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  • wheat  (87)
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  • Springer  (218)
  • American Meteorological Society
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  • 1
    Electronic Resource
    Electronic Resource
    Preserving communication context: Virtual workspace and interpersonal space in Japanese CSCW (1999)
    Springer
    AI & society 13 (1999), S. 357-376 
    Details
    ISSN: 1435-5655
    Keywords: Context ; CSCW ; Culture ; Design ; Interface ; Japan ; Work
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract The past decade has seen the development of a perspective holding that technology is socially constructed. This paper examines the social construction of one group of technologies: systems for computer-supported cooperative work (CSCW). It describes the design of CSCW in Japan, with particular attention to the influence of culture on the design process. Two case studies are presented to illustrate the argument that culture is an important factor in technology design, despite commonly held assumptions about the neutrality and objectivity of science and technology. The paper further argues that, by looking at CSCW systems as texts which reflect the context of their production and the society from which they come, we may be better able to understand the transformations that operate when these texts are ‘read’ in the contexts of their implementation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01205983
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  • 2
    Electronic Resource
    Electronic Resource
    Improving neural network performance on the classification of complex geographic datasets (1999)
    Springer
    Journal of geographical systems 1 (1999), S. 3-22 
    Details
    ISSN: 1435-5949
    Keywords: Key words: Classification ; neural networks ; G15 ; JEL classification: C88 ; C63 ; C45 ; C44
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography
    Notes: Abstract. Neural Networks are now established computational tools used for search minimisation and data classification. They offer some highly desirable features for landuse classification problems since they are able to take in a variety of data types, recorded on different statistical scales, and combine them. As such, neural networks should offer advantages of increased accuracy. However, a barrier to their general acceptance and use by all but `experts' is the difficulty of configuring the network initially.  This paper describes the architectural problems of applying neural networks to landcover classification exercises in geography and details some of the latest developments from an ongoing research project aimed at overcoming these problems. A comprehensive strategy for the configuration of neural networks is presented, whereby the network is automatically constructed by a process involving initial analysis of the training data. By careful study of the functioning of each part of the network it is possible to select the architecture and initial weights on the node connections so the constructed network is `right first time'. Further adaptations are described to control network behaviour, to optimise functioning from the perspective of landcover classification. The entire configuration process is encapsulated by a single application which may be treated by the user as a `black box', allowing the network to the applied in much the same way as a maximum likelihood classifier, with no further effort being required of the user.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s101090050002
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  • 3
    Electronic Resource
    Electronic Resource
    Using computational intelligence techniques to model subglacial water systems (1999)
    Springer
    Journal of geographical systems 1 (1999), S. 37-60 
    Details
    ISSN: 1435-5949
    Keywords: Key words: Computational intelligence ; glacier hydrology ; genetic programming ; neural networks ; fuzzy logic ; self-organizing map ; JEL classification: C61 ; C63 ; C80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography
    Notes: Abstract. Measurements of water pressure beneath Trapridge Glacier, Yukon Territory, Canada show that the basal water system is highly heterogeneous. Three types of behaviour were recorded: pressure records which are strongly correlated, records which are strongly anticorrelated, and records which alternate between strong correlation and strong anticorrelation. We take the pressure in bore-holes that are connected to the evacuation route for basal water as the forcing, and the other pressures as the response to this forcing. Previous work (Murray and Clarke 1995) has shown that these relationships can be modelled using low-order nonlinear differential equations optimized by inversion. However, despite optimizing the model parameters we cannot be sure that the final model forms are themselves optimal. Computational intelligence techniques provide alternative methods for fitting models and are robust to missing or noisy data, applicable to non-smooth models, and attempt to derive optimal model forms as well as optimal model parameters. Four computational intelligence techniques have been used and the results compared with the more conventional mathematical model. These methods were genetic programming, artificial neural networks, fuzzy logic and self-organizing maps. We compare each technique and offer an evaluation of their suitability for modelling the pressure data. The evaluation criteria are threefold: (1) goodness of fit and an ability to predict subsequent data under different surface weather conditions; (2) interpretability, and the extent and significance of any new insights offered into the physics of the glacier; (3) computation time. The results suggest that the suitability of the computational intelligence techniques to model these data increases with the complexity of the system to be modelled.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s101090050004
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  • 4
    Electronic Resource
    Electronic Resource
    Temporal changes in the egglaying behaviour of the Hessian fly (1989)
    Springer
    Entomologia experimentalis et applicata 53 (1989), S. 17-29 
    Details
    ISSN: 1570-7458
    Keywords: Mayetiola destructor ; Cecidomyiidae ; oviposition ; host specificity ; wheat ; oats ; insect-plant interactions ; thresholds ; deprivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les réactions de femelles préalablement accouplées de Mouches de Hesse ont été examinées en analysant le comportement de femelles isolées sur blé et sur avoine. Le répertoire comportemental de ces femelles comprenait: le vol, l'atterrissage sur feuille, la flexion du corps de sorte que l'extrémité de l'abdomen touchât la surface de la feuille, l'antennation, les mouvements de l'extrémité de l'abdomen sur la feuille à angle droit des nervures, le repos avec la tarière droite et encore dévaginée, le repos avec la tarière télescopée à l'intérieur du corps. Sur blé plus que sur avoine, les femelles après atterrissage ont présenté une fréquence plus élevée de passage de la flexion à l'antennation que de la flexion à l'abdomen droit. Durant les 5 premières minutes d'observation, les individus libérés dans des enceintes avec blé fléchirent et ‘antennèrent’ 2 à 3 fois plus que ceux libérés sur avoine. Les durées des différentes séquences différaient aussi: sur blé, pendant les 5 premières minutes, les femelles passèrent plus de 50% du temps à fléchir, tandis que sur avoine elles passèrent plus de 50% du temps en repos. Les femelles restèrent aussi plus longtemps sur les feuilles de blé et y pondirent 4 fois plus d'oeufs que sur avoine. Les femelles de M. destructor ont montré une plasticité du seuil d'acceptation. Pendant les premières heures de ponte, elles ont été très sélectives et refusèrent, ou ne pondirent que quelques oeufs sur avoine, mais acceptèrent volontiers le blé. La discrimination s'est poursuivie tant que les femelles ont eu accès au blé en même temps qu'à l'avoine. Cependant, quand les femelles ont été privées de blé pendant plusieures heures, l'acceptation de l'avoine a augmenté. Cet accroissement de l'acceptation a eu lieu à peu près au moment où les femelles sur blé pondaient leurs derniers oeufs.
    Notes: Abstract Responses of mated female Hessian flies were investigated by analysing the behaviour of individual flies in wheat and oats. The behavioural repertoire of such females included: flying, alighting on leaves, arching of the body so that the tip of the abdomen touched the leaf surface, antennation, movements of the tip of the abdomen across the leaf at right angles to leaf veins, sitting with the ovipositor straight but still extended, and sitting with the ovipositor telescoped into the body. After alighting, females on wheat showed a higher frequency of transitions from arching to antennation and a lower frequency of transitions from arching to abdomen straight than females on oats. During the first 5 min of observations, individuals released into arenas with wheat arched and antennated 2–3 times more frequently than females released into oats. Time allotted to behaviours also differed; during the first 5 min, females in wheat spent 50 percent more time arching, whereas females in oats spent 50 percent more time sitting. Females in wheat also stayed longer and laid 4 times more eggs than females in oats. Temporal changes in egglaying were monitored by quantifying hourly rates of egglaying in no-choice assays for several hours following mating at 9:00 am. During the first and second hours post-mating, egglaying occurred infrequently. However, during the third hour post-mating (11:00 am to noon) females on wheat laid 5 times more eggs than females on oats. Rates of egglaying decreased on wheat but increased on oats during the fourth hour, and then during the fifth hour, decreased on both wheat and oats. Changes in egglaying responses were also evident when behaviours of individual females were measured 1–3 h vs. 3–7 h post-mating. Females deprived of host plants and released into wheat or oats later in the day showed higher frequencies of arching and antennation and laid more eggs before leaving the arena.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369228
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  • 5
    Electronic Resource
    Electronic Resource
    Within-plant distribution of Rhopalosiphum padi on wheat seedlings is affected by induced responses (1999)
    Springer
    Entomologia experimentalis et applicata 93 (1999), S. 227-230 
    Details
    ISSN: 1570-7458
    Keywords: Rhopalosiphum padi ; cereal aphids ; wheat ; induced responses ; feeding site
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003874225681
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  • 6
    Electronic Resource
    Electronic Resource
    Design of parts for cellular manufacturing using neural network-based approach (1999)
    Springer
    Journal of intelligent manufacturing 10 (1999), S. 251-265 
    Details
    ISSN: 1572-8145
    Keywords: Feature-based design for manufacture ; feature recognition ; feature families formation ; cell grouping ; neural networks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A neural network approach is applied to the problem of integrating design and manufacturing engineering. The self organising map (SOM) neural network recognizes products and parts which are modeled as boundary representation (B-rep) solids using a modified face complexity code scheme adopted, and forms the necessary feature families. Based on the part features, machines, tools and fixtures are selected. These information are then fed into a four layer feed-forward neural network that provides a designer with the desired features that meet the current manufacturing constraints for design of a new product or part. The proposed methodology does not involve training of the neural networks used and is seen to be a significant potential for application in concurrent engineering where design and manufacturing are integrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008947824050
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  • 7
    Electronic Resource
    Electronic Resource
    Manufacturing features recognition using backpropagation neural networks (1999)
    Springer
    Journal of intelligent manufacturing 10 (1999), S. 289-299 
    Details
    ISSN: 1572-8145
    Keywords: Feature recognition ; feature representation ; neural networks ; BPN
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A backpropagation neural network (BPN) is applied to the problem of feature recognition from a boundary representation (B-rep) solid model to facilitate process planning of manufactured products. It is based on the use of the face complexity code to represent the features and a neural network for the analysis of the recognition. The face complexity code is a measure of the face complexity of a feature based on the convexity or concavity of the surrounding geometry. The codes for various features are fed to the network for analysis. A backpropagation network is implemented for recognition of features and tested on published results to measure its performance. Any two or more features having significant differences in face complexity codes were used as exemplars for training the network. A new feature presented to the network is associated with one of the existing clusters, if they are similar, or the network creates a new cluster, if otherwise. Experimental results show that the network was consistent in recognizing features, hence is appropriate for application to the problem of feature recognition in automated manufacturing environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008904109029
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  • 8
    Electronic Resource
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    Intelligent scheduling and control of rail-guided vehicles and load/unload operations in a flexible manufacturing system (1999)
    Springer
    Journal of intelligent manufacturing 10 (1999), S. 405-421 
    Details
    ISSN: 1572-8145
    Keywords: Flexible manufacturing systems control ; intelligent manufacturing ; neural networks ; simulation ; material handling systems ; automated guided vehicles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper presents a framework of intelligent manufacturing scheduling and control with specific applications to operations of rail-guided vehicle systems (RGVS). A RGVS control architecture is discussed with a focus on a simulated experiment in operations of the load/unload area of a real industrial flexible manufacturing system (FMS). In the operation stage of a material handling system (MHS), all shop floor data are subject to change as time goes. These data can be collected using a data acquisition device and stored in a dynamic database. The RGVS simulator used in this experimental study is designed to incorporate some possible situations representing existing material handling scenarios in order to evaluate alternative control policies. At the development stage of the controller, all possible combinations of most commonly encountered scenarios such as RGV failures, production schedule changes, machine breakdowns, and rush orders are to be simulated and corresponding results collected. The data are then structured into training data pairs to properly train an artificial neural network. The neural network, trained by using input/output data sets obtained from a number of simulation runs, will then provide control strategy recommendations. At the application stage, whenever an abnormal scenario occurs, a pre-processor will be activated to pre-screen and prepare an input vector for the trained neural network. If such an abnormal scenario falls outside the existing domain of data sets employed to train the neural network, as judged by the MHS supervisory controller, an off-line training module will be activated to eventually update the neural network. The recommended control strategies will be transmitted to the MHS control for real-time execution. If there is no further abnormal event detected, the dynamic data base (DDB) module simply continues to monitor the MHS activities. The proposed MHS control system combines the features of example based neural network technology and simulation modeling for true intelligent, on-line, pseudo real-time control. Not only will the system assure that feasible material handling control actions be taken, but also it will implement better control decisions through continuous learning from experiences captured as the operation time of the MHS accumulates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008919013557
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  • 9
    Electronic Resource
    Electronic Resource
    La répartition spatiale des différents stades de Coccinella septempunctata dans un champ de blé: variation au cours de la saison (1989)
    Springer
    Entomologia experimentalis et applicata 53 (1989), S. 229-236 
    Details
    ISSN: 1570-7458
    Keywords: Coccinella septempunctata ; Coccinellidae ; wheat ; egg laying ; larva ; adult ; vertical distribution ; Coccinella septempunctata ; Coccinellidae ; blé ; ponte ; larve ; adulte ; répartition spatiale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary At the beginning of spring, post-hibernating adults of Coccinella septempunctata L. (Col., Coccinellidae), larvae and nymphs are found on the lower part of wheat plants. In June, adults born in the field as well as their progeny are dispersed all over the plant and a significant proportion of them is found on the apical parts of plants. Most of the egg clutches are layed on soil lumps, stones and small wild plants which represent preferential sites. Variations in coccinellid distribution may be influenced by climatic conditions, especially the temperature, by the thermophilic nature of this species and by the repartition of the three main aphid species on the plants. These results are relevant for the selection of a sampling methods.
