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  • 1995-1999  (1,064)
  • 1985-1989
  • 1860-1869
  • 1995  (1,064)
  • Engineering General  (737)
  • Genetics  (327)
  • 1
    ISSN: 1432-5233
    Keywords: Maturity-onset diabetes of the young (MODY) ; Genetics ; Diabetes mellitus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Genetic linkage studies of families with earlyonset type 2 diabetes have facilitated the identification of diabetes-susceptibility genes. In order to assess the feasibility of using linkage approaches to identify genes responsible for the development of type 2 diabetes in Japanese subjects, we examined our clinical records for multigenerational families suitable for genetic studies. We identified 16 families in which at least one subject was diagnosed with type 2 diabetes before 25 years of age. Seven of these families had a pattern of inheritance consistent with a diagnosis of maturity-onset diabetes of the young (MODY) and nine families showed a complex pattern of inheritance of type 2 diabetes with transmission of diabetes-susceptibility genes from both parents. The glucokinase and mitochondrial tRNALeu(UUR) genes were screened for mutations in at least one affected subject from each family in order to assess the contribution of mutations in these genes to the development of the diabetes. No mutations were found, which suggests that the diabetes in these families resulted from mutations in other genes.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 90 (1995), S. 380-388 
    ISSN: 1432-2242
    Keywords: Genetics ; Breeding ; Sorghum bicolor Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The objective of this study was to use restriction fragment length polymorphisms (RFLPs) to determine the genetic location and effects of genomic regions controlling plant height in sorghum. F2 plants (152) from the cross CK60 x PI229828 were used. Genomic and cDNA clones (106) identified 111 loci distributed among ten linkage groups covering 1299 cM. Interval mapping identified four regions, each in a separate linkage group. These regions may correspond to loci (dw) previously identified by alleles with qualitative effects. Also, these regions identified in sorghum may be orthologous to those previously reported for plant height in maize. Gene effects and gene action varied among genomic regions. In each region, PI229828 alleles resulted in increased plant height. Each region accounted for 9.2–28.7% of the phenotypic variation. Positive, additive effects ranged from 15 to 32cm. Tallness was dominant or overdominant and conferred by alleles from PI229828 for three quantitative trait loci (QTL). At the fourth QTL, PI229828 contributed to increased plant height, but short stature was partially dominant. One digenic interaction was significant. The presence of a PI229828 allele at one region diminished the effects of the other region. A multiple model indicated that these four regions collectively accounted for 63.4% of the total phenotypic variation. The utility of this information for germplasm conversion through backcross breeding is discussed.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0533
    Keywords: Primitive neuroepithelial tumor ; Desmoplastic small cell tumor ; Brain tumor of infancy Immunocytochemistry ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe a case of a desmoplastic brain tumor which was initially resected from the right fronto-temporal region in a 2 year-old boy. This nodular, calcified tumor was vascularized by the internal carotid artery and the middle meningeal artery branches. Grossly, it contained several mucoid cysts. Light microscopy showed cords or nests of small cuboidal cells surrounded by a loose connective tissue and desmoplasic areas containing fibers and spindle cells. The cuboidal cells expressed epithelial, neuronal and neuroendocrine markers. Some foci of spindle cells showed glial differentiation. The tumor recurred 16 months later and displayed some characteristics of the small cell neuroepithelial component, mitoses being conspicuous. Electron microscopy revealed undifferentiated clear cells, some containing neurosecretory granules. Karyotyping demonstrated the following formula: 〈 15 〉 46, t(8;11) (a13; q11). The chromosome 11 breakpoint was different from that described in Ewing's sarcoma. This isolated translocation has not been previously reported to our knowledge. These unusual features lead us to report this case and to discuss its pathogenesis.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 154 (1995), S. 654-657 
    ISSN: 1432-1076
    Keywords: Key words Fetal development ; Brain diseases ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report two female siblings with the fetal brain disruption sequence. Extensive investigation of both children failed to define a definitive aetiology but clinical and laboratory findings are consistent with a hitherto unknown storage disease. We postulate that the accumulation of a neurotoxic metabolite may be responsible for the disease phenotype observed. This is the first report of recurrence of the fetal brain disruption sequence and supports the existence of a genetic form of this condition. Previous reports have emphasized possible environmental aetiologies. Infants with fetal brain disruption sequence should be investigated exhaustively and, in the absence of definitive evidence of an environmental cause, the possibility of a genetic aetiology should be considered. In some families the recurrence risk may be as high as one in four.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1076
    Keywords: Key words Floating-Harbor ; syndrome ; Growth retardation ; Dysmorphology ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The Floating-Harbor syndrome is a growth retardation syndrome with delayed bone age, speech development, and typical facial features. The face is triangular with deep-set eyes, long eyelashes, bulbous nose, wide columella, short philtrum, and thin lips. We present an additional patient and review 16 cases from the literature. The possible phenotype in the patient's mother suggests a dominant mode of inheritance for the syndrome. Conclusion The Floating Harbor syndrome is a growth deficiency syndrome characterized by proportionate short stature, characteristic face and delayed speech development. Inheritance is possibly autosomal dominant.
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  • 6
    ISSN: 1432-1076
    Keywords: Key words Osteogenesis imperfecta ; Collagen I ; Mosaicism ; Genetics ; Recurrence risk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Osteogenesis imperfecta (OI), a dominantly inherited connective tissue disorder, is usually caused by defects in collagen I. There is growing evidence for parental mosaicism that results in affected children born to unaffected parents. This situation poses a difficult task for the geneticist because a mosaic parent may appear clinically healthy while carrying the mutation in a fraction of her or his gonadal cells. To illustrate this problem, we report a Swiss couple whose first child was affected with severe OI. The unexpected recurrence of the disorder in the second child raised the suspicion of a recessive trait or, rather, of parental mosaicism. We identified the responsible collagen mutation in the COL1A2 gene (Gly688Ser in the α2(I)-chain) in both children and demonstrated the father to be a somatic mosaic for this mutation and to have subtle clinical signs such as soft skin and short stature that may be a result of his mosaic state.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 154 (1995), S. 654-657 
    ISSN: 1432-1076
    Keywords: Fetal development ; Brain diseases ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report two female siblings with the fetal brain disruption sequence. Extensive investigation of both children failed to define a definitive aetiology but clinical and laboratory findings are consistent with a hitherto unknown storage disease. We postulate that the accumulation of a neurotoxic metabolite may be responsible for the disease phenotype observed. This is the first report of recurrence of the fetal brain disruption sequence and supports the existence of a genetic form of this condition. Previous reports have emphasized possible environmental aetiologies. Infants with fetal brain disruption sequence should be investigated exhaustively and, in the absence of definitive evidence of an environmental cause, the possibility of a genetic aetiology should be considered. In some families the recurrence risk may be as high as one in four.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1076
    Keywords: Floating-Harbor syndrome ; Growth retardation ; Dysmorphology ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Abstract The Floating-Harbor syndrome is a growth retardation syndrome with delayed bone age, speech development, and typical facial features. The face is triangular with deep-set eyes, long eyelashes, bulbous nose, wide columella, short philtrum, and thin lips. We present an additional patient and review 16 cases from the literature. The possible phenotype in the patient's mother suggests a dominant mode of inheritance for the syndrome. Conclusion The Floating Harbor syndrome is a growth deficiency syndrome characterized by proportionate short stature, characteristic face and delayed speech development. Inheritance is possibly autosomal dominant.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Der Hautarzt 46 (1995), S. 394-399 
    ISSN: 1432-1173
    Keywords: Schlüsselwörter Malignes Melanom ; Genetische Instabilität ; Genetik ; Syndrom der dysplastischen Nävi ; Xeroderma pigmentosum ; Key words Malignant melanoma ; Genetic instability ; Genetics ; Dysplastic nevus syndrome ; Xeroderma pigmentosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Exposure of the skin to ultraviolet irradiation is an important risk factor for the development of malignant melanoma, with UVA possibly playing an important role. Hereditary factors are also relevant. In the dysplastic nevus syndrome a genetic instability has been shown by different methods. In xeroderma pigmentosum the DNA repair defect is thought to be responsible for the high incidence of malignant melanoma. Frequent and non-random changes in certain chromosomes have been demonstrated in melanoma cells. These might contain sequences that control melanoma growth or melanoma suppressor genes. Especially the short arm of chromosome 9 is thought to contain one of these genes. This hypothesis is supported by a genetic linkage analysis in melanoma families and the demonstration of a germ line deletion of the locus 9p21 in a patient with eight primary melanomas. Changes in known tumor suppressor genes and oncogenes have also been reported in melanoma, but no consistent sequence of genetic events is known.
