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  • 1
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    Identification of piezoelectric complex parameters in rings for power ultrasound applications (2012)
    Institute of Physics (IOP)
    Details
    Publication Date: 2012-12-11
    Description: Power ultrasonic devices frequently use Langevin type transducers. These types of transducers are essentially constructed using a sandwich of piezoelectric rings and two metal masses at the ends. The whole assembly is tuned to resonate in a desired main frequency and the total length corresponds to a half of the wavelength of that frequency. Finite element simulations (FEM) are used in the design of such complex structures; however the accuracy of the results is limited by the knowledge of the constitutive properties for the materials used in the transducer construction. Metals like aluminum or steel are well characterized, but the complete set of piezoelectric parameters for piezoceramics are difficult to find in the literature. In the few cases where the manufacturer gives the complete set of parameters, strong differences are observed between simulated and experimental data. In this work a novel methodology proposed by our research group is applied in the case of piezoelectri...
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Institute of Physics (IOP)
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  • 2
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    Worldwide scientific publishing activity (2002)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2002-07-30
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Perez-Iratxeta, Carolina -- Andrade, Miguel A -- New York, N.Y. -- Science. 2002 Jul 26;297(5581):519.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12143877" target="_blank"〉PubMed〈/a〉
    Keywords: *Developed Countries ; *Developing Countries ; *Medline ; *Publishing/trends ; Research Support as Topic
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Loss of fish actinotrichia proteins and the fin-to-limb transition (2010)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2010-06-25
    Description: The early development of teleost paired fins is strikingly similar to that of tetrapod limb buds and is controlled by similar mechanisms. One early morphological divergence between pectoral fins and limbs is in the fate of the apical ectodermal ridge (AER), the distal epidermis that rims the bud. Whereas the AER of tetrapods regresses after specification of the skeletal progenitors, the AER of teleost fishes forms a fold that elongates. Formation of the fin fold is accompanied by the synthesis of two rows of rigid, unmineralized fibrils called actinotrichia, which keep the fold straight and guide the migration of mesenchymal cells within the fold. The actinotrichia are made of elastoidin, the components of which, apart from collagen, are unknown. Here we show that two zebrafish proteins, which we name actinodin 1 and 2 (And1 and And2), are essential structural components of elastoidin. The presence of actinodin sequences in several teleost fishes and in the elephant shark (Callorhinchus milii, which occupies a basal phylogenetic position), but not in tetrapods, suggests that these genes have been lost during tetrapod species evolution. Double gene knockdown of and1 and and2 in zebrafish embryos results in the absence of actinotrichia and impaired fin folds. Gene expression profiles in embryos lacking and1 and and2 function are consistent with pectoral fin truncation and may offer a potential explanation for the polydactyly observed in early tetrapod fossils. We propose that the loss of both actinodins and actinotrichia during evolution may have led to the loss of lepidotrichia and may have contributed to the fin-to-limb transition.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zhang, Jing -- Wagh, Purva -- Guay, Danielle -- Sanchez-Pulido, Luis -- Padhi, Bhaja K -- Korzh, Vladimir -- Andrade-Navarro, Miguel A -- Akimenko, Marie-Andree -- MC_U137761446/Medical Research Council/United Kingdom -- Canadian Institutes of Health Research/Canada -- England -- Nature. 2010 Jul 8;466(7303):234-7. doi: 10.1038/nature09137. Epub 2010 Jun 23.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉CAREG, Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20574421" target="_blank"〉PubMed〈/a〉
    Keywords: Animal Structures/*anatomy & histology/embryology/*physiology ; Animals ; *Biological Evolution ; Collagen/chemistry/metabolism ; Ectoderm/embryology/metabolism ; Embryo, Nonmammalian/anatomy & histology/embryology/metabolism ; Evolution, Molecular ; Extremities/anatomy & histology/embryology/*physiology ; Fish Proteins/*deficiency/genetics/metabolism ; Gene Expression Profiling ; Gene Expression Regulation, Developmental ; Gene Knockdown Techniques ; Limb Buds/anatomy & histology/embryology/metabolism ; Models, Biological ; Phylogeny ; Zebrafish/*anatomy & histology/embryology/genetics/*metabolism ; Zebrafish Proteins/deficiency/genetics/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 4
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    Identification of LRRC8 heteromers as an essential component of the volume-regulated anion channel VRAC (2014)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2014-05-03
    Description: Regulation of cell volume is critical for many cellular and organismal functions, yet the molecular identity of a key player, the volume-regulated anion channel VRAC, has remained unknown. A genome-wide small interfering RNA screen in mammalian cells identified LRRC8A as a VRAC component. LRRC8A formed heteromers with other LRRC8 multispan membrane proteins. Genomic disruption of LRRC8A ablated VRAC currents. Cells with disruption of all five LRRC8 genes required LRRC8A cotransfection with other LRRC8 isoforms to reconstitute VRAC currents. The isoform combination determined VRAC inactivation kinetics. Taurine flux and regulatory volume decrease also depended on LRRC8 proteins. Our work shows that VRAC defines a class of anion channels, suggests that VRAC is identical to the volume-sensitive organic osmolyte/anion channel VSOAC, and explains the heterogeneity of native VRAC currents.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Voss, Felizia K -- Ullrich, Florian -- Munch, Jonas -- Lazarow, Katina -- Lutter, Darius -- Mah, Nancy -- Andrade-Navarro, Miguel A -- von Kries, Jens P -- Stauber, Tobias -- Jentsch, Thomas J -- New York, N.Y. -- Science. 2014 May 9;344(6184):634-8. doi: 10.1126/science.1252826. Epub 2014 Apr 10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Leibniz-Institut fur Molekulare Pharmakologie (FMP), Berlin.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24790029" target="_blank"〉PubMed〈/a〉