    Notes: Résumé Au début du printemps les adultes de Coccinella septempunctata L. (Col., Coccinellidae) issus des sites d'hivernation, les larves et les nymphes qui en proviennent, fréquentent le sol et les parties basses du blé. En juin, les adultes nés dans le champ et leur descendance sont dispersés sur toute la hauteur des talles bien qu'une fraction non négligeable de leur population se rencontre à l'extrémité supérieure. La plupart des pontes sont déposées sous les mottes de terre, les pierres et les petites adventices qui constituent des sites privilégiés. Ces variations de la distribution de cette coccinelle peuvent être mises en relation avec le climat, en particulier la température, avec la thermophilie de cette espèce et avec la répartition sur les différentes parties des talles des 3 espèces de puceron qui se succèdent au cours de la saison. Ces observations sont importantes à considérer lors du choix ou de la mise au point d'une méthode d'échantillonnage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00162854
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  • 10
    Electronic Resource
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    Comparison of Diuraphis noxia resistance in wheat isolines and plant introduction lines (1999)
    Springer
    Entomologia experimentalis et applicata 92 (1999), S. 157-164 
    Details
    ISSN: 1570-7458
    Keywords: plant resistance ; antibiosis ; tolerance ; antixenosis ; Russian wheat aphid ; wheat ; Homoptera ; Aphididae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Russian wheat aphid, Diuraphis noxia (Mordvilko), is one of the most important aphid pests of wheat, Triticum aestivum L., worldwide. Among the various pest management options, plant resistance is an economical management tactic to control D. noxia in cereal crops such as wheat. Researchers have identified D. noxia resistant germplasm and it has been incorporated into wheat. This study compared D. noxia resistance between the ‘Betta’ wheat isolines Betta-Dn1, Betta-Dn2, and Betta-Dn5 and their corresponding donor gene plant introduction (PI) lines PI 137739 (Dn1), PI 262660 (Dn2), and PI 294994 (Dn5). Although the Betta isolines and PI lines showed D. noxia resistance when compared with Betta wheat, the degree of resistance in the isolines to D. noxia was different from their corresponding PI donors. Aphid number, aphid fecundity, and biomass per aphid were not different between Betta-Dn1 and PI 137739 or Betta-Dn2 and PI 262660; however, the same parameters were significantly lower on PI 294994 compared with Betta-Dn5. This indicated that aphid resistance in PI 137739 and PI 262660 was probably governed by a single dominant gene, while the resistance in PI 294994 was controlled by more than one gene. Additionally, plant biomass reduction was aphid density dependent, which suggested that use of appropriate aphid infestation level is important when using plant biomass reduction as an indicator of resistance. Plant resistance categorization showed that there was no detectable difference in antixenosis among the seven lines evaluated. However, the higher aphid fecundity observed on PI 262660 compared with PI 137739 and PI 294994, in addition to no significant differences among the three PIs in plant biomass reduction, suggested PI 262660 was a tolerant line, while PI 137739 and PI 294994 were antibiotic lines. Plant tolerance could not be elucidated among the three Betta isolines using aphid fecundity and plant biomass reduction as indicators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003719325094
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  • 11
    Electronic Resource
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    Salivation into sieve elements in relation to plant chemistry: the case of the aphid Sitobion fragariae and the wheat, Triticum aestivum (1999)
    Springer
    Entomologia experimentalis et applicata 91 (1999), S. 111-114 
    Details
    ISSN: 1570-7458
    Keywords: sieve element ; salivation ; aphid ; plant resistance ; wheat ; Sitobion fragariae ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Extended sieve element salivation (E1 waveform in the electrical penetration graph) is a characteristic activity during early sieve element punctures, particularly in resistant plants. In order to explore a chemically-mediated mechanism of resistance associated with sieve element salivation, we compared the pattern of feeding behaviour of the aphid, Sitobion fragariae (Walker), on two cultivars of the wheat Triticum aestivum L., with different concentrations of hydroxamic acids (Hx). During 24 h of electronic monitoring, aphids dedicated over 50% of the total time to phloem ingestion from the sieve elements. Total time allocated to E1 in the experiment, time to first E1 within the experiment, time allocated to E1 before a sustained phloem ingestion (E2) and the contribution of sieve element salivation to the phloem phase (E1/[E1+E2]) were significantly higher in the high-Hx cultivar. The increased salivation in plants with higher contents of Hx suggests the existence, at least in this system, of a chemically-mediated sieve element constraint.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003628703035
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  • 12
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    Structural Learning: Attraction and Conformity in Task-Oriented Groups (1999)
    Springer
    Computational & mathematical organization theory 5 (1999), S. 129-145 
    Details
    ISSN: 1572-9346
    Keywords: collective action ; informal control ; social influence ; neural networks ; computer simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This study extends previous research that showed how informal social sanctions can backfire when members prefer friendship over enforcement of group norms. We use a type of neural network to model the coordination of informal social control in a small group of adaptive agents confronted with a social dilemma. This model incorporates two mechanisms of social influence, informal sanctions and imitation. Both mechanisms vary with the strength of the social tie between source and target. Previous research focused on the effects of social sanctions. Here, we demonstrate a curvilinear effect of imitation on compliance with prosocial norms. Moderate doses of imitation reduce the coordination complexity of self-organized collective action and help the network achieve satisfactory levels of cooperation. High doses, however, undermine the agent-based learning required to find cooperative solutions. Increasing group size also diminishes compliance due to increased complexity, with larger groups requiring more imitation to overcome the coordination problem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009670804792
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  • 13
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    A Taxonomy of Evolutionary Algorithms in Combinatorial Optimization (1999)
    Springer
    Journal of heuristics 5 (1999), S. 145-158 
    Details
    ISSN: 1572-9397
    Keywords: evolutionary algorithms ; genetic algorithms ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This paper shows how evolutionary algorithms can be described in a concise, yet comprehensive and accurate way. A classification scheme is introduced and presented in a tabular form called TEA (Table of Evolutionary Algorithms). It distinguishes between different classes of evolutionary algorithms (e.g., genetic algorithms, ant systems) by enumerating the fundamental ingredients of each of these algorithms. At the end, possible uses of the TEA are illustrated on classical evolutionary algorithms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009625526657
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  • 14
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    Mathematics and Neural Networks –A Glance at some Basic Connections (1999)
    Springer
    Acta applicandae mathematicae 55 (1999), S. 303-311 
    Details
    ISSN: 1572-9036
    Keywords: neural networks ; density ; complexity ; sigmoidal functions ; ridge-type functions ; hyperbolic-type functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In the following paper, we present a brief and easily accessible introduction to the theory of neural networks under special emphasis on the rôle of pure and applied mathematics in this interesting field of research. In order to allow a quick and direct approach even for nonspecialists, we only consider three-layer feedforward networks with sigmoidal transfer functions and do not cover general multi-layer, recursive or radial-basis-function networks. Moreover, we focus our attention on density and complexity results while construction problems based on operator techniques are not discussed in detail. Especially, in connection with complexity results, we show that neural networks in general have the power to approximate certain function spaces with a minimal number of free parameters. In other words, under this specific point of view neural networks represent one of the best possible approximation devices available. Besides pointing out this remarkable fact, the main motivation for presenting this paper is to give some more mathematicians an idea of what is going on in the theory of neural networks and, perhaps, to encourage, at least a few of them, to start working in this highly interdisciplinary and promising field, too.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006161218940
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  • 15
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    Why not Artificial Consciousness or Thought? (1999)
    Springer
    Minds and machines 9 (1999), S. 3-28 
    Details
    ISSN: 1572-8641
    Keywords: physical symbols ; formal programs ; neural networks ; designation ; interpretation ; representation ; semantics ; intensional meaning ; extensional meaning ; causal capacities ; emergence ; levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Philosophy
    Notes: Abstract The purpose of this article is to show why consciousness and thought are not manifested in digital computers. Analyzing the rationale for claiming that the formal manipulation of physical symbols in Turing machines would emulate human thought, the article attempts to show why this proved false. This is because the reinterpretation of ‘designation’ and ‘meaning’ to accommodate physical symbol manipulation eliminated their crucial functions in human discourse. Words have denotations and intensional meanings because the brain transforms the physical stimuli received from the microworld into a qualitative, macroscopic representation for consciousness. Lacking this capacity as programmed machines, computers have no representations for their symbols to designate and mean. Unlike human beings in which consciousness and thought, with their inherent content, have emerged because of their organic natures, serial processing computers or parallel distributed processing systems, as programmed electrical machines, lack these causal capacities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008374714117
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  • 16
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    Hohfeld in cyberspace and other applications of normative reasoning in agent technology (1999)
    Springer
    Artificial intelligence and law 7 (1999), S. 81-96 
    Details
    ISSN: 1572-8382
    Keywords: agents ; user interface metaphors ; agent programming languages ; agent communication languages ; agent protocols ; Hohfeld ; formal theories of rights ; normative structures ; deontic logic ; groupware ; CSCW ; electronic commerce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Law
    Notes: Abstract Two areas of importance for agents and multiagent systems are investigated: design of agent programming languages, and design of agent communication languages. The paper contributes in the above mentioned areas by demonstrating improved or novel applications for deontic logic and normative reasoning. Examples are taken from computer-supported cooperative work, and electronic commerce.
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    URL: http://dx.doi.org/10.1023/A:1008367514393
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  • 17
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    Introduction: from legal theories to neural networks and fuzzy reasoning (1999)
    Springer
    Artificial intelligence and law 7 (1999), S. 115-128 
    Details
    ISSN: 1572-8382
    Keywords: analogy ; fuzzy logic ; learning ; legal formalism ; neural networks ; vagueness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Law
    Notes: Abstract Computational approaches to the law have frequently been characterized as being formalistic implementations of the syllogistic model of legal cognition: using insufficient or contradictory data, making analogies, learning through examples and experiences, applying vague and imprecise standards. We argue that, on the contrary, studies on neural networks and fuzzy reasoning show how AI & law research can go beyond syllogism, and, in doing that, can provide substantial contributions to the law.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008371600675
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    Out of their minds: legal theory in neural networks (1999)
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    Artificial intelligence and law 7 (1999), S. 129-151 
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    ISSN: 1572-8382
    Keywords: connectionism ; legal philosophy ; legal theory ; neural networks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Law
    Notes: Abstract This paper examines the use of connectionism (neural networks) in modelling legal reasoning. I discuss how the implementations of neural networks have failed to account for legal theoretical perspectives on adjudication. I criticise the use of neural networks in law, not because connectionism is inherently unsuitable in law, but rather because it has been done so poorly to date. The paper reviews a number of legal theories which provide a grounding for the use of neural networks in law. It then examines some implementations undertaken in law and criticises their legal theoretical naïvete. It then presents a lessons from the implementations which researchers must bear in mind if they wish to build neural networks which are justified by legal theories.
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    URL: http://dx.doi.org/10.1023/A:1008301122056
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    A Modular Vector for Agrobacterium Mediated Transformation of Wheat (1999)
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    Plant molecular biology reporter 17 (1999), S. 323-331 
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    ISSN: 1572-9818
    Keywords: Agrobacterium ; modular vector ; transformation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wheat (cv Chinese Spring) tissues were transformed using Agrobacterium tumefasciens and a new plasmid modular vector, pMVTBP. We constructed pMVTBP with unique restriction sites connecting (1) the CaMV 35S promoter, (2) a Kozak sequence, (3) the FLAG epitope, (4) the (His)6 epitope, (5) a coding region (for wheat TATA Binding Protein, wTBP) and (6) the CaMV 35S 3′UTR. This vector thus allows easy exchange of different regulatory or coding sequences. Explants of either germinating mature seeds, or immature embryos, were induced to callus for up to two weeks, treated with virulence-induced bacteria for one hour, then regenerated into plantlets. Transient expression of a GUS reporter gene, assayed at about one week, occurred in 10–12% of calluses. Expression of the FLAG-tagged wTBP was also detected, by immunostaining. Stable expression, by selective growth on geneticin, and by GUS expression at about six weeks, occurred in 1–2% of calluses, quite comparable to that achieved by other methods.
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    URL: http://dx.doi.org/10.1023/A:1007686408369
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    Object Recognition and Selective Handling by a Robot (1999)
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    Journal of intelligent and robotic systems 25 (1999), S. 121-132 
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    ISSN: 1573-0409
    Keywords: invariant object recognition ; pattern recognition ; neural networks ; flexible manufacturing
    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 A small flexible production cell has been built around a selectively compliant articulated robot arm. Moving on a conveyor belt, boxes marked with different labels are presented to the robot in a random order. Using a camera and a vision card, the labels on the boxes are recognized. Each one of the labels can be rotated, translated or scaled. Three different invariant feature extraction methods (signature, invariant moments of Hu and Zernike) are compared. A neural net is used to classify the labels. The task of the SCARA robot is to pick up the moving boxes and to sort them according to their labels.
