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  • stability  (61)
  • RAPD  (55)
  • Springer  (116)
  • American Institute of Physics (AIP)
  • 1995-1999  (116)
  • 1999  (116)
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  • 1995-1999  (116)
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  • 1
    ISSN: 1432-203X
    Keywords: Key words Somaclonal variation ; Picea glauca ; RAPD ; Somatic embryogenesis ; Cryopreservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Trees were regenerated from six white spruce embryogenic clones after cryopreservation for 3 and 4 years, respectively. Genetic stability was evaluated using randomly amplified polymorphic DNA (RAPD) fingerprints. Somaclonal variation was detected in some in vitro embryogenic cultures 2 and 12 months after they were re-established following cryopreservation but not in the corresponding regenerated trees. These results suggest that trees regenerated from cryopreserved cultures in subsequent years are primarily genetically stable in the genomic regions tested and that variation observed due to the in vitro culture process infrequently affects trees regenerated from normally maturing and germinating somatic embryos. However, trees regenerated from somatic embryos that matured or germinated abnormally in in vitro culture exhibited altered RAPD fragment patterns.
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  • 2
    ISSN: 1432-203X
    Keywords: Key wordsAllium sativum ; Garlic ; Genetic instability ; RAPD ; Somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plants were regenerated by somatic embryogenesis from long-term callus cultures derived from five garlic (Allium sativum L.) cultivars. Thirty-five of these plants were subjected to RAPD analysis. The frequency of variation was found to be cultivar dependent: approximately 1% in the two clones Solent White and California Late and around 0.35% in another three clones, Chinese, Long Keeper and Madena. Certain band changes were found in regenerants of different cultivars, suggesting the existence of a mutation-sensitive part of the garlic genome. The karyotypes of another 75 regenerants derived from the same callus cultures of three parental garlic clones were examined. Of these plants, 9.3% were found to be tetraploids, 4% aneuploid and 2.6% showed a change in the position of the secondary constriction. No association could be shown between the rate of variation for molecular and cytological characters either by comparing cultivars or examining individual regenerants.
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  • 3
    ISSN: 1432-2242
    Keywords: Key words Glycoalkaloids ; Potato ; Metabolic pathways ; RAPD ; Leptine ; Insect resistance ; Solanum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract   Solanum chacoense Bitter, a wild relative of the cultivated potato, produces several glycoalkaloids, including solanine, chaconine, and the leptines. The foliar-specific leptine glycoalkaloids are believed to confer resistance to the Colorado Potato Beetle (CPB). Using two bulked DNA samples composed of high- and low-percent leptine individuals from a segregating F1 population of S. chacoense, we have identified two molecular markers that are closely linked to high percent solanine+chaconine and, conversely, to nil/low percent leptine. One of these, a 1,500-bp RAPD product (UBC370-1500), had a recombination value of 3% in the F1 progeny, indicating tight linkage. UBC370-1500 mapped to the end of the short arm of potato chromosome 1, in the region of a previously mapped major QTL for solanidine, from a S. tuberosum (solanidine)×S. berthaultii (solasodine) cross. Taken together, these results suggest that either (1) a major locus determining solanidine accumulation in Solanum spp. is on chromosome 1 in the region defined by the RFLP markers TG24, CT197, and CT233, or (2) this region of chromosome 1 may harbor two or more important genes which determine accumulation of steroidal aglycones. These findings are important for the genetics of leptine (as well as other glycoalkaloid) accumulation and for the development of CPB-resistant potato varieties.
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  • 4
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    Theoretical and applied genetics 98 (1999), S. 86-92 
    ISSN: 1432-2242
    Keywords: Key words Cannabis sativa ; Dioecy ; Sex ; RAPD ; SCAR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A 400-bp RAPD marker generated by a primer of random decamer sequence has been found associated with the male sex phenotype in 14 dioecious cultivars and accessions of hemp (Cannabis sativa L.). The primer OPA8 generates a set of bands, most of which polymorphic among all the individual plants tested, and 1 of which, named OPA8400, present in all male plants and absent in female plants. A screening of 167 plants belonging to different genotypes for the association of the OPA8400 marker with the sex phenotype revealed that only in 3 cases was the 400-bp band was present in plants phenotypically female; on the contrary, in male plants the band was never missing, while in monoecious plants it was never present. Despite this sex-specific association, the sequences corresponding to OPA8400 were present in both staminate and carpellate plants, as revealed by Southern blotting and hybridization with the cloned RAPD band. The RAPD marker was sequenced, and specific primers were constructed. These primers generated, on the same genotypes used for RAPD analysis, a SCAR marker 390 bp in length and male-specific. This SCAR is suitable for a precise, early and rapid identification of male plants during breeding programs of dioecious and monoecious hemp.
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  • 5
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    Theoretical and applied genetics 98 (1999), S. 602-607 
    ISSN: 1432-2242
    Keywords: Key words Triticum ; Germplasm ; RAPD ; Misclassification ; Duplication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Crop germplasm collections contain a considerable percentage of misclassified accessions which may affect the use of germplasm for agricultural crop improvement. The objective of this study was to determine if random amplified polymorphic DNA (RAPD) analysis could be used to reclassify misclassified Triticum accessions. Twelve accessions suspected to be misclassified, based on morphological characters, as either macha or vavilovii wheat were studied using RAPD and cytological analyses. In the RAPD analysis, a dendrogram, based on Jaccard genetic similarity coefficients, grouped 5 dicoccum-like, 1 timopheevii-like, and 6 monococcum-like accessions with Triticum dicoccum, T. timopheevii, and T. monococcum accessions, respectively. These results were confirmed by the cytological analysis. A RAPD marker specific to the D genome was also detected. This study suggests that RAPD analysis can be used to classify germplasm and to distinguish some species in Triticum.
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  • 6
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    Theoretical and applied genetics 98 (1999), S. 657-663 
    ISSN: 1432-2242
    Keywords: Key words Cicer ; Species relationships ; DNA fingerprinting ; RAPD ; Chickpea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Random amplified polymorphic DNA markers were used to distinguish between nine different Cicer taxa representing the cultivated chickpea and eight other related annual wild species. Of the 75 random10-mer primers tested, only 8 amplified genomic DNA across all the species. A total of 115 reproducibly scorable RAPD markers were generated, all except 1 polymorphic, and these were utilized to deduce genetic relationships among the annual Cicer species. Four distinct clusters were observed and represented C. arietinum, C. reticulatum and C. echinospermum in first cluster followed by C. chorassanicum and C. yamashitae in the second cluster, while C. pinnatifidum, C. judaicum and C. bijugum formed the third cluster. Cicer cuneatum did not cluster with any of the species and was most distantly placed from the cultivated species. Except for the placement of C. chorassanicum and C. yamashitae, deduced species’ relationships agreed with previous studies. In addition, species-diagnostic amplification products specific to all the nine species were identified. The results clearly demonstrate a methodology based on random-primed DNA amplification that can be used for studying Cicer phylogeny and chickpea improvement.
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  • 7
    ISSN: 1432-2242
    Keywords: Key words Vicia faba ; Genetic map ; Trisomics ; RAPD ; Seed-protein genes ; QTLs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Seven F2 families of faba bean descendent from plants trisomic for chromosomes 3, 4, 5 and 6 were analyzed for isozyme markers and two of these were also studied for morphological and RAPD markers and seed-protein genes. Linkage analysis revealed 14 linkage groups, 8 of which were unambiguously assigned to specific chromosomes. Several QTLs for seed weight were identified, the most important of which, located on chromosome 6, explained approximately 30% of the total phenotypic variation. Comparison of results from Vicia faba with the maps of the related species Pisum sativum L. and Cicer arietinum L. revealed one possible new case of linkage conservation. A composite linkage analysis based on 42 markers analyzed in this and previous studies, where line Vf 6 was also used as the female parental, allowed the new assignment of previously independent linkage groups and/or markers to specific chromosomes. Thus, the number of linkage groups was reduced to 13, each comprising an increased number of markers. No contradictory results were detected, indicating the suitability of the statistical procedure and methodology used so far in the development of the map of this species.
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  • 8
    ISSN: 1432-2242
    Keywords: Key words Addition lines ; Multiplexed PCR ; RAPD ; Sequence tagged site ; Tritordeum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  RAPD markers were developed for octoploid×Tritordeum (amphiploid Hordeum chilense×Triticum aestivum) and its parents. Addition lines were used to identify specific RAPD markers for the Hordeum chilense chromosomes detectable in a wheat background. Twelve RAPD fragments have been cloned, sequenced and converted into STS markers. Eleven of these STSs have maintained both the chromosome specificity and the possibility of detection in a wheat background. The use of these markers in multiplexed PCRs facilitates both the efficient and reliable screening of new addition lines as well as the monitoring of introgression of H. chilense in bread and durum wheat.
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  • 9
    ISSN: 1432-2242
    Keywords: Key words Cucumis melo ; Molecular markers ; RAPD ; CAPS ; RFLP ; Fusarium oxysporum ; Fusarium resistance ; Marker-assisted selection (MAS)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Fusarium wilt, caused by Fusarium oxysporum Schlecht f. sp. melonis Snyder & Hans, is a worldwide soil-borne disease of melon (Cucumis melo L.). Resistance to races 0 and 1 of Fusarium wilt is conditioned by the dominant gene Fom-2. To facilitate marker-assisted backcrossing with selection for Fusarium wilt resistance, we developed cleaved amplified polymorphic sequences (CAPS) and restriction fragment length polymorphisms (RFLP) markers by converting RAPD markers E07 (a 1.25-kb band) and G17 (a 1.05-kb band), respectively. The RAPD-PCR polymorphic fragments from the susceptible line ’Vedrantais’ were cloned and sequenced in order to construct primers that would amplify only the target fragment. The derived primers, E07SCAR-1/E07SCAR-2 from E07 and G17SCAR-1/G17SCAR-2 from G17, yielded a single 1.25-kb fragment (designated SCE07) and a 1.05-kb fragment (designated SCG17) (the same as RAPD markers E07 and G17), respectively, from both resistant and susceptible melon lines, thus demonstrating locus-specific associated primers. Potential CAPS markers were first revealed by comparing sequence data between fragments amplified from resistant (PI 161375) and susceptible (’Vedrantais’) lines and were then confirmed by electrophoresis of restriction endonuclease digestion products. Twelve restriction endonucleases were evaluated for their potential use as CAPS markers within the SCE07 fragment. Three (BclI, MspI, and BssSI) yielded ideal CAPS markers and were subsequently subjected to extensive testing using an additional 88 diverse melon cultigens, 93 and 119 F2 individuals from crosses of ’Vedrantais’ x PI 161375 and ’Ananas Yokneam’×MR-1 respectively, and 17 families from a backcross BC1S1 population derived from the breeding line ’MD8654’ as a resistance source. BclI- and MspI-CAPS are susceptible-linked markers, whereas the BssSI-CAPS is a resistant-linked marker. The CAPS markers that resulted from double digestion by BclI and BssSI are co-dominant. Results from BclI- and MspI-CAPS showed over 90% accuracy in the melon cultigens, and nearly 100% accuracy in the F2 individuals and BC1S1 families tested. This is the first report of PCR-based CAPS markers linked to resistance/susceptibility for Fusarium wilt in melon. The RFLP markers resulting from probing with a clone-derived 1.05-kb SCG17 PCR fragment showed 85% correct matches to the disease phenotype. Both the CAPS and RFLP markers were co-dominant, easier to score, and more accurate and consistent in predicting the melon phenotype than the RAPD markers from which they were derived.
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  • 10
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    Theoretical and applied genetics 99 (1999), S. 1061-1067 
    ISSN: 1432-2242
    Keywords: Key words Native American maize ; RAPD ; Genetic relationships ; Reproducibility ; Geography and evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Genetic variation among 15 accessions of Native American maize from the Great Plains was investigated using random amplified polymorphic DNA (RAPD). RAPDs revealed very high levels of polymorphism among accessions. Banding patterns ranged in percentage polymorphism from 46.7% to 86.2% with an overall mean of 70.7% for the primers analyzed. The construction of genetic relationships using cluster analysis and principal coordinates analysis revealed that RAPDs are successful in confirming hypothesized relationships and in identifying misclassified specimens. Furthermore, the phenogram fails to reveal a strong correspondence between genetic relationships and the geographical position of Native Americans prior to contact. This provides support for the hypothesis that multiple introductions of maize into the Great Plains via trade may have resulted in the great morphological variation found among accessions in the region. Based on these data, it is unlikely that a separate Great Plains race of maize can be distinguished. In general, we conclude that RAPDs are potentially very useful in organizing seed collections and understanding intraspecific genetic differentiation.
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  • 11
    ISSN: 1432-2242
    Keywords: Key words Bs2 resistance gene ; Pepper ; RAPD ; AFLP ; Positional cloning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The Bs2 resistance gene of pepper confers resistance against the bacterial pathogen Xanthomonas campestris pv. vesicatoria. As a first step toward isolation of the Bs2 gene, molecular markers tightly linked to the gene were identified by randomly amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) analysis of near-isogenic lines. Markers flanking the locus were identified and a high-resolution linkage map of the region was developed. One AFLP marker, A2, was found to cosegregate with the locus, while two others, F1 and B3, flank the locus and are within 0.6 cM. Physical mapping of the A2 and F1 markers indicates that these markers may be within 150 kb of each other. Together, these results indicate that the Bs2 region may be cloned either by chromosome walker or landing. The linked markers were also used to characterize gamma-irradiation-induced mutants at the Bs2 locus.
