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  • 1995-1999  (1,475)
  • 1955-1959  (4)
  • 1900-1904
  • 1890-1899
  • Engineering General  (1,423)
  • Agrobacterium
  • 1
    Electronic Resource
    Electronic Resource
    Transgenic almond (Prunus dulcis Mill.) plants obtained by Agrobacterium-mediated transformation of leaf explants (1999)
    Springer
    Plant cell reports 18 (1999), S. 387-393 
    Details
    ISSN: 1432-203X
    Keywords: Key words Almond ; Prunus ; Transformation ; Agrobacterium ; Adventitious regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Almond (Prunus dulcis Mill.) leaves were transformed with the marker genes gusA (β-glucuronidase) and nptII (neomycin phosphotransferase II) via Agrobacterium-mediated transformation. Bacterial strains and preculture of explants affected efficiency of gene transfer evaluated by transient expression assays. Following transformation, shoots were induced from primary explants on medium without kanamycin and exposed to selection 20 days after cocultivation. From 1419 original leaves, four shoots (A, B, C and D) were obtained that showed amplification of the predicted DNA fragments by polymerase chain reaction (PCR). After micropropagation of these shoots, only those cloned from shoot D gave consistently positive results in histochemical GUS detection and PCR amplification. Southern blot hybridisation confirmed stable transgene integration in clone D, which was also negative in PCR amplification of an Agrobacterium gene. Additional molecular analysis suggested that the remaining three shoots (A, B and C) were chimeric.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050591
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  • 2
    Electronic Resource
    Electronic Resource
    Green-fluorescent protein facilitates rapid in vivo detection of genetically transformed plant cells (1999)
    Springer
    Plant cell reports 18 (1999), S. 707-714 
    Details
    ISSN: 1432-203X
    Keywords: Key words Green-fluorescent protein ; Transformation ; Particle bombardment ; Agrobacterium ; Sugarcane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Early detection of plant transformation events is necessary for the rapid establishment and optimization of plant transformation protocols. We have assessed modified versions of the green fluorescent protein (GFP) from Aequorea victoria as early reporters of plant transformation using a dissecting fluorescence microscope with appropriate filters. Gfp-expressing cells from four different plant species (sugarcane, maize, lettuce, and tobacco) were readily distinguished, following either Agrobacterium-mediated or particle bombardment-mediated transformation. The identification of gfp-expressing sugarcane cells allowed for the elimination of a high proportion of non-expressing explants and also enabled visual selection of dividing transgenic cells, an early step in the generation of transgenic organisms. The recovery of transgenic cell clusters was streamlined by the ability to visualize gfp-expressing tissues in vitro.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050647
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  • 3
    Electronic Resource
    Electronic Resource
    A Modular Vector for Agrobacterium Mediated Transformation of Wheat (1999)
    Springer
    Plant molecular biology reporter 17 (1999), S. 323-331 
    Details
    ISSN: 1572-9818
    Keywords: Agrobacterium ; modular vector ; transformation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wheat (cv Chinese Spring) tissues were transformed using Agrobacterium tumefasciens and a new plasmid modular vector, pMVTBP. We constructed pMVTBP with unique restriction sites connecting (1) the CaMV 35S promoter, (2) a Kozak sequence, (3) the FLAG epitope, (4) the (His)6 epitope, (5) a coding region (for wheat TATA Binding Protein, wTBP) and (6) the CaMV 35S 3′UTR. This vector thus allows easy exchange of different regulatory or coding sequences. Explants of either germinating mature seeds, or immature embryos, were induced to callus for up to two weeks, treated with virulence-induced bacteria for one hour, then regenerated into plantlets. Transient expression of a GUS reporter gene, assayed at about one week, occurred in 10–12% of calluses. Expression of the FLAG-tagged wTBP was also detected, by immunostaining. Stable expression, by selective growth on geneticin, and by GUS expression at about six weeks, occurred in 1–2% of calluses, quite comparable to that achieved by other methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007686408369
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  • 4
    Electronic Resource
    Electronic Resource
    Positive-negative selection and T-DNA stability in Arabidopsis transformation (1999)
    Springer
    Plant molecular biology 39 (1999), S. 83-93 
    Details
    ISSN: 1573-5028
    Keywords: Arabidopsis ; Agrobacterium ; T-DNA ; CodA ; positive-negative selection ; recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have analysed the application of positive-negative selection for the selection of homologous recombination interactions between the chromosome and a T-DNA molecule after transformation of plant cells. Two different genomic loci in a cell suspension of Arabidopsis thaliana were chosen to study gene targeting events. One was the chalcone synthase (CHS) gene present as a single copy and the second an hemizygous chromosomally inserted T-DNA containing the hpt gene, conferring resistance to hygromycin, flanked by CHS sequences. The target lines were transformed with replacement-type T-DNA vectors which contained a positive selectable marker flanked by the regions of the CHS gene and a negative selectable marker to counter-select random insertions. As negative marker we used the Escherichia coli codA gene encoding cytosine deaminase, conferring upon the cells sensitivity to 5-flourocytosine (5-FC). Doubly selected transformants represent 1–4% of the primary transformed cells. Targeting events were not found at the chalcone synthase locus nor at the artificial hpt locus in a total of 4379 doubly selected calli, corresponding to at least 109 475 individual primary transformants. We show by PCR and Southern analysis that the 5-FC resistance in the majority of these cells is associated with substantial deletions of the T-DNA molecule from the right-border end.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006192225464
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  • 5
    Electronic Resource
    Electronic Resource
    Evidence of Migration and Endophytic Presence of Agrobacterium tumefaciens in Rose Plants (1999)
    Springer
    European journal of plant pathology 105 (1999), S. 39-50 
    Details
    ISSN: 1573-8469
    Keywords: Agrobacterium ; crown gall ; systemic infection ; rose ; endophyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Agrobacterium tumefaciens was isolated from stem tumors of several rose cultivars showing that the bacterium is the causal agent of aerial galls in rose plants. No differences were observed in the characteristics of the Agrobacterium isolates from crown or aerial galls. Stem inoculation of ten rose cultivars showed that all of them were susceptible to A. tumefaciens but differences in the size of the resulting tumors were observed. The movement of A. tumefaciens in rose plants was demonstrated using two wild type strains and two antibiotic resistant mutants. Three months after inoculation, the inoculated strains were recovered in the roots, crown and below and above the inoculation site but low numbers of pathogenic Agrobacterium cells were isolated. New tumors appeared in 5% of the noninoculated wounds. A. tumefaciens was isolated from the stem at different distances from the tumor in naturally infected plants. In symptomless commercial plants, the isolation from the roots, crown and at different stem levels demonstrated the existence of systemic and latent infections in rose. Direct isolation using a nonselective and selective media with or without a previous enrichment step were efficient methods for isolating tumorigenic Agrobacterium from the different parts of rose plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008660500107
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  • 6
    Electronic Resource
    Electronic Resource
    Sequence and functional analysis of the left-hand part of the T-region from the nopaline-type Ti plasmid, pTiC58 (1999)
    Springer
    Plant molecular biology 41 (1999), S. 765-776 
    Details
    ISSN: 1573-5028
    Keywords: Agrobacterium ; Ti plasmid ; oncogenes ; e gene ; 3′ gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Agrobacterium tumefaciens nopaline strain C58 transfers a large, 29 kb T-DNA into plant cells during infection. Part of this DNA (the `common DNA') is also found on the T-DNA of octopine strains, the remaining DNA is nopaline strain-specific. Up to now, only parts of the C58 T-DNA and related T37 T-DNA have been sequenced. We have sequenced the remainder of the nopaline-specific T-DNA (containing genes a to d) and acs to iaaM. Gene c codes for a new unknown T-DNA protein. Gene a is homologous to the agrocinopine synthase gene. Genes b, c′, d and e are part of a larger family: they are related to the T-DNA genes 5, rolB, lso and 3′. Genes 5, rolB and lso induce or modify plant growth and have been called T-DNA oncogenes. Our studies show that gene 3′ (located on the TR-DNA of octopine strains) is also oncogenic. Although the b–e T-DNA fragment from C58 and its individual genes lack growth-inducing activity, an a-acs deletion mutant was distinctly less virulent on Kalanchoe daigremontiana and showed reduced shoot formation on Kalanchoe tubiflora. Shoot formation could be restored by genes c and c′ in co-infection experiments. Contrary to an earlier report, a C58 e gene deletion mutant was fully virulent on all plants tested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006370207379
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  • 7
    Electronic Resource
    Electronic Resource
    Stable genetic transformation of white pine (Pinus strobus L.) after cocultivation of embryogenic tissues with Agrobacterium tumefaciens (1999)
    Springer
    Molecular breeding 5 (1999), S. 429-440 
    Details
    ISSN: 1572-9788
    Keywords: transgenic trees ; scaffold attachment region ; Agrobacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A genetic transformation procedure for white pine has been developed after cocultivation of embryogenic tissues with Agrobacterium tumefaciens. This efficient transformation procedure led to an average of four independent transformed lines per gram of cocultivated embryogenic tissue and up to 50 transformed lines can be obtained in a routine experiment. Constructs bearing the uidA gene or the green fluorescent protein (GFP) gene were introduced and β-glucuronidase (GUS) activity was followed over time. The expression of the uidA gene was lowest with a 35S-gus-intron construct and was 20-fold higher with a 35S-35S-AMVgus::nptII construct. The addition of scaffold attachment region (SAR) sequences surrounding the gus::nptII fusion did not significantly enhance the GUS activity. Transformed mature somatic embryos have been germinated and plantlets are presently being acclimatized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009683605841
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  • 8
    Electronic Resource
    Electronic Resource
    Transformation of arctic bramble (Rubus arcticus L.) by Agrobacterium tumefaciens (1998)
    Springer
    Plant cell reports 17 (1998), S. 822-826 
    Details
    ISSN: 1432-203X
    Keywords: Key words Rosaceae ; β-Glucuronidase ; Regeneration ; Agrobacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genetic transformation of arctic bramble (Rubus arcticus L.) was achieved utilizing a Ti-plasmid vector system of Agrobacterium tumefaciens. Internodal stem segments were inoculated with Agrobacterium strain EHA101 carrying a T-DNA with the CaMV 35 S promoter-gus-int marker gene from which β-glucuronidase (GUS) is expressed only in plants. Regenerants were produced on Murashige and Skoog medium. Growth of Agrobacterium was inhibited with cefotaxime. Kanamycin was used as the selective agent for the transformants. Regenerants were assayed by histochemical GUS staining, and by Southern analysis using a gus-int probe. Transgenic arctic bramble plants containing gus-int and expressing GUS were recovered. Expression has been stable for 3 years in micropropagation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050491
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  • 9
    Electronic Resource
    Electronic Resource
    Transformation and regeneration of Lobelia erinus using Agrobacterium tumefaciens (1998)
    Springer
    Plant cell reports 18 (1998), S. 308-311 
    Details
    ISSN: 1432-203X
    Keywords: Key words Campanulaceae ; Lobelia erinus ; Transformation ; Agrobacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A transformation/regeneration system was developed for the common garden Lobelia (Lobelia erinus). Using an Agrobacterium-based protocol, over 40 transformants have been generated with four different binary vectors. The explant source was hypocotyl-root sections from axenically grown seedlings. Stable transformation was demonstrated by Southern hybridization analysis, β-glucuronidase staining, and transmission of the T-DNA to progeny. This extends the ever-widening range of transformable plant species to the Campanulaceae and will allow molecular studies of development and physiology in this easily cultured and popular garden plant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050577
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  • 10
