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  • Springer  (6)
  • Blackwell Publishing Ltd
  • Geological Society of America
  • 2005-2009
  • 1995-1999  (6)
  • 1999  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Collision avoidance and resolution multiple access with transmission queues (1999)
    Springer
    Wireless networks 5 (1999), S. 95-109 
    Details
    ISSN: 1572-8196
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Computer Science
    Notes: Abstract We introduce a stable multiple access protocol for broadcast channels shared by bursty stations, which we call CARMA-NTQ (for collision avoidance and resolution multiple access with non-persistence and transmission queues). Like previous efficient MAC protocols based on tree-splitting algorithms (e.g., DQRAP), CARMA-NTQ maintains a distributed queue for the transmission of data packets and a stack for the transmission of control packets used in collision resolution. However, CARMA-NTQ does not require the mini-slots commonly used in protocols based on collision resolution. CARMA-NTQ dynamically divides the channel into cycles of variable length; each cycle consists of a contention period and a queue-transmission period. The queue-transmission period is a variable-length train of packets, which are transmitted by stations that have been added to the distributed transmission queue by successfully completing a collision-resolution round in a previous contention period. During the contention period, stations with packets to send compete for the right to be added to the data-transmission queue using a deterministic first-success tree-splitting algorithm, so that a new station is added to the transmission queue. A lower bound is derived for the average throughput achieved with CARMA-NTQ as a function of the size of the transmission queue and the number of queue-addition requests that need to be resolved. This bound is based on the upper bound on the average number of collision resolution steps needed to resolve a given number of queue-add requests.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019178423020
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of Skeletal Site of Origin and Donor Age on Osteoblastic Cell Growth and Differentiation (1999)
    Springer
    Calcified tissue international 64 (1999), S. 280-286 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Human osteoblastic cells — Skeletal site — Aging.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Bone loss with aging may be due, at least in part, to inadequate bone formation. Moreover, the process of bone aging is known to follow a different pattern throughout the skeleton. In this study, we examined the cell proliferation rate (area under the cell growth curve, AUC) and the secretion of C-terminal type I procollagen (PICP), alkaline phosphatase (ALP), and osteocalcin (OC) in primary cultures of osteoblastic cells from human trabecular bone. Osteoblastic cells were obtained for 168 donors (100 women and 68 men). Ninety-eight bone samples were obtained from subjects undergoing knee arthroplastia, 52 aged 50–70 years (64 ± 5) and 46 over age 70 (73 ± 2). Another 70 bone samples were obtained from subjects undergoing hip arthroplastia; 51 were 50–70 years old (64 ± 4) and 19 were over 70 (75 ± 5). Osteoblastic cells from the older donors had a lower proliferation rate and OC secretion than those from younger subjects. However, ALP secretion was higher in the former subjects, whereas PICP secretion was unchanged. Osteoblastic cells from hip had a lower proliferation rate than those from knee. PICP secretion was also lower and ALP secretion was higher in the former cells. In age-matched cell cultures, osteoblastic cells from the knee had higher proliferation rate and PICP secretion than osteoblastic cells from the hip. However, ALP secretion was lower in knee osteoblastic cells than those from hip only in the younger group. With aging, ALP secretion was found to increase in knee osteoblactic cells, whereas OC secretion decreased in osteoblastic cell cultures from the hip. Our findings suggest that bone loss with aging may be accounted for, at least in part, by a decreased osteoblastic cell proliferation and an increased osteoblastic maturation. In addition, our data indicate that these changes with aging do not occur similarly at different skeletal sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900619
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  • 3
    Electronic Resource
    Electronic Resource
    Enzymatic characterisation of high-palmitic acid sunflower (Helianthus annuus L.) mutants (1999)
    Springer