    Notes: Zusammenfassung Die Exposition der Haut mit ultravioletten Strahlen ist ein wichtiger Risikofaktor für die Entwicklung eines malignen Melanoms. Möglicherweise spielt hierbei UVA-A eine besondere Rolle. Daneben sind hereditäre Faktoren von Bedeutung. Während beim Syndrom der dysplastischen Nävi eine genetische Instabilität mit verschiedenen Methoden nachgewiesen wurde, wird bei Xeroderma pigmentosum der DNA-Reparaturdefekt für die hohe Melanominzidenz verantwortlich gemacht. In Melanomzellen sind überzufällig häufig karyotypische Veränderungen in bestimmten Chromosomen gefunden worden. Diese enthalten möglicherweise Melanomwachstumsregulierende Sequenzen oder Melanom-Suppressorgene. Insbesondere der kurze Arm des Chromosoms 9 steht in Verdacht, eines dieser Gene zu enthalten. Diese Hypothese wird auch unterstützt durch eine genetische Kopplungsanalyse an Melanomfamilien und dem Nachweis einer Keimbahndeletion des Lokus 9p21 bei einer Patientin mit 8 primären Melanomen. Veränderungen an bereits bekannten Tumorsuppressorgenen oder Onkogenen sind ebenfalls in Melanomen beschrieben worden, ohne daß jedoch eine konsistente Reihenfolge von genetischen Ereignissen bekannt wäre.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 90 (1995), S. 146-149 
    ISSN: 1432-2242
    Keywords: Capsicum chinense ; Resistance gene ; Genetics ; Pepper ; Tomato spotted wilt virus ; Tospoviruses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pepper (Capsicum chinense Jacq.) has been reported to be an important reservoir of resistance genes to tomato spotted wilt virus (TSWV). The genes for TSWV resistance present in three C. chinense lines (‘PI 152225’, ‘PI 159236’ and ‘Panca’) were investigated for allelism. All resistant lines were crossed with each other. Parents, F1, backcrosses and F2 populations (including reciprocals) developed from those crosses were mechanically inoculated with a highly virulent TSWV isolate. Susceptible C. annuum cv ‘Magda’ was used to check inoculum virulence. Fifty plants of the F1 hybrids; ‘Magda’ x ‘PI 152225’, ‘Magda’ x ‘PI 159236’, and ‘Magda’ x 'Panca, were also inoculated with the TSWV isolate. The resistance response in all C. chinense sources was associated with a localized, hypersensitive-like reaction that was phenotypically expressed as a prompt formation of large local lesions accompanied by premature leaf abscission. All F1 generations presented a final score of resistant; indicating that the expression of resistance to TSWV is conditioned by a dominant gene regardless of the source. The absence of segregation for resistance to TSWV that was observed in all generations of the crosses between C. chinense lines indicated that either a tightly linked group of genes exists or that the resistance is governed by the same single major gene (probably the already described Tsw gene). Previous reports have indicated that the Tsw gene is not effective against tospovirus members of serogroup II, i.e. tomato chlorotic spot virus (TCSV) and groundnut ring spot virus (GRSV). In the assay described here, all of the C. chinense lines showed, after mechanical inoculation, an identical susceptibility response to the TCSV and GRSV isolates.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 90 (1995), S. 707-713 
    ISSN: 1432-2242
    Keywords: Mineral stress ; Nutrient efficiency ; Aluminium tolerance ; Inheritance ; Genetics ; Breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Brazilian tropical adapted soybeans contains, in addition to superior morphological characters, genetic factors for tolerance to cultivation in acidic, mineral-stressed soils. However, the selection process for these hindrances has been empirical, and information on the genetics of mineral element uptake by the plant is necessary. The objective of this investigation was to identify the mode of inheritance for the absorption of phosphorus, potassium, calcium, magnesium, iron, aluminium, manganese, zinc and copper in a 9 × 9 diallel cross. General combining ability (GCA) was higher than specific combining ability (SCA), with the exception of copper, manganese and zinc, indicating predominantly additive effects. The ratios of GCA/SCA varied between 3.4 (calcium) and 8.5 (magnesium). The regression of covariance (Wr) on variance (Vr) showed that the additive-dominance model explained the genetic differences in this germ plasm. However, the detection of overdominance could be related to possible heterozygosity in the parental varieties for mineral absorption. Broad-sense heritability values were higher than narrow sense heritability values for aluminium, iron, potassium, calcium and magnesium, being in the range of 67.9–86.9% and 42.0–56.6%, respectively. This is an indication that soybeans can be further improved to efficient utilisation of nutrients and to tolerate toxic factors in the soil.
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  • 12
    ISSN: 1432-2072
    Keywords: Opioid ; Genetics ; Self-administration ; CXBK/ByJ ; Reinforcement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It is commonly thought thatμ-receptors play an important role in the reinforcing effects of opioids. In the present study, inbred strains widely divergent in CNS opiate receptor densities were used to investigate the influence of genetic variation in receptor concentration on opioid-reinforced behavior. In particular, the CXBK/ByJ mice were used as an investigative tool because of their significantly lower number of CNSμ opioid receptors. The behavioral pharmacology of opioids in theμ-deficient CXBK/ByJ mice was compared to other commonly used inbred mouse strains, C57BL/6J and BALB/cJ, and the opiate receptor rich CXBH/ByJ mice. Operant opioid reinforced behavior, opioid-induced locomotor stimulation, analgesia and respiratory depression were investigated in all four inbred strains. To assess the acquisition and maintenance of opioid reinforced behavior, oral self-administration of the potent benzimidazole opioid, etonitazene, was determined using an operant fixed-ratio schedule of reinforcement (FR 8). Acquisition of etonitazene-reinforced behavior was established in all four strains including theμ-deficient CXBK/ByJ mice. However, there were significant genetic differences in the amount of drug intake during the maintenance of opioid-reinforced behavior and extinction behavior following vehicle substitution. For example, drug intake was significantly greater in the BK versus BH mice during the maintenance phase and an extinction burst was seen in the BH but not the BK mice following vehicle substitution. Thus,μ-receptor density may not account for individual variability in the acquisition of opioid-reinforced behavior under these conditions. Sensitivity to etonitazene-induced respiratory depression, stimulation of locomotor activity and analgesia were unrelated to drug intake during self-administration sessions across these four inbred strains. These data indicate that inherited differences in CNSμ-opiate receptor concentrations do not affect acquisition of etonitazene-reinforced behavior.
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  • 13
    ISSN: 1432-2072
    Keywords: Cocaine ; Quantitative trait loci ; Seizure ; Recombinant inbred strains ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Among inbred mice, genetic factors mediate differences in sensitivity to the convulsant properties of cocaine; however, the gene(s) underlying cocaine's effects have not been identified. To help elucidate the gene(s) responsible for cocaine seizure susceptibility, we used recombinant inbred-quantitative trait loci (RI-QTL) analyses to identify chromosomal loci associated with cocaine-induced seizures. RI-QTL analyses seek to identify associations between a quantitative measure of a particular phenotype and one or more previously mapped marker genes across a panel of RI strains. This report describes an RI-QTL analysis of cocaine seizure susceptibility among 26 BXD RI strains. These strains showed a skewed, bimodal range of seizure susceptibility which could be the result of one or more modifying genes acting in concert with a major gene to influence cocaine sensitivity. Correlating the percent seizures displayed by each strain following 60 mg/kg cocaine with chromosomal marker data for these strains revealed a number of significant correlations clustered in two regions on chromosomes 12 and 6. This is the first identification of putative chromosomal loci associated with a cocaine-related phenotype and should facilitate identification of the gene(s) underlying cocaine toxicity and other cocaine-related phenotypes.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 8 (1995), S. 129-132 
    ISSN: 1432-2145
    Keywords: Sex control ; Disomic segregation ; Dioecy Kiwifruit ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sex segregation ratio was checked in bi-parental families of Actinidia deliciosa (2n=6x=174) obtained by crossing four females (A12, Mo3, Br4, Hw1) with two males (T2, M1) and one fruiting male (M3h, subandroecious) according to a factorial mating design. The M3h fruiting male was also selfed. The sex ratio was checked in maternal families of A. kolomikta (2n=2x) and A. chinensis (2n=2x) as well as in A. deliciosa. Seedlings of both diploid species took 3–4 years to progress beyond juvenility, whereas a noticeable number of seedlings from biparental crosses of A. deliciosa involving A12 and Hw1 as seed parents were still non-flowering after seven growing seasons. Open-pollinated families of both diploid and hexaploid species as well as most families from biparental crosses showed a sex segregation ratio approaching 1∶1. Subandroecious lines with different degrees of ovary and pistil development appeared in proportions of 0–4.2%, depending on the cross, but only 6 of the 2567 male vines checked were capable of setting fruit. No case of self-fertility or apomixis was detected among 1866 bagged female vines. Selfed M3h progenies gave only female and male phenotypes in a ratio of 1 female to 3 males. No off-type vines were found among these progenies. The same disomic sex segregation ratio seems to be operating at different ploidy levels in the genus Actinidia. Since selfed fruiting males produced both female and male individuals, the male sex appears to be the heterogametic one. Such evidence indicates that a monofactorial system based on one or more linked genes or on an X/Y chromosome set must be controlling sex expression. How a monofactorial sex-determining mechanism could operate in polyploids to give a 1∶1 female: male ratio is discussed. Minor modifying gene(s) seem to be responsible for the feminization of males, and their expression appears enhanced by environmental conditions. Masculinizing gene(s) seem to be lacking in female genotypes.