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    URL: http://dx.doi.org/10.1023/A:1008088209663
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    Phosphorus fertilizer response in narrow-leafed lupin (Lupinus angustifolius L.) and chickpea (Cicer arietinum) compared to wheat (Triticum aestivum) in early growth (1989)
    Springer
    Nutrient cycling in agroecosystems 19 (1989), S. 1-6 
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    ISSN: 1573-0867
    Keywords: Phosphorus ; lupin ; chickpea ; wheat ; nodulation ; dry matter production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A glasshouse experiment was conducted to examine the comparative growth and P uptake response following P fertilizer application in lupins (Lupinus angustifolius L. cv. Chittick) and chickpeas (Cicer arietinum cv. Tyson) compared to wheat (Triticum aestivum cv. Sunstar). Measurements of dry matter, phosphorus uptake and nodule numbers were made at 50 and 100 days after sowing. At the 50 day harvest, the two legume crops produced less dry matter and accumulated less plant P than wheat but no such species interactions were present at the 100 day harvest. Chickpeas showed strong positive responses in nodule numbers with increasing rates of P fertilizer while such effects were less and more variable with lupins.
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    URL: http://dx.doi.org/10.1007/BF01080679
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    Phosphorus management of a rice-wheat cropping system (1989)
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    Nutrient cycling in agroecosystems 20 (1989), S. 27-32 
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    ISSN: 1573-0867
    Keywords: Cropping system ; phosphorus ; rice ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A long term field experiment was conducted on a sandy loam soil from 1983 to 1987 to determine how to best apply phosphorus fertilizer in a rice-wheat cropping system. The treatments included 9 combinations of phosphorus application either to both rice and wheat or to rice or wheat alone. Direct application of phosphorus at 13 kg/ha to both the crops resulted in significantly higher total productivity of the rice-wheat cropping system as compared with 26 kg P/ha applied either to rice or wheat alone. Phosphorus at 13 kg/ha for rice and 26 kg/ha for wheat was as efficient as 13 kg P/ha for rice and 13 kg P/ha for wheat. The higher rate of P (26 kg/ha) applied to both rice and wheat resulted a decline in the total productivity. The residual effects of phosphorus applied to either rice or wheat were significant to the succeeding crop but was inferior to its direct application. Phosphorus increased the leaf area index, chlorophyll content of leaves, and interception of more photosynthetically active radiation (PAR) which resulted in increased grain yield of rice and wheat. Phosphorus status of the surface soil declined markedly, in the absence of P application from 15.4 to 6.4 kg P/ha. Phosphorus applied at 26 kg P/ha to both the crops resulted a build up of the available P status of soil. Phosphorus application at 13 kg/ha to both rice and wheat maintained the phosphorus status of the soil at original level.
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    URL: http://dx.doi.org/10.1007/BF01055398
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    Nitrogen loss from different tillage systems and the effect on cereal grain yield (1989)
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    Nutrient cycling in agroecosystems 20 (1989), S. 59-66 
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    ISSN: 1573-0867
    Keywords: Ammonia volatilization ; nitrogen leaching ; denitrification ; time of N application ; wheat ; Triticum aestivum ; Triticale ; irrigation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Grain yield, nitrogen (N) assimilation, ammonia (NH3) volatilization, denitrification and fertilizer N distribution were examined in three commercially grown cereal crops; two were sown into conventionally tilled fields, while the third was direct drilled into an untilled field. The crops were top dressed with urea at establishment, tillering or ear initiation. Crop yield and N assimilation were measured in 16 m by 2.5 m plots receiving 0, 35, 70, 105, 140 or 175 kg N ha−1. A mass balance micrometeorological technique was used to measure NH3 volatilization, and other fertilizer N transformations and transfers were studied using15N labelled urea in microplots. On the conventionally tilled sites application of urea increased the grain yield of wheat from 3.9 to 5.5 t ha−1, when averaged over the five application rates, three application times and two sites. There were no site or application time effects. However, on the direct drilled site, time of application had a significant effect on grain yield. When urea was applied at establishment, grain yield was not significantly increased and the mean yield (2.81 t ha−1) was less than that obtained from treatments fertilized at tillering or ear initiation (4.09 and 4.0 t ha−1, respectively). Much of the variation in grain yield at the no-till site could be ascribed to differences in NH3 volatilization. At the no-till site, NH3 losses were equivalent to 24, 12 and 1% of the N applied at establishment, tillering and ear initiation, respectively. Negligible volatilization of NH3 occurred at the other sites. The surface soil at the no-till site had the highest urease activity and the soil was covered with alkaline ash resulting from stubble burning. Plant recovery of fertilizer N did not vary with application time on conventionally tilled sites (mean 62%). However, plant recovery of15N applied to the no-till site at establishment (35% of the applied N) was significantly less than that from plots where the application was delayed (45% at tillering and 55% at ear initiation, respectively). Leaching of N to below 300 mm depth was minimal (0 to 5% of the applied N). The calculated denitrification losses ranged from 1% to 14% of the applied N. The results show that the relative importance of NH3 volatilization, leaching and denitrification varied with site and fertilization time. The importance of the various N loss mechanisms needs to be taken into account when N fertilization strategies are being developed.
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    Evaluation of soil extractants for Mn availability and response of wheat to applied Mn in soils of semi-arid zone of Punjab, India (1999)
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    Nutrient cycling in agroecosystems 53 (1999), S. 139-146 
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    ISSN: 1573-0867
    Keywords: critical levels of Mn ; soil extractants ; Mn-deficiency ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seven chemical extractants were tested for their relative performance to predict the response of wheat to Mn application in coarse textured alkaline soils of semi-arid region. Five out of the seven extractants were found to be promising for the estimation of critical level of available Mn in these soils, as the amount of Mn extracted by these extractants was positively and significantly correlated with relative grain yield as well as Mn uptake. The critical deficiency level of soil available Mn with 0.005 M DTPA, 0.02% hydroquinone, 0.02 N sodium pyrophosphate, 0.1N H3PO4 and 0.05N HCl+0.025N H2SO4 was 3.1, 13.8, 23.5, 5.3 and 17.8 mg kg-1 soil, respectively. The 1N ammonium acetate and 0.01M CaCl2 were found to be unsuitable extractants for these soils. Further field trials at eight locations with varying levels of Mn deficiency showed successive increase in the grain yield of wheat with foliar Mn application, emphasizing the need for Mn fertilization when wheat is grown on Mn deficient soils.
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    New basidiomycetous yeasts from Southern Africa. IV. Sporobolomyces phylladus sp. nov., characterized by the coenzyme Q9 system (Sporobolomycetaceae) (1989)
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    Antonie van Leeuwenhoek 55 (1989), S. 189-195 
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    ISSN: 1572-9699
    Keywords: Sporobolomyces phylladus ; yeasts ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Six strains of an undescribed, leaf-borne species of the genus Sporobolomyces were recovered. A description of the new species, Sporobolomyces phylladus, is given.
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    URL: http://dx.doi.org/10.1007/BF00404758
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    Zygozyma suomiensis, sp. nov. (Lipomycetaceae), a new species from Finland (1989)
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    Antonie van Leeuwenhoek 56 (1989), S. 283-288 
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    ISSN: 1572-9699
    Keywords: Zygozyma suomiensis ; Lipomycetaceae ; yeasts ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new species of the genus Zygozyma, Z. suomiensis, is described, based on the study of a single strain, derived from a bovine skin lesion.
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    URL: http://dx.doi.org/10.1007/BF00418940
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    Coenzyme Q systems in ascomycetous black yeasts (1989)
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    Antonie van Leeuwenhoek 56 (1989), S. 349-356 
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    ISSN: 1572-9699
    Keywords: coenzyme Q ; ubiquinones ; black yeasts ; Exophiala ; Aureobasidium ; Hormonema ; yeast-like fungi ; ascomycetes ; taxonomy ; chemotaxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 72 Strains belonging to 44 species of ascomycetous black yeasts were analyzed for their coenzyme Q systems. Prevalent were Q-10 and dihydrogenated Q-10 systems. Members of the Dothidealean suborder Dothideineae have Q-10 (H2), while those belonging to the suborder Pseudosphaeriineae mostly have Q-10. The anamorph genus Exophiala Carmichael and the teleomorph genus Capronia Sacc. seem to be heterogenous.
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    Influence of within-field and landscape factors on aphid predator populations in wheat (1999)
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    Landscape ecology 14 (1999), S. 239-252 
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    ISSN: 1572-9761
    Keywords: Coccinellidae ; Aphididae ; wheat ; spatial scale ; species diversity ; numerical response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of prey density, within-field vegetation, and the composition and patchiness of the surrounding landscape on the abundance of insect predators of cereal aphids was studied in wheat fields in eastern South Dakota, USA. Cereal aphids, aphid predators, and within-field vegetation were sampled in 104 fields over a three year period (1988–1990). The composition and patchiness of the landscape surrounding each field were determined from high altitude aerial photographs. Five landscape variables, aggregated at three spatial scales ranging from 2.6 km2 to 581 km2, were measured from aerial photographs. Regression models incorporating within-field and landscape variables accounted for 27–49% of the variance in aphid predator abundance in wheat fields. Aphid predator species richness and species diversity were also related to within-field and landscape variables. Some predators were strongly influenced by variability in the composition and patchiness of the landscape surrounding a field at a particular spatial scale while others responded to variability at all scales. Overall, predator abundance, species richness, and species diversity increased with increasing vegetational diversity in wheat fields and with increasing amounts of non-cultivated lands and increasing patchiness in the surrounding landscape.
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    Management of Stored Wheat Insect Pests in the USA (1999)
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    Integrated pest management reviews 4 (1999), S. 127-143 
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    ISSN: 1572-9745
    Keywords: wheat ; stored-grain ; integrated pest management ; aeration ; biological control ; grain sampling ; insect monitoring ; modeling ; area-wide IPM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Management of stored-grain insect pests by farmers or elevator managers should be based upon a knowledge of the grain storage environment and the ecology of insect pests. Grain storage facilities and practices, geographical location, government policies, and marketing demands for grain quality are discussed as factors influencing stored-grain insect pest management decisions in the United States. Typical practices include a small number of grain samples designed to provide grain quality information for segregation, blending and marketing. This low sampling rate results in subjective evaluation and inconsistent penalties for insect-related quality factors. Information on the efficacy of insect pest management practices in the United States, mainly for farm-stored wheat, is discussed, and stored-grain integrated pest management (IPM) is compared to field-crop IPM. The transition from traditional stored-grain insect pest control to IPM will require greater emphasis on sampling to estimate insect densities, the development of sound economic thresholds and decision-making strategies, more selective use of pesticides, and greater use of nonchemical methods such as aeration. New developments in insect monitoring, predictive computer models, grain cooling by aeration, biological control, and fumigation are reviewed, their potential for improving insect pest management is discussed, and future research needs are examined.
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    Learning Complex Tasks Using a Stepwise Approach (1999)
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    Journal of intelligent and robotic systems 24 (1999), S. 43-68 
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    ISSN: 1573-0409
    Keywords: learning robots ; system organization ; optimization ; physical equation ; look-ut table ; neural networks ; fuzzy controllers
    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 This paper explores a stepwise learning approach based on a system's decomposition into functional subsystems. Two case studies are examined: a visually guided robot that learns to track a maneuvering object, and a robot that learns to use the information from a force sensor in order to put a peg into a hole. These two applications show the features and advantages of the proposed approach: i) the subsystems naturally arise as functional components of the hardware and software; ii) these subsystems are building blocks of the robot behavior and can be combined in several ways for performing various tasks; iii) this decomposition makes it easier to check the performances and detect the cause of a malfunction; iv) only those subsystems for which a satisfactory solution is not available need to be learned; v) the strategy proposed for coordinating the optimization of all subsystems ensures an improvement at the task-level; vi) the overall system's behavior is significantly improved by the stepwise learning approach.