    Electronic Resource
    Electronic Resource
    Transgenic peppermint (Mentha×piperita L.) plants obtained by cocultivation with Agrobacterium tumefaciens (1998)
    Springer
    Plant cell reports 17 (1998), S. 165-171 
    Details
    ISSN: 1432-203X
    Keywords: Key words Peppermint ; Transformation ; Agrobacterium ; GUS ; Transgenic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The first transgenic peppermint (Mentha×piperita L. cultivar Black Mitcham) plants have been obtained by Agrobacterium-mediated transformation by cocultivation with morphogenically responsive leaf explants. Basal leaf explants with petioles, from leaves closest to the apex of in-vitro-culture-maintained shoots (5 cm), exhibited optimal shoot organogenetic responsiveness on medium supplemented with thidiazuron (8.4 µm). Shoot formation occurred at sites of excision on the leaf blade and petiole either directly from cells of the explant or via a primary callus. Analyses of transient GUS activity data indicated that DNA delivery by microprojectile bombardment was more effective than Agrobacterium infection. However, no transgenic plants were obtained from over 22,000 leaf explants after particle bombardment. Cocultivation of leaf explants with Agrobacterium strain EHA 105 and kanamycin selection produced transgenic plants. Greater transient and stable -glucuronidase (GUS) activities were detected in explants or propagules transformed with the construct where gusA was driven by the pBISN1 promoter rather than a CaMV 35S promoter. Eight plants were subsequently regenerated and verified as transgenic based on detection of the nptII transgene by PCR and Southern blot analyses. The Southern analyses indicated that the plants were derived from eight unique transformation events. All transgenic plants appeared morphologically normal. Analyses of GUS activities in leaves sampled from different portions of these transgenic plants, 10 months after transfer to the greenhouse, indicated that six out of the eight original regenerants were uniformly transformed, i.e., did not exhibit chimeric sectors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050372
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  • 11
    Electronic Resource
    Electronic Resource
    CaMV 35S promoter directs β-glucuronidase expression in the laticiferous system of transgenic Hevea brasiliensis (rubber tree) (1998)
    Springer
    Plant cell reports 17 (1998), S. 621-625 
    Details
    ISSN: 1432-203X
    Keywords: Key wordsHevea brasiliensis ; Agrobacterium ; CaMV 35S ; β-Glucuronidase ; Latex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hevea brasiliensis anther calli were genetically transformed using Agrobacterium GV2260 (p35SGUSINT) that harboured the β-glucuronidase (gus) and neomycin phosphotransferase (nptII) genes. β-Glucuronidase protein (GUS) was expressed in the leaves of kanamycin-resistant plants that were regnerated, and the presence of the gene was confirmed by Southern analysis. GUS was also observed to be expressed in the latex and more importantly in the serum fraction. Transverse sections of the leaf petiole from a transformed plant revealed GUS expression to be especially enhanced in the phloem and laticifers. GUS expression was subsequently detected in every one of 194 plants representing three successive vegetative cycles propagated from the original transformant. Transgenic Hevea could thus facilitate the continual production of foreign proteins expressed in the latex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050454
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  • 12
    Electronic Resource
    Electronic Resource
    Agrobacterium tumefaciens-mediated transformation of Eucalyptus camaldulensis and production of transgenic plants (1998)
    Springer
    Plant cell reports 17 (1998), S. 675-680 
    Details
    ISSN: 1432-203X
    Keywords: Key words Genetic transformation ; Agrobacterium ; Eucalyptus ; Regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An efficient system for Agrobacterium-mediated transformation of Eucalyptus camaldulensis and production of transgenic plants was developed. Transformation was accomplished by cocultivation of hypocotyl segments with Agrobacterium tumefaciens containing a binary Ti-plasmid vector harboring chimeric neomycin phosphotransferase and β-glucuronidase (GUS) genes. A modified Gamborg's B5 medium used in this study was effective for both callus induction and regeneration of transgenic shoots. This medium could also effectively maintain the organogenic capability of callus for more than a year. Culturing transgenic shoots in Murashige and Skoog medium supplemented with 0.1 mg ⋅ l–1 benzylaminopurine prior to root induction in rooting medium markedly increased the rootability of shoots that were recalcitrant to rooting. Histochemical assay revealed the expression of the GUS gene in leaf, stem, and root tissues of transgenic plants. Insertion of the GUS gene in the nuclear genome of transgenic plants was verified by genomic Southern hybridization analysis, further confirming the integration and expression of T-DNA in these plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050464
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  • 13
    Electronic Resource
    Electronic Resource
    Activity of the CaMV 35S promoter in various parts of transgenic early flowering birch clones (1998)
    Springer
    Plant cell reports 18 (1998), S. 243-248 
    Details
    ISSN: 1432-203X
    Keywords: Key wordsBetula pendula ; Transformation ; Agrobacterium ; Gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Early flowering together with small size would be useful for various biotechnical or genetic studies on trees. We report here the selection and micropropagation of early flowering birch (Betula pendula) clones (BPM1–12) obtained from seeds of birches bred elsewhere for early flowering. Under conditions that accelerate flowering (a high CO2 level, strong and continuous illumination), the first male inflorescences emerged in 3–5 months, the trees then being 20–80 cm high. Transgenic lines (CaMV 35S-GUS INT) were produced through Agrobacterium-mediated gene transfer from BPM2, BPM5 and JR1/4 (a normally flowering birch). β-Glucuronidase (GUS) activities in the different lines, assayed 1–1.5 years after transformation, varied greatly. During further in vitro culture for 10 months, the activities decreased to 0.3–7% of the original values. GUS activities were detected in all organs studied, including the developing male inflorescences; the highest activity was in the roots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050564
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  • 14
    Electronic Resource
    Electronic Resource
    Factors affecting soybean cotyledonary node transformation (1998)
    Springer
    Plant cell reports 18 (1998), S. 180-186 
    Details
    ISSN: 1432-203X
    Keywords: Key words Soybean ; SAAT (sonication assisted Agrobacterium-mediated transformation) ; Agrobacterium ; Transformation ; KYRT1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cotyledonary node transformation efficiency was evaluated using a sonication assisted Agrobacterium-mediated transformation (SAAT) protocol, three dissimilar A. tumefaciens strains, and explants derived from 28 diverse cultivars and/or genotypes of soybean [Glycine max (L.) Merr.]. The explants were evaluated at 10 and 45 days after co-cultivation for transformation with a binary vector containing both a GUS-intron gene and an NPTII selectable marker. The best overall strain of A. tumefaciens was determined to be KYRT1 based on stable GUS transformation of soybean cotyledonary node explants measured at the terminal 45 day evaluation point. SAAT did not increase stable transformation at 45 days post co-cultivation. SAAT was determined to significantly decrease shoot proliferation of some genotypes, but it is unclear what effect this may have on the recovery of transformed shoots. Significant differences were also detected between genotypes for transformation and shoot proliferation frequency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050553
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  • 15
    Electronic Resource
    Electronic Resource
    Origin and evolution of plasmids (1998)
    Springer
    Antonie van Leeuwenhoek 73 (1998), S. 117-126 
    Details
    ISSN: 1572-9699
    Keywords: riboplasmids ; encapsidation ; pseudovirions ; selfish plasmids ; replicons ; ribozyme ; Agrobacterium ; Rhizobium ; grapevines ; L-tartrate ; lignin ; methoxyphenols ; satellite viruses ; opines ; crown gall ; T-DNA ; origin of replication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Studies on the origin and evolution of plasmids may provide valuable insights on the promiscuous nature of DNA. The first examples of the selfish nature of nucleic acids are exemplified by primordial oligoribonucleotides which evolved into primitive replicons. The propagation of these molecules were likely patterned after the current viral RNA ribozymes, which have been recently shown to possess RNA synthesizing and template mediated polymerizing capabilities in the absence of proteins. The parasitic nature of nucleic acids is depicted by satellite nucleic acid molecules associated with viruses. The satellites of adenovirus and tobacco ringspot virus serve as established examples: they contain no open reading frames. Comparative analysis of the replication origins of virions and plasmids show them to be conserved, originating from the simplest autocatalytic replicon to highly complex and evolved plasmids, replicating by a rolling circle mechanism. The eventual association of proteins with nucleic acids provided added efficiency and protective advantages for molecular perpetuation. The promiscuous and selfish nature of plasmids is demonstrated by their ability to genetically engineer their host so that the host cell is best able to cope and survive in hostile environments. Survival of the host ensures survival of the plasmid. Sequestering of genes by plasmids occurs when the environmental conditions negatively affect the host. The sequestering mechanism is fundamental and forms the outreach mechanisms to generate and propagate macromolecules of increasing size when necessary for survival. The level of sophistication of plasmids increases with the addition of new genes such as those that allow the host to occupy a specific environment normally inhospitable to the host cell. The vast range of plasmid types which have obtained genes interchangeably reflect the levels of sophistication achieved by these macromolecules. The Ti plasmid in Agrobacterium tumefaciens and the pSym and accessory plasmids in Rhizobium illustrate the level of complexity attained by replicons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1000652513822
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  • 16
    Electronic Resource
    Electronic Resource
    The use of visual marker genes as cell-specific reporters of Agrobacterium-mediated T-DNA delivery to wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). (1998)
    Springer
    Euphytica 99 (1998), S. 17-25 
    Details
    ISSN: 1573-5060
    Keywords: Agrobacterium ; barley ; C1/Lc ; GFP ; GUS ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Transfer of T-DNA from Agrobacterium tumefaciens and A. rhizogenes to cells of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) is demonstrated following the inoculation of immature embryos and immature embryo-derived callus. Agrobacterium T-DNA vectors containing the C1/Lc anthocyanin-biosynthesis regulatory genes, the gusA gene or a synthetic green fluorescent protein gene (sgfp-S65T) were constructed from original binary vectors. The visual T-DNA markers were used as cell-autonomous reporters of early Agrobacterium-mediated transformation events in the wheat and barley cells. This localization of the transformed cells revealed a non-random distribution throughout each embryo and callus piece.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018303102488
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  • 17
    Electronic Resource
    Electronic Resource
    Agrobacterium tumefaciens-mediated transformation of cauliflower, Brassica oleracea var. botrytis (1998)
    Springer
    Molecular breeding 4 (1998), S. 531-541 
    Details
    ISSN: 1572-9788
    Keywords: Agrobacterium ; Brassica oleracea ; cauliflower ; regeneration ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We have developed an efficient and simpler method for genetic transformation and regeneration of cauliflower, Brassica oleracea var. botrytis plants. Explants from 4-day old seedlings were inoculated and cocultivated with Agrobacterium tumefaciens strain LBA4404 harbouring a binary vector with the neomycin phosphotransferase-II gene under the regulatory control of nopaline synthase promoter and terminator sequences, permitting transformed shoots to be selected on kanamycin containing medium. After three months rooted transformed plantlets were successfully transferred and grown under glasshouse conditions. Higher numbers of transformed plants were obtained from cotyledon than hypocotyl explants, presumably indicating cotyledons of cauliflower are more amenable to genetic transformation. Integration and expression of the introduced transgene were analysed by DNA gel blot and PCR analysis and NPT-II expression assay. Factors influencing transformation efficiency include explant age, concentration of bacterium used for infection, duration of infection and cocultivation with Agrobacterium. Transgenic plants of three commercial genotypes of cauliflower were produced using this method. We also show that introduction of antisense Bcp1 (pollen-specific gene) linked to a pollen-specific promoter (Lat52) resulted in the expected sterility of 50% pollen carrying this transgenic construct.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009658614579