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  • 12
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    Theoretical and applied genetics 99 (1999), S. 837-843 
    ISSN: 1432-2242
    Keywords: Key words Daucus carota spp. sativus ; RAPD ; Cytoplasmic male sterility (CMS) ; Asymmetric cell fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The mitochondrial DNA of various carrot lines was characterized by random amplified polymorphic DNA (RAPD) analysis, and six sequence-tagged sites (STSs) led to identification of the petaloid type of cytoplasmic male sterility (CMS). Using six STS primer combinations, we were able to classify five CMS lines into two groups and eight fertile carrots into six groups. Both the STS1 and the STS4 primer combinations differentiated CMS cytoplasms from the fertile cytoplasms, and the STS2 primer combination revealed two different types of CMS cytoplasms – of Wisconsin Wild and Cornell origins. Cybrid carrot lines with petaloid flowers which had been obtained by asymmetric cell fusion could also be separated from fertile cybrids by the STS1 primer combination. The STS1 fragment contained a homologous sequence with the orfB gene. DNA gel blot analysis indicated that homologous regions to the STS1 fragment existed in fertile types as well as the CMS types, although the restriction fragment size patterns differed. These observations demonstrate that rearrangements involving this region occurred in the mitochondrial genome. The STS4 fragment had a more complicated gene structure, including retrotransposon-like sequences and small segments of chloroplast genome.
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  • 13
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    Computational mechanics 23 (1999), S. 8-19 
    ISSN: 1432-0924
    Keywords: Keywords: Material characteristic length ; strain-rate gradient ; dominant growth rate ; viscoplastic material ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We study thermomechanical deformations of a viscoplastic body deformed in simple shear. The strain gradients are taken as independent kinematic variables and the corresponding higher order stresses are included in the balance laws, and the equation for the yield surface. Three different functional relationships, the power law, and those proposed by Wright and Batra, and Johnson and Cook are used to relate the effective strain rate to the effective stress and temperature. Effects of strain hardening of the material and elastic deformations are neglected. The homogeneous solution of the problem is perturbed and the stability of the problem linear in the perturbation variables is studied. Following Wright and Ockendon's postulate that the wavelength whose initial growth rate is maximum determines the minimum spacing between adjacent shear bands, the shear band spacing is computed. It is found that the minimum shear band spacing is very sensitive to the thermal softening coefficient/exponent, the material characteristic length and the nominal strain-rate. Approximate analytical expressions for the critical wave length for heat conducting nonpolar materials and locally adiabatic deformations of gradient dependent materials are also derived.
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  • 14
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    Optical review 6 (1999), S. 28-36 
    ISSN: 1349-9432
    Keywords: optical propagation equation ; stability ; picosecond pulse ; 3-dimensional computation ; Fresnel’s distribution ; fast Fourier transform
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a new simulation code able to simulate the entire propagation of laser pulse, from the amplifiers level up to the focusing stage. This algorithm has some new characteristics that we intend to present. It computes the three-dimensional optical propagation equation using no approximation other than its picosecond expression. The stability has been carefully studied so that it can be applied to any geometry. This is a great improvement since, up to now only cylindrical geometry was accessible for accuracy. In this paper we also present a method using Fast Fourier Transform able to evaluate with a high accuracy, Fresnel’s distribution of a focused laser pulse. The advantages provided by our algorithm are its rapidity and its high physical understanding of the focusing phenomena.
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  • 15
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    Theoretical and applied genetics 98 (1999), S. 171-177 
    ISSN: 1432-2242
    Keywords: Key words Varietal identification ; RAPD ; Microsatellite ; Vitis vinifera L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The aim of this study was to develop a cultivar identification tool based on molecular analysis and a statistical approach. From the PIC parameter we defined the D parameter, which evaluates the efficiency of a primer for the purpose of identification of varieties; i.e. the probability that two randomly chosen individuals have different patterns. D can be used to compare different types of markers even if only the allelic frequencies are known. We used this parameter to develop an algorithm for selecting the optimal combination of primers necessary to identify a set of varieties. The optimal combination of primers determined for a small elite group of varieties applied on a larger set induces a risk of confusion involving 1 of the elite varieties. We estimated the risk of confusion using the D value of each primer of the combination. We applied this methodology on a set of 224 varieties of Vitis vinifera screened with 21 RAPD primers and two microsatellite loci. The discriminating power of the primers did not only depend on the number of patterns it generates but also on the frequencies of the different patterns. A combination of 8 primers (6 RAPD and two microsatellite) was found to be optimum for the discrimination of these 224 varieties. A subset of 38 elite varieties was also investigated. The determined optimal combination of 4 primers (3 RAPD and one microsatellite) applied on the 224 varieties gave 9 risks of confusion involving 1 of the elite varieties. Confusion can happen between varieties with the same origin as well as between varieties of very diverse geographical origins.
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  • 16
    ISSN: 1432-2242
    Keywords: Key words Rosa sect. Caninae ; Biometrics ; Heterogamy ; RAPD ; Segregation distortion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The dogroses, Rosa sect. Caninae, are polyploid and characterized by their unique meiosis with an unequal number of chromosomes in the male and female gametes. The pollen cells have 7 chromosomes and the egg cells 21, 28 or 35 depending on the ploidy level of the species. The resulting matroclinal inheritance was studied with both morphological and molecular markers in a pair of reciprocal crosses between R. dumalis and R. rubiginosa (2n=35). A canonical discriminant analysis based on seven morphological characters showed only a minor overlapping between the two progeny groups. In addition, the R. dumalis×R. rubiginosa offspring were more heterogeneous than the offspring from the reciprocal cross in each of the characters analysed. Eleven RAPD markers specific for the R. dumalis parent and 10 RAPD markers specific for the R. rubiginosa parent were scored in the offspring. Each of the offspring exhibited either all, or all-but-one, of the seed parent markers. The average number of pollen donor markers found in the offspring was 3.2 (R. dumalis×R. rubiginosa) and 2.7 (R. rubiginosa×R. dumalis). About half of the pollen donor markers were never transmitted to the progeny. This is, to our knowledge, the first time the highly skewed chromosome distribution in Rosa sect. Caninae has been demonstrated with statistically evaluated morphological data and with molecular markers.
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  • 17
    ISSN: 1432-2242
    Keywords: Key words Pinus contorta ; Silviculture ; Reforestation ; Gene conservation ; RAPD ; SSR ; DNA analyses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We examined the effects of different methods of forest regeneration on the genetic diversity of lodgepole pine (Pinus contorta var ‘latifolia’) using two different DNA-based molecular markers [randomly amplified polymorphic DNA (RAPDs) and microsatellites or simple sequence repeats (SSRs)]. Genetic diversity was estimated for 30 individuals in each of four populations for the following three stand types: (1) mature lodgepole pine (〉100 years); (2) 20- to 30-year-old harvested stands left for natural regeneration; (3) 20- to 30-year-old planted stands (4 stands of each type); and one group of 30 operationally produced seedlings. There was no significant effect of stand type on expected heterozygosity, although allelic richness and diversity were much higher for SSRs than for RAPDs. Expected heterozygosity ranged from 0.39 to 0.47 based on RAPDs and from 0.67 to 0.77 based on SSRs. The number of alleles per locus for SSRs ranged from 3 to 34 (mean 21.0), and there was a significant relationship between sequence repeat length and the number of alleles at a locus. Both marker types showed that over 94% of the variation was contained within the populations and that the naturally regenerated stands sampled had lower (not significant) expected heterozygosity than the planted or unharvested stands. The group of seedlings (assessed by RAPDs only) had expected heterozygosity and allele frequencies similar to those of the unharvested stands. Genetic distance measures were higher than obtained previously in the species using isozyme markers. There was no correlation between the two marker types for pair-wise genetic distances based on populations analyzed by both methods. Pair-wise genetic distance measures and an ordination of allele frequencies for both marker types showed little effect of geographic location or stand type on genetic similarity.
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  • 18
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    Theoretical and applied genetics 99 (1999), S. 11-15 
    ISSN: 1432-2242
    Keywords: Key words Fagus crenata ; Fagus japonica ; Microsatellite ; RAPD ; RAHM ; SSR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We have developed microsatellite markers (SSRs) applicable to Fagus crenata using the RAHM method and investigated their polymorphisms. We also applied the SSRs in an analysis of a closely related species, F. japonica. Here we describe the isolation and characterization of nine polymorphic microsatellite markers, of which eight are applicable to both species. Among 30 individuals of each of F. crenata and F. japonica we detected a total of 79 and 77 alleles, respectively, with an average of 9.9 and 8.6 alleles per locus. The mean expected heterozygosity (He) was 0.615 (range: 0.216–0.925) in F. crenata and 0.660 in F. japonica (range: 0.259–0.827). The He values were considerably higher than those previously found for isozymes. Paternity exclusion probabilities for multiple loci, calculated over all loci, were extremely high (0.999 and 0.998 in F. crenata and F. japonica, respectively): sufficiently high to study pollen flow in both species.
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  • 19
    ISSN: 1570-7458
    Keywords: Sitobion avenae ; Sitobion fragariae ; RAPD ; PCR ; microsatellites ; mtDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A set of molecular markers to differentiate the aphid (Hemiptera: Aphidoidea) species Sitobion avenae (Fabricius) from Sitobion fragariae (Walker), is presented. These markers correspond to (1) a region of the mitochondrial DNA, (2) five species-specific RAPD banding patterns and (3) four microsatellite loci. Each of the markers was able to clearly distinguish between the species. The utility of each molecular marker is discussed. Mitochondrial DNA is best applicable to species determination and relative abundance, RAPDs to the evaluation of genetic diversity, and microsatellites to the assessment of the population genetic structure; the combined use of mtDNA with the other techniques can be of importance when the presence of hybrids is suspected, and RAPDs with microsatellites are best used together in population genetics and host preference studies.
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  • 20
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    The journal of Fourier analysis and applications 5 (1999), S. 105-125 
    ISSN: 1531-5851
    Keywords: 26B05 ; 42B10 ; 42C99 ; frame ; Gabor system ; Riesz basis ; stability ; wavelet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract If the sequence of functions ϕj, k is a wavelet frame (Riesz basis) or Gabor frame (Riesz basis), we obtain its perturbation system ψj,k which is still a frame (Riesz basis) under very mild conditions. For example, we do not need to know that the support of ϕ or ψ $$(\hat \phi or\hat \psi )$$ is compact as in [14]. We also discuss the stability of irregular sampling problems. In order to arrive at some of our results, we set up a general multivariate version of Littlewood-Paley type inequality which was originally considered by Lemarié and Meyer [17], then by Chui and Shi [9], and Long [16].
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  • 21
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    Journal of thermal analysis and calorimetry 56 (1999), S. 1177-1184 
    ISSN: 1572-8943
    Keywords: differential scanning calorimetry ; DNA triple helix ; oligonucleotides ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In this work we report a thermodynamic characterization of stability and melting behaviour of two 24-mer DNA triplexes. The third strand, that binds the Watson-Crick double helix with Hoogsteen hydrogen bonds, contains 3′-3′ phosphodiester junction that determines the polarity inversion. The target double helix is composed of adjacent and alternate fragments of oligopurine-oligopyrimidine tracts. The two helices differ from the substitution of the cytosine, involved in the junction, with the thymine. Calorimetric data reported here provide a quantitative measure of the influence of pH and base modification on the stability of a DNA triplex.
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  • 22
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    Journal of productivity analysis 12 (1999), S. 55-75 
    ISSN: 1573-0441
    Keywords: Data envelopment analysis (DEA) ; returns to scale (RTS) ; sensitivity ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract Sensitivity of the returns to scale (RTS) classifications in data envelopment analysis is studied by means of linear programming problems. The stability region for an observation preserving its current RTS classification (constant, increasing or decreasing returns to scale) can be easily investigated by the optimal values to a set of particular DEA-type formulations. Necessary and sufficient conditions are determined for preserving the RTS classifications when input or output data perturbations are non-proportional. It is shown that the sensitivity analysis method under proportional data perturbations can also be used to estimate the RTS classifications and discover the identical RTS regions yielded by the input-based and the output-based DEA methods. Thus, our approach provides information on both the RTS classifications and the stability of the classifications. This sensitivity analysis method can easily be applied via existing DEA codes.
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  • 23
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    Plant molecular biology reporter 17 (1999), S. 171-178 
    ISSN: 1572-9818
    Keywords: Camellia sinensis ; DNA isolation ; PCR ; RAPD ; Tea
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    Topics: Biology
    Notes: Abstract A simple procedure for DNA isolation from processed dried commercial samples of tea is described. The method involves a modified CTAB procedure employing extensive washing, use of 1% PVP to remove polyphenolics and a single phenol:chloroform extraction step. The average yield ranges from 164–494 μg/g tea sample for various market samples. The DNA obtained from 11 different brands of tea using this procedure were consistently amplifiable (using both RAPD primers as well as defined sequences as primers) and digestible with restriction endonucleases.