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    URL: http://dx.doi.org/10.1023/A:1008058131402
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    Stable Neuro-Adaptive Control for Robots with the Upper Bound Estimation on the Neural Approximation Errors (1999)
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    Journal of intelligent and robotic systems 26 (1999), S. 91-100 
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    ISSN: 1573-0409
    Keywords: robots ; neural networks ; adaptiveness ; stability ; approximation
    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 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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    Genetic Tuning of PID Controllers Using a Neural Network Model: A Seesaw Example (1999)
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    Journal of intelligent and robotic systems 25 (1999), S. 43-59 
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    ISSN: 1573-0409
    Keywords: PID control ; GAs ; neural networks ; multivariable systems
    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 When genetic algorithms (GAs) are applied for PID parameter tuning, since the PID parameters are adjusted almost randomly, it is possible that the plant will be damaged due to abrupt changes in PID parameters. To solve this problem, a neural network will be used to model the plant and the genetic tuning procedure will be performed on the neural network instead of the plant. After determining the PID parameters in this off-line manner, these gains are then applied to the plant for on-line control. Moreover, considering that the neural network model may not be accurate enough, a method is also proposed for on-line fine-tuning of PID parameters. To show the validity of the proposed method, a seesaw system that has one input and two outputs will be used for experimental evaluation
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    Taxonomy and the Personal Equation: The Historical Fates of Charles Girard and Louis Agassiz (1999)
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    Journal of the history of biology 32 (1999), S. 509-555 
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    ISSN: 1573-0387
    Keywords: Louis Agassiz ; Spencer Baird ; Charles Girard ; reputation ; taxonomy ; ichthyology ; Museum of Comparative Zoology ; Smithsonian Institution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , History
    Notes: Abstract The reputations of scientists among their contemporaries depend not only on accomplishment, but also on interactions affected by influence and personality. The historical lore of most fields of scientific endeavor preserve these reputations, often through the identification of founders, innovators, and prolific workers whose contributions are considered fundamental to progress in the field. Historians frequently rely on the historical lore of scientists to guide their studies of the development of ideas, exhibiting justifiable caution in reassessing reputations in the light of current knowledge. However, the transmission of historical lore can obscure the relative importance of accomplishment, influence and personality in shaping contemporary reputations, leaving the historian to either accept reputations at face value or attempt to reconstruct the context in which they were created. The science of taxonomy, because of its rules of priority, leaves a relatively accurate record of historical accomplishment through the persistence of taxa in catalogues and faunal guides. These records allow the modern historian an unbiased means to assess the relative accomplishments of historical figures and therefore a means to critically reassess reputations independent of personality and influence. In the historical lore of North American ichthyology, Louis Agassiz at Harvard and Spencer Baird at the Smithsonian emerge as central figures in the early development of the field during the mid-1800s, contributing not only through the quality and quantity of their science, but also through their roles as institutional leaders and mentors to workers who followed. Charles Girard, originally a student of Agassiz's and later a coworker with Baird, receives little notice in the history of ichthyology, and his reputation is that of a minor player in the initial description of the North American fish fauna, and one whose work appears to have been flawed or even careless when compared to his contemporaries. However, a review of both contemporary and modern taxonomic works reveals that Girard's productivity far exceeded that of either Agassiz or Baird. Furthermore, an examination of the tendency of Girard and his contemporaries to introduce synonymous names into the literature, which might reflect careless or uncritical work, suggests that Girard was among the more accomplished workers of hisera, including Agassiz and Baird. Girard's low ranking in the folklore of North American ichthyology, therefore, can not be attributed to discernible shortcomings in his scientific work, but rather to a public and private campaign of criticism waged by Agassiz after Girard's departure from Harvard. While Agassiz's dispute with Girard stemmed from their personal interactions, he expressed them as criticisms of Girard's work, and thus helped shape Girard's scientific reputation as it has been transmitted through the lore of ichthyology. This case study reveals how scientific reputation may not always rest on accomplishment, but can be influenced by personal interactions obscured by time but nonetheless important to history.
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    An Introduction to Variational Methods for Graphical Models (1999)
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    Machine learning 37 (1999), S. 183-233 
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    ISSN: 0885-6125
    Keywords: graphical models ; Bayesian networks ; belief networks ; probabilistic inference ; approximate inference ; variational methods ; mean field methods ; hidden Markov models ; Boltzmann machines ; neural networks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper presents a tutorial introduction to the use of variational methods for inference and learning in graphical models (Bayesian networks and Markov random fields). We present a number of examples of graphical models, including the QMR-DT database, the sigmoid belief network, the Boltzmann machine, and several variants of hidden Markov models, in which it is infeasible to run exact inference algorithms. We then introduce variational methods, which exploit laws of large numbers to transform the original graphical model into a simplified graphical model in which inference is efficient. Inference in the simpified model provides bounds on probabilities of interest in the original model. We describe a general framework for generating variational transformations based on convex duality. Finally we return to the examples and demonstrate how variational algorithms can be formulated in each case.
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    On the Sample Complexity for Nonoverlapping Neural Networks (1999)
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    Machine learning 37 (1999), S. 131-141 
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    ISSN: 0885-6125
    Keywords: neural networks ; read-once formulas ; threshold gates ; sigmoidal gates ; PAC learning ; Vapnik-Chervonenkis dimension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A neural network is said to be nonoverlapping if there is at most one edge outgoing from each node. We investigate the number of examples that a learning algorithm needs when using nonoverlapping neural networks as hypotheses. We derive bounds for this sample complexity in terms of the Vapnik-Chervonenkis dimension. In particular, we consider networks consisting of threshold, sigmoidal and linear gates. We show that the class of nonoverlapping threshold networks and the class of nonoverlapping sigmoidal networks on n inputs both have Vapnik-Chervonenkis dimension Ω(nlog n). This bound is asymptotically tight for the class of nonoverlapping threshold networks. We also present an upper bound for this class where the constants involved are considerably smaller than in a previous calculation. Finally, we argue that the Vapnik-Chervonenkis dimension of nonoverlapping threshold or sigmoidal networks cannot become larger by allowing the nodes to compute linear functions. This sheds some light on a recent result that exhibited neural networks with quadratic Vapnik-Chervonenkis dimension.
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    Rechnerunterstützung für Interaktionen zwischen Menschen Begriffsklärung, Anwendungsgebiete und Basiswerkzeuge (1999)
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    Informatik-Spektrum 22 (1999), S. 422-435 
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    ISSN: 1432-122X
    Keywords: CSCW ; Groupware ; Teleteaching ; Workflow-Management ; Elektronischer Handel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
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    URL: http://dx.doi.org/10.1007/s002870050149
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    A photosystem II polypeptide is encoded by an open reading frame co-transcribed with genes for cytochrome b-559 in wheat chloroplast DNA (1989)
    Springer
    Plant molecular biology 12 (1989), S. 141-151 
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    ISSN: 1573-5028
    Keywords: chloroplast DNA ; cytochrome b-559 ; photosystem II ; psbL ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The N-terminal amino acid sequence of a 3.2 kDa photosystem II polypeptide is shown to be identical to that of a polypeptide encoded by an open reading frame of 38 codons (orf38) in wheat chloroplast DNA. Orf38 is located just downstream of the psbE and psbF genes for the polypeptides of cytochrome b-559. Analysis of the transcription of this region of chloroplast DNA shows that psbE, psbF and orf38 are co-transcribed to give a 1.1 kb polycistronic transcript which also contains another open reading frame of 40 codons. The orf38 and orf40 products are hydrophobic polypeptides which are both predicted to span the thylakoid membrane once. Orf38 and orf40 are highly conserved, and map to similar locations adjacent to psbE and psbF, in all organisms from which this region of DNA has been sequenced. We propose that orf38 is named psbL.
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    Isolation and nucleotide sequences of cDNA clones encoding ADP-glucose pyrophosphorylase polypeptides from wheat leaf and endosperm (1989)
    Springer
    Plant molecular biology 12 (1989), S. 525-538 
    Details
    ISSN: 1573-5028
    Keywords: ADP-glucose pyrophosphorylase ; cDNAs ; gene organisation ; polypeptides ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA clone (WL : AGA.1) encoding wheat leaf ADP-glucose pyrophosphorylase has been isolated from a λgt11 expression library, by immunological screening with anti-spinach leaf ADP-glucose pyrophosphorylase serum. The WL : AGA.1 cDNA is 948 bp long and contains approximately 55% of the complete wheat leaf ADP-glucose pyrophosphorylase mRNA sequence, estimated from Northern blot experiments. A wheat endosperm cDNA library was subsequently constructed in λgt11 and six clones hybridising to the cDNA insert of clone WL : AGA.1 were isolated. The longest of these wheat endosperm ADP-glucose pyrophosphorylase cDNAs, clone WE : AGA.7, is nearly full-length (1798 bp), indicated by Northern blot analysis of wheat endosperm mRNA and nucleotide sequence analysis. Southern hybridisation analysis and restriction enzyme mapping indicated that the wheat leaf and wheat endosperm ADP-glucose pyrophosphorylase cDNAs and genes are members of two distinct gene families. In addition, restriction enzyme mapping revealed polymorphism in the wheat endosperm ADP-glucose pyrophosphorylase cDNAs, indicating the existence of at least two wheat endosperm ADP-glucose pyrophosphorylase gene sub-families. Subsequent nucleotide sequence analysis indicates that there is approximately 55% identity between wheat leaf and wheat endosperm ADP-glucose pyrophosphorylase cDNAs. In contrast, members of each sub-family of endosperm cDNA, represented by clones WE : AGA.3 and WE : AGA.7, are 96% identical.
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    Transient gene expression in aleurone protoplasts isolated from developing caryopses of barley and wheat (1989)
    Springer
    Plant molecular biology 13 (1989), S. 21-29 
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    ISSN: 1573-5028
    Keywords: aleurone ; barley ; protoplasts ; transient expression ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Methods have been developed for the isolation of aleurone protoplasts from developing caryopses of Hordeum vulgare and Triticum aestivum in order to study transient expression of introduced genes. Chimaeric gene constructs were introduced into aleurone protoplasts by polyethylene glycol (PEG). Transient expression directed by the 35S promoter from cauliflower mosaic virus (CaMV) of the reporter gene encoding chloramphenicol acetyl transferase (CAT) was detected in aleurone protoplasts from developing barley and wheat grains. Using a similar construct, CAT activity increased when the alcohol dehydrogenase intron 1 fragment from maize was ligated between the 35S promoter and the CAT coding region. The demonstration of transient expression in protoplasts from developing aleurone layers indicates that they may be useful for investigating tissue and developmental control of genes coding for cereal seed proteins.
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    Comparison of the wheat mitochondrial atp9 gene sequence with mitochondrial and chloroplast homologues from other plants (1989)
    Springer
    Plant molecular biology 13 (1989), S. 395-397 
    Details
    ISSN: 1573-5028
    Keywords: F1F0 ATPase ; chloroplast coupling factor ; mitochondrial gene ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1007/BF00015551
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    Mycena auricoma, a new species ofMycena sectionRadiatae from Japan, andMycena spinosissima, a new record in Japan (1999)
    Springer
    Mycoscience 40 (1999), S. 73-80 
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    ISSN: 1618-2545
    Keywords: Mycena auricoma ; Mycena sect.Radiatae ; Mycena spinosissima ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two lignicolous species ofMycena (Agaricales, Basidiomycetes) are described and illustrated from eastern, Japan:Mycena auricoma sp. nov., forming ephemeral coprinoid basidiomata and belonging to sectionRadiatae, was found on a dead fallen twig ofQuercus serrata. It appears to close to a Malaysian species,“Trogia” crinipelliformis. Mycena spinosissima in sectionSacchariferae, new to Japan, was collected from dead bark ofAphananthe aspera, a dead fallen inflorescence ofCryptomeria japonica, and a dead fallen twig ofQuercus serrata.
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    Macrocyst formation in three dictyostelid species,Dictyostelium monochasioides, Polysphondylium candidum, andP. pseudo-candidum (1999)
    Springer
    Mycoscience 40 (1999), S. 359-361 
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    ISSN: 1618-2545
    Keywords: cellular slime molds ; dictyostelids ; macrocyst ; mating system ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Macrocyst formation in the sexual cycle was found in three dictyostelid species:Dictyostelium monochasioides, Polysphondylium candidum, andP. pseudo-candidum. Mating tests suggested thatD. monochasioides andP. pseudocandidum were heterothallic andP. candidum was homothallic. The primary walls of macrocysts had partially or fully degenerated, while the inner walls, believed to be tertiary walls, showed an undulate structure.
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    Spatial conferencing using a wearable computer (1999)
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    Personal and ubiquitous computing 3 (1999), S. 72-80 
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    ISSN: 1617-4917
    Keywords: Augmented reality ; Collaboration ; CSCW ; Wearable computers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Wearable computers provide constant access to computing and communications resources; however, there are many unanswered questions as to how this computing power can be used to enhance communication. We describe a wearable augmented reality communication space that uses spatialised 3D graphics and audio cues to aid communication. The user is surrounded by virtual avatars of the remote collaborators that they can interact with using natural head and body motions. The use of spatial cues means that the conferencing space can potentially support dozens of simultaneous users. We report on two experiments that show users can understand speakers better with spatial rather than non-spatial audio, and that minimal visual cues may be sufficient to distinguish between speakers. Additional informal user studies with real conference participants suggest that wearable communication spaces may offer significant advantages over traditional communication devices.
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    The new media paradigm: Users as creators of content (1999)
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    Personal and ubiquitous computing 3 (1999), S. 153-159 
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    ISSN: 1617-4917
    Keywords: Immersive ; Participatory ; Media ; Communication ; Internet ; Virtual reality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Increasingly, computers are being used just for fun. Computer-based entertainment titles and Internet usage are now the main factors driving computer sales in the both the US and European markets. Games, specialised entertainment web sites, personal creativity, online chat and similar leisure pursuits are the dominant interests of young users. This paper explores how these activities are foreshadowing a change in media attitudes which is currently under way. This change is traceable through a series of transitions in how we perceive the media, entertainment experiences and our own roles in relation to them, transitions that are both guiding and following the evolution of the technology itself. These transitions in public perception will lead to a fundamentally different form of media, one which directly engages users, allowing them to take active, enjoyable roles in co-creating the new media esperience. This paper also briefly introduces work under way at Cambridge University's Centre for Communications Systems Research, which is aimed at addressing these events by developing systems that will allow future users to take full advantage of the unfolding possibilities.