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  • 15
    ISSN: 1432-1440
    Keywords: Adrenergic receptors ; Human genetics ; Restriction fragment length polymorphism ; Chromosome mapping ; Linkage ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have genetically mapped the genes encoding four human adrenergic receptors (ARs) of subtypes α1C, α2A, α2B, and β1, which are prototypic G protein coupled receptors that mediate the physiological effects of neurotransmitters, hormones, and drugs. We placed these genes onto the Cooperative Human Linkage Center (CHLC) and Genethon framework maps, within confidence intervals with greater than 1000∶1 odds. With multipoint analysis the α1C gene (locus ADRA1C) mapped to the interval between NEFL and D8S283; α2-C4, the gene encoding the α2C AR (locus ADRA2C), mapped to the interval between D4S126 and D4S62; and the α2-C10 (α2A AR)/β1 haplotype (loci ADRA2A/ ADRB1) mapped to the interval between D10S259 and D10S187. A fifth AR gene, β2, yielded significant LOD scores with markers on the long arm of chromosome 5; however, this locus (ADRB2) could not be mapped to any specific interval with odds of greater than 1000∶1. The two AR genes that are completely linked, α2-C10 and β1, were oriented on their shared 225-kb genomic fragment relative to the direction of transcription, with β1 being 5′ to α2-C10. The positioning of these genes on high-density framework maps allows them to be tested as candidates in a spectrum of diseases that might involve AR dysfunction.
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  • 16
    ISSN: 1432-1440
    Keywords: Atherosclerosis ; Hypertension ; Type 2 diabetes ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the search for new risk factors for diabetic macroangiopathy the insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme gene was studied in 237 consecutive patients (125 men and 112 women) with non-insulin-dependent diabetes. The female population showed an excess of ischemic electro-cardiographic changes or definite myocardial infarctions in the patients homozygous for the deletion [D/D; odds ratio (OR) 2.8; 95% confidence interval (CI) 1.4–5.3] and in the insertion/deletion heterozygotes (I/D; OR 1.8; CI 1.1–3.1) compared with the patients homozygous for the insertion (I/I). In the total series coronary heart disease, cerebrovascular disease, and claudication were more often observed in the patients with I/D (OR 1.5; CI 1.0–2.2) or the D/D genotype patients (OR 1.7; CI 1.1–2.6) than in those with the genotype I/I. The systolic blood pressure was lower in patients with genotype I/I (138±19 mmHg) than in those with the genotype I/D (149±22 mmHg) or D/D (150±21 mmHg; P〈0.02). The prevalence of hypertension and the median urinary albumin excretion rate also tended to be lowest in the I/I genotype patients. Multiple logistic analysis revealed that in women the angiotensin-converting enzyme D/D genotype is independently associated with coronary heart disease. Our findings suggest that variation at the angiotensin-converting enzyme gene locus is one of the factors involved in the predisposition of diabetic patients to the development of arterial disease and hypertension.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 242 (1995), S. 508-511 
    ISSN: 1432-1459
    Keywords: Dystonia ; Torticollis ; Blepharospasm ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The inheritance of focal dystonias was investigated in 43 families containing 43 index cases with torticollis (n = 21), blepharospasm (n = 18) and writer's cramp (n = 4). They generated a potential population of 235 first-degree relatives, and 168 out of 179 living first-degree relatives were examined. Ten relatives with dystonia were identified in ten families. Another two parents from two of the same group of ten families were affected according to the family history. The majority of the secondary cases (six patients, five siblings, and one child) were not aware of any dystonia. The tendency for affected relatives to have the same type of dystonia as index patients was observed only for torticollis. Overall, 23% of index patients had relatives with dystonia. Segregation analysis suggested the presence of an autosomal dominant gene or genes with reduced penetrante underlying focal dystonia.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Rheumatology international 15 (1995), S. 89-93 
    ISSN: 1437-160X
    Keywords: SLE Lupus ; BBV transformation ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Epstein-Barr-virus (EBV)-transformed lymphoblastoid B-cell lines were generated from peripheral blood lymphocytes of 55 patients with systemic lupus erythematosus (SLE) and 44 healthy relatives. All donors have previously been extensively characterized with regard to clinical, serologic, and genetic parameters. Here, peripheral blood lymphocytes and lines were characterized for cell surface antigens. Furthermore, autoantibody production and proliferation rate of the cell lines were monitored. A significant difference between patients and relatives was the lower proliferation rate of EBV-transformed cell lines of the SLE patients. All SLE cell lines are available for interested researches and can be obtained from the European Cell Bank, Salisbury, UK.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 14 (1995), S. 355-364 
    ISSN: 1476-5535
    Keywords: Transformation ; Fungi ; Yeast ; Genetics ; Biotechnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The genetic investigation of fungi has been extended substantially by DNA-mediated transformation, providing a supplement to more conventional genetic approaches based upon sexual and parasexual processes. Initial transformation studies with the yeastSaccharomyces cerevisiae provided the model for transformation systems in other fungi with regard to methodology, vector construction and selection strategies. There are, however, certain differences betweenS. cerevisiae and filamentous fungi with regard to type of genomic insertion and the availability of shuttle vectors. Single-site linked insertions are common in yeast due to the high level of homology required for recombination between vectored and genomic sequences, whereas mycelial fungi often show a high frequency of heterologous and unlinked insertions, often in the form of random and multiple-site integrations. While extrachromosomally-maintained or replicative vectors are readily available for use with yeasts, such vectors have been difficult to construct for use with filamentous fungi. The development of vectors for replicative transformation with these fungi awaits further study. It is proposed that replicative vectors may be inherently less efficient for use with mycelial fungi relative to yeasts, since the mycelium, as an extended and semicontinuous network of cells, may delimit an adequate diffusion of the vector carrying the selectable gene, thus leading to a high frequency of abortive or unstable transformants.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical medicine and bioethics 16 (1995), S. 347-373 
    ISSN: 1573-1200
    Keywords: Genetics ; human research ; adolescence ; child ; informed consent ; decision making ; medical ethics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Philosophy
    Notes: Abstract The participation of adolescents in genetic research engenders unusual problems concerning the nature of their informed consent. In this study we analyze 70 consent documents collected from genetics investigators in the United States who conduct research with children and adolescents. We find that many consent documents do not reflect either the current or the developing ethical and legal standards for research with adolescents and that in many cases the documents are simply confusing or unclear. We make recommendations for change to reflect more adequately the changing perspective concerning the autonomous decision-making capacity of adolescents.
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  • 21
    Electronic Resource
    Electronic Resource
    Springer
    Environmental biology of fishes 43 (1995), S. 1-27 
    ISSN: 1573-5133
    Keywords: Conservation ; Extinction ; Rarity ; Biodiversity ; Breeding guilds ; Endemism ; Speciation ; Habitat degradation ; Environmental management ; Invasive fishes ; Genetics ; Ecology ; Stenotopy ; Captive propagation ; Legislation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The conservation status and factors threatening fishes worldwide are reviewed in order to introduce a series of one-page articles on ‘Threatened fishes of the world’, and to encourage the incorporation of information on threatened fishes into international conservation programmes. Information on fish extinction and threat rates are compared with those of other animal groups, and the unique characteristics of fish conservation problems are highlighted. At present 979 species of fishes are listed as threatened in the IUCN Red List and at least 36 species and three subspecies are listed as recently extinct. It is argued that these figures are probably gross underestimates and that they may mislead conservation authorities and resource users about the seriousness of the situation. Freshwater fishes may be the most threatened group of vertebrates after the Amphibia. Urgent action is required to save many narrowly endemic, stenotopic species from extinction, especially in Africa, Asia and South America. The conservation of common species that drive essential ecological processes is also important. Anthropogenic pressures, especially habitat degradation, the introduction of invasive species and pollution, on inland and coastal waters are particularly severe and many major fish communities are threatened with elimination throughout the world. The conservation of marine fishes is complicated by the fact that it is difficult to ascertain their rarity. The importance of the retention of genetic variation is highlighted, and both orthodox and innovative conservation measures are encouraged. Further research on minimum viable populations, genetics, and the factors that cause fishes to become vulnerable to extinction, is urgently required.
