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  • Electronic Resource  (2)
  • 1995-1999  (1)
  • 1980-1984  (1)
  • Cleavage stimulation factor  (1)
  • acoustic microscopy  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of nondestructive evaluation 2 (1981), S. 203-207 
    ISSN: 1573-4862
    Keywords: ultrasonics ; synthetic aperture ; spatial frequency ; interior imaging ; acoustic microscopy ; defect detection ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A new acoustic synthetic aperture geometry is demonstrated in which the image field is sampled in the spatial frequency domain. This means the sampled field is recorded in a particularly convenient form for presentation to the back propagation algorithms used to reconstruct the field at the object plane. The method has applications in interior visualization. It is difficult to image the interior of solid objects using lens based imaging systems because a different lens geometry must be used for each distinct object material. The system presented here overcomes such problems since both the angular variation of the transmission coefficient at the object-water interface and the aberrations introduced by the velocity mismatch at the object surface may be readily compensated for in the back propagation routine. Experimental results are presented illustrating the detection of four half wavelength diameter defects, spaced by three wavelengths, at a depth of eight wavelengths below the surface of an aluminum block.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1617-4623
    Keywords: Key words Cleavage and polyadenylation specificity factor ; Cleavage stimulation factor ; Drosophila melanogaster ; mRNA processing ; Additional sex combs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Processing of the 3′ end of mRNA precursors depends on several proteins. The multisubunit cleavage and polyadenylation specificity factor (CPSF) is required for cleavage of the mRNA precursor as well as polyadenylation. CPSF interacts with the cleavage stimulatory factor complex (CstF), and this interaction increases the specificity of binding. Following cleavage downstream of the AAUAAA site, CPSF and poly(A) polymerase (PAP) are required for efficient polyadenylation. Recently, it has been shown that 160-kDa subunit of CPSF interacts directly with the 77-kDa subunit of CstF, which is homologous to the product encoded by the Drosophila gene su(f), and with PAP. Here we report the cloning and characterization of a Drosophila homologue of CPSF-160. The 1329-amino acid dCPSF protein exhibits about 45% and 20% sequence identity, respectively, to its mammalian and yeast counterparts over its entire length. We show that the CPSF homologue is expressed throughout development and that CPSF is essential for viability. Mutations in the cpsf gene did not alter the phenotype of homozygous su(f) mutations, suggesting that, for most genes, processing of 3′ termini is not sensitive to small changes in cpsf and su(f) dosage.
    Type of Medium: Electronic Resource
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