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    Using digital but physical surrogates to mediate awareness, communication and privacy in media spaces (1999)
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    Personal and ubiquitous computing 3 (1999), S. 182-198 
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    ISSN: 1617-4917
    Keywords: Ambient displays ; Awareness ; Casual interaction ; CSCW ; Groupware ; Tangible bits ; Ubiquitous media spaces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Digital but physical surrogates are tangible representations of remote people (typically members of small intimate teams), positioned within an office and under digital control. Surrogates selectively collect and present awareness information about the people they represent. They also react to people's explicit and implicit physical actions: a person's explicit acts include grasping and moving them, while their implicit acts include how they move towards or away from the surrogate. By responding appropriately to these physical actions of people, surrogates can control the communication capabilities of a media space in a natural way. Surrogates also balance awareness and privacy by limiting and abstracting how activities are portrayed, and by offering different levels of salience to its users. The combination of all these attributes means that surrogates can make it easy for intimate collaborators to move smoothly from awareness of each other to casual interaction while mitigating privacy and distraction concerns. Exploring different surrogate designs and how they work together can be straightforward if a good infrastructure is in place. We use anawareness server based on a distributed model-view-controller architecture, which automatically captures, stores and distributes events. We also package surrogates as physical widgets orphidgets with a well-defined interface; this makes it easy for a programmer to plug a surrogate into the awareness server as a controller (to generate awareness events), or view (to display events that others have produced), or both. Because surrogate design, implementation and use is still a new discipline, we also present several issues and next steps.
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    Cryptophiale sphaerospora sp. nov. occurring onJanetia synnematosa (1999)
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    Mycoscience 40 (1999), S. 189-191 
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    ISSN: 1618-2545
    Keywords: bamboo fungus ; hyperparasitism ; hyphomycetes ; mycoparasites ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cryptophiale sphaerospora sp. nov. is described and illustrated based on a single collection attached to a synnematous fungus,Janetia synnematosa, from a dead bamboo culm. It differs from other species ofCryptophiala in having spherical to subspherical conidia and a cerebroid layer of phialides. The overall morohology of this species is smaller than that of previously described species.
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    Trichome structure of fourAphanizomenon taxa (Cyanophyceae) from Czechoslovakia, with notes on the taxonomy and delimitation of the genus (1989)
    Springer
    Plant systematics and evolution 164 (1989), S. 47-64 
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    ISSN: 1615-6110
    Keywords: Cyanophyta ; Cyanophyceae ; Nostocales ; Nostocaceae ; Aphanizomenon ; Anabaena ; Morphology ; morphometry ; variation ; trichome structure ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dimension and variation range of terminal and intercalary cells, heterocysts, and akinetes of fourAphanizomenon taxa occurring in Czechoslovakia were studied. Statistical and graphical procedures were used for evaluation. With regard toA. flos-aquae, the results support the distinction of two varieties (var.flos-aquae and var.klebahnii). In the samples determined asA. gracile two clearly distinguishable morphological types could be found; one of them is recognized as a new species:A. flexuosum. Its diacritical features are established and problems of the intrageneric taxonomy ofAphanizomenon and its demarcation from the genusAnabaena are discussed.
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    Cladistic analyses of some net-veinedLiliiflorae (1989)
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    Plant systematics and evolution 168 (1989), S. 123-141 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Liliiflorae ; Liliales ; Dioscoreales ; Asparagales ; Cladistics ; relationships ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Comparisons between previous intuitive or phenetic classifications of the netveinedLiliiflorae was used to determine a suitable group of taxa for cladistic analyses. The resultant 48 genera and generic groupings comprising 19 families from within theAsparagales, Liliales andDioscoreales were then analysed. The cladistics largely supported previous treatments, with theLiliales, Dioscoreales andAsparagales all monophyletic.
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    Taxonomic and functional implications of stigma morphology in species ofCassia, Chamaecrista, andSenna (Leguminosae:Caesalpinioideae) (1989)
    Springer
    Plant systematics and evolution 163 (1989), S. 93-105 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Leguminosae (Fabaceae) ; Caesalpinioideae (Caesalpiniaceae) ; Cassia ; Chamaecrista ; Senna ; Stigma morphology ; taxonomy ; floral ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two stigma forms occur inChamaecrista andSenna, but only one inCassia. In the common chambered form, a stigma pore is positioned on the reflexed style tip and is the entrance to a tapering chamber. The pore rim is fringed by hairs which vary in number, size, distribution and shape. In the alternative form the stigma is situated at the apex of the curved style and is crateriform. The crater rim is fringed by hairs of variable number and shape. The stigmatic hairs are predominantly unicellular and cutinized. Stigma and hair differences aid in the taxonomy of the genera. Their functions in pollination biology are discussed.
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    DNA divergency and speciation inSymbiodinium (Dinophyceae) (1989)
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    Plant systematics and evolution 163 (1989), S. 153-163 
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    ISSN: 1615-6110
    Keywords: Algae ; Dinophyceae ; Gymnodiniales ; Gymnodiniaceae ; Symbiodinium ; S. microadriaticum subsp.condylactis ; subsp. nov. ; DNA ; hybridization ; karyotypes ; phenotypes ; symbiosis ; taxonomy ; zooxanthellae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Relationship among symbiotic dinoflagellates of the genusSymbiodinium derived from seven different host species has been studied by means of DNA/DNA hybridization. DNA homologies range from about 70 to 30%D. Highest homology is regarded as subspecific level. Based on the characteristics of DNA and phenotypes,Symbiodinium microadriaticum subsp.microadriaticum is separated fromSymbiodinium microadriaticum subsp.condylactis. Lowest homology occurs at the methodical background, and is similar to that obtained with DNA of algae belonging to different classes. The data are in excellent agreement with DNA base composition, karyotypes, and morpohological as well as biochemical markers, emphasizing speciation among these gymnodinioid zooxanthellae.
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    Morphology, biology, and systematics ofCryptochlora perforans (Chlorarachniophyta), a phagotrophic marine alga (1989)
    Springer
    Plant systematics and evolution 163 (1989), S. 165-176 
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    ISSN: 1615-6110
    Keywords: Algae ; Chlorarachniophyta ; Cryptochlora perforans ; Biology ; taxonomy ; phylogeny ; inter-specific relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The life cycle ofCryptochlora perforans is described under culture conditions, including the following stages: Naked and walled amoebae, cysts, coccoid, palmelloid and flagellate stages. Phagotrophy of living diatoms, movement and reproduction are documented. Amoebae ofCryptochlora are chemotactically attracted by damaged algal filaments, perforate and penetrate such filaments, and subsequently engulf part of their contents. A comparison is made with a culture ofChlorarachnion reptans Geitler, according to earlier and own observations. Chloroplast structure as well as zoospore morphology confirm close affinities betweenCryptochlora andChlorarachnion. Generic characters as well as possible phylogenetic affinities with amoeboidXanthophyta andProtozoa are discussed.
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    A molecular phylogeny of bryophytes based on nucleotide sequences of the mitochondrialnad5 gene (1999)
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    Plant systematics and evolution 218 (1999), S. 179-192 
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    ISSN: 1615-6110
    Keywords: Bryophyta ; Mitochondria ; nad5 gene ; group I intron ; molecular phylogeny ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In contrast to animals, the slowly evolving mitochondrial nucleotide sequences of plants appear well suited to investigate phylogenetic relations between old taxonomic groups. Analysis ofnad5 gene sequences in 47 bryophytes, the living representatives of very early land plants, confirm this assessment. Statistically reliable phylogenetic trees are obtained with different mathematical approaches. A group I intron sequence conserved in thenad5 gene of all 30 mosses and 15 liverworts investigated supports a sister group relationship of the two classes. The intron sequence adds phylogenetic information for fine resolution on top of the conserved exon sequences down to the level of classically defined orders or families, respectively. This intron is not present in the hornwortsAnthoceros husnotii andA. punctatus. The results allow statements on diverging taxonomic interpretations and support the monophyly of the liverworts, mosses, Jungermanniidae, Marchantiidae and Bryidae, and allow recognition of subclasses like Hypnanae and Dicrananae. Among the mosses, the derived orders (subclass Bryidae) are confidently set apart from the Sphagnales, Andreaeales, Polytrichales and Tetraphidales with Buxbaumiales occupying a mediating position. Among the liverworts, full support is found for the classic separation of simple (jungermanniid) and complex thalloid (marchantiid) species with a strikingly low mitochondrial sequence divergence among the latter.
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    An evaluation of characters obtained from life history studies for distinguishing New Zealand Porphyra species (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 411-419 
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    ISSN: 1573-5176
    Keywords: Bangiales ; Porphyra life history ; culture ; conchocelis ; conchosporangia ; spores ; neutral conchospores morphology ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Since 1992, as part of a study to circumscribe the genus Porphyra in New Zealand, an extensive culture programme has been developed at the Museum of New Zealand Te Papa Tongarewa. This collection currently houses more than 800 cultures and 150strains. We currently recognise at least 20 species in New Zealand, most of which are undescribed. Close observation of reproduction and the development of conchocelis-phase filaments grown in the laboratory, under controlled conditions of temperature, irradiance and photoperiod, has enabled the recognition of characters that can assist in species separation. The comparative taxonomic value of a range of such characters is discussed, including reporting a novel reproductive mode.
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    Distribution and population dynamics of Porphyra (Bangiales, Rhodophyta) in the southern Western Cape, South Africa (1999)
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    Journal of applied phycology 11 (1999), S. 429-436 
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    ISSN: 1573-5176
    Keywords: distribution ; harvesting ; Porphyra ; recruitment ; seasonality ; South Africa ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although Porphyra is commercially farmed in many countries, in South Africa only small harvests of wild populations for sale as nori have been carried out. The discovery that Porphyra improves growth of South African abalone (Haliotis midae) farmed inland-based tanks has led to increased pressure to harvest wild populations. This paper reports on a survey of the distribution and seasonality of Porphyra in the southern Western Cape. Porphyrawas present at all sites surveyed, and showed considerable temporal variation. A significant amount of the Porphyra present is in reserves and therefore protected from harvesting. Close rexamination of one site revealed seasonal populations of Porphyra that occupied different niches dependent on season. Recruitment peaked in spring and autumn, leading to dense summer and winter populations. Summer populations generally grew lower in the eulittoral than winter populations. No pattern in the mortality of larger thalli wasde tected, though sporeling mortality was high following recruitment peaks. Although it seems that most sites in the southern Western Cape are suitable for harvesting, the taxonomy of the genus in the region urgently needs revision if populations are to be appropriately managed.
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    The generaAniptodera, Halosarpheia, Nais andPhaeonectriella from freshwater habitats (1999)
    Springer
    Mycoscience 40 (1999), S. 165-183 
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    ISSN: 1618-2545
    Keywords: freshwater fungi ; Halosphaeriaceae ; taxonomy ; tropics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The generic concepts inAniptodera, Halosarpheia, Nais andPhaeonectriella are discussed and those species occurring in freshwater are described, some with illustrations. Five new species:Aniptodera lignicola, A. mauritaniensis, A. megalospora, A. palmicola, Phaeonectriella appendiculata are also described. A key to the freshwater species in the above genera and a synoptic diagram of their ascospores are provided.
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    Dactylospora mangrovei sp. nov. (Discomycetes, ascomycota) from mangrove wood (1999)
    Springer
    Mycoscience 40 (1999), S. 317-320 
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    ISSN: 1618-2545
    Keywords: Ascomycota ; marine fungi ; new species ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new speciesDactylospora mangrovei is described and illustrated and compared withD. haliotrepha andD. canariensis, all marine inhabiting species.Dactylospora haliotrepha andD. mangrovei are tropical/sub-tropical mangrove species collected in Hong Kong, Malaysia, Taiwan and Thailand, whileD. canariensis was described from temperate waters. A map of the geographical distribution of the three marineDactylospora species is presented.
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    Arecophila bambusae sp. nov. andA. coronata comb. nov., from dead culms of bamboo (1999)
    Springer
    Mycoscience 40 (1999), S. 185-188 
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    ISSN: 1618-2545
    Keywords: Amphisphaeria ; ascomycetes ; bamboo fungi ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new species ofArecophila and a species previously known asAmphisphaeria coronata are described and illustrated from dead culms of bamboo.Arecophila bambusae sp. nov. is distinct in the genus in having ellipsoidal ascospores with slightly round ends, and asci with a narrow subapical ring.Arecophila coronata comb. nov. has asci with a wedgeshaped apical ring and weakly striated ascospores enclosed in wide mucilaginous sheath.
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    Basic equations, theory and principles of computational stock market (II) —Basic principles (1999)
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    Applied mathematics and mechanics 20 (1999), S. 721-728 
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    ISSN: 1573-2754
    Keywords: Saint-Venant's principle ; variational principles ; neural networks ; computational stock market ; F224.9
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract In this paper, three basic principles for computational stock market are proposed namely, “the Nearest-Time Principle” (NTP), “the Following Tendency Principle” (FTP), and “the Variational Principle on Difference of Supply and Demand” (VPDSD). The issue, expression, mathematical description and applications of these principles are stated. These applications involve the use in neural networks, basic equations of computational stock market, and the prediction of equilibrium price of stocks etc.