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  • 22
    Electronic Resource
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    Springer
    Theoretical and applied genetics 91 (1995), S. 639-646 
    ISSN: 1432-2242
    Keywords: Gene introgression ; Genetics ; Linkage ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The wild tetraploid (2n=28) oat species Avena magna and A. murphyi have been domesticated by having been transferred from the common oat, A sativa (2n=42), the characteristics of non-shedding spikelets glabrous and yellow lemma, and reduced awn formation. Domestication has been achieved by crossing the common oat with either of the tetraploid species and then backcrossing the pentaploid hybrids with pollen of the tetraploid wild parent. Among the BC plants obtained only a few produced some seeds. Fertile tetraploids exhibiting the domesticated syndrome have been selected for in the F2 generation. Although morphologically they were almost indistinguishable from the common oat, they were tetraploids. Wild x domesticated A. magna hybrids were vigorous and fertile. They retained their spikelets at maturity, lemma color and pubescence were intermediate between the parental lines, and awns were formed only on the lower floret of the spikelet. Each of these characteristics segregated in a 3∶1 fashion, indicating single gene control, as in the common oat. These four characteristics formed a linkage group in one F2 family and two linkage groups in the other two families. The usefulness of the domesticated tetraploids for oat research and production has been discussed. Taxonomically, the domesticated tetraploids were ranked as subspecies: A. magna ssp. domestica, and A. murphyi ssp. rigida.
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  • 23
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    Numerical Linear Algebra with Applications 2 (1995), S. 415-429 
    ISSN: 1070-5325
    Keywords: indefinite ; inverse ; preconditioning ; symmetric ; Toeplitz ; Trench algorithm ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: A modification is presented of the classical O(n2) algorithm of Trench for the direct solution of Toeplitz systems of equations. The Trench algorithm is stable for symmetric matrices that are positive definite, but can be unstable for the indefinite case (and for general matrices). Our modification permits extension of the algorithm to compute approximate inverses of indefinite symmetric Toeplitz matrices, for which the unmodified algorithm breaks down when principal submatrices are singular. As a preconditioner, the approximate inverse has an advantage that only matrix - vector multiplications are required for the solution of a linear system, without forward and backward solves. The approximate inverse so obtained can be sufficiently accurate, moreover, that, when it is used as a preconditioner for the applications investigated, subsequent iteration may not even be necessary. Numerical results are given for several test matrices. The perturbation to the original matrix that defines the modification is related to a perturbation in a quantity generated in the Trench algorithm; the associated stability of the Trench algorithm is discussed.
    Additional Material: 1 Tab.
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  • 24
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    Numerical Linear Algebra with Applications 2 (1995), S. 483-485 
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
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  • 25
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    Numerical Linear Algebra with Applications 2 (1995), S. 447-465 
    ISSN: 1070-5325
    Keywords: preconditioned iterative methods ; SSOR factorization ; parallelization ; connection machine ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: A class of parallelizable preconditioned iterative methods for the solution of certain finite difference or finite element linear systems of equations is presented. The methods are based on calculation of approximate inverses of the SSOR factorization. The speed of the methods may be increased by making the approximation of the inverse more accurate. The construction of the preconditioning as well as the solution of the preconditioning systems (realized by matrix-vector multiplication) can be made in parallel over the total amount of meshpoints. The methods are suitable for implementation on massively parallel computers such as connection machines. Problems with constant as well as strongly varying orthotropy are examined and the methods are compared to other parallel techniques with respect to rate of convergence, computational complexity and consumed CM200 computing time. We report a small but significant decrease in computing time compared to the (until now) most frequently used completely parallel preconditioning, the Jacobi method.
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  • 26
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    Numerical Linear Algebra with Applications 2 (1995), S. 533-541 
    ISSN: 1070-5325
    Keywords: plane rotation ; shear product ; Saxpy operation ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: An algorithm for pre- or post-multiplication of a matrix by a plane rotation, using only three vector saxpy operations instead of the four vector operations usually considered necessary, is described. No auxiliary storage for overwriting is required. The method is shown to be numerically stable.
    Additional Material: 6 Tab.
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  • 27
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    Numerical Linear Algebra with Applications 2 (1995), S. 487-505 
    ISSN: 1070-5325
    Keywords: biharmonic equation ; rectangular finite elements ; preconditioning ; multilevel methods ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Recently, some new multilevel preconditioners for solving elliptic finite element discretizations by iterative methods have been proposed. They are based on appropriate splittings of the finite element spaces under consideration, and may be analyzed within the framework of additive Schwarz schemes. In this paper we discuss some multilevel methods for discretizations of the fourth-order biharmonic problem by rectangular elements and derive optimal estimates for the condition numbers of the preconditioned linear systems. For the Bogner-Fox-Schmit rectangle, the generalization of the Bramble-Pasciak-Xu method is discussed. As a byproduct, an optimal multilevel preconditioner for nonconforming discretizations by Adini elements is also derived.
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  • 28
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    Numerical Linear Algebra with Applications 2 (1995), S. 87-93 
    ISSN: 1070-5325
    Keywords: QR algorithm ; zero pattern ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The QR algorithm is a basic algorithm for computing the eigenvalues of dense matrices. For efficiency reasons it is prerequisite that the algorithm is applied only after the original matrix has been reduced to a matrix of a particular shape, most notably Hessenberg and tridiagonal, which is preserved during the iterative process. In certain circumstances a reduction to another matrix shape may be advantageous. In this paper, we identify which zero patterns of symmetric matrices are preserved under the QR algorithm.
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  • 29
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    Numerical Linear Algebra with Applications 2 (1995), S. 95-113 
    ISSN: 1070-5325
    Keywords: arrowhead matrix ; band matrix ; inverse eigenvalue problem ; givens rotations ; singular value decomposition ; updating ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Various plane rotation patterns are presented, which provide stable algorithms for reducing a b-band matrix bordered by p rows and/or columns to (b + p)-band form. These schemes generalize previously presented O(N2) reduction algorithms for matrices of order N, b = 1, and p = 1 to the reduction of more general b-band, p-bordered matrices where b ≥ 1 and p ≥ 1. Moreover, by splitting the matrix into two similarly structured submatrices and chasing nonzeros to the corners in two directions, the newly proposed patterns reduce the number of required rotations and hence the computational cost by one half compared to the other existing one-way chasing algorithms. Symmetric, as well as more general matrices, are considered. An example of the first type is the symmetric arrowhead matrix that arises in solving inverse eigenvalue problems. Examples of the second type are found in updating the singular value decomposition (SVD) and the partial SVD.
    Additional Material: 7 Ill.
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  • 30
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    Numerical Linear Algebra with Applications 2 (1995), S. 243-250 
    ISSN: 1070-5325
    Keywords: Cholesky ; norm inequality ; perturbation ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: We show that a certain matrix norm ratio studied by Parlett has a supermum that is O(\documentclass{article}\pagestyle{empty}\begin{document}$\mathop \[\sqrt n \] $\end{document}) when the chosen norm is the Frobenius norm, while it is O(log n) for the 2-norm. This ratio arises in Parlett's analysis of the Cholesky decomposition of an n by n matrix.
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  • 31
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    Numerical Linear Algebra with Applications 2 (1995), S. 271-286 
    ISSN: 1070-5325
    Keywords: linear least squares ; backward perturbations ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Let A be an m × n matrix, b be an m-vector, and x̃ be a purported solution to the problem of minimizing ‖b  -  Ax‖2. We consider the following open problem: find the smallest perturbation E of A such that the vector x̃ exactly minimizes ‖b  -  (A+E)x‖2. This problem is completely solved when E is measured in the Frobenius norm. When using the spectral norm of E, upper and lower bounds are given, and the optimum is found under certain conditions.
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    Numerical Linear Algebra with Applications 2 (1995), S. 287-296 
    ISSN: 1070-5325
    Keywords: block Hessenberg matrix ; block Toeplitz matrix ; linear system ; queue ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: This paper describes a divide-and-conquer strategy for solving block Hessenberg systems. For dense matrices the method is as efficient as Gaussian elimination; however, because it works almost entirely with the original blocks, it is much more efficient for sparse matrices or matrices whose blocks can be generated on the fly. For Toeplitz matrices, the algorithm can be combined with the fast Fourier transform.
