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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Autonomous agents and multi-agent systems 1 (1998), S. 39-57 
    ISSN: 1573-7454
    Keywords: Artificial Life ; Adaptive Behavior ; Evolutionary Computation ; Entertainment Software
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract We present a technical description of Creatures, a commercial home-entertainment software package. Creatures provides a simulated environment in which exist a number of synthetic agents that a user can interact with in real-time. The agents (known as “creatures”) are intended as sophisticated “virtual pets”. The internal architecture of the creatures is strongly inspired by animal biology. Each creature has a neural network responsible for sensory-motor coordination and behavior selection, and an “artificial biochemistry” that models a simple energy metabolism along with a “hormonal” system that interacts with the neural network to model diffuse modulation of neuronal activity and staged ontogenetic development. A biologically inspired learning mechanism allows the neural network to adapt during the lifetime of a creature. Learning includes the ability to acquire a simple verb–object language. Additionally, both the network architecture and details of the biochemistry for a creature are specified by a variable-length “genetic” encoding, allowing for evolutionary adaptation through sexual reproduction. Creatures, available on Windows95 platforms since late 1996, offers users an opportunity to engage with Artificial Life technologies. In addition to describing technical details, this paper concludes with a discussion of the scientific implications of the system.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-8205
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Physics
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Family studies have shown that in some populations up to 75% of the variation of body mass index can be explained by genetic factors. However, in humans, no major obesity gene has been identified to date. In contrast, there are a number of genetically well defined animal models for obesity. In two of those models (ob/ob and db/db), defects in the same pathway are responsible for obesity. Recently, some evidence has been found for the OB gene also being involved in human obesity. In this study we investigated the potential role of the OB receptor (OBR) in the etiology of massive obesity in humans using familial linkage analyses and case-control association studies. The typing of two microsatellite markers (D1S198 and D1S209), flanking the OBR gene, in 256 sib pairs showed no evidence for linkage with obesity. In order to be able to detect small gene effects, association studies with a 3′-UTR insertion/deletion polymorphism were carried out. The results of these analyses remained non-significant (χ2 = 3.442, P = 0.18). However, subjects heterozygous for the insertion/deletion polymorphism showed a slight trend towards lower insulin values 30 min after an oral glucose load compared to homozygous individuals (P = 0.02). In summary, our results do not support a major role of the human OBR gene in the development of morbid obesity in our population.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2048
    Keywords: Cinnamyl alcohol dehydrogenase ; Lignification ; Populus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two organic compounds, N-(O-hydroxyphenul)-and N-(O-aminophenyl)sulfinamoyltertiobutyl acetate (OHPAS and NH2PAS, respectively) have been designed for inhibiting cinnamylalcohol dehydrogenase (EC 1.1.1.2), a zinc metalloenzyme involved specifically in lignification. This paper describes their effects in vitro on the activity of the enzyme isolated from poplar and in vivo on the lignification of poplar tissues. The enzyme inhibition was time- and dose-dependent and pseudoirreversible indicating that these compounds could act as suicide inhibitors. Neither OHPAS nor NH2PAS exhibited affinity towards other plant zinc metalloenzymes or phenolic enzymes tested. Only NH2PAS exerted an effect on cinnamoyl: CoA reductase, another specific enzyme of lignification. In addition, these inhibitors, at the concentration of 80 μM, reduced the fluxes of lignin synthesis in poplar stems by 45%. These results show that OHPAS and NH2PAS could become useful tools for reducing lignification in plants.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2048
    Keywords: Guaiacyl units ; Light effect ; Lignification ; Membrane permeability ; Populus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When fed with [14C] phenylalanine in the light, xylem tissues isolated from poplar stems were able to incorporate part of the radioactivity into both the guaiacyl and the syringyl residues of lignins. In the dark, only syringyl units were integrated into the polymer whereas the guaiacyl residues remained unlabeled. When a membrane perturber (isopropanol) was added to the incubation mixture, the label was incorporated into the guaiacyl units either in the light or in the dark. Conversely, a membrane stabilizer (CaCl2) prevented the labeling of the guaiacyl units even when the tissues were illuminated. These results suggest that light acts through the modification of membrane permeabilities, altering specifically the synthesis and the transport or the polymerization of guaiacyl-type units during the process of lignification.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2048
    Keywords: Hydroxycinnamate: CoA ligase (tissue distribution) ; Lignification ; Populus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three different forms of hydroxycinnamate: CoA ligase (EC 6.2.1-) have been separated by chromatofocusing from poplar stems. These three forms exhibit different substrate specificities and tissue distribution. A correlation was established between the monomeric composition of lignins isolated from xylem and sclerenchyma and the pattern of hydroxycinnamate: CoA ligase isoforms in these tissues. The results obtained indicate that, in poplar, the hydroxycinnamate: CoA ligase isoenzymes could play an important role in the control of the monomeric composition of lignins.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-2242
    Keywords: Key words RAPD ; Orobanche cumana ; Helianthus annuus ; Genetic diversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The parasitic plant Orobanche cumana Wallr. has become a limiting factor for sunflower crops in infested countries. Over the past few years the progression of this parasitic plant, its introduction into new countries, and the development of new and more virulent races have all been observed. Consequently, the survey and understanding of broomrape population evolution is now crucial for the establishment of efficient breeding programmes. With this in prospect, the genetic variability of O. cumana populations from infested European countries, Bulgaria, Romania, Turkey and Spain, was studied using RAPD markers. Eight populations with a total of 180 plants were analysed. Twenty three primers were used to obtain 133 reproducible bands which led to a binary matrix. This matrix was subjected to various complementary analyses including pairwise distances computed with the Nei and Li coefficient, AMOVA, Nei’s genetic diversity statistics, and an estimation of gene flow among populations with the infinite-island formula. The results gave consistent conclusions whatever the method used for data treatment. We show that this parasitic plant is probably self-pollinated, that there is little intra-population variability, and very little gene exchange appears to occur between different geographic regions. Populations were well structured and organized into two distinct groups (one group corresponding to the East European countries, Bulgaria, Romania and Turkey, and the other group corresponding to Spanish populations) and could have a monophyletic origin. These results are discussed in relation to the applied uses of RAPD markers in the determination of true O. cumana races instead of populations.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 42 (2004), S. 309-319 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. It was shown recently [1] that the structural $\alpha $ -relaxation time $\tau $ of supercooled o-terphenyl depends on a single control parameter $\Gamma $ , which is the product of a function of density $E(\rho )$ , by the inverse temperature T -1. We extend this finding to other fragile glassforming liquids using light scattering data. Available experimental results do not allow to discriminate between several analytical forms of the function $E(\rho )$ , the scaling arising from the separation of density and temperature in $\Gamma $ . We also propose a simple form for $\tau (\Gamma )$ , which depends only on three material-dependent parameters, reproducing relaxation times over 12 orders of magnitude.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 2 (1907), S. 41-49 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 2 (1907), S. 83-84 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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