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    Mapping loci associated with milling yield in wheat (Triticum aestivum L.) (1999)
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    Molecular breeding 5 (1999), S. 561-568 
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    ISSN: 1572-9788
    Keywords: wheat ; milling yield ; QTL mapping ; RFLP ; microsatellite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A partial genetic linkage map constructed using 150 single seed descent (SSD) lines generated from a cross between the hexaploid wheat varieties ‘Schomburgk’ and ‘Yarralinka’ was used to identify loci controlling milling yield. Milling yield data were obtained using seed collected from field trials conducted at different sites over two seasons. The estimated broad-sense heritability of milling yield in this population was calculated as 0.48. In the preliminary analysis, two regions were identified on chromosomes 3A and 7D, which were significantly associated with milling yield and accounted for 22% and 19% of the genetic variation, respectively. Bulked segregant analysis in combination with AFLP identified other markers linked to these loci, as well as an additional region on chromosome 5A, which accounted for 19% of the genetic variation. The applicability of these markers as selection tools for breeding purposes is discussed.
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    URL: http://dx.doi.org/10.1023/A:1009678023431
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    Expression of the insecticidal lectin from snowdrop (Galanthus nivalis agglutinin; GNA) in transgenic wheat plants: effects on predation by the grain aphid Sitobion avenae (1999)
    Springer
    Molecular breeding 5 (1999), S. 65-73 
    Details
    ISSN: 1572-9788
    Keywords: insect resistance ; aphids ; GNA ; lectins ; transgenic plants ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Transgenic wheat plants containing the gene encoding snowdrop lectin (Galanthus nivalis agglutinin; GNA) under the control of constitutive and phloem-specific promoters were generated through the particle bombardment method. Thirty-two independently derived plants were subjected to molecular and biochemical analyses. Transgene integration varied from one to twelve estimated copies per haploid genome, and levels of GNA expression from 0 to ca. 0.2% of total soluble protein were observed in different transgenic plants. Seven transgenic plants were selected for further study. Progeny plants from these parental transformants were selected for transgene expression, and tested for enhanced resistance to the grain aphid (Sitobion avenae) by exposing the plants to nymphal insects under glasshouse conditions. Bioassay results show that transgenic wheat plants from lines expressing GNA at levels greater than ca. 0.04% of total soluble protein decrease the fecundity, but not the survival, of grain aphids. We propose that transgenic approaches using insecticidal genes such as gna in combination with integrated pest management present promising opportunities for the control of damaging wheat pests.
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    URL: http://dx.doi.org/10.1023/A:1009616413886
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    Identification of molecular markers for the detection of the yellow rust resistance gene Yr17 in wheat (1999)
    Springer
    Molecular breeding 5 (1999), S. 167-175 
    Details
    ISSN: 1572-9788
    Keywords: wheat ; DNA markers ; yellow rust resistance ; Yr17
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The Yr17 gene, which is present in many European wheat cultivars, displays yellow rust resistance at the seedling stage. The gene introduced into chromosome 2A from Aegilops ventricosa was previously found to be closely linked (0.5 cM) to leaf and stem rust resistance genes Lr37 and Sr38, respectively. The objective of this study was to identify molecular markers linked to the Yr17 gene. We screened with RAPD primers, for polymorphism, the DNAs of cv. Thatcher and the leaf rust-resistant near-isogenic line (NIL) RL 6081 of cv. Thatcher carrying the Lr37 gene. Using a F2 progeny of the cross between VPM1 (resistant) and Thésée (susceptible), the RAPD marker OP-Y15580 was found to be closely linked to the Yr17 gene. We converted the OP- Y15580 RAPD marker into a sequence characterized amplified region (SCAR). This SCAR marker (SC-Y15) was linked at 0.8 ± 0.7 cM to the Yr17 resistance gene. We tested the SC-Y15 marker over a survey of 37 wheat cultivars in order to verify its consistency in different genetic backgrounds and to explain the resistance of some cultivars against yellow rust. Moreover, we showed that the Xpsr150-2Mv locus marker of Lr gene described by Bonhomme et al. [6] which possesses A. ventricosa introgression on the 2A chromosome was also closely linked to the Yr17 gene. Both the SCAR SC-Y15 and Xpsr150-2Mv markers should be used in breeding programmes in order to detect the cluster of the three genes Yr17, Lr37 and Sr38 in cross progenies.
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    URL: http://dx.doi.org/10.1023/A:1009672021411
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    Measures of variability for geological data (1989)
    Springer
    Mathematical geology 21 (1989), S. 233-254 
    Details
    ISSN: 1573-8868
    Keywords: Compositional data ; locational data ; replicate data ; statistics ; taxonomy ; topography ; variance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Diverse global and local measures of variability appear in the geological literature and, along with methods used to apply them, have been subject to some debate. Measures of variability for three data types—replicate, locational, and compositional—are considered; the source and nature of the variability determine the appropriate type of measure. To illustrate the effects of these measures and expose their inadequacy when improperly applied, the variability of a three-column data set is interpreted under three different suppositions. Geologists need to be aware of the confusion and misleading results that can develop from the use of variance as a measure of variability for locational or compositional data.
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    URL: http://dx.doi.org/10.1007/BF00893217
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    Neural Networks and Structured Knowledge: Knowledge Representation and Reasoning (1999)
    Springer
    Applied intelligence 11 (1999), S. 5-13 
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    ISSN: 1573-7497
    Keywords: neural networks ; knowledge representation ; structured knowledge reasoning ; connectionism ; symbol processing ; hybrid systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This collection of articles is the first of two parts of a special issue on “Neural Networks and Structured Knowledge.” The contributions to the first part shed some light on the issues of knowledge representation and reasoning with neural networks. Their scope ranges from formal models for mapping discrete structures like graphs or logical formulae onto different types of neural networks, to the construction of practical systems for various types of reasoning. In the second part to follow, the emphasis will be on the extraction of knowledge from neural networks, and on applications of neural networks and structured knowledge to practical tasks.
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    Comparing Structures Using a Hopfield-Style Neural Network (1999)
    Springer
    Applied intelligence 11 (1999), S. 15-30 
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    ISSN: 1573-7497
    Keywords: neural networks ; structured objects ; machine learning ; classification ; similarity ; nearest neighbor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Labeled graphs are an appropriate and popular representation of structured objects in many domains. If the labels describe the properties of real world objects and their relations, finding the best match between two graphs turns out to be the weakly defined, NP-complete task of establishing a mapping between them that maps similar parts onto each other preserving as much as possible of their overall structural correspondence. In this paper, former approaches of structural matching and constraint relaxation by spreading activation in neural networks and the method of solving optimization tasks using Hopfield-style nets are combined. The approximate matching task is reformulated as the minimization of a quadratic energy function. The design of the approach enables the user to change the parameters and the dynamics of the net so that knowledge about matching preferences is included easily and transparently. In the last section, some examples demonstrate the successful application of this approach in classification and learning in the domain of organic chemistry.
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    URL: http://dx.doi.org/10.1023/A:1008320413168
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    Visualizing Common Artefacts to Support Awareness in Computer-Mediated Cooperation (1999)
    Springer
    Computer supported cooperative work 8 (1999), S. 207-238 
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    ISSN: 1573-7551
    Keywords: awareness ; common artefact ; CSCW ; distortion ; notification ; state presentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract The idea of a “common artefact” is a useful metaphor for the design of CSCW systems. Our ACCT model of a common artefact describes structural elements that provide awareness about the work of others. The ACCT model identifies actors, contents, conversations, and tools as the central components of a common artefact, arranged on a shared background. The elements of a common artefact provide both a background visualization of the activity, but also permit dynamic notification of particular events. We explore this process of notification, which is composed of a selection and a presentation stage. We identify the critical factors of the process, in particular we highlight techniques related to temporal and spatial distortion. The framework helps to prepare design decisions of multi-user systems more consciously.
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    URL: http://dx.doi.org/10.1023/A:1008608425504
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    Exploiting Hierarchy in Text Categorization (1999)
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    Information retrieval 1 (1999), S. 193-216 
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    ISSN: 1573-7659
    Keywords: information retrieval ; text mining ; topic spotting ; text categorization ; knowledge management ; problem decomposition ; machine learning ; neural networks ; probabilistic models ; hierarchical models ; performance evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract With the recent dramatic increase in electronic access to documents, text categorization—the task of assigning topics to a given document—has moved to the center of the information sciences and knowledge management. This article uses the structure that is present in the semantic space of topics in order to improve performance in text categorization: according to their meaning, topics can be grouped together into “meta-topics”, e.g., gold, silver, and copper are all metals. The proposed architecture matches the hierarchical structure of the topic space, as opposed to a flat model that ignores the structure. It accommodates both single and multiple topic assignments for each document. Its probabilistic interpretation allows its predictions to be combined in a principled way with information from other sources. The first level of the architecture predicts the probabilities of the meta-topic groups. This allows the individual models for each topic on the second level to focus on finer discriminations within the group. Evaluating the performance of a two-level implementation on the Reuters-22173 testbed of newswire articles shows the most significant improvement for rare classes.
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    URL: http://dx.doi.org/10.1023/A:1009983522080
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    A Re-Engineering, Methodology for Cooperative Management of Enterprise Networks (1999)
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    Journal of network and systems management 7 (1999), S. 105-126 
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    ISSN: 1573-7705
    Keywords: ENTERPRISE NETWORKS ; CSCW ; NETWORK AND SYSTEMS MANAGEMENT ; REENGINEERING ; MANAGEMENT PROCESSES
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract With the increasing implementation by networkedmission-critical applications, an enterprise network isbecoming the lifeline of an organization. Massiveinvestments are being made in the modernization of enterprise networks of diverse serviceorganizations, such as telecommunications andhealth-care providers. Organizations need to adapt tochanging business environment, such as the deregulationof telecommunication services. This necessitates a seamlessintegration of business management processes withenterprise network management processes. Hence there isa need for the formulation of new methodologies for there-engineering of management solutions (with focus onintegrated business processes), though most present daysolutions concentrate on the management of networkequipment only. This paper presents a new methodologyfor the reengineering of the management processesfor enterprise networks, based on Computer SupportedCooperative Work (CSCW) techniques.
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    URL: http://dx.doi.org/10.1023/A:1018769917171
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    Medical Data Mining on the Internet: Research on a Cancer Information System (1999)
    Springer
    Artificial intelligence review 13 (1999), S. 437-466 
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    ISSN: 1573-7462
    Keywords: CancerLit ; concept spaces ; data mining ; Hopfield net ; information retrieval ; Kohonen net ; medical knowledge ; neural networks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper discusses several data mining algorithms and techniques thatwe have developed at the University of Arizona Artificial Intelligence Lab.We have implemented these algorithms and techniques into severalprototypes, one of which focuses on medical information developed incooperation with the National Cancer Institute (NCI) and the University ofIllinois at Urbana-Champaign. We propose an architecture for medicalknowledge information systems that will permit data mining across severalmedical information sources and discuss a suite of data mining tools that weare developing to assist NCI in improving public access to and use of theirexisting vast cancer information collections.
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    A Hybrid Architecture for Situated Learning of Reactive Sequential Decision Making (1999)
    Springer
    Applied intelligence 11 (1999), S. 109-127 
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    ISSN: 1573-7497
    Keywords: hybrid models ; sequential decision making ; neural networks ; reinforcement learning ; cognitive modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In developing autonomous agents, one usually emphasizes only (situated) procedural knowledge, ignoring more explicit declarative knowledge. On the other hand, in developing symbolic reasoning models, one usually emphasizes only declarative knowledge, ignoring procedural knowledge. In contrast, we have developed a learning model CLARION, which is a hybrid connectionist model consisting of both localist and distributed representations, based on the two-level approach proposed in [40]. CLARION learns and utilizes both procedural and declarative knowledge, tapping into the synergy of the two types of processes, and enables an agent to learn in situated contexts and generalize resulting knowledge to different scenarios. It unifies connectionist, reinforcement, and symbolic learning in a synergistic way, to perform on-line, bottom-up learning. This summary paper presents one version of the architecture and some results of the experiments.
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    A Neural Network Diagnosis Approach for Analog Circuits (1999)
    Springer
    Applied intelligence 11 (1999), S. 169-186 
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    ISSN: 1573-7497
    Keywords: neural networks ; multiple fault diagnosis ; analog circuits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper presents a neural network system for the diagnosis of analog circuits and shows how the performance of such a system can be affected by the choice of different techniques used by its submodules. In particular we discuss the influence of feature extraction techniques such as Fourier Transforms, Wavelets and Principal Component Analysis. The system uses several different power supplies and as many neural networks “in parallel”. Two different algorithms that can be used to combine the candidate sets produced by each network are also presented. The system is capable of diagnosing multiple faults even if trained on single ones.
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    A New Symmetric Probabilistic Encryption Scheme Based on Chaotic Attractors of Neural Networks (1999)
    Springer
    Applied intelligence 10 (1999), S. 71-84 
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    ISSN: 1573-7497
    Keywords: encryption ; chaotic attractors ; neural networks ; symmetric-key
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A new probabilistic symmetric-key encryption scheme based on chaotic-classified properties of Hopfield neural networks is described. In an overstoraged Hopfield Neural Network (OHNN) the phenomenon of chaotic-attractors is well documented and messages in the attraction domain of an attractor are unpredictably related to each other. By performing permutation operations on the neural synaptic matrix, several interesting chaotic-classified properties of OHNN were found and these were exploited in developing a new cryptography technique. By keeping the permutation operation of the neural synaptic matrix as the secret key, we introduce a new probabilistic encryption scheme for a symmetric-key cryptosystem. Security and encryption efficiency of the new scheme are discussed.