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  • 33
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    Numerical Linear Algebra with Applications 2 (1995), S. ii 
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
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  • 34
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    Numerical Linear Algebra with Applications 2 (1995), S. 507-531 
    ISSN: 1070-5325
    Keywords: Cholesky decomposition ; singular values ; eigenvalues ; null spaces ; noise spaces ; URV and ULV factorizations ; QR algorithm ; LR algorithm ; Jacobi methods ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The implicit Cholesky algorithm has been developed by several authors during the last 10 years but under different names. We identify the algorithm with a special version of Rutishauser's LR algorithm. Intermediate quantities in the transformation furnish several attractive approximations to the smallest singular value.The paper extols the advantages of using shifts with the algorithm. The nonorthogonal transformations improve accuracy.
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  • 35
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    Numerical Linear Algebra with Applications 2 (1995), S. 543-545 
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
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  • 36
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    Numerical Linear Algebra with Applications 2 (1995), S. 115-133 
    ISSN: 1070-5325
    Keywords: Krylov subspace ; Lanczos process ; symmetric matrix ; conjugate gradients ; minimum residual ; Lehmann intervals ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Approximations to the solution of a large sparse symmetric system of equations are considered. The conjugate gradient and minimum residual approximations are studied without reference to their computation. Several different bases for the associated Krylov subspace are used, including the usual Lanczos basis. The zeros of the iteration polynomial for the minimum residual approximation (harmonic Ritz values) are characterized in several ways and, in addition, attractive convergence properties are established. The connection of these harmonic Ritz values to Lehmann's optimal intervals for eigenvalues of the original matrix appears to be new.
    Additional Material: 3 Ill.
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  • 37
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    Numerical Linear Algebra with Applications 2 (1995), S. 155-171 
    ISSN: 1070-5325
    Keywords: condition number ; norm of a matrix ; matrix completion ; dilation theory ; robust regularization of descriptor systems ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: We study the problem of minimizing the norm, the norm of the inverse and the condition number with respect to the spectral norm, when a submatrix of a matrix can be chosen arbitrarily. For the norm minimization problem we give a different proof than that given by Davis/Kahan/Weinberger. This new approach can then also be used to characterize the completions that minimize the norm of the inverse. For the problem of optimizing the condition number we give a partial result.
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  • 38
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    Numerical Linear Algebra with Applications 2 (1995), S. 191-194 
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
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  • 39
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    Numerical Linear Algebra with Applications 2 (1995), S. 173-190 
    ISSN: 1070-5325
    Keywords: block algorithm ; LAPACK ; level 3 BLAS ; iterative refinement ; LU factorization ; backward error analysis ; block diagonal dominance ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Many of the currently popular ‘block algorithms’ are scalar algorithms in which the operations have been grouped and reordered into matrix operations. One genuine block algorithm in practical use is block LU factorization, and this has recently been shown by Demmel and Higham to be unstable in general. It is shown here that block LU factorization is stable if A is block diagonally dominant by columns. Moreover, for a general matrix the level of instability in block LU factorization can be bounded in terms of the condition number K(A) and the growth factor for Gaussian elimination without pivoting. A consequence is that block LU factorization is stable for a matrix A that is symmetric positive definite or point diagonally dominant by rows or columns as long as A is well-conditioned.
    Additional Material: 4 Tab.
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  • 40
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    Numerical Linear Algebra with Applications 2 (1995), S. 135-153 
    ISSN: 1070-5325
    Keywords: orthogonal projection ; numerical rank ; total least squares ; rank revealing QR factorization ; acute perturbation ; subspace angle ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Overdetermined linear systems often arise in applications such as signal processing and modern communication. When the overdetermined system of linear equations AX ≍ B has no solution, compatibility may be restored by an orthogonal projection method. The idea is to determine an orthogonal projection matrix P by some method M such that [à B̃] = P[A B], and ÃX = B̃ is compatible. Denote by XM the minimum norm solution to ÃX = B̃ using method M. In this paper conditions for compatibility of the lower rank approximation and subspace properties of à in relation to the nearest rank-k matrix to A are discussed. We find upper and lower bounds for the difference between the solution XM and the SVD-based total least squares (TLS) solution XSVD and also provide a perturbation result for the ordinary TLS method. These results suggest a new algorithm for computing a total least squares solution based on a rank revealing QR factorization and subspace refinement. Numerical simulations are included to illustrate the conclusions.
    Additional Material: 4 Tab.
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  • 41
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    Numerical Linear Algebra with Applications 2 (1995) 
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
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  • 42
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    Numerical Linear Algebra with Applications 2 (1995), S. 195-203 
    ISSN: 1070-5325
    Keywords: Jacobi matrix ; arrow matrix ; inverse problem ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: We consider the problem of reconstructing Jacobi matrices and real symmetric arrow matrices from two eigenpairs. Algorithms for solving these inverse problems are presented. We show that there are reasonable conditions under which this reconstruction is always possible. Moreover, it is seen that in certain cases reconstruction can proceed with little or no cancellation. The algorithm is particularly elegant for the tridiagonal matrix associated with a bidiagonal singular value decomposition.
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  • 43
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    Numerical Linear Algebra with Applications 2 (1995), S. 235-241 
    ISSN: 1070-5325
    Keywords: interior-point methods ; trust regions ; conic functions ; conjugate gradients ; linear programming ; nonlinear minimization ; Karmarkar's algorithm ; centering ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: An optimization method is developed based on ellipsoidal trust regions that are defined by conic functions. It provides a powerful unifying theory from which can be derived a variety of interesting and potentially useful optimization algorithms, in particular, conjugate-gradient-like algorithms for nonlinear minimization and Karmarkar-like interior-point algorithms for linear programming.
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  • 44
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    Numerical Linear Algebra with Applications 2 (1995), S. 219-234 
    ISSN: 1070-5325
    Keywords: nonsymmetric matrices ; sparse matrices ; eigenvalue problem ; EISPACK ; LAPACK ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: With the growing demands from disciplinary and interdisciplinary fields of science and engineering for the numerical solution of the nonsymmetric eigenvalue problem, competitive new techniques have been developed for solving the problem. In this paper we examine the state of the art of the algorithmic techniques and the software scene for the problem. Some current developments are also outlined.
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  • 45
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    Numerical Linear Algebra with Applications 2 (1995), S. 251-269 
    ISSN: 1070-5325
    Keywords: eigenvalues ; eigenvectors ; symmetric matrices ; Rayleigh quotient iteration ; convergence ; basins of attraction ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The Rayleigh quotient iteration method finds an eigenvector and the corresponding eigenvalue of a symmetric matrix. This is a fundamental problem in science and engineering. Parlett and Kahan have shown, in 1968, that for almost any initial vector in the unit sphere, the Rayleigh quotient iteration method converges to some eigenvector. In this paper, the regions of the unit sphere which include all possible initial vectors converging to a specific eigenvector are studied. The generalized eigenvalue problem Ax = λBx is considered. It is shown that the regions do not change when the matrix is shifted or multiplied by a scalar. These regions are completely characterized in the three-dimensional case. It is shown that, in this case, the area of the region of convergence corresponding to the interior eigenvalue is larger than the area of those corresponding to any extreme one. This can be interpreted, with the appropriate choice of probability distribution, as: the probability of converging to an eigenvector corresponding to the interior eigenvalue is larger than the probability of converging to an eigenvector corresponding to any extreme eigenvalue. It is conjectured that the same is true for matrices of any order. Experiments in higher dimensions are presented which conform with the conjecture.
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  • 46
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    Numerical Linear Algebra with Applications 2 (1995), S. 205-217 
    ISSN: 1070-5325
    Keywords: Lanczos method ; spectral Lanczos ; decompostion method ; eigenpairs ; matrix functions ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Many researchers are now working on computing the product of a matrix function and a vector, using approximations in a Krylov subspace. We review our results on the analysis of one implementation of that approach for symmetric matrices, which we call the spectral lanczos decomposition method (SLDM).We have proved a general convergence estimate, relating SLDM error bounds to those obtained through approximation of the matrix function by a part of its Chebyshev series. Thus, we arrived at effective estimates for matrix functions arising when solving parabolic, hyperbolic and elliptic partial differential equations. We concentrate on the parabolic case, where we obtain estimates that indicate superconvergence of SLDM. For this case a combination of SLDM and splitting methods is also considered and some numerical results are presented.We implement our general estimates to obtain convergence bounds of Lanczos approximations to eigenvalues in the internal part of the spectrum. Unlike Kaniel-Saad estimates, our estimates are independent of the set of eigenvalues between the required one and the nearest spectrum bound.We consider an extension of our general estimate to the case of the simple Lanczos method (without reorthogonalization) in finite computer arithmetic which shows that for a moderate dimension of the Krylov subspace the results, proved for the exact arithmetic, are stable up to roundoff.