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  • 18
    Electronic Resource
    Electronic Resource
    An efficient protocol for sugarcane (Saccharum spp. L.) transformation mediated by Agrobacterium tumefaciens (1998)
    Springer
    Transgenic research 7 (1998), S. 213-222 
    Details
    ISSN: 1573-9368
    Keywords: Saccharum ; Agrobacterium ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This is the first successful report of the recovery of morphologically normal transgenic sugarcane plants from co-cultivation of calluses with Agrobacterium tumefaciens. Transformation frequencies (total of transgenic plants/number of cell clusters) were between 9.4 × 10−3 and 1.15 × 10−2. In our experiments, both LBA4404 (pTOK233) and EHA101 (pMTCA3IG), carrying a super-binary vector or supervirulent strain, respectively, were successful for sugarcane transformation. We found that three main factors: (1) the use of young regenerable calluses as target explants; (2) induction and/or improvement of the A. tumefaciens virulence system with sugarcane cell cultures and (3) pre-induction of organogenesis or somatic-embryogenesis-like sexual embryos, seem to be crucial in order to increase the cells competence for T-DNA transfer process. Patterns generated by Southern hybridization confirmed that T-DNAs were randomly integrated into sugarcane genome without th e persistence of A. tumefaciens in the transgenic plants
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008845114531
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  • 19
    Electronic Resource
    Electronic Resource
    Genetic transformation and regeneration of mature tissues of woody fruit plants bypassing the juvenile stage (1998)
    Springer
    Transgenic research 7 (1998), S. 51-59 
    Details
    ISSN: 1573-9368
    Keywords: sweet orange ; Citrus ; woody ; transformation ; Agrobacterium ; mature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regeneration and transformation systems from mature plant material of woody fruit species have to be achieved as a necessary requirement for the introduction of useful genes into specific cultivars and the rapid evaluation of resulting horticultural traits. We report here, for the first time, a procedure for genetic transformation and regeneration of mature tissues of woody plants that overcomes the long juvenile periods and high heterozygosity that are characteristic of most of these species. An improved regeneration frequency from mature explants was obtained by invigoration of the plant material through grafting of mature buds on juvenile seedlings. Co-cultivation of the explants in feederplates after inoculation with Agrobacterium tumefaciens resulted in enhanced transformation frequencies. Furthermore, in vitro shoot-tip grafting of the regenerated mature shoots on seedling rootstocks provided a rapid and efficient system for plant production. Citrus is the most extensivel y grown fruit crop worldwide and sweet orange (Citrus sinensis L. Osbeck) accounts for approximately 70% of the Citrus total production. Mature transgenic sweet orange plants have been obtained, which flowered and bore fruit in 14 months
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008855922283
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  • 20
    Electronic Resource
    Electronic Resource
    Investigation of Agrobacterium-mediated transformation of apple using green fluorescent protein: high transient expression and low stable transformation suggest that factors other than T-DNA transfer are rate-limiting (1998)
    Springer
    Plant molecular biology 37 (1998), S. 549-559 
    Details
    ISSN: 1573-5028
    Keywords: Agrobacterium ; apple ; GFP ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To investigate early events of Agrobacterium-mediated transformation of apple cultivars, a synthetic green fluorescent protein gene (SGFP) was used as a highly sensitive, vital reporter gene. Leaf explants from four apple cultivars (‘Delicious’, ‘Golden Delicious’, ‘Royal Gala’ and ‘Greensleeves’) were infected with Agrobacterium EHA101 harboring plasmid pDM96.0501. Fluorescence microscopy indicated that SGFP expression was first detected 48 h after infection and quantitative analysis revealed a high T-DNA transfer rate. Plant cells with stably incorporated T-DNA exhibited cell division and developed transgenic calli, followed by formation of transgenic shoots at low frequencies. The detection of SGFP expression with an epifluorescence stereomicroscope confirmed the effectiveness of SGFP as a reporter gene for detection of very early transformation events and for screening of putative transformants. The efficiency of the transformation and regeneration process decreased ca. 10000-fold from Agrobacterium infection to transgenic shoot regeneration, suggesting that factors other than Agrobacterium interaction and T-DNA transfer are rate-limiting steps in Agrobacterium-mediated transformation of apple.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006041313209
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  • 21
    Electronic Resource
    Electronic Resource
    Cre/lox-mediated site-specific integration of Agrobacterium T-DNA in Arabidopsis thaliana by transient expression of cre (1998)
    Springer
    Plant molecular biology 38 (1998), S. 393-406 
    Details
    ISSN: 1573-5028
    Keywords: Agrobacterium ; Arabidopsis ; Cre/lox ; recombination ; site-specific integration ; T-DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Cre/lox system was used to obtain targeted integration of an Agrobacterium T-DNA at a lox site in the genome of Arabidopsis thaliana. Site-specific recombinants, and not random events, were preferentially selected by activation of a silent lox-neomycin phosphotransferase (nptII) target gene. To analyse the effectiveness of Agrobacterium-mediated transfer we used T-DNA vectors harbouring a single lox sequence (this vector had to circularize at the T-DNA left- and right-border sequences prior to site-specific integration) or two lox sequences (this vector allowed circularization at the lox sequences within the T-DNA either prior to or after random integration, followed by targeting of the circularized vector), respectively. Furthermore, to control the reversibility of the integration reaction, Cre recombinase was provided transiently by using a cotransformation approach. One precise stable integrant was found amongst the recombinant calli obtained after transformation with a double-lox T-DNA vector. The results indicate that Agrobacterium-mediated transformation can be used as a tool to obtain site-specific integration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006024500008
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  • 22
    Electronic Resource
    Electronic Resource
    Role of the host cell cycle in theAgrobacterium-mediated genetic transformation ofPetunia: Evidence of an S-phase control mechanism for T-DNA transfer (1997)
    Springer
    Planta 201 (1997), S. 160-172 
    Details
    ISSN: 1432-2048
    Keywords: Agrobacterium ; Leaf mesophyll cells ; Petunia ; Transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chimeric β-glucuronidase (GUS) gene expression in an efficientAgrobacterium-mediated transformation system utilising mesophyll cells ofPetunia hybrida synchronized with cell cycle phase-specific inhibitors (mimosine and colchicine) was used to show the absolute requirement of S-phase for transfer and/or integration of the transferred DNA (T-DNA). Flow-cytometric analysis of nuclear DNA content and immunohistological detection of bromodeoxyuridine (BrdUrd) incorporation showed that, prior to phytohormone treatment, most (98%) mesophyll cells were at GO-Gl-phase (quiescent phase) and no cell division was occurring. After 48 h and 72 h of phytohormone treatment, there was a rapid increase in S-G2-M-phase populations (〉 75%) and a concomitant decrease (down to 24%) in G0–-G1-phase cells. Assays of GUS showed that maximum transformation (〉 95% of explants) also occurred after this period. Our data showed that mimosine and colchicine blocked the mesophyll cells at late Gl-phase and M-phase, respectively. No transformation (= GUS expression) was observed in phytohormone-treated cells inhibited in late G1 by mimosine. However, after removal of mimosine, 82% of the explants were transformed, indicating the non-toxic and reversible effect of the inhibitor. On the other hand, a relatively high transformation frequency (65% of explants) was observed after blocking the cell cycle at M-phase with colchicine. However, only transient, but no stable, gene expression (= kanamycin-resistant callus formation) was observed in colchicine-treated M-phase-arrested cells. Similarly, endoreduplication of nuclear DNA, which occurred during the 48 h of phytohormone treatment in some mesophyll cells and cells located along the minor veins in the leaf explants, resulted in transient GUS expression only. These observations indicate a direct correlation between endoreduplication and transient GUS gene expression. Obviously, for stable GUS gene expression, cell division and proliferation are required, indicating that both DNA duplication (S-phase) and cell division (M-phase) are strongly related to stable transformation. We propose that the present system should facilitate further dissection of the process of T-DNA integration in the host genome and therefore should aid in developing new strategies for transformation of recalcitrant plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01007700
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  • 23
    Electronic Resource
    Electronic Resource
    Expression and inheritance of foreign genes in transgenic peanut plants generated by Agrobacterium-mediated transformation (1997)
    Springer
    Plant cell reports 16 (1997), S. 541-544 
    Details
    ISSN: 1432-203X
    Keywords: Key words Transgenic peanut ; Agrobacterium ; Transformation ; Transgene expression ; Transgene inheritance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To evaluate and characterize the stability of traits transferred via Agrobacterium transformation, foreign gene expression must be examined in sexually derived progeny. The objective of this study was to analyze three transgenic peanut plants, 1-10, 12-1, and 17-1, for the inheritance and expression of their foreign genes. Segregation ratios for the introduced genes in T2 plants gave either 100% or 3:1 expression of the β-glucuronidase (GUS) gene, demonstrating recovery of both homozygous and heterozygous T1 plants. Fluorometric GUS assay in T1 and T2 generations of all three plants showed that the GUS gene was stably expressed in the progeny. DNA analyses showed 100% concordance between the presence of the foreign gene and enzyme activity. Our results demonstrate that transgenes in peanut introduced by Agrobacterium can be inherited in a Mendelian manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01142320
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  • 24
    Electronic Resource
    Electronic Resource
    Isolation of new 6-methylnicotinic-acid-degrading bacteria, one of which catalyses the regioselective hydroxylation of nicotinic acid at position C2 (1997)
    Springer
    Archives of microbiology 168 (1997), S. 355-361 
    Details
    ISSN: 1432-072X
    Keywords: Key words 6-Methylnicotinic acid ; 2-Hydroxy-6-methylnicotinic acid ; Nicotinic acid ; 2-Hydroxynicotinic acid ; Ralstonia ; Burkholderia ; Paenibacillus ; Agrobacterium ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 2-Hydroxynicotinic acid is an important building block for herbicides and pharmaceuticals. Enrichment strategies to increase the chances of finding microorganisms capable of hydroxylating at the C2 position and to avoid the degradation of nicotinic acid via the usual intermediate, 6-hydroxynicotinic acid, were used. Three bacterial strains (Mena 23/3–3c, Mena 25/4–1, and Mena 25/ 4–3) were isolated from enrichment cultures with 6-methylnicotinic acid as the sole source of carbon and energy. Partial characterization of these strains indicated that they represent new bacterial species. All three strains completely degraded 6-methylnicotinic acid, and evidence is presented that the first step in the degradation pathway of strain Mena 23/3–3c is hydroxylation at the C2 position. Resting cells of this strain grown on 6-methylnicotinic acid also hydroxylated nicotinic acid at the C2 position, but did not further degrade the product. Strain Mena 23/ 3–3c showed the highest degree of 16S rRNA sequence similarity to members of the genera Ralstonia and Burkholderia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050509
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  • 25
    Electronic Resource
    Electronic Resource
    Tapetum-specific expression of theOsg6B promoter-β-glucuronidase gene in transgenic rice (1997)
    Springer
    Plant cell reports 16 (1997), S. 363-367 
    Details
    ISSN: 1432-203X
    Keywords: Agrobacterium ; Tapetum-specific promoter ; Transformation ; Rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The promoter of an anther tapetum-specific gene,Osg6B, was fused to aβ-glucuronidase (GUS) gene and introduced into rice byAgrobacterium-mediated gene transfer. Fluorometric and histochemical GUS assay showed that GUS was expressed exclusively within the tapetum of anthers from the uninucleate microspore stage (7 days before anthesis) to the tricellular pollen stage (3 days before anthesis). This is the first demonstration of an anther-specific promoter directing tapetum-specific expression in rice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01146774