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    ISSN: 1572-9818
    Keywords: Date-palm ; DNA library ; RAPD
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    Topics: Biology
    Notes: Abstract A random genomic library of Tunisian date-palm varieties has been built from total cellular DNA, previously amplified according to an RAPD procedure. The resultant recombinant DNA is characterised by a size ranging from 200 to 1600 bp inserts. This DNA would constitute a large number of anonymous probes useful in Southern hybridisation experiments. It would also provide potential markers aimed at the molecular characterisation of date-palm varieties, aid the search of those associated with bayoud disease and suggest a sex determination of trees.
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    Journal of statistical physics 95 (1999), S. 835-850 
    ISSN: 1572-9613
    Keywords: quasicrystals ; nonperiodic tilings ; classical lattice-gas models ; nonperiodic ground states ; nonperiodic Gibbs states ; stability ; frustration
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    Topics: Physics
    Notes: Abstract One of the fundamental problems of quasicrystals is to understand their occurrence in microscopic models of interacting particles. We review here recent attempts to construct stable quasicrystalline phases. In particular, we compare two recently constructed classical lattice-gas models with translation-invariant interactions and without periodic ground-state configurations. The models are based on nonperiodic tilings of the plane by square-like tiles. In the first model, all interactions can be minimized simultaneously. The second model is frustrated; its nonperiodic ground state can arise only by the minimization of the energy of competing interactions. We put forward some hypotheses concerning stabilities of nonperiodic ground states. In particular, we introduce two criteria, the so-called strict boundary conditions, and prove their equivalence to the zero-temperature stability of ground states against small perturbations of potentials of interacting particles. We discuss the relevance of these conditions for the low-temperature stability, i.e., for the existence of thermodynamically stable nonperiodic equilibrium states.
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    Journal of statistical physics 95 (1999), S. 867-902 
    ISSN: 1572-9613
    Keywords: kinetics of phase transitions ; domain coarsening ; asymptotic behavior ; self-similarity ; stability ; chaos
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    Topics: Physics
    Notes: Abstract The classical Lifshitz–Slyozov–Wagner theory of domain coarsening predicts asymptotically self-similar behavior for the size distribution of a dilute system of particles that evolve by diffusional mass transfer with a common mean field. Here we consider the long-time behavior of measure-valued solutions for systems in which particle size is uniformly bounded, i.e., for initial measures of compact support. We prove that the long-time behavior of the size distribution depends sensitively on the initial distribution of the largest particles in the system. Convergence to the classically predicted smooth similarity solution is impossible if the initial distribution function is comparable to any finite power of distance to the end of the support. We give a necessary criterion for convergence to other self-similar solutions, and conditional stability theorems for some such solutions. For a dense set of initial data, convergence to any self-similar solution is impossible.
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    Journal of intelligent and robotic systems 26 (1999), S. 91-100 
    ISSN: 1573-0409
    Keywords: robots ; neural networks ; adaptiveness ; stability ; approximation
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    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An indirect adaptive control approach is developed in this paper for robots with unknown nonlinear dynamics using neural networks (NNs). A key property of the proposed approach is that the actual joint angle values in the control law are replaced by the desired joint angles, angle velocities and accelerators, and the bound on the NN reconstruction errors is assumed to be unknown. Main theoretical results for designing such a neuro-controller are given, and the control performance of the proposed controller is verified with simulation studies.
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    Queueing systems 32 (1999), S. 99-130 
    ISSN: 1572-9443
    Keywords: neural network ; inhibition ; stability ; Markov process ; fluid limit ; Harris-recurrence ; transience
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    Topics: Computer Science
    Notes: Abstract The subject of the paper is the stability analysis of some neural networks consisting of a finite number of interacting neurons. Following the approach of Dai [5] we use the fluid limit model of the network to derive a sufficient condition for positive Harris-recurrence of the associated Markov process. This improves the main result in Karpelevich et al. [11] and, at the same time, sheds some new light on it. We further derive two different conditions that are sufficient for transience of the state process and illustrate our results by classifying some examples according to positive recurrence or transience.
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    Queueing systems 33 (1999), S. 293-325 
    ISSN: 1572-9443
    Keywords: stability ; fluid models ; multiclass queueing networks ; piecewise linear Lyapunov functions ; linear Lyapunov functions ; monotone global stability ; static buffer priority disciplines
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    Topics: Computer Science
    Notes: Abstract This paper studies the stability of a three‐station fluid network. We show that, unlike the two‐station networks in Dai and Vande Vate [18], the global stability region of our three‐station network is not the intersection of its stability regions under static buffer priority disciplines. Thus, the “worst” or extremal disciplines are not static buffer priority disciplines. We also prove that the global stability region of our three‐station network is not monotone in the service times and so, we may move a service time vector out of the global stability region by reducing the service time for a class. We introduce the monotone global stability region and show that a linear program (LP) related to a piecewise linear Lyapunov function characterizes this largest monotone subset of the global stability region for our three‐station network. We also show that the LP proposed by Bertsimas et al. [1] does not characterize either the global stability region or even the monotone global stability region of our three‐station network. Further, we demonstrate that the LP related to the linear Lyapunov function proposed by Chen and Zhang [11] does not characterize the stability region of our three‐station network under a static buffer priority discipline.
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    Celestial mechanics and dynamical astronomy 74 (1999), S. 19-57 
    ISSN: 1572-9478
    Keywords: stability ; Hamiltonian ; two centers ; oblate planet ; galactic disks ; dipole
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    Topics: Physics
    Notes: Abstract Relative equilibria occur in a wide variety of physical applications, including celestial mechanics, particle accelerators, plasma physics, and atomic physics. We derive sufficient conditions for Lyapunov stability of circular orbits in arbitrary axisymmetric gravitational (electrostatic) and magnetic fields, including the effects of local mass (charge) and current density. Particularly simple stability conditions are derived for source‐free regions, where the gravitational field is harmonic (∇2U = 0) or the magnetic field irrotational (∇ × B = 0). In either case the resulting stability conditions can be expressed geometrically (coordinate‐free) in terms of dimensionless stability indices. Stability bounds are calculated for several examples, including the problem of two fixed centers, the J2 planetary model, galactic disks, and a toroidal quadrupole magnetic field.
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    Celestial mechanics and dynamical astronomy 75 (1999), S. 251-285 
    ISSN: 1572-9478
    Keywords: unrestricted problem ; rotational motion ; rigid body dynamics ; libration points ; stability ; resonances
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    Topics: Physics
    Notes: Abstract We present an analysis of the model introduced by Kokoriev and Kirpichnikov (1988) for the study of unrestricted planar motion of a point mass and a symmetric rigid body whose gravity field is approximated by two point masses (a dumb-bell model). To show possible generalization of the model, we give a systematic derivation of equations of motion for a more general unrestricted problem of a point and a rigid body possessing a plane of dynamical symmetry. We give a simple description of bifurcation of triangular libration points, and we perform an analysis of their linear stability. We propose to extend the model of Kokoriev and Kirpichnikov (1988) to a case when the symmetric body is oblate. In the proposed model the gravity field of moving and rotating body is approximated by two complex masses at complex distance (a complex dumb-bell model). An analysis of bifurcation of the triangular libration points in this model is also presented.
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    Set-valued analysis 7 (1999), S. 209-238 
    ISSN: 1572-932X
    Keywords: nonsmooth analysis ; subdifferentials ; coderivatives ; implicit function theorem ; solvability ; stability ; open mapping theorem ; metric regularity ; multidirectional mean value inequality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We prove a general implicit function theorem for multifunctions with a metric estimate on the implicit multifunction and a characterization of its coderivative. Traditional open covering theorems, stability results, and sufficient conditions for a multifunction to be metrically regular or pseudo-Lipschitzian can be deduced from this implicit function theorem. We prove this implicit multifunction theorem by reducing it to an implicit function/solvability theorem for functions. This approach can also be used to prove the Robinson–Ursescu open mapping theorem. As a tool for this alternative proof of the Robinson–Ursescu theorem, we also establish a refined version of the multidirectional mean value inequality which is of independent interest.
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    Computational & mathematical organization theory 5 (1999), S. 5-30 
    ISSN: 1572-9346
    Keywords: network models ; organization theory ; rule following ; self organized ; stability ; work teams ; work routine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Self-organized rule-following systems are increasingly relevant objects of study in organization theory due to such systems&2018; capacity to maintain control while enabling decentralization of authority. This paper proposes a network model for such systems and examines the stability of the networks&2018; repetitive behavior. The networks examined are Ashby nets, a fundamental class of binary systems: connected aggregates of nodes that individually compute an interaction rule, a binary function of their three inputs. The nodes, which we interpret as workers in a work team, have two network inputs and one self-input. All workers in a given team follow the same interaction rule. We operationalize the notion of stability of the team&2018;s work routine and determine stability under small perturbations for all possible rules these teams can follow. To study the organizational concomitants of stability, we characterize the rules by their memory, fluency, homogeneity, and autonomy. We relate these measures to work routine stability, and find that stability in ten member teams is enhanced by rules that have low memory, high homogeneity, and low autonomy.
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    Queueing systems 32 (1999), S. 131-168 
    ISSN: 1572-9443
    Keywords: stability ; positive recurrence ; fluid limit ; polling system ; exhaustive service policy
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    Topics: Computer Science
    Notes: Abstract We introduce a generalized criterion for the stability of Markovian queueing systems in terms of stochastic fluid limits. We consider an example in which this criterion may be applied: a polling system with two stations and two heterogeneous servers.
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    Queueing systems 31 (1999), S. 171-206 
    ISSN: 1572-9443
    Keywords: scheduling ; open multiclass queueing networks ; discrete-review policies ; fluid models ; stability
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    Topics: Computer Science
    Notes: Abstract This paper describes a family of discrete-review policies for scheduling open multiclass queueing networks. Each of the policies in the family is derived from what we call a dynamic reward function: such a function associates with each queue length vector q and each job class k a positive value r k (q), which is treated as a reward rate for time devoted to processing class k jobs. Assuming that each station has a traffic intensity parameter less than one, all policies in the family considered are shown to be stable. In such a policy, system status is reviewed at discrete points in time, and at each such point the controller formulates a processing plan for the next review period, based on the queue length vector observed. Stability is proved by combining elementary large deviations theory with an analysis of an associated fluid control problem. These results are extended to systems with class dependent setup times as well as systems with alternate routing and admission control capabilities.
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    Queueing systems 32 (1999), S. 195-231 
    ISSN: 1572-9443
    Keywords: window flow control ; TCP ; stability ; multiclass networks ; stationary ergodic point processes ; (max,+)-linear system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract We focus on window flow control as used in packet-switched communication networks. The approach consists in studying the stability of a system where each node on the path followed by the packets of the controlled connection is modeled by a FIFO (First-In-First-Out) queue of infinite capacity which receives in addition some cross traffic represented by an exogenous flow. Under general stochastic assumptions, namely for stationary and ergodic input processes, we show the existence of a maximum throughput allowed by the flow control. Then we establish bounds on the value of this maximum throughput. These bounds, which do not coincide in general, are reached by time-space scalings of the exogenous flows. Therefore, the performance of the window flow control depends not only on the traffic intensity of the cross flows, but also on fine statistical characteristics such as the burstiness of these flows. These results are illustrated by several examples, including the case of a nonmonotone, nonconvex and fractal stability region.
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    BIT 39 (1999), S. 385-402 
    ISSN: 1572-9125
    Keywords: Gaussian elimination ; stability ; backward error analysis ; growth factor
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    Topics: Mathematics
    Notes: Abstract A new backward error analysis of LU factorization is presented. It allows to obtain a sharper upper bound for the forward error and a new definition of the growth factor that we compare with the well known Wilkinson growth factor for some classes of matrices. Numerical experiments show that the new growth factor is often of order approximately log2 n whereas Wilkinson's growth factor is of order n or $$\sqrt n$$ .
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  • 38
    ISSN: 1572-9036
    Keywords: (discrete-time) Markov control processes ; expected total cost ; value iteration ; policy iteration ; stability ; transient control models
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    Topics: Mathematics
    Notes: Abstract This paper studies the expected total cost (ETC) criterion for discrete-time Markov control processes on Borel spaces, and possibly unbounded cost-per-stage functions. It presents optimality results which include conditions for a control policy to be ETC-optimal and for the ETC-value function to be a solution of the dynamic programming equation. Conditions are also given for the ETC-value function to be the limit of the α-discounted cost value function as α ↑ 1, and for the Markov control process to be `stable" in the sense of Lagrange and almost surely. In addition, transient control models are fully analized. The paper thus provides a fairly complete, up-dated, survey-like presentation of the ETC criterion for Markov control processes on Borel spaces.
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    Advances in computational mathematics 10 (1999), S. 115-133 
    ISSN: 1572-9044
    Keywords: Runge–Kutta–Nyström methods ; predictor–corrector methods ; stability ; parallelism ; 65M12 ; 65M20
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    Topics: Mathematics
    Notes: Abstract This paper describes the construction of block predictor–corrector methods based on Runge–Kutta–Nyström correctors. Our approach is to apply the predictor–corrector method not only with stepsize h, but, in addition (and simultaneously) with stepsizes a i h, i = 1 ...,r. In this way, at each step, a whole block of approximations to the exact solution at off‐step points is computed. In the next step, these approximations are used to obtain a high‐order predictor formula using Lagrange or Hermite interpolation. Since the block approximations at the off‐step points can be computed in parallel, the sequential costs of these block predictor–corrector methods are comparable with those of a conventional predictor–corrector method. Furthermore, by using Runge–Kutta–Nyström corrector methods, the computation of the approximation at each off‐step point is also highly parallel. Numerical comparisons on a shared memory computer show the efficiency of the methods for problems with expensive function evaluations.