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  • 47
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    Numerical Linear Algebra with Applications 2 (1995), S. 311-312 
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 48
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    Numerical Linear Algebra with Applications 2 (1995), S. 313-315 
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
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  • 49
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    Numerical Linear Algebra with Applications 2 (1995), S. 297-310 
    ISSN: 1070-5325
    Keywords: dynamical systems ; eigenvalues ; QR algorithm ; Francis shift ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: For many years techniques from numerical analysis have been applied fruitfully to the study of dynamical systems. In this paper it is shown that the theory of dynamical systems may be applied to certain computational problems. In particular the question of global convergence of various QR algorithms can be reduced to the study of certain vector iterations derived from Schur forms of matrices. The technique is illustrated in determining the convergence behavior of normal Hessenberg matrices under the Francis and multishift QR iterations.
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    Numerical Linear Algebra with Applications 2 (1995) 
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
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  • 51
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    Numerical Linear Algebra with Applications 2 (1995), S. 335-346 
    ISSN: 1070-5325
    Keywords: multisplittings ; overlapping ; comparison results ; M-matrices ; waveform relaxation ; parallel algorithms ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: We show that certain multisplitting iterative methods based on overlapping blocks yield faster convergence than corresponding nonoverlapping block iterations, provided the coefficient matrix is an M-matrix. This result can be used to compare variants of the waveform relaxation algorithm for solving initial value problems. The methods under consideration use the same discretization technique, but are based on multisplittings with different overlaps. Numerical experiments on the Intel iPSC/860 hypercube are included.
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    Numerical Linear Algebra with Applications 2 (1995), S. 317-334 
    ISSN: 1070-5325
    Keywords: envelope reduction ; eigenvalues of graphs ; Gibbs - King algorithm ; Gibbs - Poole - Stockmeyer algorithm ; Laplacian matrices ; reordering algorithms ; reverse Cuthill - McKee algorithm ; sparse matrices ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The problem of reordering a sparse symmetric matrix to reduce its envelope size is considered. A new spectral algorithm for computing an envelope-reducing reordering is obtained by associating a Laplacian matrix with the given matrix and then sorting the components of a specified eigenvector of the Laplacian. This Laplacian eigenvector solves a continuous relaxation of a discrete problem related to envelope minimization called the minimum 2-sum problem. The permutation vector computed by the spectral algorithm is a closest permutation vector to the specified Laplacian eigenvector. Numerical results show that the new reording algorithm usually computes smaller envelope sizes than those obtained from the current standards such as the Gibbs - Poole - Stockmeyer (GPS) algorithm or the reverse Cuthill - McKee (RCM) algorithm in SPARSPAK, in some cases reducing the envelope by more than a factor of two.
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  • 53
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    Numerical Linear Algebra with Applications 2 (1995), S. 401-414 
    ISSN: 1070-5325
    Keywords: conjugate gradient ; distributed computing ; analytic model ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: In this paper, we demonstrate the scalability of the Reduced System Conjugate Gradient (RSCG) algorithm on distributed memory architectures. We present speed-up results obtained on the Intel iPSC/860 that compare one-, two-, and three-dimensional decompositions of the domain for both positive definite and positive semidefinite test problems. We develop a model for the RSCG algorithm to analyze computational and communication costs. The model is validated using experimental data and then used to examine and predict behavior of the RSCG algorithm as a function of architecture parameters including communication latency and transmission times and memory access costs.
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    Numerical Linear Algebra with Applications 2 (1995), S. 481-481 
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
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  • 55
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    Numerical Linear Algebra with Applications 2 (1995), S. 467-479 
    ISSN: 1070-5325
    Keywords: generalized conjugate gradient ; orthogonal residual ; rate of convergence ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: To solve a linear system of equations with a generally nonsymmetric matrix, a generalized conjugate gradientorthogonal residual method is presented. The method uses all previous search directions (or a truncated set of them) at each step but, contrary to standard implementations of similar methods, it requires storage of only one set with a linearly growing number of vectors (or the number in the truncated set). Furthermore, there is only one vector (the residual), which must be updated using all the vectors in this set, at each step. In this respect it is similar to the popular GMRES method but it has the additional advantage that it can stop at any stage when the norm of the residual is sufficiently small and no extra computation is needed to compute this norm. Furthermore, the new method can be truncated.The rate of convergence of the method is also discussed.
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  • 56
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    Numerical Linear Algebra with Applications 2 (1995) 
    ISSN: 1070-5325
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
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  • 57
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    Communications in Numerical Methods in Engineering 11 (1995) 
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
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  • 58
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    Communications in Numerical Methods in Engineering 11 (1995), S. iii 
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 59
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    Communications in Numerical Methods in Engineering 11 (1995), S. 1-11 
    ISSN: 1069-8299
    Keywords: vibration ; spline prism method ; thick rectangular plate ; 3D elasticity theory ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The paper presents an application of the spline prism method to analyse vibration of isotropic, thick rectangular plates with two opposite edges simply supported. Three-dimensional spline prism models are formulated by combining B-spline functions with beam eigenfunctions. Because of the orthogonality of the beam functions, three-dimensional problems are reduced to a series of two-dimensional ones. To demonstrate the accuracy and convergence of the semi-numerical method, the results are compared with those obtained by other numerical methods. Good convergence and accuracy are obtained. The effects of the ratio of thickness to width and the aspect ratio on the frequencies of thick rectangular plates with several boundary conditions are analysed, and the results are compared with those calculated by the Mindlin plate theory.
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  • 60
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    Communications in Numerical Methods in Engineering 11 (1995), S. 33-40 
    ISSN: 1069-8299
    Keywords: boundary conditions ; streamfunction-vorticity equations ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The appropriate specification of boundary conditions is the main difficulty in the finite element solution of the streamfunction-vorticity equations for two-dimensional incompressible laminar flows. In this context, we show that the appropriate specification of both the outflow and the inflow boundary conditions is required for the successful modelling of two well known test problems.
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  • 61
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    Communications in Numerical Methods in Engineering 11 (1995), S. 13-23 
    ISSN: 1069-8299
    Keywords: mass transport problems ; error estimation ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In order to make an exact estimation of discretization error for finite/infinite element methods, it is necessary to develop analytical solutions for some transient mass transport problems in infinite media. These transient mass transport problems may be viewed as the benchmark problems for the discretization error estimation of a new numerical method so that they generally have the following characteristics: (1) their initial and boundary conditions can be exactly modelled by the finite/infinite element method; (2) their solutions can be rigorously expressed in a closed form. In this paper, several of the aforementioned problems have been constructed and solved mathematically for transient mass transport problems in both 1D and 2D infinite media.
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  • 62
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    Communications in Numerical Methods in Engineering 11 (1995), S. 25-32 
    ISSN: 1069-8299
    Keywords: Riccati equation ; transmission line modelling ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In this communication, the application of the transmission line modelling (TLM) technique to the solution of the differential Riccati equation is described. A comparison is made between the TLM, fourth-order Runge-Kutta and the first-order Gear methods, for the case where one is applying the Kalman filter to the estimation of a voltage in a passive analogue circuit. In the particular example studied, the state equation is second-order. It is found that, when the system is underdamped, the fourth-order Runge-Kutta method has the best performance, followed by the TLM method. When the system is overdamped and stiff, the TLM method yields results that are closest to the analytical solution. Finally, a discussion is presented of the effects of errors in the TLM solution of the Riccati equation on the accuracy of the solution to the continuous Kalman filter estimation equation.
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  • 63
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    Communications in Numerical Methods in Engineering 11 (1995), S. 49-58 
    ISSN: 1069-8299
    Keywords: gears ; fracture mechanics ; service life ; fatigue process ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The paper describes the influence of contact area on the service life of dynamically loaded gears with a crack in a tooth root. Numerical results obtained with the finite element method using the program package BERSAFE are compared with the experimental results obtained on the universal testing machine INSTRON 1255. Numerical and experimental results are in good agreement. The analysis shows that the contact area directly influences the speed and direction of the crack propagation and the service life of the gear with a crack in a tooth root.
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  • 64
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    Communications in Numerical Methods in Engineering 11 (1995), S. 41-47 
    ISSN: 1069-8299
    Keywords: shear correction ; laminates ; cylindrical bending hypothesis ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Mindlin-type plate and shell finite elements are the most widely used ones in the analysis of laminated composite structures. In the commercially available finite element programs, the transverse shear correction factors for these elements are usually the same as for structures made of isotropic materials. In the paper the shear correction factors are determined using energy principles for general laminates in cylindrical bending. Results for various materials and laminates are presented.