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  • 26
    Electronic Resource
    Electronic Resource
    Expression and inheritance of foreign genes in transgenic peanut plants generated byAgrobacterium-mediated transformation (1997)
    Springer
    Plant cell reports 16 (1997), S. 541-544 
    Details
    ISSN: 1432-203X
    Keywords: Transgenic peanut ; Agrobacterium ; Transformation ; Transgene expression ; Transgene inheritance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To evaluate and characterize the stability of traits transferred viaAgrobacterium transformation, foreign gene expression must be examined in sexually derived progeny. The objective of this study was to analyze three transgenic peanut plants, 1-10, 12-1, and 17-1, for the inheritance and expression of their foreign genes. Segregation ratios for the introduced genes in T2 plants gave either 100% or 3:1 expression of the β-glucuronidase (GUS) gene, demonstrating recovery of both homozygous and heterozygous T1 plants. Fluorometric GUS assay in T1 and T2 generations of all three plants showed that the GUS gene was stably expressed in the progeny. DNA analyses showed 100% concordance between the presence of the foreign gene and enzyme activity. Our results demonstrate that transgenes in peanut introduced byAgrobacterium can be inherited in a Mendelian manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01142320
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  • 27
    Electronic Resource
    Electronic Resource
    Transgenic Populus tremula: a step-by-step protocol for its Agrobacterium-mediated transformation (1997)
    Springer
    Plant molecular biology reporter 15 (1997), S. 219-235 
    Details
    ISSN: 1572-9818
    Keywords: Agrobacterium ; Populus ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In recent years, Populus species have acquired an important place in basic and applied research of woody plants. The practical role of Populus species in world forestry and their importance to research as a woody-plant model have led to increasing interest in tissue-culture and molecular techniques, as well as the development of transformation procedures for this genus. A simple technical procedure is described here step-by-step, for the first time, as a routine method for transforming Populus tremula using a disarmed Agrobacterium tumefaciens hypervirulent strain. The procedure begins with the inoculation of stem explants with bacterial suspension, followed by a short period of co-cultivation on a highly regenerative medium. Transformed shoots are selected on regeneration medium containing antibiotics and the presence of the inserted target genes is checked using a rapid and efficient PCR test. Selected shoots are transferred to a rooting medium, under the same selection pressure, and propagated via stem cuttings. Selected plants can be hardened and transferred to the green-house within 4 months of inoculation. The method has proven efficient for several gene constructs, selection on Kan or Hyg, and three different Agrobacterium strains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007484917759
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  • 28
    Electronic Resource
    Electronic Resource
    Isolation and identification of N2-fixing microorganisms from the rhizosphere of Capparis spinosa (L.) (1997)
    Springer
    Plant and soil 197 (1997), S. 19-23 
    Details
    ISSN: 1573-5036
    Keywords: Agrobacterium ; Capparis spinosa ; Comamonas ; N2 fixation ; Pseudomonas ; rhizosphere ; Sphingobacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Four bacterial strains, Pseudomonas stutzeri var. mendocina, Comamonas sp., Agrobacterium tumefaciens biovar. 2 and Sphingobacterium sp., isolated from the rhizosphere of wild-grown caper (Capparis spinosa L.) plants were able to fix N2 as shown by their growth in nitrogen-free medium and by the acetylene reduction test. P. stutzeri var. mendocina and Comamonas sp. contained DNA homologous to the Klebsiella pneumoniae M5a1 nifHDK genes. No hybridization was found with total DNA from either A. tumefaciens biovar. 2 or Sphingobacterium sp. using nifHDK probes from either K. pneumoniae or Rhizobium meliloti.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004211909641
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  • 29
    Electronic Resource
    Electronic Resource
    Agrobacterium rhizogenes and A. tumefaciens co-transformation to obtain grapevine hairy roots producing the coat protein of grapevine chrome mosaic nepovirus (1997)
    Springer
    Plant cell, tissue and organ culture 49 (1997), S. 53-62 
    Details
    ISSN: 1573-5044
    Keywords: Agrobacterium ; coat protein ; grapevine ; hairy root ; nepovirus ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hairy root cultures of grapevine were obtained from plantlets co-inoculated by virulent Agrobacterium rhizogenes strains and disarmed A. tumefaciens strains harbouring the binary vectors pKHG4 and pKVHG 2+. These plasmids contain the nptII, hpt and gus genes and differ for the presence of the gene encoding for the grapevine chrome mosaic virus coat protein. For the cultivar ‘Gravesac’, 72% of the excised root tips initiated hairy root cultures on growth regulator-free media. According to the nature of the strains used in co-inoculation, co-transformation frequencies of the hairy root clones ranged from 4 to 16%. Co-transformed roots showed resistance to kanamycin and hygromycin but responses varied from clone to clone. Fluorometric GUS expression and GCMV coat protein production showed a large variability among hairy root clones co-transformed by pKHVG2+. Though the presence of gus, nptII and GCMV coat protein genes was checked by polymerase chain reaction and Southern blotting, it was difficult to establish a clear relationship between expression of the different transgenes. The regeneration of plants was not achieved, but the possibility to graft in vitro transgenic roots to non transformed shoot systems could permit rapid testing of the resistance induced by nepovirus coat protein in roots of cultivars that are recalcitrant to A. tumefaciens-mediated transformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005854212592
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  • 30
    Electronic Resource
    Electronic Resource
    Excision of the maize transposable element Ac in periclinal chimeric leaves of 35S-Ac-rolC transgenic aspen-Populus (1997)
    Springer
    Plant molecular biology 33 (1997), S. 1097-1103 
    Details
    ISSN: 1573-5028
    Keywords: Ac ; Agrobacterium ; periclinal chimera ; rolC ; transgenic Populus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The transposable element Ac from maize, in combination with the phenotypic selectable marker rolC, was employed in transformation experiments of a hybrid aspen clone. A number of transgenic clones exhibited light-green sectors on green leaves. In vitro regeneration from leaves showing a high number of light-green spots resulted in R2 plants, which also showed light-green sectored leaves. However, only one out of 385 regenerated plants obtained showed green leaves. Both PCR and northern analysis indicated Ac excision and restoration of rolC expression. In Southern blot analysis of this green plant additional bands were observed as compared to the original R1 plant. The occurrence of these bands and a suggested Ac excision in the non-green L1-epidermal layer leading to periclinal chimerism of this plant is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005788706864
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  • 31
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    Electronic Resource
    Genetic transformation of Populus genotypes with different chimaeric gene constructs: transformation efficiency and molecular analysis (1997)
    Springer
    Transgenic research 6 (1997), S. 111-121 
    Details
    ISSN: 1573-9368
    Keywords: Ac ; Agrobacterium ; aspen ; Populus ; transformation ; transposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aspen (Populus tremula) and hybrid aspen (P. tremula × P. tremuloides) were transformed with different gene constructs using two types of promoter. The aim was to determine the influence of the reporter gene rolC, controlled by promoters of viral or plant origin, on genetic and morphologic expression of different transgenic aspen clones. An improved transformation method using leaf discs was developed, by which putative transgenic plantlets were regenerated at high efficiencies (up to 34%) on kanamycin-containing medium. Transgenic aspen carrying the rolC gene from Agrobacterium rhizogenes under control of the cauliflower-35S-promoter are reduced in size with smaller leaves, whereas aspen transgenic for the same rolC gene, but under control of the light inducible rbcS promoter from potato, are only slightly reduced in size compared to untransformed controls. However, all clones carrying 35S-rolC and rbcS-rolC genes revealed light-green colouration of leaves when compared to untransformed aspen. Owing to this special feature, constructs were used in which expression of the rolC gene was inhibited by insertion of a transposable element, Ac, from maize. Transgenic aspen transformed with the 35S-Ac-rolC and rbcS-Ac-rolC genes were morphologically similar to untransformed aspen, but out of 54 independently regenerated 35S-Ac-rolC transgenic aspen clones, 30 clones showed light-green/dark green variegated leaves. In contrast, out of 19 independently transformed rbcS-Ac-rolC aspen clones, only two clones revealed light-green/dark green variegated leaves. The role of bacterial strains in transformation, and molecular genetics of transgenic aspen plants (including the function of the transposable element, Ac, in the aspen genome) are discussed
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018421620040
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  • 32
    Electronic Resource
    Electronic Resource
    Matrix attachment regions (MARs) enhance transformation frequency and transgene expression in poplar (1997)
    Springer
    Transgenic research 6 (1997), S. 415-420 
    Details
    ISSN: 1573-9368
    Keywords: GUS ; matrix attachment regions ; Populus ; transformation ; transgene expression ; Agrobacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We tested the value of a matrix attachment region (MAR) fragment derived from a tobacco gene for increasing the frequency of Agrobacterium-mediated transformation. A binary vector that carried a GUS reporter gene containing an intron and an nptII gene was modified to contain flanking MAR elements within the T-DNA borders. Vectors containing or lacking MARs were then used to transform tobacco, a readily transformabl e poplar clone (Populus tremula × P. alba), and a recalcitrant poplar clone (Populus trichocarpa × P. deltoides). MARs increased GUS gene expression approximately 10-fold in the two hybrid poplar clones and twofold in tobacco one month after cocultivation with Agrobacterium; MARs also increased the frequency of kanamycin-resistant poplar shoots recovered
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018439518649
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  • 33
    Electronic Resource
    Electronic Resource
    SAAT: sonication-assisted Agrobacterium-mediated transformation (1997)
    Springer
    Transgenic research 6 (1997), S. 329-336 
    Details
    ISSN: 1573-9368
    Keywords: Agrobacterium ; SAAT ; sonication ; transformation ; wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plant transformation via Agrobacterium can be limited by both host specificity and the inability of Agrobacterium to reach the proper cells in the target tissue. Described here is a new and efficient Agrobacterium-based transformation technology that overcomes these barriers and enhances DNA transfer in such diverse plant groups as dicots, monocots, and gymnosperms. This new technology, called sonication-assisted Agrobacterium-mediated transformation (SAAT), involves subjecting the plant tissue to brief periods of ultrasound in the presence of Agrobacterium. Scanning electron and light microscopy reveal that SAAT treatment produces small and uniform fissures and channels throughout the tissue allowing the Agrobacterium easy access to internal plant tissues. Unlike other transformation methods, this system has the potential to transform meristematic tissue buried under several cell layers. SAAT increases transient transformation efficiency in several different plant tissues including leaf tissue, immature cotyledons, somatic and zygotic embryos, roots, stems, shoot apices, embryogenic suspension cells and whole seedlings. A 100- to 1400-fold increase in transient β- glucuronid ase expression has been demonstrated in various tissues of soybean, Ohio buckeye, cowpea, white spruce, wheat and maize. Stable transformation of both soybean and Ohio buckeye has been obtained using SAAT of embryogenic suspension culture tissues. For soybean, SAAT treatment was necessary to obtain stable transformation with this tissue
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018470930944
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  • 34
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    Electronic Resource
    Transgenic plant production mediated by Agrobacterium in Indica rice (1996)
    Springer
    Plant cell reports 15 (1996), S. 727-730 
    Details
    ISSN: 1432-203X
