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  • 1
    Electronic Resource
    Electronic Resource
    Molecular Clock Calibrations and Metazoan Divergence Dates (1999)
    Springer
    Journal of molecular evolution 49 (1999), S. 385-391 
    Details
    ISSN: 1432-1432
    Keywords: Key words: Molecular clock — Divergence times — Calibration — Fossils — Metazoans — Cambrian explosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. It has recently been argued that living metazoans diverged over 800 million years ago, based on evidence from 22 nuclear genes for such a deep divergence between vertebrates and arthropods (Gu 1998). Two ``internal'' calibration points were used. However, only one fossil divergence date (the mammal–bird split) was directly used to calibrate the molecular clock. The second calibration point (the primate–rodent split) was based on molecular estimates that were ultimately also calibrated by the same mammal–bird split. However, the first tetrapods that can be assigned with confidence to either the mammal (synapsid) lineage or the bird (diapsid) lineage are approximately 288 million years old, while the first mammals that can be assigned with confidence to either the primate or the rodent lineages are 65 million years old, or 85 million years old if ferungulates are part of the primate lineage and zhelestids are accepted as ferungulate relatives. Recalibration of the protein data using these fossil dates indicates that metazoans diverged between 791 and 528 million years ago, a result broadly consistent with the palaeontological documentation of the ``Cambrian explosion.'' The third, ``external'' calibration point (the metazoan–fungal divergence) was similarly problematic, since it was based on a controversial molecular study (which in turn used fossil dates including the mammal–bird split); direct use of fossils for this calibration point gives the absurd dating of 455 million years for metazoan divergences. Similar calibration problems affect another recent study (Wang et al. 1999), which proposes divergences for metazoans of 1000 million years or more: recalibrations of their clock again yields much more recent dates, some consistent with a ``Cambrian explosion'' scenario. Molecular clock studies have persuasively argued for the imperfection of the fossil record but have rarely acknowledged that their inferences are also directly based on this same record.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006562
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  • 2
    Electronic Resource
    Electronic Resource
    OTTER: The design and development of an intelligent underwater robot (1996)
    Springer
    Autonomous robots 3 (1996), S. 297-320 
    Details
    ISSN: 1573-7527
    Keywords: autonomous underwater robot ; task-level control ; control/software architecture ; vision-sensing system ; coordinated arm/vehicle control ; 3D graphical user interfaces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Recent advances in sensing and intelligent control technologies open a whole new dimension in underwater autonomy. However, before truly-capable, autonomous underwater robots can be created for subsea intervention and exploration, many research issues must be first investigated and developed experimentally on testbed platforms. OTTER is an underwater robot designed to be used as a testbed for autonomous technologies. Both OTTER's hardware and software systems are configured to support simultaneous development and testing of different concepts for underwater robotic by independent researchers. A general control-software framework enables common access to all subsystems and avoids the duplication of basic robotic functionality jointly required by all projects. Additionally, the new autonomous technologies enabled by the results of individual research are mutually compatible and can be easily integrated into a single robotic system. Examples of new technologies demonstrated on the OTTER underwater robot include control from a real-time vision-sensing system, coordinated arm/vehicle control, and control from 3D graphical user interfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00141161
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  • 3
    Electronic Resource
    Electronic Resource
    Detection of Quantitative Trait Loci for Grain Yield and Yield Components in Maize across Generations in Stress and Nonstress Environments (1998)
    Springer
    Crop science 38 (1998), S. 1296-1308 
    Details
    ISSN: 1435-0653