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  • 65
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    Communications in Numerical Methods in Engineering 11 (1995), S. 59-68 
    ISSN: 1069-8299
    Keywords: RLW equation ; finite elements ; splines ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A B-spline finite element method is used to solve the regularized long wave equation numerically. This approach involves a Galerkin method with quadratic B-spline finite elements so that there is continuity of the dependent variable and its first derivative throughout the solution range. Time integration of the resulting system of ordinary differential equations is effected using a Crank-Nicolson approximation. Standard problems are used to validate the algorithm, which is then used to model the smooth development of an undular bore.
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  • 66
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    Communications in Numerical Methods in Engineering 11 (1995), S. 69-72 
    ISSN: 1069-8299
    Keywords: finite element method ; thermoplasticity ; internal dissipation ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In the paper, a simple modification of the internal dissipation term in coupled thermoplastic finite element equations is presented. A modified form of the heat capacity and the thermomechanical coupling matrices are derived. These modifications are based on a decomposition of the internal dissipation term into two parts, which depend on the total strain rate and the rate of temperature change, respectively.
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    Communications in Numerical Methods in Engineering 11 (1995), S. 91-92 
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Communications in Numerical Methods in Engineering 11 (1995), S. 93-94 
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 69
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    Communications in Numerical Methods in Engineering 11 (1995), S. 95-95 
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
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  • 70
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    Communications in Numerical Methods in Engineering 11 (1995), S. 73-90 
    ISSN: 1069-8299
    Keywords: circular plate ; viscoelasticity ; equilibrium states ; deformation map ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The geometrically non-linear response of a circular plate is investigated by means of a ‘deformation map’. The plate is subjected to static radial forces and bending moments, both uniformly distributed along the supported edges, in addition to a transverse load. The deformation map gives the complete picture for the investigated structure. The classical formulation of large deformation for the above-mentioned problem goes back to Timoshenko (1940). To create a deformation map, it is necessary to convert the boundary value problem into an initial value problem (Cauchy's problem). The Runge-Kutta (RK) method can then be used to solve numerically the equilibrium equations for the above-mentioned circular plate. In the paper several kinds of transverse loading are considered and their influence on the plate response is examined. It is shown that in some cases the plate's behaviour is chaotic-like (unpredictable), in the sense that various equilibrium states are possible for a certain given set of loads. Yet, it is shown that the viscoelasticity reduces the range of the possible equilibrium states, and thus stabilizes the system.
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  • 71
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    Communications in Numerical Methods in Engineering 11 (1995) 
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    Keywords: Engineering ; Engineering General
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  • 72
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    Communications in Numerical Methods in Engineering 11 (1995), S. iii 
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 73
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    Communications in Numerical Methods in Engineering 11 (1995), S. 105-115 
    ISSN: 1069-8299
    Keywords: finite element method ; conceptual diagrams ; error estimation ; postprocessing ; teaching ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The success of the finite element method depends on the highly systematic way the analysis is built up, which means that the structure of the theoretical description and the code is transferable between different applications. It is advisable to teach the subject in such a way that this fact is fully exploited. It is a fact that most FE calculations today do not contain a check of the accuracy/quality of the solution. In the teaching of the FE method nothing is more important than the basic knowledge and understanding of the properties and behaviour of the obtained FE solution. The paper deals with the methodology in presenting the method, by use of conceptual diagrams. It also discusses the interpretation of the results from a classical FE analysis and the extraction of high quality information. Finally, error estimation and postprocessing are discussed. The detailed description of the boundary conditions is lost in the FE solution. In the postprocessing stage they should be taken into account once more.
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  • 74
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    Communications in Numerical Methods in Engineering 11 (1995), S. 97-103 
    ISSN: 1069-8299
    Keywords: dispersion relation ; isotropy ; numerical dispersion ; stiffness integration ; zero wave speed ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The dispersion properties of plane waves, propagating in an infinite uniform mesh with linear cubic 3D finite elements, are investigated. Time discretization is performed with the central-difference time-stepping scheme in combination with lumped mass matrices. The stiffness matrices are integrated analytically with different integration schemes, and dispersion relations are derived. The results show that the stiffness integration scheme can be chosen to reduce dispersion and improve the isotropy of wave propagation. It is also observed that the numerical wave speed becomes zero along certain wave propagation directions for specific wave numbers.
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  • 75
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    Communications in Numerical Methods in Engineering 11 (1995), S. 127-135 
    ISSN: 1069-8299
    Keywords: conformal mapping ; numerical grids ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: We develop some special conformal maps and related strategies for grid generation in certain ‘difficult’ domains. Of particular interest are non-convex domains, and domains with corners and cusps.
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  • 76
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    Communications in Numerical Methods in Engineering 11 (1995), S. 117-125 
    ISSN: 1069-8299
    Keywords: self similarity ; FEM ; plasticity ; crack growth ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Self-similar situations are idealized states often referred to in continuum mechanics. Such a situation is generally expected when the formulated problem only involves one significant length parameter. The state at a stationary or at a steadily moving concentrated load may be self-similar. In heat conductivity, the progressive phase transformation near a point-shaped heat source results in a self-similar situation. The problem may be non-linear and history-dependent. Thus, an incremental theory is needed, generally implying that the load has to be applied in small increments. However, at self-similarity the solutions for different loads are similar. The final solution therefore includes its own history, which may be exploited.This short communication demonstrates how an available FEM code (including many commercial codes) may be conveniently used for investigations of self-similar situations in solid mechanics. Quasistatic elastic-plastic problems are considered. The theory covers a general material behaviour including large strains and large deformations. The FEM code must allow for a user-defined material. The technique is demonstrated on a problem for an edge crack growing while the scale of yielding is large. The result is compared with calculations using a node relaxation technique.
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  • 77
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    Communications in Numerical Methods in Engineering 11 (1995), S. 137-148 
    ISSN: 1069-8299
    Keywords: pseudomaterial ; forming processes ; porous wall ; moving surfaces ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A fixed-mesh method for the analysis of transient forming processes is presented. The mesh covers material regions and zones through which the material may flow. These last zones are identified by a pseudomaterial with relatively small physical parameters. During time processing, the interface between both materials is followed by an arbitrary Lagrangian mesh. This technique appears to be suitable for the treatment of moving surfaces with sharp corners. A particular boundary condition for the Navier-Stokes equations is also introduced in order to model a porous wall.
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  • 78
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    Communications in Numerical Methods in Engineering 11 (1995), S. 149-158 
    ISSN: 1069-8299
    Keywords: FEM ; stability analysis ; algorithms ; shell structures ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The investigation of the non-linear response of shell-like structures requires insight into stability behaviour. In the paper we compare two strategies to compute singular points based on different eigenvalue problems. We show a simple algorithm to calculate critical load factors A used in engineering buckling analysis from the eigenvalues of the standard eigenvalue problem (KT - ω1) ϕ = 0. Some numerical examples illustrate the derived results and algorithms.
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  • 79
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    Communications in Numerical Methods in Engineering 11 (1995), S. 159-166 
    ISSN: 1069-8299
    Keywords: assumed displacement fields ; shallow curved shell ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An essential requirement for a satisfactory curved shell finite element is a capability for exact representation of rigid body movements: otherwise serious difficulties can occur, as is well known from early developments in shell finite element analysis. It is shown in this paper that appropriate assumed displacement fields for a particular shallow curved shell finite element with 18 degrees of freedom can be obtained in a very simple, yet apparently novel, way which permits the exact recovery of all rigid body movements. The shallow curved shell finite element considered here is constructed on a triangular flat facet approximation to a general thin elastic shell; it has quadratic middle surface geometry to allow for accurate modelling of arbitrary curvatures.
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  • 80
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    Communications in Numerical Methods in Engineering 11 (1995), S. 167-177 
    ISSN: 1069-8299
    Keywords: boundary element method ; crack growth ; fracture mechanics ; stress intensity factors ; hypersingular ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In the paper the application of the dual boundary element method to three-dimensional crack growth problems is presented. A procedure for remeshing of the free surfaces is presented to allow the simulation of surface breaking crack growth.
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    Communications in Numerical Methods in Engineering 11 (1995), S. 179-185 
    ISSN: 1069-8299
    Keywords: finite elements ; fluid flow ; open boundaries ; Sommerfield boundary conditions ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: We examine a method to impose boundary conditions on arbitrary boundaries, introduced to make domains of infinite extent finite for the purpose of numerical calculations, when a finite element discretization based on linear, bilinear or trilinear elements is used, in one, two or three dimensions, respectively. In particular, we look at the so-called ‘free’ boundary condition, which consists in retaining the boundary integrals generated by the weighted-residuals formulation along the open boundaries and adding them to the stiffness matrix. We show that this procedure is exactly equivalent to imposing on the boundary nodes a Sommerfeld radiation condition in one dimension, and a slightly modified form of the Sommerfeld boundary condition in two and three dimensions. We also show that the procedure is not applicable to the purely elliptic case.