    Keywords: Acetosyringone ; Agrobacterium ; Indica rice ; Oryza sativa L. ; Transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A reproducible system has been developed for the production of transgenic plants in indica rice using Agrobacterium-mediated gene transfer. Three-week-old scutella calli served as an excellent starting material. These were infected with an Agrobacterium tumefaciens strain EHA101 carrying a plasmid pIG121Hm containing genes for β-glucuronidase (GUS) and hygromycin resistnace (HygR). Hygromycin (50 mg/l) was used as a selectable agent. Inclusion of acetosyringone (50μM) in the Agrobacterium suspension and co-culture media proved to be indispensable for successful transformation. Transformation efficiency of Basmati 370 was 22% which was as high as reported in japonica rice and dicots. A large number of morphologically normal, fertile transgenic plants were obtained. Integration of foreign genes into the genome of transgenic plants was confirmed by Southern blot analysis. GUS and HygR genes were inherited and expressed in R1 progeny. Mendelian segregation was observed in some R1 progeny.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232216
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  • 35
    Electronic Resource
    Electronic Resource
    Agrobacterium tumefaciens-mediated transformation of japonica and indica rice varieties (1996)
    Springer
    Planta 199 (1996), S. 612-617 
    Details
    ISSN: 1432-2048
    Keywords: Agrobacterium ; indica rice ; Inheritance ; Japonica rice ; Oryza ; Transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genetic transformation of rice (Oryza sativa L.) mediated by Agrobacterium ttumefaciens has been confirmed for japonica varieties and extended to include the more recalcitrant indica varieties. Immature embryos were inoculated with either A. tumefaciens At656 (pCNL56) or LBA4404 (pTOK233). Experimental conditions were developed initially for immature embryos treated with strain At656, based upon both transient and stable β-glucuromdase (GUS) activities. However, plant regeneration following selection on G418 (pCNL56 contained the nptII gene) did not occur. Using the same basic protocol, but inoculating immature embryos of rice with LBA4404 (pTOK233), resulted in efficient (about 27%) production of transgenic plants of the japonica variety, Radon, and an acceptable efficiency (from 1–5%) for the indica varieties IR72 and TCS10. Transformation was based upon resistance to hygromycin (pTOK233 contains the hpt gene), the presence of GUS activity (from the gusA gene), Southern blots for detection of the integrated gusA gene, and transmission of GUS activity to progeny in a Mendelian 3:1 segregation ratio. Southern blots indicated two to three copies of the gene integrated in most transformants. Transgenic plants of both the japonica and indica varieties were self-fertile and comparable in this respect to seed-grown plants. Key factors facilitating the transformation of rice by Agrobacterium tumefaciens appeared to be the use of embryos as the expiant, the use of hygromycin as the selection agent (which does not interfere with rice regeneration), the presence of extra copies of certain vir genes on the binary vector of pTOK233, and maintaining high concentrations of acetosyringone for inducing the vir genes during co-cultivation of embryos with Agrobacterium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195194
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  • 36
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    Electronic Resource
    Transient expression of uidA constructs in in vitro onion (Allium cepa L.) cultures following particle bombardment and Agrobacterium-mediated DNA delivery (1996)
    Springer
    Plant cell reports 15 (1996), S. 958-962 
    Details
    ISSN: 1432-203X
    Keywords: Transformation ; particle bombardment ; Agrobacterium ; Allium cepa.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Particle bombardment and Agrobacterium-mediated DNA delivery into immature embryos and microbulbs were used to investigate the expression of the uidA gene in in vitro onion cultures. Both methods were successful in delivering DNA and subsequent uidA expression was observed. Optimal transient β-glucuronidase activity was observed in immature embryos that had been pre-cultured for three days and bombarded at a distance of 3 cm from the stopping plate, under 25 in Hg vacuum, using 900–1300 psi rupture discs. The CaMV35S-uidA gene construct gave five fold higher transient β-glucuronidase activity than the uidA gene construct regulated by any of four other promoters initially chosen for high experession in monocotyledonous tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231596
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  • 37
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    Electronic Resource
    Production of an extracellular polysaccharide byAgrobacterium sp DS3 NRRL B-14297 isolated from soil (1996)
    Springer
    Journal of industrial microbiology and biotechnology 16 (1996), S. 129-133 
    Details
    ISSN: 1476-5535
    Keywords: extracellular polysaccharide ; Agrobacterium ; viscous polysaccharide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A bacterium isolated from soil and identified asAgrobacterium sp produced a water-soluble extracellular polysaccharide capable of producing highly viscous solutions. Gas chromatographic analysis revealed a sugar composition of glucose, galactose and mannose in the molar ratio of 7.5∶2.4∶1, together with 3.7% (w/w) pyruvic acid. Methylation analyses showed the presence of (1→3)-, (1→4)- and (1→6)-linked glucose, (1→3)- and (1→4, 1→6)-linked galactose and a small portion of (1→3)-linked mannose residues. Succinic acid was not present. The molecular weight of the polysaccharide was estimated by light scattering to be 2×106 Da. The viscosity of solutions containing the polysaccharide remained constant from pH 3 to 11, and decreased by 50% when heated from 5 to 55°C. Maximum yield of the polysaccharide, 20 g L−1, was reached in 48 h at 30°C incubation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01570073
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  • 38
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    Electronic Resource
    Sequence and characterisation of a ribosomal RNA operon from Agrobacterium vitis (1996)
    Springer
    Molecular genetics and genomics 251 (1996), S. 99-107 
    Details
    ISSN: 1617-4623
    Keywords: Key words Ribosomal genes ; Agrobacterium ; Evolution ; 23S rRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  One of the four ribosomal RNA operons (rrnA) from the Agrobacterium vitis vitopine strain S4 was sequenced. rrnA is most closely related to the rrn operons of Bradyrhizobium japonicum and Rhodobacter sphaeroides and carries an fMet-tRNA gene downstream of its 5S gene, as in the case of R. sphaeroides. The 16S rRNA sequence of S4 differs from the A. vitis K309 type strain sequence by only one nucleotide, in spite of the fact that S4 and K309 have very different Ti plasmids. The predicted secondary structure of the S4 23S rRNA shows several features that are specific for the alpha proteobacteria, and an unusual branched structure in the universal B8 stem. The 3′ ends of the three other rrn copies of S4 were also cloned and sequenced. Sequence comparison delimits the 3′ ends of the four repeats and defines two groups: rrnA/rrnB and rrnC/rrnD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02174350
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  • 39
    Electronic Resource
    Electronic Resource
    Sequence and characterisation of a ribosomal RNA operon fromAgrobacterium vitis (1996)
    Springer
    Molecular genetics and genomics 251 (1996), S. 99-107 
    Details
    ISSN: 1617-4623
    Keywords: Ribosomal genes ; Agrobacterium ; Evolution ; 23S rRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract One of the four ribosomal RNA operons (rrnA) from theAgrobacterium vitis vitopine strain S4 was sequenced.rrnA is most closely related to therrn operons ofBradyrhizobium japonicum andRhodobacter sphaeroides and carries an fMet-tRNA gene downstream of its 5S gene, as in the case ofR. sphaeroides. The 16S rRNA sequence of S4 differs from theA. vitis K309 type strain sequence by only one nucleotide, in spite of the fact that S4 and K309 have very different Ti plasmids. The predicted secondary structure of the S4 23S rRNA shows several features that are specific for the alpha proteobacteria, and an unusual branched structure in the universal B8 stem. The 3′ ends of the three otherrrn copies of S4 were also cloned and sequenced. Sequence comparison delimits the 3′ ends of the four repeats and defines two groups:rrnA/rrnB andrrnC/rrnD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02174350
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  • 40
    Electronic Resource
    Electronic Resource
    Identification of Agrobacterium and Rhizobium species based on cellular fatty acid composition (1996)
    Springer
    Plant and soil 184 (1996), S. 143-158 
    Details
    ISSN: 1573-5036
    Keywords: Agrobacterium ; FAME ; fatty acid analysis ; rapid identification ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The increasing number of phylogenetically defined species in the genera Agrobacterium, Rhizobium and Sinorhizobium suggests a need for a rapid identification method which will distinguish between these species. We have examined 65 strains of Agrobacterium representing: A. tumefacies, (34); A. rhizogenes, (16) A. vitis, (10) A. rubi (2) and some unclassified strains, and 150 strains of Rhizobium and Sinorhizobium representing: R. etli (21); R. galegae (20); R. huakuii (17); R. leguminosarum (20); R. loti (16); R. topici (18); S. fredii (19); and S. meliloti (20). Fatty acid methyl esters (FAME) were obtained from each strain, as previously described, and analysed by gas-chromatography using the MIDI Hewlett-Packard Microbial Identification System (MIS). Fatty acid profiles were recorded, characteristic fatty acids noted and the overall similarities between fatty acid profiles for each species calculated. Relationships between species were also derived from the fatty acid data by principal component analysis. This showed overlapping clusters for strains of R. leguminosarum and R. etli, R. topici and A. rhizogenes and S. fredii and S. meliloti within one supercluster. Strains of A. tumefaciens, A rubi, A. vitis and R. galegae formed a second supercluster while R. loti and R. huakuii strains formed a third cluster well separated from all the other strains. The fatty acid profiles were used to correctly identify at least 94% of the strains representing each species in the collection except R. etli. R. etli strains (23.8%) were misidentified as R. leguminosarum. This was attributed to the high similarity (44.7%) between R. etli and R. leguminosarum. It is concluded that whole cell fatty acid analysis should form part of the polyphasic description of new species of root nodule bacteria, with the proviso that growth conditions and analytical methods be carefully standardized. It is suggested that FAME-MIS system and the database we have compiled provide a basis for future development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029284
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  • 41
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    Corresponding 16S rRNA gene segments in Rhizobiaceae and Aeromonas yield discordant phylogenies (1996)
    Springer
    Plant and soil 186 (1996), S. 69-74 
    Details
    ISSN: 1573-5036
    Keywords: Agrobacterium ; population genetics ; Rhizobium ; systematics ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Previous evidence has indicated that the 16S rRNA genes in certain species of Aeromonas may have a history of lateral transfer and recombination. A comparative analysis of patterns of 16S nucleotide sequence polymorphism among species of Rhizobium and Agrobacterium was conducted to determine if there is similar evidence for chimeric 16S genes in members of the Rhizobiaceae. Results from phylogenetic analyses and comparison of patterns of nucleotide sequence polymorphism in portions of rhizobial 16S genes revealed the same type of segment-dependent polymorphic site partitioning that was previously reported for Aeromonas. These results support the hypothesis that certain 16S segments in rhizobia may have a history of lateral transfer and recombination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00035057
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  • 42
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    Preconditioning Mixed Finite Element Saddle-point Elliptic Problems (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 1-20 
    Details
    ISSN: 1070-5325
    Keywords: preconditioning saddle-point problems ; eigenvalue estimation ; mixed finite element method ; minimum residual method ; second-order elliptic problems ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: We consider saddle-point problems that typically arise from the mixed finite element discretization of second-order elliptic problems. By proper equivalent algebraic operations the considered saddle-point problem is transformed to another saddle-point problem. The resulting problem can then be efficiently preconditioned by a block-diagonal matrix or by a factored block-matrix (the blocks correspond to the velocity and pressure, respectively). Both preconditioners have a block on the main diagonal that corresponds to the bilinear form(δ is a positive parameter) and a second block that is equal to a constant times the identity operator. We derive uniform bounds for the negative and positive eigenvalues of the preconditioned operator. Then any known preconditioner for the above bilinear form can be applied. We also show some numerical experiments that illustrate the convergence properties of the proposed technique.