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    BIT 39 (1999), S. 620-645 
    ISSN: 1572-9125
    Keywords: Numerical integrator ; oscillatory solutions ; Schrödinger equation ; quantum-classical coupling ; error bounds ; stability
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    Topics: Mathematics
    Notes: Abstract We study time integration methods for equations of mixed quantum-classical molecular dynamics in which Newtonian equations of motion and Schrödinger equations are nonlinearly coupled. Such systems exhibit different time scales in the classical and the quantum evolution, and the solutions are typically highly oscillatory. The numerical methods use the exponential of the quantum Hamiltonian whose product with a state vector is approximated using Lanczos' method. This allows time steps that are much larger than the inverse of the highest frequencies. We describe various integration schemes and analyze their error behaviour, without assuming smoothness of the solution. As preparation and as a problem of independent interest, we study also integration methods for Schrödinger equations with time-dependent Hamiltonian.
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    Lithuanian mathematical journal 39 (1999), S. 20-32 
    ISSN: 1573-8825
    Keywords: Schrödinger equation ; explicit finite-difference schemes ; stability ; energy conservation ; convergence
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    Topics: Mathematics
    Notes: Abstract We consider three-level explicit schemes for solving the nonlinear variable coefficient Schrödinger-type equation. Using spectral and energy methods we establish the stability and convergence of these schemes. The existence of discrete conservation laws is investigated. General results are applied for the DuFort-Frankel and leap-frog diffenrence schemes.
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    Mechanics of composite materials 35 (1999), S. 495-506 
    ISSN: 1573-8922
    Keywords: layered structure ; shells ; frames ; stringers ; nonlinearity ; stability ; pulsed loading ; numerical methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Nonlinear three-dimensional problems of dynamic deformation, buckling, and posteritical behavior of composite shell structures under pulsed loads are analyzed. The structure is assumed to be made of rigidly joined plates and shells of revolution along the lines coinciding with the coordinate directions of the joined elements. Individual structural elements can be made of both composite and conventional isotropic materials. The kinematic model of deformation of the structural elements is based on Timoshenko-type hypotheses. This approach is oriented to the calculation of nonstationary deformation processes in composite structures under small deformations but large displacements and rotation angles, and is implemented in the context of a simplified version of the geometrically nonlinear theory of shells. The physical relations in the composite structural elements are based on the theory of effective moduli for individual layers or for the package as a whole, whereas in the metallic elements this is done in the framework of the theory of plastic flow. The equations of motion of a composite shell structure are derived based on the principle of virtual displacements with some additional conditions allowing for the joint operation of structural elements. To solve the initial boundary-value problem formulated, an efficient numerical method is developed based on the finite-difference discretization of variational equations of motion in space variables and an explicit second-order time-integration scheme. The permissible time-integration step is determined using Neumann's spectral criterion. The above method is especially efficient in calculating thin-walled shells, as well as in the case of local loads acting on the structural element, when the discretization grid has to be condensed in the zones of rapidly changing solutions in space variables. The results of analyzing the nonstationary deformation processes and critical loads are presented for composite and isotropic cylindrical shells reinforced with a set of discrete ribs in the case of pulsed axial compression and external pressure.
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  • 43
    ISSN: 1573-904X
    Keywords: calcitonin ; polyethylene glycol ; PEGylation ; peptide ; tryptic digestion ; stability ; HPLC
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To separate and characterize the different positional isomers of mono-PEGylated salmon calcitonins (mono-PEG-sCTs) and to evaluate the effects of the PEGylation site on the stability of different mono-PEG-sCTs in rat kidney homogenate. Methods. Mono-PEG-sCTs were prepared using succinimidyl carbonate monomethoxy polyethylene glycol (5,000 Da) and separated by gel-filtration HPLC followed by reversed-phase HPLC. To characterize PEGylated sCTs, matrix-assisted laser desorption ionization time of flight mass spectrometry (M ALDI-TOF MS) and reversed-phase HPLC of the trypsin digested samples were performed. Mono-PEG-sCTs and sCT in rat kidney homogenates were measured by column-switching reversed-phase HPLC with on-line detection of the radioiodinated samples using a flow-through radioisotope detector. Results. Three different mono-PEGylated sCTs were separated by reversed-phase gradient HPLC. From the MALDI-TOF MS analysis, the average molecular weight of mono-PEG-sCTs was confirmed as around 8650 Da. The presence of PEG moiety in the mono-PEG-sCTs was also manifested by the fact that the distance between two adjacent mass spectum lines was 44 Da which corresponds to PEG monomer unit. Tryptic digestion analysis demonstrated that these mono-PEG-sCTs are 3 positional isomers of N-terminus, Lys18- and Lys11-residue modified mono-PEGylated sCTs. The degradation half-life of these 3 positional isomers in rat kidney homogenates significantly increased in order of the N-terminus (125.5 min), Lys11- (157.3 min), and Lysl8-residue modified mono-PEGylated sCT (281.5 min) over the native sCT (4.8 min). Conclusions. Three positional isomers of mono-PEGylated sCTs were purified and characterized. Of these, the resistance to proteolytic degradation was highest for the Lysl8-residue modified mono-PEG-sCT. These studies demonstrate that the in vivo stability of PEGylated sCTs is highly dependent on the site of PEG molecule attachment.
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  • 44
    ISSN: 1573-904X
    Keywords: nanoparticles ; poly(lactic acid) ; poly(lactic acid-co-ethylene oxide) ; freeze-drying ; stability ; flow cytometry
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To investigate the feasibility of producing freeze-dried poly-(ethylene oxide) (PEO)-surface modified nanoparticles and to study their ability to avoid the mononuclear phagocytic system (MPS), as a function of the PEO chain length and surface density. Methods. The nanoparticles were produced by the salting-out method using blends of poly(D,L-lactic acid) (PLA) and poly(D,L-lactic acid-co-ethylene oxide) (PLA-PEO) copolymers. The nanoparticles were purified by cross-flow filtration and freeze-dried as such or with variable amounts of trehalose as a lyoprotectant. The redispersibility of the particles was determined immediately after freeze-drying and after 12 months of storage at −25° C. The uptake of the nanoparticles by human monocytes was studied in vitro by flow cytometry. Results. PLA-PEO nanoparticles could be produced from all the polymeric blends used. Particle aggregation after freeze-drying was shown to be directly related to the presence of PEO. Whereas this problem could be circumvented by use of trehalose, subsequent aggregation was shown to occur during storage. These phenomena were possibly related to the specific thermal behaviours of PEO and trehalose. In cell studies, a clear relationship between the PEO content and the decrease of uptake was demonstrated. Conclusions. The rational design of freeze-dried PEO-surface modified nanoparticles with potential MPS avoidance ability is feasible by using the polymer blends approach combined with appropriate lyoprotection and optimal storage conditions.
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    ISSN: 1573-904X
    Keywords: polymer implant ; brain cancer ; carmustine ; polyanhydride ; stability ; controlled release
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    Topics: Chemistry and Pharmacology
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    Archive of applied mechanics 69 (1999), S. 47-54 
    ISSN: 1432-0681
    Keywords: Key words Bifurcation ; stability ; multibody system dynamics ; singularity theory ; Liapunov's direct method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary In this paper, the global behavior of relative equilibrium states of a three-body satellite with flexible connection under the action of the gravitational torque is studied. With geometric method, the conditions of existence of nontrivial solutions to the relative equilibrium equations are determined. By using reduction method and singularity theory, the conditions of occurrence of bifurcation from trivial solutions are derived, which agree with the existence conditions of nontrivial solutions, and the bifurcation is proved to be pitchfork-bifurcation. The Liapunov stability of each equilibrium state is considered, and a stability diagram in terms of system parameters is presented.
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    ISSN: 1432-0770
    Keywords: Key words: Hebbian learning rule ; attractor dynamics ; symmetric connections ; multiplicative normalization ; self-organization ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract. While learning and development are well characterized in feedforward networks, these features are more difficult to analyze in recurrent networks due to the increased complexity of dual dynamics – the rapid dynamics arising from activation states and the slow dynamics arising from learning or developmental plasticity. We present analytical and numerical results that consider dual dynamics in a recurrent network undergoing Hebbian learning with either constant weight decay or weight normalization. Starting from initially random connections, the recurrent network develops symmetric or near-symmetric connections through Hebbian learning. Reciprocity and modularity arise naturally through correlations in the activation states. Additionally, weight normalization may be better than constant weight decay for the development of multiple attractor states that allow a diverse representation of the inputs. These results suggest a natural mechanism by which synaptic plasticity in recurrent networks such as cortical and brainstem premotor circuits could enhance neural computation and the generation of motor programs.
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    International tax and public finance 6 (1999), S. 621-639 
    ISSN: 1573-6970
    Keywords: expectations ; bubbles ; uniqueness ; stability ; state variables ; multiplicity
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    Topics: Economics
    Notes: Abstract This paper concerns the minimal-state-variable (MSV) criterion for selection among solutions in rational expectationsmodels that feature a multiplicity of paths that satisfy all of the model's conditions. It compares the MSVcriterion with others, including the widely used saddle-path (dynamic stability) criterion. It is emphasized that theMSV criterion can be viewed as a scientifically useful classification scheme that delineates the unique solutionthat is free of bubble components. In the process of demonstrating uniqueness for a broad class of linear models,the paper exposits a convenient computational procedure. Applications to current issues are outlined.
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    ISSN: 1573-8590
    Keywords: Artemia ; genetic polymorphism ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract We have applied the technique of random amplification of polymorphic DNA (RAPD) to the analysis of the relationships among four species of brine shrimp: Artemia franciscana, A. urmiana, A. sinica, and A. parthenogenetica. Seventy ten-base synthetic oligonucleotides were used to amplify a total of 458 distinct fragments. DNA polymorphisms were found in all the species examined; the highest percentage of polymorphic bands was found in A. parthenogenetica, with 28.8 per cent. Each species was scored for the presence or absence of every amplification product and the data entered into a binary data matrix. Cluster analysis was then performed to create a dendrogram using UPGMA by the NTSYS program. There are significant differences between bisexual species and parthenogenetic populations. A. parthenogenetica provided 94 specific molecular markers, while bisexual species gave 27 specific molecular markers. A. sinica is a species distinct from the other Old World bisexual species.
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    European journal of plant pathology 105 (1999), S. 667-680 
    ISSN: 1573-8469
    Keywords: asexual reproduction ; mating types ; oomycetes ; origin ; RAPD ; RFLP ; population genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phytophthora cinnamomi isolates from South Africa and Australia were compared to assess genetic differentiation between the two populations. These two populations were analysed for levels of phenotypic diversity using random amplified polymorphic DNAs (RAPDs) and gene and genotypic diversity using restriction fragment length polymorphisms (RFLPs). Sixteen RAPD markers from four decanucleotide Operon primers and 34 RFLP alleles from 15 putative loci were used. A few isolates from Papua New Guinea known to posses alleles different from Australian isolates were also included for comparative purposes. South African and Australian P. cinnamomi populations were almost identical with an extremely low level of genetic distance between them (Dm=0.003). Common features for the two populations include shared alleles, low levels of phenotypic/genotypic diversity, high clonality, and low observed and expected levels of heterozygosity. Furthermore, relatively high levels of genetic differentiation between mating type populations (Dm South Africa=0.020 and Dm Australia=0.025 respectively), negative fixation indices, and significant deviations from Hardy–Weinberg equilibrium, all provided evidence for the lack of frequent sexual reproduction in both populations. The data strongly suggest that both the South African and Australian P. cinnamomi populations are introduced.
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  • 51
    ISSN: 1573-8469
    Keywords: genetic variability ; plant pathogen ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Crinipellis perniciosa (Stahel) Singer is the causal agent of witches' broom disease in the Sterculiaceae, Solanaceae, and Bixaceae families. The disease is endemic to the Brazilian Amazon, and was first reported infecting Theobroma cacao (cocoa) in the State of Bahia, Brazil, in 1989. Random amplified polymorphic DNA (RAPD) analyses were performed on 46 isolates of C. perniciosa from cocoa that were collected from 15 counties in Bahia and the Brazilian Amazon. A total of 258 RAPD loci from 20 primers and three mixed primers were analyzed. Of these loci, 108 (42%) were polymorphic, with an average of 4.7 polymorphic loci per primer produced. Genetic similarities were estimated using Nei and Li's index and UPGMA clustering. Bootstrap analysis divided the phenogram into four significantly different clusters: two groups contained isolates from Ariquemes and from Ouro Preto, Rondônia, and the other two separated the isolates from Bahia into two major groups of C. perniciosa, classified as Group 1 (G1) and Group 2 (G2). The two groups of isolates from Bahia differed for their genetic similarity with the isolates from the Brazilian Amazon. The geographic distribution of the groups in Bahia suggests two independent focal points of introduction. Ongoing programs to screen for resistant cocoa genotypes should consider both groups of isolates.
