ©2013 Springer-Verlag Wien
    Print ISSN: 0177-798X
    Electronic ISSN: 1434-4483
    Topics: Geosciences , Physics
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  • 7
    Publication Date: 2014-04-22
    Description: Background: The zygomycete fungi like Rhizomucor miehei have been extensively exploited for the production of various enzymes. As a thermophilic fungus, R. miehei is capable of growing at temperatures that approach the upper limits for all eukaryotes. To date, over hundreds of fungal genomes are publicly available. However, Zygomycetes have been rarely investigated both genetically and genomically. Results: Here, we report the genome of R. miehei CAU432 to explore the thermostable enzymatic repertoire of this fungus. The assembled genome size is 27.6-million-base (Mb) with 10,345 predicted protein-coding genes. Even being thermophilic, the G + C contents of fungal whole genome (43.8%) and coding genes (47.4%) are less than 50%. Phylogenetically, R. miehei is more closerly related to Phycomyces blakesleeanus than to Mucor circinelloides and Rhizopus oryzae. The genome of R. miehei harbors a large number of genes encoding secreted proteases, which is consistent with the characteristics of R. miehei being a rich producer of proteases. The transcriptome profile of R. miehei showed that the genes responsible for degrading starch, glucan, protein and lipid were highly expressed. Conclusions: The genome information of R. miehei will facilitate future studies to better understand the mechanisms of fungal thermophilic adaptation and the exploring of the potential of R. miehei in industrial-scale production of thermostable enzymes. Based on the existence of a large repertoire of amylolytic, proteolytic and lipolytic genes in the genome, R. miehei has potential in the production of a variety of such enzymes.
    Electronic ISSN: 1471-2164
    Topics: Biology
    Published by BioMed Central
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  • 8
    Publication Date: 2014-04-05
    Description: Background: Enzymes of the cellulose synthase (CesA) family and CesA-like (Csl) families are responsible for the synthesis of celluloses and hemicelluloses, and thus are of great interest to bioenergy research. We studied the occurrences and phylogenies of CesA/Csl families in diverse plants and algae by comprehensive data mining of 82 genomes and transcriptomes. Results: We found that 1) charophytic green algae (CGA) have orthologous genes in CesA, CslC and CslD families; 2) liverwort genes are found in the CesA, CslA, CslC and CslD families; 3) The fern Pteridium aquilinum not only has orthologs in these conserved families but also in the CslB, CslH and CslE families; 4) basal angiosperms, e.g. Aristolochia fimbriata, have orthologs in these families too; 5) gymnosperms have genes forming clusters ancestral to CslB/H and to CslE/J/G respectively; 6) CslG is found in switchgrass and basal angiosperms; 7) CslJ is widely present in dicots and monocots; 8) CesA subfamilies have already diversified in ferns. Conclusions: We speculate that: (i) ferns and horsetails might both have CslH enzymes, responsible for the synthesis of mixed-linkage glucans and (ii) CslD and similar genes might be responsible for the synthesis of mannans in CGA. Our findings led to a more detailed model of cell wall evolution and suggested that gene loss played an important role in the evolution of Csl families. We also demonstrated the usefulness of transcriptome data in the study of plant cell wall evolution and diversity.
    Electronic ISSN: 1471-2164
    Topics: Biology
    Published by BioMed Central
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  • 9
    Publication Date: 2014-04-09
    Description: This paper introduces an invariant Hough random ferns (IHRF) incorporating rotation and scale invariance into the local feature description, random ferns classifier training, and Hough voting stages. It is especially suited for object detection under changes in object appearance and scale, partial occlusions, and pose variations. The efficacy of this approach is validated through experiments on a large set of challenging benchmark datasets, and the results demonstrate that the proposed method outperforms state-of-the-art conventional methods such as bounding-box-based and part-based methods. Additionally, we also propose an efficient clustering scheme based on the local patches’ appearance and their geometric relations that can provide pixel-accurate, top-down segmentations from IHRF back-projections. This refined segmentation can be used to improve the quality of online object tracking because it avoids the drifting problem. Thus, an online tracking framework based on IHRF, which is trained and updated in each frame to distinguish and segment the object from the background, is established. Finally, the experimental results on both object segmentation and long-term object tracking show that this method yields accurate and robust tracking performance in a variety of complex scenarios, especially in cases of severe occlusions and nonrigid deformations.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
    Published by Hindawi
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  • 10
    Publication Date: 2012-04-04
    Description: Langmuir DOI: 10.1021/la300239c
    Print ISSN: 0743-7463
    Electronic ISSN: 1520-5827
    Topics: Chemistry and Pharmacology
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