    Additional Material: 2 Tab.
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  • 43
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    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996) 
    Details
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nla.1680030101
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  • 44
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    Multifrontal QR Factorization in a Multiprocessor Environment (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 275-300 
    Details
    ISSN: 1070-5325
    Keywords: sparse QR factorization ; multifrontal method ; parallelism ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: We describe the design and implementation of a parallel QR decomposition algorithm for a large sparse matrix A. The algorithm is based on the multifrontal approach and makes use of Householder transformations. The tasks are distributed among processors according to an assembly tree which is built from the symbolic factorization of the matrix ATA.We first address uniprocessor issues and then discuss the multiprocessor implementation of the method. We consider the parallelization of both the factorization phase and the solve phase. We use relaxation of the sparsity structure of both the original matrix and the frontal matrices to improve the performance. We show that, in this case, the use of Level 3 BLAS can lead to very significant gains in performance. We use the eight processor Alliant˜FX/80 at CERFACS to illustrate our discussion.
    Additional Material: 12 Ill.
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  • 45
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    Two-stage Multisplitting Methods with Overlapping Blocks (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 113-124 
    Details
    ISSN: 1070-5325
    Keywords: iterative methods ; linear systems ; multisplittings ; overlap ; parallel algorithms ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Parallel two-stage multisplitting methods with overlap for the solution of linear systems of algebraic equations are studied. It is shown that, under certain hypotheses, the method with overlap is asymptotically faster than that without overlap. Experiments illustrating this phenomenon are presented.
    Additional Material: 2 Ill.
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  • 46
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    On Fast Computations with the Inverse to Harmonic Potential Operators via Domain Decomposition (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 91-111 
    Details
    ISSN: 1070-5325
    Keywords: boundary integral operators ; domain decomposition ; interface operators ; fast elliptic problem solvers ; parallel algorithms ; preconditioning ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: In this paper a method for fast computations with the inverse to weakly singular, hypersingular and double layer potential boundary integral operators associated with the Laplacian on Lipschitz domains is proposed and analyzed. It is based on the representation formulae suggested for above-mentioned boundary operations in terms of the Poincare-Steklov interface mappings generated by the special decompositions of the interior and exterior domains. Computations with the discrete counterparts of these formulae can be efficiently performed by iterative substructuring algorithms provided some asymptotically optimal techniques for treatment of interface operators on subdomain boundaries. For both two- and three-dimensional cases the computation cost and memory needs are of the order O(N logp N) and O(N log2 N), respectively, with 1 ≤ p ≤ 3, where N is the number of degrees of freedom on the boundary under consideration (some kinds of polygons and polyhedra). The proposed algorithms are well suited for serial and parallel computations.
    Additional Material: 2 Ill.
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  • 47
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    Short Communication: Two Properties of Diagonally Dominant Matrices (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 173-177 
    Details
    ISSN: 1070-5325
    Keywords: diagonally dominant matrix ; determinant ; norm ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: A property of strictly diagonally dominant matrices and a generalization of a Varga's bound for ∥ A-1∥∞ to the case ∥ A-1B∥∞ are given and the two-sided bounds for the determinants of strictly diagonally dominant matrices are derived
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  • 48
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    Piecewise Polynomial Solutions Without a priori Break Points (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 513-524 
    Details
    ISSN: 1070-5325
    Keywords: regularization ; I-norm ; discontinuous solutions ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: In certain inverse problems it is useful to be able to compute solutions which are, in some sense, as simple as possible. For example,k one may wish to compute solutions which are piecewise constant and with as few discontinuities as possible. Such solutions are suited to describe models, e.g., geological layers, where the coarse structure is more important than the fine structure. A natural generalization of piecewise constant functions is piecewise polynomial solutions. In this paper we present a new algorithm which is capable of computing solutions that are piecewise polynomials, without having to specify a priori the positions of the break points between the polynomial pieces.
    Additional Material: 5 Ill.
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  • 49
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    On IOM(q): The Incomplete Orthogonalization Method for Large Unsymmetric Linear Systems (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 491-512 
    Details
    ISSN: 1070-5325
    Keywords: unsymmetric ; Krylov subspace ; IOM(q) ; FOM ; truncated ; basis vector ; orthonormality ; convergence ; restarted ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The incomplete orthogonalization method (IOM(q)), a truncated version of the full orthogonalization method (FOM) proposed by Saad, has been used for solving large unsymmetric linear systems. However, no convergence analysis has been given. In this paper, IOM(q) is analysed in detail from a theoretical point of view. A number of important results are derived showing how the departure of the matrix A from symmetric affects the basis vectors generated by IOM(q), and some relationships between the residuals for IOM(q) and FOM are established. The results show that IOM(q) behaves much like FOM once the basis vectors generated by it are well conditioned. However, it is proved that IOM(q) may generate an ill-conditioned basis for a general unsymmetric matrix such that IOM(q) may fail to converge or at least cannot behave like FOM. Owing to the mathematical equivalence between IOM(q) and the truncated ORTHORES(q) developed by Young and Jea, insights are given into the convergence of the latter. A possible strategy is proposed for choosing the parameter q involved in IOM(q). Numerical experiments are reported to show convergence behaviour of IOM(q) and of its restarted version.
    Additional Material: 6 Tab.
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  • 50
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    Block Two-stage Methods for Singular Systems and Markov Chains (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 413-426 
    Details
    ISSN: 1070-5325
    Keywords: iterative methods ; linear systems ; singular matrices ; block methods ; multisplitting ; two-stage ; non-stationary ; Markov chains ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The use of block two-stage methods for the iterative solution of consistent singular linear systems is studied. In these methods, suitable for parallel computations, different blocks, i.e., smaller linear systems, can be solved concurrently by different processors. Each of these smaller systems are solved by an (inner) iterative method. Hypotheses are provided for the convergence of non-stationary methods, i.e., when the number of inner iterations may vary from block to block and from one outer iteration to another. It is shown that the iteration matrix corresponding to one step of the block method is convergent, i.e., that its powers converge to a limit matrix. A theorem on the convergence of the infinite product of matrices with the same eigenspace corresponding to the eigenvalue 1 is proved, and later used as a tool in the convergence analysis of the block method. The methods studied can be used to solve any consistent singular system, including discretizations of certain differential equations. They can also be used to find stationary probability distribution of Markov chains. This last application is considered in detail.
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    Editorial (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 349-350 
    Details
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: No Abstract
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  • 52
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    Multilevel Preconditioners for Mixed Methods for Second Order Elliptic Problems (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 427-453 
    Details
    ISSN: 1070-5325
    Keywords: mixed method ; nonconforming method ; multilevel preconditioner ; condition number ; second order elliptic problem ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: A new approach for constructing algebraic multilevel preconditioners for mixed finite element methods for second order elliptic problems with tensor coefficients on general geometry is proposed. The linear system arising from the mixed methods is first algebraically condensed to a symmetric, positive definite system for Lagrange multipliers, which corresponds to a linear system generated by standard nonconforming finite element methods. Algebraic multilevel preconditioners for this system are then constructed based on a triangulation of the domain into tetrahedral substructures. Explicit estimates of condition numbers and simple computational schemes are established for the constructed preconditioners. Finally, numerical results for the mixed finite element methods are presented to illustrate the present theory.
    Additional Material: 4 Ill.
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  • 53
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    Conference diary (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 455-457 
    Details
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nla.1680030502
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  • 54
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    A Comparison of Three Basic Conjugate Direction Methods (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 473-489 
    Details
    ISSN: 1070-5325
    Keywords: conjugate gradients ; biconjugate gradients ; conjugate directions ; non-symmetric linear systems ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: In this paper three basic conjugate direction methods for solving non-symmetric linear systems are described and compared. All three have entirely different basic structures and, consequently, completely different characteristics. The motivation for this work is the comparative assessment of the methods in order to decide which of the three is the most suitable for further development.
    Additional Material: 8 Ill.
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  • 55
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    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996) 
    Details
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nla.1680030601
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  • 56
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    Conference diary (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 543-545 
    Details
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nla.1680030602
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  • 57
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    Toeplitz Preconditioners with Block Structure for First-order PDEs (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 21-44 
    Details
    ISSN: 1070-5325
    Keywords: first-order PDEs ; iterative methods ; preconditioners ; Toeplitz ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Preconditioners to nonsymmetric, nondiagonally dominant systems of equations are constructed and examined numerically. The preconditioners are based on a Toeplitz approach with a certain symmetry that we define. The inversion of the preconditioners is defined through a Fast Modified Sine Transform. As a model problem we study the systems of equations arising from a implicit time-discretization with a large time-step of a scalar hyperbolic PDE.
    Additional Material: 17 Ill.
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    Generalization of Strang's Preconditioner with Applications to Toeplitz Least Squares Problems (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 45-64 
    Details
    ISSN: 1070-5325
    Keywords: Toeplitz least squares problems ; circulant preconditioned conjugate gradient method ; deconvolution ; image restoration ; atmospheric imaging ; medical imaging ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: In this paper, we propose a method to generalize Strang's circulant preconditioner for arbitrary n-by-n matrices An. The th column of our circulant preconditioner Sn is equal to the th column of the given matrix An. Thus if An is a square Toeplitz matrix, then Sn is just the Strang circulant preconditioner. When Sn is not Hermitian, our circulant preconditioner can be defined as . This construction is similar to the forward-backward projection method used in constructing preconditioners for tomographic inversion problems in medical imaging. We show that if the matrix An has decaying coefficients away from the main diagonal, then is a good preconditioner for An. Comparisons of our preconditioner with other circulant-based preconditioners are carried out for some 1-D Toeplitz least squares problems: min ∥ b - Ax∥2. Preliminary numerical results show that our preconditioner performs quite well, in comparison to other circulant preconditioners. Promising test results are also reported for a 2-D deconvolution problem arising in ground-based atmospheric imaging.
    Additional Material: 5 Ill.
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    A Parallel Preconditioned Iterative Realization of the Panel Method in 3D (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 65-80 
    Details
    ISSN: 1070-5325
    Keywords: boundary value problem ; boundary element method ; preconditioning ; iterative method ; fast Fourier transform ; parallel algorithm ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The parallel version of precondition iterative techniques is developed for matrices arising from the panel boundary element method for three-dimensional simple connected domains with Dirichlet boundary conditions. Results were obtained on an nCube-2 parallel computer showing that preconditioned iterative methods are very well suited also in three-dimensional cases for implementation on an MIMD computer and that they are much more efficient than usual direct solution techniques.
    Additional Material: 6 Ill.