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  • 52
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    Reaction kinetics and catalysis letters 68 (1999), S. 243-247 
    ISSN: 1588-2837
    Keywords: Methane partial oxidation ; nickel-based catalysts ; stability ; sintering and loss of nickel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal stability and an 80 h life test over nickel-based catalysts for CH4/O2 to syngas reaction were investigated by flow-reactor, XPS, XRD and AAS analysis. The results indicate that the introduction of Li and La not only stabilized the support γ-Al2O3 phase, but also suppressed the sintering and loss of nickel, and in addition, enhanced the ability to suppress the carbon-deposition over NiO/Al2O3 during the high-temperature reaction.
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  • 53
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    Advances in computational mathematics 10 (1999), S. 271-289 
    ISSN: 1572-9044
    Keywords: delay differential equations ; steady state solutions ; stability ; 34K20 ; 65J10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The characteristic equation of a system of delay differential equations (DDEs) is a nonlinear equation with infinitely many zeros. The stability of a steady state solution of such a DDE system is determined by the number of zeros of this equation with positive real part. We present a numerical algorithm to compute the rightmost, i.e., stability determining, zeros of the characteristic equation. The algorithm is based on the application of subspace iteration on the time integration operator of the system or its variational equations. The computed zeros provide insight into the system’s behaviour, can be used for robust bifurcation detection and for efficient indirect calculation of bifurcation points.
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  • 54
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    Agroforestry systems 45 (1999), S. 131-158 
    ISSN: 1572-9680
    Keywords: competition ; fertility ; microclimate ; risk ; stability ; water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The first ecosystem mimic hypothesis suggests clear advantages if man-made land use systems do not deviate greatly in their resource use patterns from natural ecosystems typical of a given climatic zone. The second hypothesis claims that additional advantages will accrue if agroecosystems also maintain a substantial part of the diversity of natural systems. We test these hypotheses for the savannah zone of sub-Saharan Africa, with its low soil fertility and variable rainfall. Where annual food crops replace the natural grass understorey of savannah systems, water use will decrease and stream and groundwater flow change, unless tree density increases relative to the natural situation. Increasing tree density, however, will decrease crop yields, unless the trees meet specific criteria. Food crop production in the parkland systems may benefit from lower temperatures under tree canopies, but water use by trees providing this shade will prevent crops from benefiting. In old parkland trees that farmers have traditionally retained when opening fields for crops, water use per unit shade is less than in most fast growing trees introduced for agroforestry trials. Strong competition between plants adapted to years with different rainfall patterns may stabilise total system productivity -- but this will be appreciated by a farmer only if the components are of comparable value. The best precondition for farmers to maintain diversity in their agroecosystem hinges on the availability of a broad basket of choices, without clear winners or 'best bets'.
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  • 55
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    Journal of thermal analysis and calorimetry 55 (1999), S. 727-739 
    ISSN: 1572-8943
    Keywords: ignition ; polymer combustion modelling ; stability ; steady state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A mathematical model of ignition and burning of organic polymers was used for evaluation and quantification of the tendency of polymers to ignition. The model permits investigation of the influence of one parameter of the polymer on the others. It was found that the model could be used for the verification of the ignitability method developed by Miller et al. [1]. Different steady states of combustion were found when using the model proposed. There is a characteristic steady state for normal flaming combustion, another for non-flaming combustion, and there are also unstable steady states that have no real physical meaning.
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  • 56
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    Journal of thermal analysis and calorimetry 56 (1999), S. 1285-1304 
    ISSN: 1572-8943
    Keywords: amorphous state ; combined techniques ; drug design ; drug product development ; drug substance ; drug technology ; DSC ; excipients ; failure investigations ; hydrates ; MDSC ; microcalorimetry ; pharmaceuticals ; polymorphism ; polymers ; preformulation ; process optimization ; purity ; quality control ; solvates ; stability ; sub-ambient DSC ; TG ; temperature resolved X-ray diffraction ; water interactions ; thermal microscopy ; water sorption-desorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Modern thermal analysis, microcalorimetry and new emerging combined techniques which deliver calorimetric, microscopic and spectroscopic data offer a powerful analytical battery for the study of pharmaceuticals. These techniques are very useful in all steps of development of new drug products as well as methods for quality control in production. The characterization of raw materials enables to understand the relationships between polymorphs, solvates and hydrates and to choose the proper development of new drug products with very small amount of material in a very short time. Information on stability, purity is valuable for new entities as well as for marketed drug substances from different suppliers. Excipients which vary from single organic or inorganic entity to complexes matrixes or polymers need to be characterized and properly controlled. The thermodynamic phase-diagrams are the basis of the studies of drug-excipients interactions. They are very useful for the development of new delivery systems. A great number of new formulations need proper knowledge of the behaviour of the glass transition temperature of the components. Semi-liquid systems, interactions in aqueous media are also successfully studied by these techniques.
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  • 57
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    Earth, moon and planets 87 (1999), S. 103-115 
    ISSN: 1573-0794
    Keywords: Accretion ; exoplanetary system ; extrasolar planets ; numerical integration ; orbital migration ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A number of extrasolar planets have been detected in close orbits around nearby stars. It is probable that these planets did not form in these orbits but migrated from their formation locations beyond the ice line. Orbital migration mechanisms involving angular momentum transfer through tidal interactions between the planets and circumstellar gas-dust disks or by gravitational interaction with a residual planetesimal disk together with several means of halting inward migration have been identified. These offer plausible schemes to explain the orbits of observed extrasolar giant planets and giant planets within the Solar System. Recent advances in numerical integration methods and in the power of computer workstations have allowed these techniques to be applied to modelling directly the mechanisms and consequences of orbital migration in the Solar System. There is now potential for these techniques also to be applied to modelling the consequences of the orbital migration of planets in the observed exoplanetary systems. In particular the detailed investigation of the stability of terrestrial planets in the habitable zone of these systems and the formation of terrestrial planets after the dissipation of the gas disk is now possible. The stability of terrestrial planets in the habitable zone of selected exoplanetary systems has been established and the possibility of the accretion of terrestrial planets in these systems is being investigated by the author in collaboration with Barrie W. Jones (Open University), and with John Chambers (NASA-Ames) and Mark Bailey of Armagh Observatory, using numerical integration. The direct simulation of orbital migration by planetesimal scattering must probably await faster hardware and/or more efficient algorithms.
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  • 58
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    Multidimensional systems and signal processing 10 (1999), S. 7-20 
    ISSN: 1573-0824
    Keywords: multivariate polynomials ; stability ; robust stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper presents a detailed analysis of some classes of stable multivariate polynomials. The main aim of the analysis is to give conditions under which polynomials preserve stability when they are subjected to small coefficient variations. The maximal class of such polynomials is introduced. Some basic properties of polynomials from this class are obtained.
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  • 59
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    Journal of inclusion phenomena and macrocyclic chemistry 34 (1999), S. 277-289 
    ISSN: 1573-1111
    Keywords: complexes ; stability ; extraction ; transport ; tetrathiolactams
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis of tetrathiolactams and related di- and tetrathioamide compounds is described. The formation constants of their heavy-metal complexes are determined by using the strong UV absorption of the thioamide chromophore. Extraction and transport abilities of tetrathioamide ionophores show selectivities for Ag(I) and Hg(II) cations over alkali, alkaline-earth or other heavy metal cations including transition metals such as Co(II).
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  • 60
    ISSN: 1573-1111
    Keywords: hexacyclen ; pentacyclen ; anion complexes ; stoichiometry ; stability ; polarography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The complexation of protonated hexacyclen and pentacyclen with pyrophosphate, selenite, selenate, molybdate and tungstate anions was studied by differential pulse polarography at 25 °C. The stoichiometry and stability of the resulting anion complexes were evaluated from the pH and concentration-dependence of the peak potentials, respectively. The results established 1 : 1 anion receptor complexation in all cases. In the case of all anions studied, hexacyclen was found to form more stable anion complexes than pentacyclen. The fact that the anion-receptor complexation depends on the structural features of both the anions and the macrocycles used is indicative of a steric controlled interaction.
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  • 61
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    World journal of microbiology and biotechnology 15 (1999), S. 381-385 
    ISSN: 1573-0972
    Keywords: Brucella abortus ; Brucella melitensis ; polymerase chain reaction ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A 1.3 kb Brucella-specific DNA fragment produced through the use of arbitrarily primed polymerase chain reaction (AP-PCR) was tested for its specificity by DNA–DNA hybridization to Brucella and non-Brucella bacteria. The digoxigenin (DIG)-labelled 1.3 kb DNA fragment hybridized with Brucella abortus and Brucella melitensis but did not hybridize with other non-Brucella bacteria tested. The sensitivity of the reaction was determined; as little as 150 fg DNA or 30 Brucella cells could be detected. The specificity and sensitivity of the 1.3 kb DNA fragment combined with the simplicity and speed of the technique suggest the potential of this fragment as a DNA probe for the quick and reliable detection of Brucella organisms.
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  • 62
    ISSN: 1573-5117
    Keywords: disturbance ; stability ; resilience ; Trichoptera ; Ephemeroptera ; Psychomyia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Benthic macroinvertebrate assemblages of Bushkill Creek, Northampton County, PA were studied at the same site during the 1970s (11 dates) and 1990s (8 dates) to evaluate stability and resilience. In the 1970s, a Surber sampler was used, and in the 1990s, a Hess sampler. Assemblages appeared stable over a wide range of environmental stresses with the exception of 1994–1995 when total numbers and total Trichoptera decreased. Taxa richness and EPT indices varied little in 1994–1995 from other sampled years. By July 1996, all metrics (Trichoptera numbers, total numbers, taxa richness, EPT index, Bray-Curtis Index) resembled the 1970s exception for lower wet weight. Bray-Curtis indices and taxa composition were similar in July 1972 and July 1996, suggesting assemblage stability over 25 years. The Trichoptera, Psychomyia (Psychomiidae) and Leucotrichia (Hydroptilidae), decreased during the 1990s and never rebounded to 1970s numbers. During winter 1994, the coldest temperatures and greatest cumulative snowfall occurred in the region. These conditions probably stressed the assemblage with low temperatures, anchor/frazil ice and ice break-up. The assemblage was then exposed to four bankful floods in winter/spring 1994 and five bankful floods in winter/spring 1996. Recovery time following these multiple disturbances was 27 months. Previous recovery times from winter and flood disturbances were considerably shorter (2–5 months). The 1990s recovery time (5–9 times previusly recorded) for this assemblage was apparently extended by multiple physical disturbances, outside the predicted range. The assemblages had not been previously exposed to such severe conditions and, therefore, recovery time was extended. Despite severe weather conditions, the assemblage recovered and exhibited both stability and resilience in its return to an assemblage similar to the 1970s.
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  • 63
    ISSN: 1573-5117
    Keywords: DNA ; RAPD ; genetic diversity ; Bruguiera ; Sri Lanka ; mangroves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The identification of populations of Bruguiera sexangula, Bruguiera gymnorhiza and their putative hybrids in the field is difficult using only morphological and phenological characters. Using a PCR based technique, RAPD (Random Amplified Polymorphic DNA), the genetic variation of Bruguiera populations was studied from contrasting climatic and geographic regions along the southwest coastal region of Sri Lanka. Out of 45 primers screened, 20 primers allowed us to observe polymorphism, not only between species (interspecific) but also within the species (intraspecific). Analysis of RAPD data appears to be helpful in determining the genetic relationship among populations of B. gymnorhiza and B. sexangula. RAPD markers revealed that the two species are well separated without any hybrid position between the two taxa though they occur in mixed stands. Although sampling sizes of populations of this study were small, genetic variation among B. gymnorhiza and B. sexangula populations could be observed. For B. sexangula, it was possible to differentiate each of the three populations, even when using a small number of primers.
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  • 64
    ISSN: 1573-5117
    Keywords: aquatic plants ; RAPD ; hybridization ; genetic diversity ; Scirpus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Enzyme polymorphisms have been widely used in aquatic plants since the 1980s. Studies on DNA polymorphisms are less numerous and a case-study using both methods on Scirpus is worked out. Along the unique freshwater tidal zone of the River Schelde (Belgium), clumps of Scirpus species are mostly scattered in small and fragmented locations on the dikes and mud flats. Most of these taxa are native S. triqueter, S. tabernaemontani or intermediate morphological forms. However, several cultivated strains of S. tabernaemontani have been introduced in recent years. Such ‘exotic’ strains have been planted to stabilize the muddy riverbanks and became well established and may perform better than the native hybrid complex. In order to determine the existing genetic diversity among these species and the possibility for genetic pollution, stems of 30 clumps from a series of locations along the tidal river were investigated for seven enzymes (SDH, PGM, EST, MNR, GOT, 6PGD and ME) and for markers at DNA level using random amplified polymorphic DNA's (RAPD) of 22 decanucleotides. Data analysis of the allozymes and of the amplified DNA fragments enabled us to classify unambiguously the different Scirpus taxa. Direct evidence of hybridization between S. triqueter and S. tabernaemontani could not be obtained, but the putative hybrids are genetically intermediate or close to S. triqueterwhen considering the DNA polymorphism. The introduced clones of S. tabernaemontani consisted of at least three groups of genotypes of which one was very related to the native ones. The escaped clumps could be assigned to a third introduced but less-related strain.