    Planta 207 (1999), S. 533-538 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Acyl-acyl carrier protein thioesterase ; Fatty acid synthetase II ; Helianthus (seed) ; β-keto-acyl-acyl carrier protein synthetase II ; Mutant fatty acid ; Palmitic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Two high-palmitic acid sunflower (Helianthus annuus L.) mutants, CAS-5 and CAS-12, have been biochemically characterised. The enzymatic activities found to be responsible for the mutant characteristics are β-keto-acyl-acyl carrier protein synthetase II (KASII; EC 2.3.1.41) and acyl-acyl carrier protein thioesterase (EC 3.1.2.14). Our data suggest that the high-palmitic acid phenotype observed in both mutant lines is due to the combined effect of a lower KASII activity and a higher thioesterase activity with respect to palmitoyl-acyl carrier protein (16:0-ACP). The level of the latter enzyme appeared to be insufficient to hydrolyse the produced 16:0-ACP completely. As a consequence of this, three new fatty acids appear: palmitoleic acid (16:1 Δ9), asclepic acid (18:1 Δ11), and palmitolinoleic acid (16:2 Δ9 Δ12). These fatty acids should be synthesised from palmitoyl-ACP or a derivative by the action of the stearoyl-ACP desaturase, fatty acid synthetase II and oleoyl-phosphatidylcholine desaturase, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050514
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  • 4
    Electronic Resource
    Electronic Resource
    Inheritance of high palmitic acid content in the seed oil of sunflower mutant CAS-5 (1999)
    Springer
    Theoretical and applied genetics 98 (1999), S. 496-501 
    Details
    ISSN: 1432-2242
    Keywords: Key words Helianthus annuus ; Sunflower mutant ; Palmitic acid ; Inheritance ; Fatty acid composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Sunflower genotypes with increased levels of palmitic acid (C16 : 0) in the seed oil could be useful for food and industrial applications. The objective of the present study was to determine the inheritance of the high C16 : 0 content in the sunflower mutant line CAS-5 (〉25% of the total oil fatty acids). This mutant was reciprocally crossed with the lines HA-89 (5.7% C16 : 0) and BSD-2-691 (5.4% C16 : 0), the latter being the parental line from which CAS-5 was isolated. No maternal effect for the C16 : 0 content was observed from the analysis of F1 seeds in any of the crosses. The inheritance study of the C16 : 0 content in F1, F2 and BC1F1 seeds from the crosses of CAS-5 with its parental line BSD-2-691 indicated that the segregation fitted a model of two alleles at one locus with partial dominance for the low content. The analysis of the fatty acid composition in the F2 populations from the crosses with HA-89 revealed a segregation fitting a ratio 19 : 38 : 7 for low (〈7.5%), middle (7.5–15%), and high (〉25%) C16 : 0 content, respectively. This segregation was explained on the basis of three loci (P1, P2, P3) each having two alleles showing partial dominance for low content. The genotypes with a high C16 : 0 content were homozygous for the recessive allele p1 and for at least one of the other two recessive alleles, p2 or p3. This model was further confirmed with the analysis of the F3 and the BC1F1 generations. It was concluded that both the recessive alleles p2 and p3 were already present in the BSD-2-691 line, the allele p1 being the result of a mutation from P1. This genetic study will facilitate breeding strategies associated with the incorporation of the high C16 : 0 trait into agronomically acceptable sunflower hybrids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051097
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  • 5
    Electronic Resource
    Electronic Resource
    Genetic control of high stearic acid content in the seed oil of the sunflower mutant CAS-3 (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 663-669 
    Details
    ISSN: 1432-2242
    Keywords: Key words Helianthus annuus ; Sunflower mutant ; Stearic acid ; Oil quality ; Genetic control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A sunflower mutant, CAS-3, with about 25% stearic acid (C18:0) in the seed oil was recently isolated after a chemical-mutagen treatment of RDF-1-532 seeds (8% C18:0). To study the inheritance of the high C18:0 content, CAS-3 was reciprocally crossed to RDF-1–532 and HA-89 (5% C18:0). Significant reciprocal-cross differences were found in one of the two crosses, indicating possible maternal effects. In the CAS-3 and RDF-1–532 crosses, the segregation patterns of the F1, BC1, and F2 populations fitted a one-locus (designated Es1) model with two alleles (Es1, es1) and with partial dominance of low over high C18:0 content. Segregation patterns in the CAS-3 and HA-89 crosses indicated the presence of a second independent locus (designated Es2) with two alleles (Es2, es2), also with partial dominance of low over high C18:0 content. From these results, the proposed genotypes (C18:0 content) of each parent were as follows: CAS-3 (25.0% C18:0) =es1es1es2es2; RDF-1–532 (8.0% C18:0) =Es1Es1es2es2; and HA-89 (4.6% C18:0) =Es1Es1Es2Es2. The relationship between the proposed genotypes and their C18:0 content indicates that the Es1 locus has a greater effect on the C18:0 content than the Es2 locus. Apparently, the mutagenic treatment caused a mutation of Es1 to es1 in RDF-1–532.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051282
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  • 6
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    Enzymatic characterisation of high-palmitic acid sunflower ( Helianthus annuus L.) mutants (1999)
    Springer
    Details
    Publication Date: 1999-02-17
    Print ISSN: 0032-0935
    Electronic ISSN: 1432-2048
    Topics: Biology
    Published by Springer
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