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    Communications in Numerical Methods in Engineering 11 (1995), S. 189-190 
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
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    Communications in Numerical Methods in Engineering 11 (1995), S. 187-188 
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    Keywords: Engineering ; Engineering General
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  • 85
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    Communications in Numerical Methods in Engineering 11 (1995), S. 191-198 
    ISSN: 1069-8299
    Keywords: triangulations ; mesh relaxation ; computational geometry ; planar mesh generation ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Recent advances in planar mesh generation of arbitrary domains incorporate methods for placing points as well as connecting them into a triangulation. Postprocessing techniques such as Laplacian smoothing and mesh relaxation enhance the shape of triangles in these meshes but do not address the construction of meshes near boundaries or provide a criterion to determine the number of interior points of the initial triangulation. The paper addresses these issues by investigating the construction of degree-6 triangulations, the primary goal of the mesh relaxation method.
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  • 86
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    Communications in Numerical Methods in Engineering 11 (1995), S. 227-233 
    ISSN: 1069-8299
    Keywords: finite element analysis ; distributed computing ; structures ; client-server model ; remote procedure calls ; structural mechanics ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The paper presents a distributed computing approach for concurrent finite element analysis of truss structures. The client-server model of distributed computation is applied to the plane frame finite element algorithm and implemented on SUN workstations. The remote procedure call combined with the ability to create threads of computation allows one to efficiently implement distributed and concurrent programs. The present approach is demonstrated through a typical truss structure to illustrate the details of the implementation. This approach can be used for very large finite element systems.
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  • 87
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    Communications in Numerical Methods in Engineering 11 (1995), S. 199-211 
    ISSN: 1069-8299
    Keywords: SUPG ; Petrov-Galerkin methods ; finite elements ; explicit scheme ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This work is devoted to the simulation by finite elements of nearly incompressible inviscid flows in real 3D geometries, by means of an Euler code based on the SUPG (streamline upwind Petrov-Galerkin) method, explicit forward Euler pseudo-temporal time integration and periodic and absorbing boundary conditions, among other features. The main goal is the application to flow around turbomachinery, with special emphasis on the performance analysis of a given machine, that involves several numerical computations at different operation points. Finally, these results are summarized in the form of characteristic curves.
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  • 88
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    Communications in Numerical Methods in Engineering 11 (1995), S. 213-226 
    ISSN: 1069-8299
    Keywords: a posteriori error estimates ; asymptotic exactness ; finite elements ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A posteriori error estimation for typical Euler-Bernoulli beam bending problems is developed using a recovery operator based on a smoothing technique that is applied in the context of one-dimensional fourth-order problems. The development exploits a discrete superconvergence property of the ‘bending moments’ of the trial space interpolant of a polynomial solution of sufficiently low degree at certain Gauss points, and the superconvegence property of the energy norm difference of the trial space interpolant (of the weak solution) and the finite element approximation. An asymptotically exact error estimator is developed.
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    Communications in Numerical Methods in Engineering 11 (1995), S. 243-254 
    ISSN: 1069-8299
    Keywords: fracture ; boundary elements ; superposition ; stress intensity factor ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: We discuss a two-step superposition method for calculating linear elastic stress intensity factors. The procedure requires the solution to the full cracked problem and the solution to a problem on the same mesh assuming the singularity due to a crack tip in an infinite region. We show that this is equivalent to the well known subtraction of singularity method if the two solutions are characterized by crack tip stress. The advantages of our procedure are that no modifications need to be made to a standard computer program and that once one singular solution is available on a given cracked mesh, solutions with different boundary conditions on the same mesh may be obtained in one step without including any singular crack effects. The mesh required to represent the singular crack tip field may also be studied independently of the complete problem. The additional computational cost of a two-step procedure is minimal since the solution matrix from step one may be reused with a new right-hand side. Numerical experiments using the boundary element method demonstrate the high accuracy and simplicity of the superposition approach.
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    Communications in Numerical Methods in Engineering 11 (1995), S. 235-242 
    ISSN: 1069-8299
    Keywords: upwinding ; iterative methods ; convection-diffusion ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The effect of upwinding on iterative performance of convection-diffusion problems is investigated. An analysis of the iterative method considered here leads to a criterion for selecting the optimal upwinding parameter to improve iterative performance for a class of two-dimensional convection-diffusion problems. Supporting numerical experiments are presented.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 91
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    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995), S. 267-279 
    ISSN: 1069-8299
    Keywords: dynamic interaction ; rigid wheel ; flexible beam ; contact force ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A numerical method is presented for the analysis of dynamic interaction between rigid wheel and flexible beam. In contrast to traditional approaches, the wheel nominal motion as well as the contact force are considered here as unknowns. The correct contact force between the wheel and the beam is computed by iteratively reducing the constraint error towards zero, and a simple time integration is employed for the solution of equations of motion. Convergence of the iterative scheme is analysed, and numerical simulations are conducted to demonstrate the accuracy of the solution.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 92
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    Electronic Resource
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995), S. 255-265 
    ISSN: 1069-8299
    Keywords: boundary element method ; error estimation ; hp-version ; Galerkin BEM ; numerical results ; elasticity ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The paper investigates the convergence of the h-, p- and hp-versions of a variational symmetric boundary element method (BEM) in plane elasticity by numerical experiments. The study discusses mixed boundary value problems on polygonal domains, i.e. problems for which the exact solution is analytic except in a finite number of points. The convergence of the error in energy norm is displayed for all versions of the BEM. All results are also compared with those obtained by the corresponding finite element methods. The theoretically predicted asymptotic convergence rates for all versions of the method can be observed in the numerical experiments. A comparison of computer times is given as well.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 93
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    Electronic Resource
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995), S. 281-282 
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
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  • 94
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    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995), S. 283-284 
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
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  • 95
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995), S. 285-286 
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
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  • 96
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995) 
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
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  • 97
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    Electronic Resource
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995), S. 287-296 
    ISSN: 1069-8299
    Keywords: eigenvalues ; integral transforms ; analytical methods ; convection ; Sturm-Liouville system ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The integral transform method is employed in the analytical solution of the non-classical eigenvalue problem that appears in connection with the analysis of forced convection in ducts, including the effect of fluid heat diffusion in the axial direction. The related eigenfunctions are expanded in terms of eigenfunctions from a simpler auxiliary eigenvalue problem, and the original eigenvalues are determined from the associated matrix eigensystem analysis. Convergence rates of the proposed solutions are illustrated and reference results established for different values of the governing parameters.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 98
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    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995), S. 331-337 
    ISSN: 1069-8299
    Keywords: nearly singular kernel integrals ; curved boundary elements ; numerical integration ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The paper concentrates on the numerical evaluation of nearly singular kernel integrals commonly encountered in boundary element analysis. Limitations of the method developed recently by Huang and Cruse (1993) for the direct evaluation of nearly singular kernel integrals are analysed and pointed out. A general method is developed that extends the idea for all practical cases. Example results are presented, demonstrating the effectiveness of the method.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 99
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    Electronic Resource
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995), S. 317-330 
    ISSN: 1069-8299
    Keywords: DKT and DST elements ; pseudo consistent load vector ; pseudo consistent mass matrix ; plate bending elements ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Many finite elements based on Reissner-Mindlin plate bending theory with discrete constraints have been developed in the past few years. This approach avoids the C1 continuity required by the classical Kirchhoff plate theory. However, in those elements the shape functions for deflections (or their derivatives) are not integrated. Particularly in DKT (discrete Kirchhoff triangle) and in DST (discrete shear triangle) elements, the lateral deflections are defined only on the boundaries. In the paper we briefly discuss the definition of the transverse displacement for these elements, and present a simple approach to define a pseudoconsistent load vector and mass matrix.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 100
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995), S. 307-316 
    ISSN: 1069-8299
    Keywords: hybrid shell finite element ; symbolic integration ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Hybrid shell elements have long been regarded with reserve by the commercial finite element developers despite the high degree of reliability and accuracy associated with such formulations. The fundamental reason is the inherent higher computational cost of the hybrid approach as compared to the displacement-based formulations. However, a noteworthy factor in favour of hybrid elements is that numerical integration to generate element matrices can entirely be avoided by the use of symbolic integration. In this paper, the use of the symbolic computational approach is presented for an assumed-stress hybrid shell element with drilling degrees of freedom, and the significant time saving achieved is demonstrated through an example.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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