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  • 65
    ISSN: 1573-5117
    Keywords: RAPD ; nile perch ; Tanganyika ; endemic ; genetic differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genetic differentiation of endemic nile perch (Lates stappersi) populations in Lake Tanganyika was studied using RAPD. DNA was extracted from alcohol stored muscle tissue by a salting method, without organic solvents. Three primers amplified 58 variable DNA fragments from 270 individuals from five localities. The genetic distances of local samples as inverse of bandsharing ranged from 0.097 to 0.312. The population sampled in Kigoma, close to the estuary of the Malagarazi river showed high values of genetic distance in pairwise comparisons with other sampled populations. Principal component analysis separated the main population and the 25 samples from Kigoma with high eigenvalues. Five individuals sampled in Kigoma were united with the main population, as confirmed by significant differences in band frequences. The local population in Kigoma had significantly different frequencies in 24 RAPD bands when compared to the pooled samples of Lates stappersi. No clearly diagnostic fragments were found. The genetic distance (1-F) between the Kigoma population and the united main stock was 0.195. Based on Slatkin's index on private alleles, the level of migration between Kigoma and all other sampling sites united, migration is restricted (Nm = 0.43) and allows genetic separation.
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  • 66
    ISSN: 1573-5109
    Keywords: core collection ; germplasm ; molecular marker ; potato ; RAPD ; Solanum phureja
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The potato crop originated in the Andean highlands where numerous farmer's varieties and non-cultivated wild species exist. An Andean potato collection is held in trust at the International Potato Center (CIP) to preserve the biodiversity of this crop and ensure the supply of germplasm for potato improvement worldwide. A core collection representing the biodiversity of the Andean potato germplasm is under construction using morphological, molecular, and geographic data. One of the eight cultivated potato species, Solanum phureja, has been genotyped using the RAPD technique. A protocol suitable for large germplasm collection genotyping has been developed to process numerous samples at reasonable costs. From 106 RAPD primers evaluated, we have selected 12 primers yielding 102 polymorphic markers, which unambiguously discriminated all 128 accessions but 2 that are possible duplicates. The S. phureja germplasm collected throughout the Andean countries appears to have a homogeneous genetic constitution. There was no clear geographic pattern as indicated by cluster analysis of the RAPD data. A sub-group of 20 accessions has been identified on the basis of the marker data and selected to maximize molecular (RAPD) variance and polymorphism. The probability of capturing equal amounts of marker polymorphism in this sub-group of 20 accessions by random sampling is less than 40%. This set accessions represents our first group of accessions that may constitute a core of the S. phureja collection. This tentative core will be challenged for diversity content by alternate markers and agronomic traits. Hence, the methodology for sampling less than 10% of the base collection, proposed for core collections by Brown (1989), can be based on molecular marker data provided cost-efficient fingerprints are developed.
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  • 67
    ISSN: 1573-5060
    Keywords: Chenopodium ; genetic relationship ; molecular markers ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The RAPD technique was used to identify genetic relationships in 19 accessions, including six species of the genus Chenopodium. A dendrogram was constructed using UPGMA from 399 DNA markers. The molecular data clustered species and accessions into five different groups. Group 1 with three cultivated varieties of C. nuttalliae, Group 2 included eight cultivars and two wild varieties of C. quinoa, Group 3 with C. berlandieri and C. album, Group 4 with two accessions of C. pallidicaule, and Group 5 with 2 accessions of C. ambrosioides. The polymorphic patterns generated by RAPD profiles showed different degrees of genetic relationship among the species studied. A low level of intraspecific variation was found within the accessions of C. quinoa, C. nuttalliae, and C. pallidicaule. The RAPD markers were found to be a useful tool for detecting genetic variation within the genus Chenopodium.
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  • 68
    ISSN: 1573-5060
    Keywords: Erwinia carotovora ; Solanum tuberosum ; somaclonal variation ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three somatic hybrid lines between potato (cv. While Lady line no. Ke 79, 2n = 2x = 48) + Solanum brevidens (PI 218228, 2n = 2x = 24) were evaluated using randomly amplified polymorphic DNA (RAPD) markers. The lines originated from the same callus but showed different reactions to Erwinia carotovora ssp. carotovora, the cause of potato soft rot. By the use of 48 oligomer primers producing 99 scorable bands, DNA polymorphism were detected on 7 of 12 S. brevidens chromosomes. Loss of certain DNA segments on chromosome 5, 6, 9 and 11 were observed. Some of the variations could have taken place in early callus stage of development; others may have occurred after initiation of individual shoot regeneration. The possible involvement of missing RAPD products specific to one somatic hybrid that shows decreased resistance to bacterial soft rot is discussed.
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  • 69
    ISSN: 1573-5060
    Keywords: Brassica napur ; doubled haploids ; RAPD ; linolenic acid ; erucic acid ; marker assisted selection ; rapeseed breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Undesirable characteristic of rapeseed oil is a relatively high level of linolenic acid (18:3), which is easily oxidized leading to rancidity and a shortened shelf life of the oil. Previous attempts to reduce linolenic acid levels in rapeseed oil through breeding have been impaired by complex genetics and strong environmental sensitivity of this trait. Therefore, our objective was to develop molecular markers for low linolenic acid that could facilitate the breeding of low linolenic rapeseed. Bulked segregant analysis was employed to identify two RAPD markers associated with 18:3 in a doubled haploid population segregating for linolenic and erucic acid levels. Based on analysis of individual DH lines, the markers RM350 and RM574, representing two independent loci, accounted for a total of 39% of the genetic variability in this population. This marker RM350 alone accounted for 25% genetic variation for this trait with no evidence of recombination. Significant interlocus interaction found between the markers RM350 and RM574 suggested that epistasis was involved in the genetic control of 18:3 level in this population. Another marker designated as RM322, which was independent of the other two, was found significantly associated with the erucic acid level and oil content. RAPD markers identified in this study should be a useful tool for the early detection of low linolenic, or low or high erucic acid genotypes in rapeseed breeding programs based on doubled haploids.
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  • 70
    ISSN: 1573-5060
    Keywords: crown rot ; fusarium crown and root rot ; genetic linkage ; Lycopersicon peruvianum ; molecular markers ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In tomato ( Lycopersicon esculentum Mill.) a single dominant gene ( Frl) on chromosome 9 confers resistance to fusarium crown and root rot (crown rot) incited by Fusarium oxysporum f. sp. radicis-lycopersici. To identify randomly amplified polymorphic DNA (RAPD) markers linked to Frl, crown rot susceptible and resistant tomato lines were screened for polymorphisms using 1000 random 10-mer primers and three reliable RAPD markers were found linked to Frl (UBC #'s 116, 194, and 655). A codominant polymorphic PCR marker of TG101, a restriction fragment length polymorphic (RFLP) marker linked to Frl, was developed to facilitate the linkage studies. Using TG101 and the four RAPD markers, on a Frl segregating backcross population of 950 plants indicated that all belong to the same linkage group. The polymorphic allele order was found to be TG101 – 655 – 116 – 194 – Frl. UBC 194 was found to be 5.1 cM from Frl in this population. Furthermore, it was the only marker found in the resistant genotypes ‘Mocis’ and Fla 7226, whereas resistant genotypes ‘Momor’, Ohio 89-1, and Fla 7464 all had UBC 194 and UBC #'s 116, 194, and 655.
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  • 71
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    Euphytica 107 (1999), S. 167-176 
    ISSN: 1573-5060
    Keywords: genetic diversity ; Lathyrus ; L.sativus ; phylogenetic relationship ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Eight Lathyrus sativus L. accessions from a variety of geographic origins were used to study intraspecific genetic diversity using RAPD analysis. Fourteen decamer primers produced 64 amplification products, 50% of which were polymorphic between the samples. Jaccard's coefficient of genetic similarity was calculated between samples and a dendrogram was constructed by an unweighted pair-group method with arithmetical averages (UPGMA). The dendrogram showed that most of the L. sativus plants clustered into accessions or common geographical areas. The average genetic similarity coefficient within accessions was 0.12 and between accessions was 0.20, indicating a low level of intraspecific genetic variation. Interspecific genetic diversity and phylogenetic relationships of eight Lathyrus species, including L. sativus and Pisum sativum L. (field pea) were examined using 14 decamer primers which produced 283 amplification products. All amplification products were polymorphic across the nine species. In the dendrogram the Lathyrus species clustered into three distinct groups which correlated with the Sections Lathyrus, Clymenum and Linearicarpus. This supports traditional taxonomic classifications of the genus Lathyrus which are based on morphological traits. Of the species from Section Lathyrus, L. gorgoni and L. cicera were the most similar to L. sativus. The results suggest that a strategy of breeding for producing lines of L. sativus with increased genetic variation would be effectively achieved through hybrid production between accessions from wide geographic areas particularly the Mediterranean area and the Indian subcontinent. However, the most effective method would be introgression of germplasm from other species in Section Lathyrus.
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  • 72
    ISSN: 1573-5060
    Keywords: genetic diversity ; germplasm ; molecular markers ; RAPD ; sesame
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fifty-eight accessions of sesame (Sesamum indicum L.), an important oil seed crop of the tropics and subtropics were analysed using random amplified polymorphic DNA (RAPD) technique. The material analysed comprised 36 collections from 18 different states of India and four adjoining countries of the Indian subcontinent, and 22 exotic accessions from 21 sesame growing countries around the world. The results from PCR amplifications with the selected 24 random 10-mer primers were statistically analysed. The value of Jaccard’s similarity coefficients ranged from 0.19 to 0.89. The results indicated the presence of high level of genetic diversity. However, the extent of genetic diversity was greater in the collections from Indian subcontinent as compared to the exotics. Among the Indian accessions, the collections from Rajasthan and North-eastern states were highly diverse. The phenetic analysis grouped 48 out of 58 accessions in six clusters and the remaining highly diverse accessions were placed outside these close-knit clusters. The Bootstrap estimates obtained by Wagner parsimony analysis were significant for seven out of 49 nodes in the majority-rule consensus tree (〈95% occurrence). The results of both the analyses were, however, broadly comparable when the constitution of the individual clusters were considered. The principal components analysis indicated that the first two components accounted for only 21% of the total variations and in order to explain 〈75% of variations 18 components were required. The high level of genetic diversity prevalent among the Indian collections is probably indicative of the nativity of this crop species. Similarly, the relatively lower level of polymorphism in exotic germplasm could be ascribed to the comparatively recent introductions of limited germplasm of this crop into some of the non-traditional sesame growing countries.
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  • 73
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    Euphytica 110 (1999), S. 139-149 
    ISSN: 1573-5060
    Keywords: cultivar identification ; genetic diversity ; Prunus ; RAPD ; rootstocks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We have used RAPD markers to characterize Prunus rootstocks from different species, both commercial, and selected clones from the breeding program at Aula Dei Experimental Station (Zaragoza, Spain). Molecular markers were used to study the genetic variation among different species, and within species. Forty one genotypes were used in this study. They included P. amygdalo-persica, and P. persica × P. davidiana hybrids; P. cerasifera, P. domestica, and P. insititia clones, and other diverse interspecific hybrids, which were divided in three groups according to postulated taxonomic classification. Diversity patterns obtained from 80 RAPD primers were evaluated in a representative subset of genotypes. This screening helped to identify 7 RAPD primers that were selected to produce a combined classification of the whole set of rootstock clones. This analysis successfully clustered rootstocks according to the classification scheme widely used to characterize Prunus clones, mainly based on morphological descriptors. Further than that, it supported the alleged origin of some interspecific materials, and confirmed a case of possible misclassification (‘Myrobalan 29 C’). A more thorough diversity analysis was conducted within each group of materials, using larger sets of primers (12–14). After this analysis, disjointed clusters were formed for P. amygdalo-persica and P. persica × P. davidiana hybrids in one group, and for Myrobalan (P. cerasifera) and Marianna (P. cerasifera × P. munsoniana) plums in another group. P. insititia and P. domestica clones, however, formed a jumbled cluster, possibly due to genetic interchange among them during their domestication and breeding history.
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  • 74
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    Journal of biomolecular NMR 13 (1999), S. 187-191 
    ISSN: 1573-5001
    Keywords: alignment ; bicelle ; dipolar coupling ; liquid crystal ; pH ; stability ; ubiquitin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract It is demonstrated that mixtures of ditetradecyl- phosphatidylcholine or didodecyl-phoshatidylcholine and dihexyl- phosphatidylcholine in water form lyotropic liquid crystalline phases under similar conditions as previously reported for bicelles consisting of dimyristoyl-phosphatidylcholine (DMPC) and dihexanoyl- phosphatidylcholine (DHPC). The carboxy-ester bonds present in DMPC and DHPC are replaced by ether linkages in their alkyl analogs, which prevents acid- or base-catalyzed hydrolysis of these compounds. 15N-1H dipolar couplings measured for ubiquitin over the 2.3–10.4pH range indicate that this protein retains a backbone conformation which is very similar to its structure at pH 6.5 over this entire range.
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  • 75
    ISSN: 1573-5060
    Keywords: classification ; DNA ; plum varieties ; Prunus ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We investigated the genetic diversity of 42 plum varieties by RAPD analysis. Twenty primers discriminated all plum varieties excepting two synonymous pairs: 'Botankyou and ‘Kelsey’, and ‘Chairn’ and ‘Tragedy’. Two North American plums, ‘Beach Plum’ and ‘Glow’, were genetically distinct from the other plums by cluster analysis. Overlaps observed between the ‘European plum group’ and the ‘Japanese plum group’, were perhaps due to intercrossing. We could also discriminate ‘Sordum’ from 'Late Sordum and ‘Bansei Sordum’, although ‘Late Sordum’ and ‘Bansei Sordum’ are thought to be derived from bud mutants of ‘Sordum’.
