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  • 1
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: It is known that an increase in plasma density in sources of multicharged ions leads to a substantial increase of ion current and slightly improves the ion distribution over charge states. The validity of this statement was verified in experiments with plasma densities not exceeding several units of 1012 cm−3. In the present work it is demonstrated experimentally that, for the electron densities exceeding 1013 cm−3, the regime of plasma confinement in a trap changes significantly and the quasigasdynamic regime of plasma confinement is realized. Comparison of numerical simulations and experimental data showed the essential influence of the anisotropy of electron velocity distribution in a plasma on the ion charge state distribution. This allows looking for the optimal conditions for the creation of highly charged ions in plasma. In this article we also address problems of plasma stability in an axisymmetric mirror trap under powerful microwave pumping. First experiments on ion extraction from a dense plasma pumped by millimeter wave radiation are described. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1090-6533
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The soft X-ray line emission from a pulsed electron-cyclotron resonance discharge in argon, maintained by a high-power millimeter-wavelength beam in a magnetic mirror trap, was studied using a multilayer mirror X-ray monochromator. The X-ray spectrum was measured, and the absolute spectral intensity of emission was determined in a 6–17 nm wavelength range. The discharge can be used as an effective source of soft X-rays with an efficiency of the microwave to X-ray power conversion on a level of 10% and a maximum spectral power density of 7.3 kW/nm at a wavelength of 9 nm.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 101 (1991), S. 115-124 
    ISSN: 1573-4919
    Keywords: DNA topoisomerase I ; camptothecin ; αA-globin gene ; c-Ha-ras gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary Two molecular forms of topoisomerase I differing in size and sensitivity to camptothecin were isolated from calf thymus. Mapping of topo I cleavage sites of the cloned chicken αA-globin and human c-Ha-ras genes was carried out. Camptothecin was shown to affect site specificity of the topoisomerases.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 242 (1994), S. 649-652 
    ISSN: 1617-4623
    Keywords: α-Globin domain ; Hypersensitive sites ; Locus control region ; Chromatin structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The distribution of DNase I hypersensitive sites upstream of the chicken α-globin gene cluster was studied. A group of hypersensitive sites with a complex pattern of tissue specificity, including erythroid-specific elements, was found at a distance of 11.5–14.5 kb upstream of the π gene, the first gene in the cluster. The observations indicate that this area, located upstream of the block of AT-rich sequences and MAR sites (at −8 kb) and upstream of the site of permanent DNA attachment to the nuclear matrix (−3 kb), still belongs to the domain of the α-globin genes.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1617-4623
    Keywords: Key words Chicken alpha-globin gene domain ; Northern analysis ; In situ hybridisation ; ggPRX gene ; -14 gene ; pre-mRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A novel gene transcribed in the direction opposite to that of the globin genes was found in the chicken α-globin gene domain. Northern hybridisation with single-stranded riboprobes revealed that a 4.5-kb poly(A)+ RNA is transcribed in antisense polarity with respect to the globin genes. The transcription unit encoding this RNA seems to overlap the entire cluster of alpha-globin genes and extends at least 15 kb upstream from π, the first of the α-globin genes. This new transcript shows partial sequence homology with that encoded by the human “-14” gene. An oligonucleotide based on part of a restriction fragment of chicken DNA that is 80% homologous to exon 4 of the human “-14” gene hybridises with a 4.5-kb RNA molecule. In situ hybridisation of globin-antisense probes, that detect polyribosomal mRNAs of 1.7 and 2.5 kb on Northern blots, shows these “antisense” transcripts to be present in the cytoplasm. The 4.5-kb RNA is absent in polyribosomal poly(A)+ RNA and may, hence, represent a nuclear pre-mRNA transcribed from the chicken gene that is homologous to the human “-14” gene. The expression of this gene is not specific to erythroid cells; analogous transcripts were also detected in poly(A)+ RNA extracted from a chicken lymphoblastoma cell line (HP50). Taken together, these data allow us to postulate the existence in the chicken genome of a novel gene, for which we suggest the name “ggPRX” in analogy to the murine mProx1, a gene identified in the upstream region of the α-globin gene domain in mice.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1617-4623
    Keywords: Nuclear matrix attachment ; GATA ; Chicken globin genes ; DNA-binding protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sequence-specific DNA-binding protein factor F6, which binds upstream of the cluster of the chicken α-globin genes, has previously been found to interact with a DNA fragment containing a replication origin and a nuclear matrix binding site. This protein has been partially characterized. Based on its molecular weight and binding affinity, F6 belongs to a family of GATA proteins, the chicken equivalent of transcription factor NFE-1. An oligonucleotide including the binding site for F6 competes for binding of the above-mentioned DNA fragment to the nuclear matrix. This indicates an involvement of this protein in the interaction between DNA and the nuclear matrix.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1617-4623
    Keywords: Bent DNA ; DNA melting pattern ; Replication origin ; Matrix attachment site ; Globin genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The distribution of specific DNA sequence elements in a 2.9 kb HindIII fragment of chicken DNA containing the replication origin and the upstream matrix attachment site (MAR) of the α-globin gene domain was investigated. The fragment was shown to contain a CR1-type repetitive element and two stably bent DNA sequences. One of them colocalizes with the previously described MAR element and with the recognition site for a proliferating-cell-specific, DNA-binding protein. The melting pattern of a set of subfragments of the region proved to be non random. No correlation between the distribution of readily melting sequences and bent DNA was found. The possible importance of curved, low-melting and repetitive DNA sequences for the organization of the upstream boundary of the α-globin gene domain and the function of the replication origin is discussed.
    Type of Medium: Electronic Resource
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