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    URL: http://dx.doi.org/10.1023/A:1008337631906
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    Fusion Via a Linear Combination of Scores (1999)
    Springer
    Information retrieval 1 (1999), S. 151-173 
    Details
    ISSN: 1573-7659
    Keywords: linear combination ; fusion ; neural networks ; routing ; performance evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract We present a thorough analysis of the capabilities of the linear combination (LC) model for fusion of information retrieval systems. The LC model combines the results lists of multiple IR systems by scoring each document using a weighted sum of the scores from each of the component systems. We first present both empirical and analytical justification for the hypotheses that such a model should only be used when the systems involved have high performance, a large overlap of relevant documents, and a small overlap of nonrelevant documents. The empirical approach allows us to very accurately predict the performance of a combined system. We also derive a formula for a theoretically optimal weighting scheme for combining 2 systems. We introduce d—the difference between the average score on relevant documents and the average score on nonrelevant documents—as a performance measure which not only allows mathematical reasoning about system performance, but also allows the selection of weights which generalize well to new documents. We describe a number of experiments involving large numbers of different IR systems which support these findings.
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    Sharrock and Button ... and Much Ado about Nothing (1999)
    Springer
    Computer supported cooperative work 8 (1999), S. 285-293 
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    ISSN: 1573-7551
    Keywords: CSCW ; critical theory ; deconstruction ; ideal speech situation ; social action theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract The paper discusses Sharrock's and Button's criticism of our attempt to use Habermas' communicative action theory to analyze group work platforms. We demonstrate that they misconstrue our goals of the paper, misinterpret our analysis of Habermas' action types, and misunderstand the concept of critical science. At the end we question the usefulness of these types of debates in furthering CSCW research.
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    URL: http://dx.doi.org/10.1023/A:1008720609782
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    The Invisible World of Intermediaries: A Cautionary Tale (1999)
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    Computer supported cooperative work 8 (1999), S. 147-167 
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    ISSN: 1573-7551
    Keywords: CSCW ; electronic commerce ; intermediary ; digital library ; electronic community ; costomer support ; librarians ; notes ; trust
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Many observers consider traditional intermediaries such as brokers, lenders and salespersons anachronisms in a world where consumers can communicate directly with providers of products and services over computer networks. Under the same rubric, information mediators such as journalists, editors, librarians and customer support representatives are being targeted for elimination. Drawing on our ethnographically-informed studies of customer support analysts and librarians, we demonstrate that the expertise and experience of intermediaries is often invisible – to the consumer, to the organization in which these intermediaries work, and even to the intermediaries' managers. The valuable services provided by intermediaries are not made unnecessary by end-user access. We argue for a richer understanding of intermediation, and a reallocation of functions and roles in which “new intermediaries” – people, software or a combination of the two – aggregate, personalize and assure the quality of information.
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    Neural Networks in Non-Euclidean Spaces (1999)
    Springer
    Neural processing letters 10 (1999), S. 201-210 
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    ISSN: 1573-773X
    Keywords: neural networks ; learning ; minimal distance methods ; similarity-based methods ; machine learning ; interpretation of neural functions ; classification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Multilayer Perceptrons (MLPs) use scalar products to compute weighted activation of neurons providing decision borders using combinations of soft hyperplanes. The weighted fun-in activation function may be replaced by a distance function between the inputs and the weights, offering a natural generalization of the standard MLP model. Non-Euclidean distance functions may also be introduced by normalization of the input vectors into an extended feature space. Both approaches influence the shapes of decision borders dramatically. An illustrative example showing these changes is provided.
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    A New Relaxation Procedure in the Hopfield Network for Solving Optimization Problems (1999)
    Springer
    Neural processing letters 10 (1999), S. 211-222 
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    ISSN: 1573-773X
    Keywords: constraint satisfaction ; Hopfield network ; neural networks ; optimization ; relaxation procedure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract When solving an optimization problem with a Hopfield network, a solution is obtained after the network is relaxed to an equilibrium state. The relaxation process is an important step in achieving a solution. In this paper, a new procedure for the relaxation process is proposed. In the new procedure, the amplified signal received by a neuron from other neurons is treated as the target value for its activation (output) value. The activation of a neuron is updated directly based on the difference between its current activation and the received target value, without using the updating of the input value as an intermediate step. A relaxation rate is applied to control the updating scale for a smooth relaxation process. The new procedure is evaluated and compared with the original procedure in the Hopfield network through simulations based on 200 randomly generated instances of the 10-city traveling salesman problem. The new procedure reduces the error rate by 34.6% and increases the percentage of valid tours by 194.6% as compared with the original procedure.
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    Performance Analysis of Neural Network Detectors by Importance Sampling Techniques (1999)
    Springer
    Neural processing letters 9 (1999), S. 257-269 
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    ISSN: 1573-773X
    Keywords: detectors ; detection and false alarm probabilities ; importance sampling techniques ; Monte Carlo simulations ; neural networks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Often, Neural Networks are involved in binary detectors of communication, radar or sonar systems. The design phase of a neural network detector usually requires the application of Monte Carlo trials in order to estimate some performance parameters. The classical Monte Carlo method is suitable to estimate high event probabilities (higher than 0.01), but not suitable to estimate very low event probabilities (say, 10−5 or less). For estimations of very low false alarm probabilities (or error probabilities), a modified Monte Carlo technique, the so-called Importance Sampling (IS) technique, is considered in this paper; some topics are developed, such as optimal and suboptimal IS probability density functions (biasing density functions), control parameters and new algorithms for the minimization of the estimator error. The main novelty of this paper is the application of an efficient IS technique on neural networks, drastically reducing the number of patterns required for testing events of low probability. As a practical application, the IS technique is applied to a neural detector on a radar (or sonar) system.
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    A Neural-Network-Based Approach to Detecting Hyperellipsoidal Shells (1999)
    Springer
    Neural processing letters 9 (1999), S. 279-292 
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    ISSN: 1573-773X
    Keywords: cluster analysis ; neural networks ; shell detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper presents a novel class of neural networks which can be trained in an unsupervised manner to detect a mixture of hyperellipsoidal shells and/or segments of hyperellipsoidal shells. This approach is computationally and implementationally simpler than other clustering algorithms that have been suggested for this purpose. Experimental results on several data sets are presented.
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    A Multilayer Perceptrons Model for the Stability of a Bipedal Robot (1999)
    Springer
    Neural processing letters 9 (1999), S. 221-227 
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    ISSN: 1573-773X
    Keywords: dynamical equilibrium ; walking robots ; neural networks ; Levenberg-Marquardt's rules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A neural network model is proposed as a means of controlling the dynamical equilibrium of a walking bipedal robot. As a criterion to determine the stability of such a robot in relation with the organization of the sensorimotor system, we have been making use of the ZMP (Zero Momentum Point). Simulations are used to check the convergence of the algorithm. In the generalization phase, it is shown that the neural network has the ability to stabilise the robot for motions which have not previously been learned. An extended model is proposed, which seeks to closely inspect the physiology of the cerebellar cortex.
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    The Septoria Tritici and Stagonospora Nodorum Blotch Diseases of Wheat (1999)
    Springer
    European journal of plant pathology 105 (1999), S. 629-641 
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    ISSN: 1573-8469
    Keywords: wheat ; Triticum spp. ; Septoria tritici ; septoria tritici blotch of wheat Stagonospora nodorum ; stagonospora nodorum blotch of wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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    Hedging Rule Optimisation for Water Supply Reservoirs System (1999)
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    Water resources management 13 (1999), S. 409-426 
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    ISSN: 1573-1650
    Keywords: hedging rule ; neural networks ; reservoir operation ; simulation–optimisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract This article presents a methodology for planning a modelfor the operation of a drinking water reservoir. The hedging ruledistributes deficits over a longer period of time by rationingthe supply of water and it makes the system sustainablewith a marginal reduction in supply. A methodology isdeveloped and demonstrated through a case study withthe Chennai city (India) water supply system which isa water shortage system requiring an efficient use ofwater. It is aimed at improving the reservoiroperation performance through the simulation–optimisationprocedure with the application of the hedging rule, whichis a more appropriate rule for reservoir operationunder deficit conditions. To speed up the optimisationprocess, a neural network model is developed for thesimulation of the reservoir system operation and is usedinstead of a conventional simulation model. Thecombined neural network simulation–optimisation modelis used for screening the operation policies.
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    Forecasting and Arbitrage of the Nikkei Stock Index Futures: An Application of Backpropagation Networks (1999)
    Springer
    Asia Pacific financial markets 6 (1999), S. 341-354 
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    ISSN: 1573-6946
    Keywords: ARIMA ; backpropagation ; cost-of-carry ; momentum ; neural networks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract A neural network model was used in forecasting the basis in SIMEX Nikkei Stock Index futures. Results for out of sample show that the neural network forecast performance was better than that of the ARIMA model. Also, a two-way ANOVA confirms that the employed neural network was able to provide the trader with more arbitrage profits than the traditional cost-of-carry model even though it observed relative less profitable arbitrage timing. The results can be attributed to the network';s higher ability to capture nonlinear market patterns.
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    URL: http://dx.doi.org/10.1023/A:1010012728229
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    Restriction fragment polymorphisms in the rDNA region among seven species ofAlnus andBetula papyrifera (1989)
    Springer
    Plant and soil 118 (1989), S. 231-240 
    Details
    ISSN: 1573-5036
    Keywords: alder ; Betulaceae ; birch ; in vitro clones ; cluster ; Frankia ; genetic divergence ; RFPs ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A study of restriction fragment polymorphisms of ribosomal DNA among seven actinorhizal species (Alnus spp.) and a non-actinorhizal species (Betula papyrifera Marsh.) of the Betulaceae was conducted, using a simple method for the extraction of high molecular weight restrictable nuclear DNA from leaf tissues of perennial angiosperms and nine restriction endonucleases. rDNA restriction fragments were variable within and among the species studied, and the variation noted was used to calculate the similarities and infer phenetic relationships among these members of the Betulaceae. The results confirmed the taxonomy of alder based on morphological characters, showing a clear clustering of the species ofAlnus sampled in each of the two different subgeneraAlnus andAlnobetula. Within each subgenus, the closely related taxa often classified as subspecies by their similar morphology and their ability to interhybridize, were similarly shown by restriction fragment polymorphisms to be more closely related to each other than to any other taxon. The analysis also suggested that some alder species may not be more divergent fromBetula papyrifera than from other alder species.
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    URL: http://dx.doi.org/10.1007/BF02232811
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    Nitrogen mineralization in a green manure-amended soil as influenced by cropping history and subsequent crop (1989)
    Springer
    Plant and soil 120 (1989), S. 125-131 
    Details
    ISSN: 1573-5036
    Keywords: canola ; fallow ; N mineralization ; N immobilization ; organic matter ; rhizosphere ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A greenhouse experiment was conducted to determine the influence of cropping variables on nitrogen dynamics in a soil amended with green manure. Surface soil from various long-term spring wheat rotations was amended with15N-labelled legume green manure (Lathyrus tingitanus) and subsequently cropped (canola [Brassica napus] and spring wheat [Triticum aestivum]) or incubated without a crop for 56 days in a greenhouse. Nitrogen mineralization from both the indigenous soil N and from green manure was suppressed in cropped soil. Net N mineralization in the uncropped and cropped treatments averaged 73 and 43 mg kg−1, respectively. This difference was attributed, in part, to enhanced biological immobilization in the rhizosphere. Previous cropping practices also had significant effect on N mineralization, largely by their influence on indigenous organic matter quality. These observations suggest that short-term N mineralization is favored by fallowing soil after green manure application whereas N retention in organic matter is favored by immediate cropping.
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    URL: http://dx.doi.org/10.1007/BF02370298
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    Characterization of a toxin produced by a rhizobacterialPseudomonas sp. that inhibits wheat growth (1989)
    Springer
    Plant and soil 114 (1989), S. 279-287 
    Details
    ISSN: 1573-5036
    Keywords: characterization ; deleterious rhizobacteria ; inhibitory bacteria ; pseudomonads ; toxin ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A toxin produced by a deleterious rhizobacterial pseudomonad that inhibits both winter wheat (Triticum aestivum L.) root andEscherichia coli growth was characterized. The toxin was rapidly deactivated at pH 2 and 12 and by autoclaving (121°C, 15 minutes). Less toxin was destroyed as the temperature and time of exposure decreased, and at 40°C it was stable for at least 24 hours. The toxin was extremely polar and could not be extracted from culture filtrates with organic solvents. The compound eluted after the void volume from a Sephadex G-10 column indicating a molecular weight of less than 700. The toxin adsorbed to Dowex 50W strong cation exchange resin and eluted with 2M NH4OH. Numerous thin layer chromatography solvent systems were unsuccessful at purifying the toxin. The partially purified toxin inhibited several different microorganisms while the producing strains were resistant. The toxin appears unique to toxins produced by recognized plant pathogenic bacteria.