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  • 76
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    Plant cell, tissue and organ culture 59 (1999), S. 81-87 
    ISSN: 1573-5044
    Keywords: asymmetric hybrid ; Citrus ; donor-recipient fusion ; Microcitrus ; RAPD ; X-ray
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract X-ray irradiated embryogenic protoplasts of Microcitrus papuana Swing. were electrically fused with iodoacetic acid-treated embryogenic protoplasts of Newhall navel orange [Citrus sinensis (L.) Osb.]. Seven cell lines were established by low-melting agarose embedding culture of fusion-treated protoplasts. Cytological examination of 4 cell lines showed that each cell line consisted of many aneuploid (45.10%, 38.98%, 32.69% and 34.85%, respectively) and diploid cells (52.94%, 59.33%, 63.46% and 62.12%. respectively), whereas only a few tetraploid cells (1.96%, 1.69%, 3.85% and 3.03%, respectively) were detected. Analyses of random amplified polymorphic DNA with four 10-mer primers confirmed the hybrid characteristics of the cell lines, which in combination with chromosome counting proved that the cell lines were asymmetric hybrids.
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  • 77
    ISSN: 1573-5060
    Keywords: Bph-1 ; linkage analysis ; mapping ; RAPD ; RFLP ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We report the tagging of a brown planthopper (BPH) resistance gene (Bph–1) in rice using RAPD and RFLP markers. The Korean rice variety ‘Gayabyeo’ has dominant duplicate genes including Bph–1 conferring resistance to biotype 1 of BPH. Bulked segregant RAPD analysis was employed for rapid identification of DNA markers linked to resistance genes. For tagging these two genes, an F2F3 population from a ‘Gayabyeo’ × ‘Nagdongbyeo’ cross was developed and evaluated for BPH resistance. Three bulked DNAs from two groups of homozygous BPH resistant (each for Bph–1 and the other unknown gene) and homozygous susceptible F2 plants were analyzed by RAPD using 140 random oligomers. One primer, OPD–7 yielded a 700-bp fragment that was present in Gayabyeo and resistant F2 plants (homozygous for Bph-1 locus) but absent in Nagdongbyeo and susceptible F2 plants. Cosegregation of this marker with Bph-1 was verified using an F2 population segregating for Bph-1. Chromosomal regions surrounding the Bph-1 were examined with additional RFLP and microsatellite markers on chromosome 12 to define the location of the RAPD marker and Bph-1. Use of this RAPD marker could facilitate early selection of resistant lines for BPH.
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  • 78
    ISSN: 1573-5060
    Keywords: AFLP ; DNA fingerprinting ; isozymes ; RAPD ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A survey of the genetic diversity among the major cuban rice cultivars was conducted using isozyme, RAPD and AFLP markers. Polymorphisms were detected for esterases, peroxidases, alcohol dehydrogenases and polyphenoloxidases systems; 21 RAPD primers and four AFLP primer combinations. Heterozygosity arithmetic mean value (Hav(p)), the effective multiplex ratio (EMR) and the marker index (MI), were calculated for isozyme, RAPD and AFLP markers. The mean value of genetic similarity among the different varieties was 0.92 for isozyme, 0.73 for RAPD and 0.58 for AFLP analyses. Thus, AFLP were able to detect polymorphisms with higher efficiency than RAPD (+15%) and isozyme (+34%). Data from the isozyme, RAPD and AFLP analyses were used to compute matrices of genetic similarities. The efficiency of the UPGMA for the estimation of genetic relatedness among varieties was supported by cophenetic correlation coefficients. The resulting values indicated that the distortion level for the estimated similarities was minimal. The correlation coefficients obtained by the Mantel matrix correspondence test, which was used to compare the cophenetic matrices for the different markers, showed that estimated values of genetic relationship given for isozyme and RAPD markers (r = 0.89), as well as for AFLP and RAPD markers (r = 0.82) were properly related. However, AFLP and isozyme data showed only moderate correlation (r = 0.63). Although the genetic variability found among the different cultivars was low, both RAPD and AFLP markers proved to be efficient tools in assessing the genetic diversity of rice genotypes.
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  • 79
    ISSN: 1432-2242
    Keywords: Key words Ascochyta lentis ; Lens culinaris ssp. culinaris ; Bulked segregant analysis ; Resistance genes ; RAPD ; QTL analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Foliar resistance to Ascochyta lentis is controlled at a single major locus by a dominant gene (AbR 1 ) in the lentil accession ILL5588 (cv ‘Northfield’). Flanking RAPD markers that are closely linked to the resistance locus in coupling phase were identified by bulked segregant analysis. Out of 261 decanucleotide primers screened 7 produced a polymorphic marker that segregated with the resistance locus, and all markers were found to exist within a single linkage group. Five of the seven RAPD markers were within 30 cM of the resistance locus. Log likelihood analysis for detecting QTL associated with the foliar resistance revealed that a single narrow peak accounted for almost 90% of the variance of resistance between the bulks. Preliminary mapping in an F3 population revealed that the closest flanking markers were approximately 6 and 14 centiMorgans (cM) away from the resistance locus. These markers should be useful for the discrimination of resistant germplasm through marker-assisted selection in future breeding programmes and represent the first essential step towards the map-based cloning of this resistance gene.
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  • 80
    ISSN: 1432-2242
    Keywords: Key words Somatic hybridization ; Hexaploid ; RAPD ; Chromosome number variation ; Genetic improvement ; Aurantioideae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Chinese wampee [Clausena lansium (Lour.) Skeels], a sexually incompatible relative of citrus, is commercially cultivated in South China. In this study, embryogenic protoplasts of ‘Bonanza’ navel orange [Citrus sinensis (L.) Osbeck] were electrically fused with leaf protoplasts isolated from ‘Chicken Heart’ Chinese wampee. After 8 months of culture, fusion products regenerated into shoots. More than 70% of the shoots unexpectedly rooted well. Chromosome counting of several shoot- and root-tips revealed that their chromosome numbers were not 2n=4x=36 as expected, but 2n=6x=54, suggesting that chromosome doubling occurred rather than chromosome elimination in this intertribal fusion combination. RAPD analysis of embryoids and the leaves of unrooted and rooted shoots verified their hybridity. This is the first report of hexaploid somatic hybrid plant regeneration from fusion between diploids in Aurantioideae.
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  • 81
    ISSN: 1432-2242
    Keywords: Key words Vicia faba L. ; RAPD ; Mahalanobis genetic distance ; Usefulness ; Genetic variance ; Mid-parent heterosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Determining the genetic potential of a base population from the properties of their parental lines would improve the efficiency of a breeding program. In the present study, we investigated whether the means of the parents and the genetic distance determined from RAPD data (GD) or multivariate analysis (Mahalanobis D2), mid-parent heterosis (MPH), and the absolute difference between means of the parents (∣P1−P2∣) can be used for predicting the means and genetic variances (σ^2 g ) of F3:4 lines derived from different crosses in faba beans. The material comprised 18 intra- and 18 inter-pool crosses among lines from the Minor, Major, and Mediterranean germplasm pools. Fifty F3:4 lines from each cross were evaluated for days to anthesis, plant height, seeds per plant, and seed yield in German (GE) and Mediterranean (ME) environments. GD estimates between parent lines ranged from 0.38 to 0.58, while D2 ranged from 45.5 to 134.7. Correlations between means of the parents and F3:4 lines were highly significant for most traits. Estimates of σ2 g for all traits showed non-significant correlations with MPH, GD, D2. In one ME, ∣P1−P2∣ had significant associations with σ^2 g for seed yield and days to anthesis. The predicted usefulness of crosses, defined as the sum of the population mean and selection responses, was most closely associated with the means of F3:4 lines. We conclude from this study that the means of F3:4 lines can be predicted from the means of the parents, whereas the prediction of genetic variance is still an unsolved problem
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    Theoretical and applied genetics 98 (1999), S. 1029-1035 
    ISSN: 1432-2242
    Keywords: Key words Brassica oleracea L. ; RAPD ; Seed bulk ; Genetic resources ; Genetic variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The concept of a core collection was elaborated to fit the necessity of optimizing the management, for both conservation and use, of genetic resources in sizeable collections. This approach requires an analysis of how the genetic variability is structured among the accessions. The large number of heterogeneous populations in our collection of Brassica oleracea makes genetic diversity studies based on plant-to-plant analysis impracticable. To overcome this limitation, the variability analysis by RAPD on seed bulks was investigated for its efficiency in assessing the structure of the genetic diversity of this collection. The optimal bulk size and the bulking or sampling variation were evaluated with bulks of different size and with replicated samples. A mixture of known genotypes was also used to characterise the band detection in bulks, and to compare the plant-to-plant and the bulk methods. Forty seeds were chosen to represent each population. In such a bulk, the detection of bands depended on the proportion of the genotype they were derived from in the mixture. Intense and frequent bands were detected in the bulk with a 15% detection limit. The observed bulking or sampling variation within populations was smaller than the variation between populations, leading to an efficient separation of populations with a clustering of all samples of the same population. The distances calculated from bulk data were highly correlated with the distances based on the plant-to-plant analysis. We demonstrated that RAPD on seed bulks can be used to describe the genetic diversity between populations.
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    Theoretical and applied genetics 98 (1999), S. 985-994 
    ISSN: 1432-2242
    Keywords: Key words Digitalis obscura ; AMOVA ; HOMOVA ; Population genetics ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Random amplified polymorphic DNA (RAPD) markers were used to assess levels and patterns of genetic diversity in Digitalis obscura L. (Scrophulariaceae), an outcrossing cardenolide-producing medicinal plant species. A total of 50 plants from six natural populations on the Iberian Peninsula were analysed by six arbitrarily chosen decamer primers resulting in 96 highly reproducible RAPD bands. To avoid bias in parameter estimation, analyses of population genetic structure were restricted to bands (35 of 96) whose observed frequencies were less than 1–3/n in each population. The analysis of molecular variance (AMOVA) with distances among individuals corrected for the dominant nature of RAPDs (genotypic analysis) showed that most of the variation (84.8%) occurred among individuals within populations, which is expected for an outcrossing organism. Of the remaining variance, 9.7% was attributed to differences between regions, and 5.5% for differences among populations within regions. Estimates of the Wright, Weir and Cockerham and Lynch and Milligan FST from null-allele frequencies corroborated AMOVA partitioning and provided significant evidence for population differentiation in D. obscura. A non-parametric test for the homogeneity of molecular variance (HOMOVA) also showed significant differences in the amount of genetic variability present in the six populations. UPGMA cluster analyses, based on Apostol genetic distance, revealed grouping of some geographically proximate populations. Nevertheless, a Mantel test did not give a significant correlation between geographic and genetic distances. This is the first report of the partitioning of genetic variability within and between populations of D. obscura and provides important baseline data for optimising sampling strategies and for conserving the genetic resources of this medicinal species.
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    Theoretical and applied genetics 99 (1999), S. 147-156 
    ISSN: 1432-2242
    Keywords: Key words Capsicum ; Diagnostic markers ; Genetic diversity ; Germplasm ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Germplasm characterization is an important link between the conservation and utilization of plant genetic resources. A total of 134 accessions from six Capsicumspecies maintained at the Asian Vegetable Research and Development Center were characterized using 110 randomly amplified polymorphic DNA (RAPD) markers. Ten pairs of potentially duplicated accessions were identified. Multidimensional scaling analysis of the genetic distances among accessions resulted in clustering corresponding to a previous species assignment except for six accessions. Diagnostic RAPDs were identified which discriminate among the Capsicumspecies. The diagnostic markers were employed for improved taxonomic identification of accessions since many morphological traits used in the identification of Capsicumare difficult to score. Three Capsicumaccessions, misclassified based on morphological traits, were reassigned species status based on diagnostic RAPDs. Three accessions, not previously classified, were assigned to a species based on diagnostic RAPDs. Definitive conclusions about the species assignment of three other accessions were not possible. The level of diversity between Capsicum annuumaccessions from the genebank and the breeding program were compared and no differences were observed either for RAPD variation or diversity. The utilization of genetic resources as a source of variance for useful traits in the breeding program may be the reason for the similarity of these two groups.
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    Theoretical and applied genetics 99 (1999), S. 58-64 
    ISSN: 1432-2242
    Keywords: Key words Genetic map ; RFLP ; AFLP ; RAPD ; SAMPL ; Daucus carota L. ssp. sativus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A 109-point linkage map consisting of three phenotypic loci (P 1, Y 2, and Rs), six restriction fragment length polymorphisms (RFLPs), two random amplified polymorphic DNAs (RAPDs), 96 amplified fragment length polymorphisms (AFLPs), and two selective amplification of microsatellite polymorphic loci (SAMPL) was constructed for carrot (Daucus carota L. ssp. sativus; 2n=2x=18). The incidence of polymorphism was 36% for RFLP probes, 20% for RAPD primers, and 42% for AFLP primers. The overall incidence of disturbed segregation was 18%. Linkage relationships at a LOD score of 4.0 and θ=0.25 indicated 11 linkage groups. The total map length was 534.4 cM and the map was clearly unsaturated with markers spaced at 4.9 cM. AFLP P6B15 was 1.7 cM from P 1, AFLP P1B34 was 2.2 cM from Y 2, and AFLP P3B30XA was 8.1 cM from Rs.