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Zea mays L.) breeding programs, but its evaluation is complicated by genetic heterogeneity, a complex biological basis, and genotype 3 environment interactions. Genetic mapping studies of grain yield and yield components, with common sets of DNA marker loci and different populations evaluated across a range of environments, might identify regions of the genome associated with more or less consistent in different genetic and environmental contexts. Our objective was to evaluate the consistency of quantitative trait loci (QTL) detection for grain yield and four yield components in maize across stress and nonstress environments. One hundred eighty-five F6:7 lines from a cross between inbred lines Mo17 and H99 were evaluated in two climatically diverse years at the same location. The stress environment was characterized by cool, wet conditions and a 56% reduction in grain yield relative to the nonstress environment. Over all five traits, 59 QTL were detected in at least one of the two environments with 10 being detected in both environments. Thirty-two (54%) of QTL were detected in the mean environment, and an additional eight QTL were detected in the mean that were not detected in either of the individual environments. Comparison of the F6:7 mean environment QTL with the mean environment (same location, different years results from the F2:3 generation of the same population revealed 13 of 40 QTL detected in the F2:3 were verified in the F6:7 generation. Little evidence of cross-over type QTL interactions was observed, and QTL 3environment interactions seem to be in the form of change in magnitude of effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/
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  • 4
    Electronic Resource
    Electronic Resource
    Genetic Mapping in Maize with Hybrid Progeny Across Testers and Generations (2000)
    Springer
    Crop science 40 (2000), S. 30-38 
    Details
    ISSN: 1435-0653
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Zea mays L.), especially grain yield, display low correlations between the trait values observed in inbred and hybrid progeny. Comparisons of quantitative trait loci (QTL) controlling inbred per se and hybrid performance are needed to understand the underlying genetic factors, and to determine the utility of QTL detected in the two progeny types. DNA markers were used to identify QTL for grain yield and grain moisture in hybrid progeny of F2:3 and F6:8 lines from a Mo17xH99 population. For both generations, testcross progeny were developed by crossing the lines to three inbred testers (B91, A632, B73). Each testcross population was evaluated in field trials with two replications in eight environments. The testcross progeny from the two generations were evaluated at the same locations but in different years. QTL were identified within each testcross population and for mean testcross (MTC) performance. Individual tester QTL effects were not consistent in rank or detection across generations; however, parental contributions were consistent. MTC effects were more consistent across generations with most of the QTL with large effects being detected across generations. QTL detected with only one tester were not necessarily detected for the other two testers, especially for grain yield, but parental contributions were consistent when QTL were detected in a region for more than one tester. The QTL for grain yield identified in this population for inbred and hybrid progeny show only partial correspondence, indicating that marker-assisted selection programs would need to identify and incorporate QTL for both progeny types.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/
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  • 5
    Electronic Resource
    Electronic Resource
    An Extraction and Regularization Approach to Additive Clustering (1999)
    Springer
    Journal of classification 16 (1999), S. 255-281 
    Details
    ISSN: 1432-1343
    Keywords: Key words: Overlapping clustering; Additive clustering; ADCLUS.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003579900056
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  • 6
    Electronic Resource
    Electronic Resource
    Changes in thyroid hormone levels in eggs and larvae and in iodide uptake by eggs of coho and chinook salmon,Oncorhynchus kisutsch andO. tschawytscha (1989)
    Springer
    Fish physiology and biochemistry 6 (1989), S. 261-278 
    Details
    ISSN: 1573-5168
    Keywords: thyroid hormones in eggs and larvae ; iodide uptake by eggs ; thyroxinogenesis ; coho salmon chinook salmon ; thyroid hormone content in yolk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Developmental profiles of thyroxin (T4), triiodothyronine (T3) and radioactive iodide uptake were established for eggs and T4 and T3 profiles were established for larvae (whole-body, yolk-only and body-only) of coho and chinook salmon. T4 and T3 were consistently present in all samples. In eggs, hormone levels remained fairly constant in all cohorst for at least the first three weeks of incubation, but then fluctuated in both directions in some sample groups. Large increases in T4 (from 9 ng/g to 245 ng/g) were seen in 1985 chinook eggs 28 days after fertilization. Radioactive iodide uptake (which was used as a possible indicator of thyroxinogenesis) increased at least 10-fold in both 1986 coho and chinook eggs from 23–30 days after fertilization. T4 (62 ng/g) and T3 (393 ng/g) were found in the bodies of 28-day-old 1986 chinook embryos. In whole larvae, hormone levels varied depending upon the cohort studied. In general, initial body-only concentrations of both T4 and T3 decreased as body weight increased, but before