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  • 60
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    Conference diary (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 91-93 
    Details
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nla.1680030102
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    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996) 
    Details
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nla.1680030401
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  • 62
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    Conference diary (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 345-348 
    Details
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nla.1680030402
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    The Finite Difference Based Fast Adaptive Composite Grid Method (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 391-411 
    Details
    ISSN: 1070-5325
    Keywords: finite difference discretization ; fast adaptive composite grid method ; convergence rate ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The fast adaptive composite grid (FAC) method is an iterative method for solving discrete boundary value problems on composite grids. McCormick introduced the method in [8] and considered the convergence behaviour for discrete problems resulting from finite volume element discretization on composite grids. In this paper we consider discrete problems resulting from finite difference discretization on composite grids. We distinguish between two obvious discretization approaches at the grid points on the interfaces between fine and coarse subgrids. The FAC method for solving such discrete problems is described. In the FAC method several intergrid transfer operators appear. We study how the convergence behaviour depends on these intergrid transfer operators. Based on theoretical insights, (quasi-)optimal intergrid transfer operators are derived. Numerical results illustrate the fast convergence of the FAC method using these intergrid transfer operators.
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    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996) 
    Details
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nla.1680030501
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    Dykstra's Algorithm for a Constrained Least-squares Matrix Problem (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 459-471 
    Details
    ISSN: 1070-5325
    Keywords: alternating projection method ; Dykstra's algorithm ; patterned matrix ; constrained least-squares ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: We apply Dykstra's alternating projection algorithm to the constrained least-squares matrix problem that arises naturally in statistics and mathematical economics. In particular, we are concerned with the problem of finding the closest symmetric positive definite bounded and patterned matrix, in the Frobenius norm, to a given matrix. In this work, we state the problem as the minimization of a convex function over the intersection of a finite collection of closed and convex sets in the vector space of square matrices.We present iterative schemes that exploit the geometry of the problem, and for which we establish convergence to the unique solution. Finally, we present preliminary numberical results to illustrate the performance of the proposed iterative methods.
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    Analysis of Algorithms for Orthogonalizing Products of Unitary Matrices (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 125-145 
    Details
    ISSN: 1070-5325
    Keywords: orthogonalization ; QR factorization ; polar decomposition ; subspace tracking ; error analysis ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: We consider the problem of computing Uk = QkUk-1(where U0 is given) in finite precision (εM = machine precision) where U0 and theQi are known to be unitary. The problem is that Ûk, the computed product may not be unitary, so one applies an O(n2) orthogonalizing step after each multiplication to(a) prevent Ûk from drifing too far from the set of untary matrices(b) prevent Ûk from drifting too far from Uk the true product.Our main results are1. Scaling the rows to have unit length after each multiplication (the cheaptest of the algorithms considered) is usually as good as any other method with respect to either of the criteria (a) or (b).2. A new orthogonalization algorithm that guarantees the distance of Ûk (k = 1, 2, …) to the set of unitary matrices is bounded by n3.5εM for any choice of Qi.
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    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996) 
    Details
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nla.1680030201
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    Estimate of the Constant in Two Strengthened C.B.S. Inequalities for F.E.M. Systems of 2D Elasticity: Application to Multilevel Methods and a Posteriori Error Estimators (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 147-159 
    Details
    ISSN: 1070-5325
    Keywords: elasticity ; finite-element ; multilevel ; a posteriori error estimation ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The constant γ in the strengthened Cauchy-Buniakowski-Schwarz (C.B.S.) inequality plays a crucial role in the convergence rate of multilevel iterative methods as well as in the efficiency of a posteriori error estimators, that is in the framework of finite element approximations of SPD problems.We consider the approximation of the 2D elasticity problem by the Courant element. Concerning multilevel convergence rate, that is the γ corresponding to nested general triangular meshes of size h and 2h, we have proved that γ2≤ 3/4$ uniformly on the mesh and the Poisson ratio. Concerning error estimator, that is the γ corresponding to quadratic and linear approximations on the same mesh, numerical computations have shown that the exact γ for a reference element deteriorates that is goes to one, when the Poisson ratio tends to 1/2
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    On the Smoothing Property of Multigrid Methods in the Non-symmetric Case (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 161-172 
    Details
    ISSN: 1070-5325
    Keywords: smoothing property ; multigrid method ; semi-iterative smoother ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: In this paper we present an extension of Reusken's Lemma about the smoothing property of a multigrid method for solving non-symmetric linear systems of equations. One of the consequences of this extended lemma is the verification of the smoothing property for all damping factors οε(0, 1). Additionally, a semi-iterative smoother is constructed which gives, in some sense, optimal smoothing rate estimates.
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    Conference diary (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 179-183 
    Details
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nla.1680030202
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    Parallel Algorithms for Orthotropic Problems (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 185-203 
    Details
    ISSN: 1070-5325
    Keywords: orthotropic partial differential equation ; preconditioned conjugate gradient method ; parallel algorithm ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Finite element meshes and node-numberings suitable for parallel solution with equally loaded processors are presented for linear orthotropic elliptic partial differential equations. These problems are of great importance, for instance in the oil and airfoil industries. The linear systems of equations are solved by the conjugate gradient method preconditioned by modified incomplete factorization, MIC. The basic method presented, is based on fronts of uncoupled nodes and unlike earlier methods it has the advantage of no requirement of a specific orientation of the mesh. This method is however, in general, restricted to small degree of anisotropy in the differential equation. Another method, which does not suffer from this limitation, uses rotation of the differential equation and spectral equivalence. The rotation is made in such a way that in the new co-ordinate system, the basic method is applicable. The spectral equivalence property is used for estimation of the condition number of the preconditioned system. Both methods are suitable for implementation on parallel computers. The computer architecture could be single instruction multiple data (SIMD) as well as multiple instruction multiple data (MIMD) with shared or distributed memory. Implementation of the basic method on a shared memory parallel computer shows a significant improvement by use of the MIC method compared with the diagonal scaling preconditioning method.
    Additional Material: 13 Ill.
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    Overlapping Domain Decomposition Algorithms for General Sparse Matrices (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 221-237 
    Details
    ISSN: 1070-5325
    Keywords: sparse matrix ; iterative methods ; preconditioning ; graph partitioning ; domain decomposition ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Domain decomposition methods for finite element problems using a partition based on the underlying finite element mesh have been extensively studied. In this paper, we discuss algebraic extensions of the class of overlapping domain decomposition algorithms for general sparse matrices. The subproblems are created with an overlapping partition of the graph corresponding to the sparsity structure of the matrix. These algebraic domain decomposition methods are especially useful for unstructured mesh problems. We also discuss some difficulties encountered in the algebraic extension, particularly the issues related to the coarse solver.
    Additional Material: 4 Ill.
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    Convergence Estimates of Multilevel Additive and Multiplicative Algorithms for Non-symmetric and Indefinite Problems (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 205-220 
    Details
    ISSN: 1070-5325
    Keywords: elliptic equations ; multilevel methods ; finite element ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: New uniform estimates for multigrid algorithms are established for certain non-symmetric indefinite problems. In particular, we are concerned with the simple additive algorithm and multigrid (V(1,0)-cycle) algorithms given in [5]. We prove, without full elliptic regularity assumption, that these algorithms have uniform reduction per iteration, independent of the finest mesh size and number of refinement levels, provided that the coarsest mesh size is sufficiently small.
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    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996) 
    Details
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nla.1680030301
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    Globalization of Newton's Method for Solving Non-linear Equations (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 239-249 
    Details
    ISSN: 1070-5325
    Keywords: non-linear equations ; global convergence ; Lagrangians ; non-linear programming ; Lagrangian globalization ; detour potentials ; homotopy methods ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The Lagrangian globalization (LG) method for non-linear equation-solving proposed in [10] is developed through theoretical analysis, the formulation of a particular LG algorithm, and a numerical illustration. New merit functions (termed detour potentials) for non-linear equation-solving, which broaden the LG concept, are also defined.
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    Conference diary (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 251-254 
    Details
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nla.1680030302
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    Two-level Preconditioner with Small Coarse Grid Appropriate for Unstructured Meshes (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 255-274 
    Details
    ISSN: 1070-5325
    Keywords: conjugate gradient method ; preconditioning ; two-level method ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The presented paper contains a suggestion and an analysis of a two-level preconditioner appropriate for unstructured meshes. The convergence analysis is done for H1-equivalent forms in the two-dimensional case; ways for generalization are discussed, too. The efficiency is demonstrated by numerical experiments.
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    DQGMRES: a Direct Quasi-minimal Residual Algorithm Based on Incomplete Orthogonalization (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 329-343 
    Details
    ISSN: 1070-5325
    Keywords: iterative methods ; GMRES ; Krylov methods ; incomplete orthogonalization ; quasi-minimization ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: We describe a Krylov subspace technique, based on incomplete orthogonalization of the Krylov vectors, which can be considered as a truncated version of GMRES. Unlike GMRES(m), the restarted version of GMRES, the new method does not require restarting. Like GMRES, it does not break down. Numerical experiments show that DQGMRES(k) often performs as well as the restarted GMRES using a subspace of dimension m=2k. In addition, the algorithm is flexible to variable preconditioning, i.e., it can accommodate variations in the preconditioner at every step. In particular, this feature allows the use of any iterative solver as a right-preconditioner for DQGMRES(k). This inner-outer iterative combination often results in a robust approach for solving indefinite non-Hermitian linear systems.
    Additional Material: 9 Tab.
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    A Regularization Procedure for Σn-i=1fi(zj)xi = g(zj), ( j = 1, 2, …, n) (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 81-90 
    Details
    ISSN: 1070-5325
    Keywords: linear systems ; regularization ; divided differences ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: A regularization procedure for linear systems of the type fi(zj)xi = g(zj), (j = 1, 2, …, n) is presented, which is particularly useful in the case when z1, z2, …, zn are close to each other. The associated numerical algorithm was tested on several examples for which analytic solutions do exist and was found to yield highly accurate results.
    Additional Material: 1 Ill.
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    Low-rank Orthogonal Decompositions for Information Retrieval Applications (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 301-327 
    Details
    ISSN: 1070-5325
    Keywords: information ; latent semantic indexing ; low-rank ; orthogonal ; matrices ; metrieval ; singular value decomposition ; sparse ; ULV and URV decompositions ; updating ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Current methods to index and retrieve documents from databases usually depend on a lexical match between query terms and keywords extracted from documents in a database. These methods can produce incomplete or irrelevant results due to the use of synonyms and polysemus words. The association of terms with documents (or implicit semantic structure) can be derived using large sparse {\it term-by-document} matrices. In fact, both terms and documents can be matched with user queries using representations in k-space (where 100 ≤ k ≤ 200) derived from k of the largest approximate singular vectors of these term-by-document matrices. This completely automated approach called latent semantic indexing or LSI, uses subspaces spanned by the approximate singular vectors to encode important associative relationships between terms and documents in k-space. Using LSI, two or more documents may be closeto each other in k-space (and hence meaning) yet share no common terms. The focus of this work is to demonstrate the computational advantages of exploiting low-rank orthogonal decompositions such as the ULV (or URV) as opposed to the truncated singular value decomposition (SVD) for the construction of initial and updated rank-k subspaces arising from LSI applications.
    Additional Material: 11 Ill.