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    Journal of optimization theory and applications 100 (1999), S. 575-597 
    ISSN: 1573-2878
    Keywords: Queueing networks ; scheduling ; stability ; performance evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We obtain new linear programs for bounding the performance and proving the stability of queueing networks. They exploit the key facts that the transition probabilities of queueing networks are shift invariant on the relative interiors of faces and the cost functions of interest are linear in the state. A systematic procedure for choosing different quadratic functions on the relative interiors of faces to serve as surrogates of the differential costs in an inequality relaxation of the average cost function leads to linear program bounds. These bounds are probably better than earlier known bounds. It is also shown how to incorporate additional features, such as the presence of virtual multi-server stations to further improve the bounds. The approach also extends to provide functional bounds valid for all arrival rates.
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    Journal of optimization theory and applications 102 (1999), S. 299-313 
    ISSN: 1573-2878
    Keywords: Comparison of methods ; optimal control ; sensitivity ; shooting methods ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A new method for solving optimal control problems, here called multiple NOC shooting, is presented. It is developed from NOC shooting. It has some advantages over its parent and over multiple shooting, which are both successful, high-accuracy methods for optimal control. A comparison of the three methods is given, incorporating two examples.
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  • 88
    ISSN: 1573-3025
    Keywords: aerosolisation effects ; bioaerosol ; bioaerosol sampling ; effects of recovery agents ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sampling and assay of bioaerosols are important ina number of industrial and health-care applications. Airborne microorganisms are notoriously difficult toenumerate accurately under such conditions and nosingle procedure is suitable for all applications. Problems are compounded by the differences in assaymethod or sampler type selected, making theinterpretation of results difficult.Understanding the airborne behaviour of microorganismsover a range of environmental conditions is vital ifprocedures are to be defined and recommended for theassessment of bioaerosols. Microorganisms that arerobust over a wide range of conditions are ideal astracer particles. Unfortunately, the large majorityof non-fungal bioaerosols are susceptible to damage. A predictable assessment procedure is required whichwill not affect the viability of the collectedsample. This paper examines how aerosolisation may affect the characteristics of two speciesof microorganism (Pseudomonas fluorescens andMS2 coliphage). It forms part of a larger programmeto develop standards for the assessment of biologicalparticles. The aim of the work was to develop procedures toexamine the effects of aerosolisation onmicroorganisms, with particular reference topre-aerosolisation protocol (spray suspension age) andpost-sampling handling protocol (aerosol age incollection solution). These procedures were then usedto examine the effect of recovery agents, addedto the spray suspension prior to aerosolisation, onthe culturability of E.coli. Aerosolisation reduces the culturability of P. fluorescensand the viability of viability of MS2coliphage. Pre-sampling and post-collection handlingand storage of these aerosolised microorganisms werealso found to have an effect. This and earlierstudies have shown that the culturable fraction ofmicroorganisms can be affected by the same factorsdescribed above. Of five microorganisms tested so farin the main programme, only Penicillium expansumspores were shown to be robust and stable with aconstant culturable fraction. Therefore, recommendinga particular microorganism (apart from P. expansum) as an airborne biological standard foraerosol studies is not advised. It is recommendedthat a microorganism, representative of the envisagedapplication, be characterised it in terms of theaerosolisation parameters, storage time and conditionsin the manner reported in this study. This can beachieved using the experimental equipment described.The addition of 0.1 mM concentrations of the sugarsinositol, trehalose and raffinose to spray suspensionsof Escherichia coli, prior to aerosolisation,made no significant difference to the culturablefraction of the aerosol.
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    Nonlinear dynamics 19 (1999), S. 173-193 
    ISSN: 1573-269X
    Keywords: fluid conveying pipes ; high-frequency pulsating fluid ; separation of slow and fast motion ; stability ; nonlinear dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Stability and nonlinear dynamics of two articulated pipes conveying fluid with a high-frequency pulsating component is investigated. The non-autonomous model equations are converted into autonomous equations by approximating the fast excitation terms with slowly varying terms. The downward hanging pipe position will lose stability if the mean flow speed exceeds a certain critical value. Adding a pulsating component to the fluid flow is shown to stabilize the hanging position for high values of the ratio between fluid and pipe-mass, and to marginally destabilize this position for low ratios. An approximate nonlinear solution for small-amplitude flutter oscillations is obtained using a fifth-order multiple scales perturbation method, and large-amplitude oscillations are examined by numerical integration of the autonomous model equations, using a path-following algorithm. The pulsating fluid component is shown to affect the nonlinear behavior of the system, e.g. bifurcation types can change from supercritical to subcritical, creating several coexisting stable solutions and also anti-symmetrical flutter may appear.
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    Nonlinear dynamics 20 (1999), S. 221-246 
    ISSN: 1573-269X
    Keywords: Coulomb friction ; asymmetric damping ; exact periodic motions ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Dynamics of a class of strongly nonlinear single degree of freedom oscillators is investigated. Their common characteristic is that they possess piecewise linear damping properties, which can be expressed in a general asymmetric form. More specifically, the damping coefficient and a constant parameter appearing in the equation of motion are functions of the velocity direction. This class of oscillators is quite general and includes other important categories of mechanical systems as special cases, like systems with Coulomb friction. First, an analysis is presented for locating directly exact periodic responses of these oscillators to harmonic excitation. Due to the presence of dry friction, these responses may involve intervals where the oscillator is stuck temporarily. Then, an appropriate stability analysis is also presented together with some quite general bifurcation results. In the second part of the work, this analysis is applied to several example systems with piecewise linear damping, in order to reveal the most important aspects of their dynamics. Initially, systems with symmetric characteristics are examined, for which the periodic response is found to be symmetric or asymmetric. Then, dynamical systems with asymmetric damping characteristics are also examined. In all cases, emphasis is placed on investigating the low forcing frequency ranges, where interesting dynamics is noticed. The analytical predictions are complemented with results obtained by proper integration of the equation of motion, which among other responses reveal the existence of quasiperiodic, chaotic and unbounded motions.
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    Journal of engineering mathematics 36 (1999), S. 327-348 
    ISSN: 1573-2703
    Keywords: Bingham fluids ; multi-layer flow ; no-flow/yield criteria ; stability ; variational methods.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Technology
    Notes: Abstract The mechanically unstable situation of a heavy Bingham fluid resting on top of a light Bingham fluid in an inclined closed-ended pipe can be stabilised if the fluids have sufficiently large yield stresses. This paper focuses on determining the yield stresses that are sufficient to keep the fluids statically stable for a given fluid density difference, pipe diameter and pipe inclination. The results are applicable to a broad class of practically observable flows. This situation provides an idealised model for the oilfield process of plug cementing.
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    Flow, turbulence and combustion 62 (1999), S. 137-162 
    ISSN: 1573-1987
    Keywords: laminar wall jet ; heat transfer ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The hydrodynamic stability of a low speed, plane, non-isothermal laminar wall jet at a constant temperature boundary condition was investigated theoretically and experimentally. The mean velocity and temperature profiles used in the stability analysis were obtained by implementing the Illingworth–Stewartson transformation that allows one to extend the classical Glauert solution to a thermally non-uniform flow. The stability calculations showed that the two unstable eigenmodes coexisting at moderate Reynolds numbers are significantly affected by the heat transfer. Heating is destabilizing the flow while cooling is stabilizing it. However, the large-scale instabilities associated with the inflection point of the velocity profile still amplify in spite of the high level of the stabilizing temperature difference. The calculated stability characteristics of the wall jet with heat transfer were compared with experimental data. The comparison showed excellent agreement for small amplitudes of the imposed perturbations. The agreement is less good for the phase velocities of the sub-harmonic wave and this is attributed to experimental difficulties and to nonlinear effects.
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    Nonlinear dynamics 20 (1999), S. 181-196 
    ISSN: 1573-269X
    Keywords: monitoring ; stability ; compressors ; axial flow compressors ; stall ; surge ; bifurcation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Monitoring systems are proposed for the detection of incipient instability in axial flow compression systems. The work employs generic features associated with the response to noise inputs of systems bordering on instability. Based on these generic features, a closed-loop monitoring system is proposed. Numerical simulation is used to illustrate the operation of the proposed closed-loop monitoring system.
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    Journal of engineering mathematics 35 (1999), S. 385-404 
    ISSN: 1573-2703
    Keywords: Bénard-Marangini convection ; conducting fluids ; stability ; two-layer system.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Technology
    Notes: Abstract The onset of steady Bénard-Marangoni convection in two horizontal liquid layers of electrically conducting immiscible fluids subjected to a uniform vertical magnetic field and temperature gradient is analysed by means of a combination of analytical and numerical techniques. The free surface can be either deformable or nondeformable and the interface between the fluids is always assumed to be flat. The effect of the lower layer on the critical values of Rayleigh, Marangoni and wave numbers for the onset of steady convection is investigated. When the free surface is nondeformable, the critical parameters for the onset of pure Marangoni convection are increased, whereas for the onset of pure Bénard convection they are decreased compared to the single-layer model. The results for a single-layer and for two-layers are qualitatively similar for Bénard-Marangoni convection when the free surface is deformable. All disturbances can be stabilized with sufficiently strong magnetic field when the free surface is nondeformable. If the free surface is allowed to deform and gravity waves are excluded, then the layers are always unstable to disturbances with sufficiently small wave number with magnetic field. Inclusion of gravity waves has a stabilizing effect on certain disturbances of small wave number in the presence of weak or moderate magnetic field.
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  • 95
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    Nonlinear dynamics 19 (1999), S. 135-158 
    ISSN: 1573-269X
    Keywords: perturbation methods ; higher-order approximations ; dynamical systems ; codimension ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Higher-order multiple-scale methods for general multiparameter mechanical systems are studied. The role played by the control and imperfection parameters in deriving the perturbative equations is highlighted. The definition of the codimension of the problem, borrowed from the bifurcation theory, is extended to general systems, excited either externally or parametrically. The concept of a reduced dynamical system is then invoked. Different approaches followed in the literature to deal with reconstituted amplitude equations are discussed, both in the search for steady-state solutions and in the analysis of stability. Four classes of methods are considered, based on the consistency or inconsistency of the approach, and on the completeness or incompleteness of the terms retained in the analysis. The four methods are critically compared and general conclusions drawn. Finally, three examples are illustrated to corroborate the findings and to show the quantitative differences between the various approaches.
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  • 96
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    Nonlinear dynamics 19 (1999), S. 313-332 
    ISSN: 1573-269X
    Keywords: double pendulum system ; double Hopf bifurcation ; stability ; chaos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A double pendulum system is studied for analyzing the dynamic behaviour near a critical point characterized by nonsemisimple 1:1 resonance. Based on normal form theory, it is shown that two phase-locked periodic solutions may bifurcate from an initial equilibrium, one of them is unstable and the other may be stable for certain values of parameters. A secondary bifurcation from the stable periodic solution yields a family of quasi-periodic solutions lying on a two-dimensional torus. Further cascading bifurcations from the quasi-periodic motions lead to two chaoses via a period-doubling route. It is shown that all the solutions and chaotic motions are obtained under positive damping.
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  • 97
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    Multibody system dynamics 3 (1999), S. 287-299 
    ISSN: 1573-272X
    Keywords: multibody dynamics ; symbol manipulation ; linearization ; stability ; Floquet theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract It is shown that use of AUTOLEV, a symbol manipulation computer program for mechanics analyses, can greatly facilitate the stability analysis of motions of multibody systems.
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  • 98
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    Discrete event dynamic systems 9 (1999), S. 45-64 
    ISSN: 1573-7594
    Keywords: hybrid dynamic systems ; event feedback ; real-time scheduling ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Based on some practical engineering problems arising from process control and space-structure control, this paper studies a class of hybrid dynamic systems in which N plants are controlled by a central controller in sharing time manner, where the plants are described by differential equations and the controller works according to the mechanism of discrete events. An event feedback strategy is suggested to be a scheduling policy such that one and only one plant among N plants is chosen to be controlled at any time. Some conditions of asymptotical and exponential stability are then given and an exponential upper bound of states norm is also estimated for the event feedback scheduling strategy. An algorithm based on event feedback strategy is presented to determine the control laws of the plants to meet the given performance. An example follows to illustrate the application and effect of the results.
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  • 99
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    Neural processing letters 10 (1999), S. 267-271 
    ISSN: 1573-773X
    Keywords: recurrent neural networks ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In this paper, we point out that the conditions given in [1] are sufficient but unnecessary for the global asymptotically stable equilibrium of a class of delay differential equations. Instead, we prove that under weaker conditions, it is still global asymptotically stable.
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  • 100
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    Mathematical methods of operations research 50 (1999), S. 245-270 
    ISSN: 1432-5217
    Keywords: Key words: Portfolio optimization ; stochastic programming ; stability ; postoptimality ; worst-case analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract. Solutions of portfolio optimization problems are often influenced by errors or misspecifications due to approximation, estimation and incomplete information. Selected methods for analysis of results obtained by solving stochastic programs are presented and their scope illustrated on generic examples – the Markowitz model, a multiperiod bond portfolio management problem and a general strategic investment problem. The approaches are based on asymptotic and robust statistics, on the moment problem and on results of parametric optimization.
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