    Keywords: Agammaglobulinemia/genetics ; *Cell Size ; Chloride Channels/*metabolism ; Gene Knockout Techniques ; Genome-Wide Association Study ; HCT116 Cells ; HEK293 Cells ; Humans ; Membrane Proteins/genetics/*metabolism ; Mutation ; Protein Multimerization ; RNA Interference ; RNA, Small Interfering/genetics ; Taurine/metabolism ; Transfection
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 5
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    Hofstadter spectra in two-dimensional superlattice potentials with arbitrary modulation strength (1995)
    American Physical Society
    Details
    Publication Date: 1995-11-15
    Print ISSN: 0163-1829
    Electronic ISSN: 1095-3795
    Topics: Physics
    Published by American Physical Society
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  • 6
    Electronic Resource
    Electronic Resource
    Non-uniformities and superimposed competition in a model of an autocatalytic network formed by error-prone self-replicative species (1993)
    Springer
    Bulletin of mathematical biology 55 (1993), S. 417-449 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The particular dynamics of the previously proposed model of a catalytic network formed byn error-prone self-replicative species without and with superimposed competition is analysed. In the first case, two situations are studied in detail: a uniform network in which all the species are inter-coordinated in the same way, and a network with a species differentiated in its catalytic relation with the remaining elements. In the second case, the superimposed competition is introduced at two levels: first, as an asymmetry in one of the network species amplification factor considering a null self-catalytic vector, and secondly, as a non-null self-catalytic vector with no asymmetry in the other propertics of the species. This kind of system does not present complex behaviour and can be adequately deseribed by performing a standard linear analysis, which gives direct information on the asymptotic behaviour of the sytem. Finally, the biological implications of this analysis within the framework of biological evolution are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460890
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  • 7
    Electronic Resource
    Electronic Resource
    A model of an autocatalytic network formed by error-prone self-replicative species (1993)
    Springer
    Bulletin of mathematical biology 55 (1993), S. 385-415 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A generalized model ofn catalytically-coupled self-replicative molecules witherror-prone replication is presented. A generalized mathematical formulation of this model and the outline of its asymptotic behaviour have been developed. Due to the complexity of the model, only in simple situations is it possible to draw general conclusions from the standard analysis. Some complex situations are illustrated by means of numerical integration of particular examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460889
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  • 8
    Electronic Resource
    Electronic Resource
    Challenging times for bioinformatics (1995)
    [s.l.] : Nature Publishing Group
    Nature 376 (1995), S. 647-648 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR-On July 28, 1995, the timely public release of the complete DNA sequence of Haemophilus influenzae Rd made the world of biology richer, in one day, by 1,830,137 characters of genetic information encoding a complete bacterial construction kit of 1,743 predicted protein genes1. While marveling at ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/376647a0
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  • 9
    Electronic Resource
    Electronic Resource
    Structural study of the development of ocularity domains using a neural network model (1996)
    Springer
    Biological cybernetics 74 (1996), S. 243-254 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract.  We present a model for the development of ocularity domains in the visual cortex of mammals during the embryonic stage. We model the thalamo-cortical pathway with a self-organising neural network with two source layers, each of them serving different retinae, and one target layer, where the connections end. The connectivity between the source layers and the target layer is driven by Hebbian learning. In both the source layers and the target layer we assume excitatory lateral signal diffusion between proximal neurons that causes them to be correlated. According to the developmental state being modelled, we do not consider either correlation or anti-correlation between the signals originated in neurons of different retinae. The basic assumptions made are proved to be sufficient to attain a distribution of connections arranged in ocularity domains. The dependence of the geometry of the ocularity domains on the parameters of the model is analysed and a correlation between the width of the signal diffusion and the extent of the domains is found. The generality of the assumptions made allows an easy translation of the model to explain the development of other elements of the sensory nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00652225
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  • 10
    Electronic Resource
    Electronic Resource
    Structural study of the development of ocularity domains using a neural network model (1996)
    Springer
    Biological cybernetics 74 (1996), S. 243-254 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract We present a model for the development of ocularity domains in the visual cortex of mammals during the embryonic stage. We model the thalamo-cortical pathway with a self-organising neural network with two source layers, each of them serving different retinae, and one target layer, where the connections end. The connectivity between the source layers and the target layer is driven by Hebbian learning. In both the source layers and the target layer we assume excitatory lateral signal diffusion between proximal neurons that causes them to be correlated. According to the developmental state being modelled, we do not consider either correlation or anti-correlation between the signals originated in neurons of different retinae. The basic assumptions made are proved to be sufficient to attain a distribution of connections arranged in ocularity domains. The dependence of the geometry of the ocularity domains on the parameters of the model is analysed and a correlation between the width of the signal diffusion and the extent of the domains is found. The generality of the assumptions made allows an easy translation of the model to explain the development of other elements of the sensory nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00652225
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