yolksac resorption was completed, both thyroid hormone content and concentration increased (except for chinook T3). T4 and T3 content in larval yolk stayed constant as yolksac size decreased, resulting in increased thyroid hormone concentration in the yolksac. All of these data suggest that the initial source of thyroid hormones in coho and chinook salmon eggs is maternal, but that by approximately 3–4 weeks after fertilization, the developing embryos begin to produce their own thyroid hormones. After hatching, increases in tissue T4 and T3 concentration coupled with constant T4 and T3 content in diminishing yolksacs suggest that larvae also produce their own thyroid hormones; yolksac content then may reflect both the original maternal hormones and the larva-producted hormones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01881680
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  • 7
    Electronic Resource
    Electronic Resource
    Implementing the fast multipole method in three dimensions (1991)
    Springer
    Journal of statistical physics 63 (1991), S. 1223-1235 
    Details
    ISSN: 1572-9613
    Keywords: Fast multipole method ; many-body problem ; N-body problem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Rokhlin-Greengard fast multipole algorithm for evaluating Coulomb and multipole potentials has been implemented and analyzed in three dimensions. The implementation is presented for bounded charged systems and systems with periodic boundary conditions. The results include timings and error characterizations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01030008
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  • 8
    Electronic Resource
    Electronic Resource
    Erratum: Implementing the fast multipole method in three dimensions (1997)
    Springer
    Journal of statistical physics 87 (1997), S. 955-955 
    Details
    ISSN: 1572-9613
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02181257
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  • 9
    Electronic Resource
    Electronic Resource
    Plant low-molecular-weight phospholipase A2s (PLA2s) are structurally related to the animal secretory PLA2s and are present as a family of isoforms in rice (Oryza sativa) (1999)
    Springer
    Plant molecular biology 41 (1999), S. 481-490 
    Details
    ISSN: 1573-5028
    Keywords: calcium-dependent ; lipid metabolism ; Oryza sativa ; phospholipase A2 ; PLA2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recently, we purified to homogeneity and characterized a low-molecular-weight calcium-dependent phospholipase A2 (PLA2) from developing elm seed endosperm. This represented the first purified and characterized PLA2 from a plant tissue. The full sequences of two distinct but homologous rice (Oryza sativa) cDNAs are given here. These encode mature proteins of 119 amino acids (PLA2-I, preceded by a 19 amino acid signal peptide) and 128 amino acids (PLA2-II, preceded by a 25 amino acid signal peptide), and were derived from four expressed sequence tag (EST) clones. Both proteins were homologous to the N-terminal amino acid sequence of the elm PLA2. They contained twelve conserved cysteine residues and sequences that are likely to represent the Ca2+-binding loop and active-site motif, which are characteristic of animal secretory PLA2s. A soluble PLA2 activity was purified 145 000-fold from green rice shoots. This had the same biochemical characteristics as the elm and animal secretory PLA2s. The purified rice PLA2 consisted of two proteins, with a molecular weight of 12 440 and 12 920, that had identical N-terminal amino acid sequences. This sequence was different from but homologous to the PLA2-I and PLA2-II sequences. Taken together, the results suggest that at least three different low-molecular-weight PLA2s are expressed in green rice shoots. Southern blot analysis suggested that multiple copies of such genes are likely to occur in the rice and in other plant genomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006323405788
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  • 10
    Electronic Resource
    Electronic Resource
    Applicability of the rheological equation of state for thermoplastic composites (1998)
    Springer
    Journal of materials science 33 (1998), S. 223-227 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A simple experimental method for determining the steady-state shear viscosity of thermoplastic composite melts has been used. Using this method, we have determined the steady-state shear viscosity of an automotive thermoplastic composite system, namely, wollastonite-filled poly(ethylene terephthalate) (WFPET), at various temperatures and shear rates. All the viscosity properties investigated can be successfully described and predicted by a thermodynamically based rheological equation of state. The effects of composition and mixing conditions on the steady-state shear viscosity of all the WFPET investigated were also determined using this rheological equation of state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004330604597
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