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    A Multigrid Method Based on Incomplete Gaussian Elimination (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 369-390 
    Details
    ISSN: 1070-5325
    Keywords: multigrid ; incomplete Gaussian elimination ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: In this paper we introduce and analyse a new Schur complement approximation based on incomplete Gaussian elimination. The approximate Schur complement is used to develop a multigrid method. This multigrid method has an algorithmic structure that is very similar to the algorithmic structure of classical multigrid methods. The resulting method is almost purely algebraic and has interesting properties with respect to variation in problem parameters.
    Additional Material: 5 Ill.
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    Multilevel Minimal Residual Methods for Nonsymmetric Elliptic Problems (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Numerical Linear Algebra with Applications 3 (1996), S. 351-367 
    Details
    ISSN: 1070-5325
    Keywords: multilevel preconditioning ; Krylov subspace methods ; GMRES, nonsymmetric elliptic problems ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The subject of this paper is to study the performance of multilevel preconditioning for nonsymmetric elliptic boundary value problems. In particular, a minimal residual method with respect to an appropriately scaled norm, measuring the size of the residual projections on all levels, is studied. This norm, induced by the multilevel splitting, is also the basis for a proper stopping criterion. Our analysis shows that the convergence rate of this minimal residual method using the multilevel preconditioner by Bramble, pasciak and Xu is bounded independently of the mesh-size. However, the convergence rate deteriorates with increasing size of the skew-symmetric part. Our numerical results show that by incorporating this into a multilevel cycle starting on the coarsest level, one can save fine-level-iterations and, therefore, computational work.
    Additional Material: 2 Ill.
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    Parallel computation of radiation view factors between two arbitrarily oriented surfaces (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 43-50 
    Details
    ISSN: 1069-8299
    Keywords: view factor ; radiation ; parallel computation ; heat transfer ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Two implementations for parallel computation of radiation heat transfer view factors are formulated and tested for a model problem. Using a sufficiently large number of processors and a suitable communications paradigm, the solution time for the problem considered here scales linearly with the number of surface elements in the parallel implementation rather than the quadratic scaling obtained using a serial approach. For larger problems, significantly shorter solution times are obtained using the massively parallel Connection Machine 5 than those obtained on a single processor of the Cray C-90, a traditional vector supercomputer. Parallel performance was degraded for implementations using too few processors or data layouts leading to inefficient processor communication.
    Additional Material: 5 Ill.
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    A Taylor expansion algorithm for integration of 3D near-hypersingular integrals (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 51-62 
    Details
    ISSN: 1069-8299
    Keywords: boundary element method ; hypersingular integrals ; singular integration ; elasticity ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An algorithm based on the Taylor series expansion is extended to deal with the problem of near-hypersingular integrals occurring in a 3D electrostatic BEM formulation. The integral is evaluated by subtracting out the leading terms in the near-hypersingular part of the integrand and adding it back. The accuracy of the proposed method is demonstrated for a curved element. It is shown that accurate values can be obtained with low orders of Gaussian quadrature.
    Additional Material: 7 Ill.
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    Masthead (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996) 
    Details
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cnm.1640120201
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    Conference diary (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 147-148 
    Details
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cnm.1640120202
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    Annoucement (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 149-150 
    Details
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cnm.1640120203
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    An asymptotic formula for correcting finite element predicted natural frequencies of membrane vibration problems (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 63-73 
    Details
    ISSN: 1069-8299
    Keywords: asymptotic solution ; natural frequencies ; membrane vibrations ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In the paper an asymptotic formula has been developed to correct the discretization error for the finite element predicted natural frequencies of membrane transverse vibration problems. The general idea behind deriving this asymptotic formula is that, when the finite element size approaches zero, a discretized finite element system approaches a continuous system and the predicted natural frequencies of the system from the finite element analysis therefore approach the exact solutions of the system. Without losing generality, several different finite element mesh patterns have been considered and the same asymptotic formula for correcting the finite element predicted natural frequency has been obtained for all the different mesh patterns because of the uniqueness of the exact solution to the natural frequency of a real structure. The usefulness, effectiveness and efficiency of the present asymptotic formula have been assessed by a simple but critical problem, for which the exact solution is available for comparison. In order to investigate the applicability of the asymptotic formula to practical engineering problems, two challenging membrane vibration problems of irregular shapes, an L-shape and a tapered shape with a circular hole in the centre, have also been analysed. The related numerical results have demonstrated that the asymptotic formula provides a very useful post-processing error corrector for the finite element predicted natural frequencies of membrane transverse vibration problems, even though the problem domains are of irregular shape. The greatest advantage in using the present asymptotic formula is that it yields a solution of higher accuracy, by simply using the formula to correct the rough solution obtained from a much coarser finite element mesh with fewer degrees of freedom, without any further finite element calculation.
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    Eigenvalue extraction for large finite element models using a new conjugate gradient algorithm (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 77-83 
    Details
    ISSN: 1069-8299
    Keywords: eigenvalue extraction ; conjugate gradient method ; finite element method ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A new conjugate gradient algorithm is presented for extracting eigenvalues from large systems of equations encountered in finite element analysis. The new algorithm involves applying the conjugate gradient method (CGM) to a static problem to generate an equivalent tridiagonal matrix used for eigenvalue computation. The eigenvalues of the tridiagonal matrix are then extracted using a QR factorization. The similarity of the new CGM with the Lanczos method is discussed regarding the need for matrix inversion and reorthogonalization. Several examples using the new method are presented to illustrate its performance.
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    A direct method to derive the boundary conditions of the homogenization equation for symmetric cells (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 185-196 
    Details
    ISSN: 1069-8299
    Keywords: homogenization ; boundary conditions ; periodicity ; finite element ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The numerical solution of homogenization equations by the finite element (FE) method is explained briefly. The issue of extracting boundary conditions from the periodicity assumption is addressed and a direct method utilizing symmetry is presented. Using this method, the computation of the elements of the constitutive matrix of a composite material is reduced to a very conventional boundary value problem with known forces and boundary conditions which can be carried out with any FE code. Two examples are presented.
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    Masthead (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996) 
    Details
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cnm.1640120401
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    Best-fit stress performance of a higher-order beam element (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 229-234 
    Details
    ISSN: 1069-8299
    Keywords: higher-order beam element ; best-fit stress prediction ; a priori error analysis ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: It is known that finite elements try to capture stresses within each discretized local region in a ‘best-fit’ sense. In the paper we examine the performance of a beam element based on a higher-order shear deformation theory and show that the best-fit paradigm accounts for the manner in which through-the-thickness displacement and stresses are modelled. An a priori prediction derived from the paradigm is confirmed by a carefully chosen numerical experiment. This provides a measure of the quality of approximation as well as another ‘falsification’ of the best-fit paradigm.
    Additional Material: 1 Ill.
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  • 93
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    A different approach to discretization for the numerical simulation of three-dimensional heat conduction in irregularly shaped materials (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 223-228 
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    ISSN: 1069-8299
    Keywords: Discretization ; heat conduction ; simulation ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A different approach to discretization is described with which complicated three-dimensional heat transfer problems can be solved with a finite volume approach on a general curvilinear grid. It represents an improvement on the existing methods in that it can easily be expanded to three-dimensional problems. A concise explanation of the transformation process is given, together with a discussion of the discretization procedure. The method is evaluated by solving two simple test problems and comparing the results with those of existing methods and the analytical solution. In conclusion it is found that this method yields equally or more accurate results than the existing methods, with the additional advantage of being easily expandable to three-dimensional problems.
    Additional Material: 5 Ill.
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  • 94
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    Automatic nodes generation in N-dimensional space (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 243-248 
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    ISSN: 1069-8299
    Keywords: finite elements ; automatic generation ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Finite element generation methods, such as Delaunay, allow the meshing of shapes from a set of nodes. These nodes must previously exist. The authors present a simple, fast and reliable method to generate them in an unstructured way in N-dimensional space. Its main characteristic is to easily allow variation of the node density by introducing a density function, either analytical or discretized. This function can also be anisotropic. Some nodes can have a pre-fixed position. Inner lines and holes can also be specified in the domain to be meshed. Generated nodes are to be connected according to triangles in 2D and tetrahedrals in 3D.
    Additional Material: 6 Ill.
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  • 95
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    Electronic Resource
    A modified non-linear member element allowing large loading and displacement increments (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 235-242 
    Details
    ISSN: 1069-8299
    Keywords: finite member element ; modified theory ; geometrical non-linearity ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In the paper a modified non-linear member element is derived which can lead to satisfactory computed results even for large loading and displacement increments from pre-instability to post-instability of structures. The high accuracy of this element is proved by numerical examples.
    Additional Material: 4 Ill.
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  • 96
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    Masthead (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996) 
    Details
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cnm.1640120501
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  • 97
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    Electronic Resource
    Quadratic programming algorithms for obstacle problems (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 249-256 
    Details
    ISSN: 1069-8299
    Keywords: obstacle problems ; quadratic programming ; finite element ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The numerical solution of problems involving frictionless contact between an elastic body and a rigid obstacle is considered. The elastic body may undergo small or large deformation. Finite element discretization and repetitive linearization lead to a sequence of quadratic programming (QP) problems for incremental displacement. The performances of several QP algorithms, including two new versions of a modified steepest descent algorithm, are compared in this context. Numerical examples include a string, a membrane and an Euler-Bernoulli beam, in contact with flat and non-flat rigid obstacles.
    Additional Material: 2 Ill.
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  • 98
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    Electronic Resource
    Conference diary (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 317-319 
    Details
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cnm.1640120502
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  • 99
    Electronic Resource
    Electronic Resource
    Optimal design for minimum weight in a cracked pressure vessel of a turboshaft (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 271-280 
    Details
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The authors study the shape optimization of a complex cracked shell under complex criteria. The shell is one of various cases of a turboshaft, and optimization criteria are associated to the cost, the technology, and above all the working conditions for the turboshaft. The optimization criteria involved are of course the weight of the structure, but also the plastic instability and critical stress intensity factor. All computations have been made with the Ansys finite element program in which an optimization module exists.
    Additional Material: 5 Ill.
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  • 100
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    Electronic Resource
    FE mode-matching schemes for the exterior Helmholtz problem and their relationship to the FE-DtN approach (1996)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 257-267 
    Details
    ISSN: 1069-8299
    Keywords: mode-matching ; Helmholtz' equation ; DtN ; finite element ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Finite element (FE) mode-matching procedures for the solution of Helmholtz' equation on an unbounded domain are reviewed and a symmetric general formulation is presented. This is a formal restatement of procedures applied previously to computations involving scattering of shallow water waves, acoustic transmission in non-uniform ducts and acoustic radiation from prismatic sheet metal ducts. An essential feature of the method is the use of a Galerkin procedure, rather than collocation, to match a finite computational model to a truncated modal expansion with the desired radiation characteristics. The method produces a symmetric set of linear equations which can be solved to give the unknown nodal values of the dependent variable and the modal coefficients of an outer expansion. Either of these sets of variables can be eliminated prior to solution to yield a reduced set of equations in the remaining parameters. The reduced equations obtained by eliminating the modal coefficients are shown to be identical to those obtained by applying a truncated Dirichlet-to-Neumann (DtN) boundary condition. If applied in this form, mode-matching can therefore be regarded as an alternative to the DtN method for generating this common set of discrete equations while permitting simultaneous solution for the modal coefficients in the outer region.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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