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    URL: http://dx.doi.org/10.1007/BF02220808
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    System Thoughts in Manufacturing (1999)
    Springer
    Journal of systems integration 9 (1999), S. 167-185 
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    ISSN: 1573-8787
    Keywords: flexibility ; complexity ; systems approach ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In this paper we present a taxonomy of manufacturing problems, labeled in a general sense as Design, Production, or Distribution problems. One or more basic systems concepts, such as complexity and adaptation, attach themselves to each such problems. By combining the hierarchical Design—Production—Distribution idea with system concepts, we establish the fact that there is, indeed, a significant systems component to most problems of modern manufacturing.
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    URL: http://dx.doi.org/10.1023/A:1008422627181
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    Prediction of Pharmacokinetic Parameters and the Assessment of Their Variability in Bioequivalence Studies by Artificial Neural Networks (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 944-948 
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    ISSN: 1573-904X
    Keywords: bioequivalence ; neural networks ; prediction ; pharmacokinetics ; verapamil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The methodology of predicting the pharmacokinetic parameters (AUC, cmax, tmax) and the assessment of their variability in bioequivalence studies has been developed with the use of artificial neural networks. Methods. The data sets included results of 3 distinct bioequivalence studies of oral verapamil products, involving a total of 98 subjects and 312 drug applications. The modeling process involved building feedforward/backpropagation neural networks. Models for pharmacokinetic parameter prediction were also used for the assessment of their variability and for detecting the most influential variables for selected pharmacokinetic parameters. Variables of input neurons based on logistic parameters of the bioequivalence study, clinical-biochemical parameters, and the physical examination of individuals. Results. The average absolute prediction errors of the neural networks for AUC, cmax, and tmax prediction were: 30.54%, 39.56% and 30.74%, respectively. A sensitivity analysis demonstrated that for verapamil the three most influential variables assigned to input neurons were: total protein concentration, aspartate aminotransferase (AST) levels, and heart-rate for AUC, AST levels, total proteins and alanine aminotransferase (ALT) levels, for cmax, and the presence of food, blood pressure, and body-frame for tmax. Conclusions. The developed methodology could supply inclusion or exclusion criteria for subjects to be included in bioequivalence studies.
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    URL: http://dx.doi.org/10.1023/A:1018857108713
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    Mallomonas alphaphora (Chrysophyceae), a new species from Western Australia (1989)
    Springer
    Plant systematics and evolution 164 (1989), S. 209-214 
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    ISSN: 1615-6110
    Keywords: Algae ; Chrysophyceae (Synurophyceae) ; Mallomonadaceae ; Mallomonas alphaphora ; Electron microscopy ; phytoplankton ; scale-bearing flagellate ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new species ofMallomonas, M. alphaphora (Chrysophyceae), was found in freshwater ponds in the Perth region, Western Australia. It is distinguished from other species ofMallomonas by its very distinctive scale and bristle morphology and is placed in a new section,Alphaphorae, of the genusMallomonas.
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    URL: http://dx.doi.org/10.1007/BF00940438
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    Recent mathematical approaches to reconstruct phylogenies: A chemosystematist's and botanist's view (1989)
    Springer
    Plant systematics and evolution 168 (1989), S. 109-121 
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    ISSN: 1615-6110
    Keywords: Algae ; bacteria ; Mathematical phylogenetics ; biological relevance ; chemosystematics ; taxonomy ; graph theory ; algorithms ; Steiner problem ; parsimony ; dichotomy ; polytomy ; cytochrome c ; parallelism ; convergent evolution ; Wagner trees ; random distribution ; molecular clock ; identity matrix ; difference matrix ; homology ; analogy ; structural constraints ; comparability of sequences ; polyphyletic hypothesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Some basic problems of mathematical phylogenetics are discussed. While algorithms regularly depend on the principle of parsimony, some features of phylogenesis interfere with that principle. Nonrandomness of the distribution of mutations as well as the inconstancy of the molecular clock in time and within a given sequence can bias the calculated relationships of closely related taxa. True comparability of sequences is difficult to establish, since this requires defining of homology of positions and of functions of amino acids as well. Parallelism and convergence can give rise to errors in establishing homology. Furthermore, they are difficult to be integrated into a consistent mathematical approach. The asymmetry of identity versus difference matrices is discussed. Common mathematical procedures implicate the monophyletic hypothesis as well as strict dichotomy of the final tree. Real phylogeny demands to introduce more flexible approaches with respect to monophyly and dichotomy. Graph theory offers the possibility to prove the minimality of a given tree and to develop more flexible approaches. The consequences of altering the procedures to compare sequences can be tested. This is demonstrated by calculations with a set of 15 cytochromes from various taxa. To interpret a calculated tree requires a sharp distinction between taxonomy and phyletics. This is exemplified for the case of directly linked taxa. The limits of resolving uncertain relationships by accumulating more data are mentioned.
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    URL: http://dx.doi.org/10.1007/BF00936092
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    Pollen morphology ofSonchus and related genera, and a general discussion (1999)
    Springer
    Plant systematics and evolution 214 (1999), S. 91-102 
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    ISSN: 1615-6110
    Keywords: Asteraceae ; Lactuceae ; Aetheorhiza ; Launaea ; Reichardia ; Sonchus ; Pollen ; taxonomy ; harmomegathy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pollen morphology of the taxa belonging to the generaAetheorhiza Cass.,Launaea Cass.,Reichardia Roth andSonchus L. in the Iberian Peninsula has been studied with light and electron microscopy. The pollen is 3(-4)-zonocolporate and echinolophate (without polar lacunae, but in general with prelacunae), with equatorial ridges and 15–20 lacunae: 3–4 poral, 6–8 abporal and 6–8 paraporal. Small to medium size, P × E = 19−36 × 23–42 µm; sometimes two different sizes have been found. Exine 3–9 µm thick and ornamentation microreticulate and echinate. The results clearly show the relationships between genera.
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    Umbilicaria freyi spec. nova und der Formenkreis vonUmbilicaria hirsuta in Europa (Lichenes, Umbilicariaceae) (1989)
    Springer
    Plant systematics and evolution 165 (1989), S. 55-69 
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    ISSN: 1615-6110
    Keywords: Lichenes ; Umbilicariaceae ; Umbilicaria freyi spec. nova ; U. hirsuta ; U. grisea ; Thallus structure ; soredia ; parasoredia ; schizidia ; taxonomy ; distribution ; Lichenflora of Europe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract InUmbilicaria hirsuta andU. grisea the so-called soredia originate from structured plectenchyma of the upper thallus layer (thus contrasting with true soredia, which are pushed off from unstructured medullar plectenchyma), and, therefore, are termed parasoredia. Both species have been regarded to comprise (in western Europe) forms with relatively large thalli and a pale lower surface; rhizinomorphs may be present (with varying density) or absent; propagation is not by parasoredia, but by flattened diaspores (schizidia s. l.) These forms are united here and described as a separate species:U. freyi (syn.U. hirsuta var.pyrenaica Frey andU. grisea resp.murina f.subpapyria Frey). So far, the species is known to occur from the western Alps through C. France to the Pyrenees, C. Spain and Italy including Sardinia.
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    Comparative ultrastructure of pyrenoids inTrebouxia (Microthamniales, Chlorophyta) (1989)
    Springer
    Plant systematics and evolution 164 (1989), S. 145-159 
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    ISSN: 1615-6110
    Keywords: Algae ; Chlorophyta ; Trebouxia ; Pseudotrebouxia ; lichens ; Parmelia ; Hypogymnia ; Pyrenoid ; ultrastructure ; systematics ; taxonomy ; phycobionts ; freeze fixation ; freeze substitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pyrenoid ultrastructure has been investigated from cultures of all 26 species ofTrebouxia with the aim of establishing pyrenoids as a taxonomic character. Different arrangements and forms of thylakoid lamellae within the pyrenoid matrix allow eight pyrenoid types to be distinguished. Each type is characteristic of a group of species. Thegigantea- andimpressa-type are similar, differing only in the form of the tubules: short, branched tubules mark thegigantea-type; ± long and straight invaginations theimpressa-type. Thearboricola-type is characterized by meandering pyrenoid membranes developing from lamellae parallel with each other in young autospores. Pyrenoids of thegelatinosa-type are traversed by thin parallel-arranged tubules. Few thylakoids with a curved profile are typical of theirregularis-type. Thecorticola-type is different from all others in having a distinct starch sheath closely connected with the pyrenoid matrix and no pyrenoglobuli being associated with the pyrenoid membranes. No true pyrenoids have been found inT. magna andT. erici. Within the chloroplast, they have indistinct areas with pyrenoglobuli, but without differentiated thylakoids. Pyrenoid morphology is stable in culture on different media as well as in phycobionts within lichen thalli. Comparing the pyrenoid of a lichenizedTrebouxia with that from cultured species, the identification of the phycobiont within the lichen thallus is possible, without the need of culturing the algae. This has been shown in species ofParmelia andHypogymnia. New aspects for the taxonomy and systematics ofTrebouxia are discussed.
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    Therps16 intron and the phylogeny of theRubioideae (Rubiaceae) (1999)
    Springer
    Plant systematics and evolution 214 (1999), S. 161-186 
    Details
    ISSN: 1615-6110
    Keywords: Rubiaceae ; Rubioideae ; Angiosperms ; cladistics ; DNA sequences ; phylogeny ; rps16 intron ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phylogeny of the subfamilyRubioideae (Rubiaceae) was estimated from sequence variation in therps16 intron (cpDNA) in 143 ingroup and 5 outgroup taxa. The analysis largely confirms a recent one based onrbcL sequences, but branch support is often much stronger. Three of the traditional subfamilies are supported,Rubioideae, Cinchonoideae s. str., andIxoroideae s. l. while there is no support forAntirheoideae. TheRubioideae are the sister group of all otherRubiaceae and comprise the tribesAnthospermeae, Coccocypseleae, Cruckshanksieae, Coussareeae, Gaertnereae, Hedyotideae, Knoxieae, Morindeae, Ophiorrhizeae, Paederieae, Pauridiantheae, Perameae, Psychotrieae, Rubieae, Spermacoceae, Theligoneae, andUrophylleae. TheHamelieae andHillieae belong to theCinchonoideae. Rachicallis andSiemensia should be transferred from theHedyotideae to theCinchonoideae. ThePauridiantheae, Urophylleae, Ophiorrhizeae, andRaritebe form the basalmost subclade of theRubioideae. The second basalmost clade consists of the generaLasianthus andPerama. The third basalmost clade consists of the tribesCoussareeae, Coccocypseleae andCruckshanksieae, and the generaDeclieuxia andHindsia. The tribesKnoxieae, Anthospermeae, Argostemmateae, Paederieae, Theligoneae, Rubieae, Hedyotideae, andSpermacoceae are members of one clade. TheKnoxieae are monophyletic ifOtiophora, Otomeria, andPentas are included. The tribeAnthospermeae is supported as monophyletic, but its subtribes are not. ThePaederieae, together withTheligonum, form a paraphyletic grade basal to theRubieae. TheHedyotideae, includingSchismatoclada, form a grade at the base of theSpermacoceae. TheGaertnereae are monophyletic and distinct from thePsychotrieae. TheMorindeae are monophyletic and includeDamnacanthus andMitchella. Schradera is the sister group of theMorindeae. ThePsychotrieae are monophyletic when theGaertnereae, Lasianthus, andDeclieuxia are excluded. The recognition of a subtribeHydnophytineae leaves the rest of thePsychotrieae paraphyletic.Psychotria is paraphyletic with respect to all other genera of the tribe. Approximately 50 genera are here classified for the first time based on molecular data.
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    DNA sequence data reveal polyphyly of Brexioideae (Brexiaceae; Saxifragaceae sensu lato) (1999)
    Springer
    Plant systematics and evolution 219 (1999), S. 199-208 
    Details
    ISSN: 1615-6110
    Keywords: Brexioideae ; Brexia ; Ixerba ; Roussea ; Saxifragaceae s. l. ; 18S rDNA andrbcL sequence analysis ; molecular systematics ; phylogenetic analysis ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous molecular phylogenetic analyses have demonstrated that Saxifragaceae sensu lato are polyphyletic, with component lineages scattered throughout the eudicots. As part of our effort to elucidate the relationships of members of Engler and Prantl's Saxifragaceae s. l., we undertook a molecular systematic study of subfamily Brexioideae, which comprises three genera:Brexia, Ixerba, andRoussea. Not all taxonomic treatments have concurred, however, in placing these genera together. To elucidate relationships among these three genera as well as their relationships to other angiosperms we constructed large data sets ofrbcL, 18S rDNA, andrbcL + 18S rDNA sequences. Our phylogenetic analyses indicate clearly that Brexioideae are polyphyletic.Brexia is part of a celastroid clade that also includesParnassia, Lepuropetalon, and Celastraceae.Ixerba appears as sister to a large eurosid I clade;Roussea appears as part of Asterales. Molecular data, therefore, indicate that Brexioideae are a polyphyletic assemblage and component genera should ultimately be incorporated into other groups. Our studies continue to demonstrate the polyphyly not only Saxifragaceae s. l., but also of its constituent subfamilies.
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    Peltier Haptic Interface (PHI) for improved sensation of touch in virtual environments (1999)
    Springer
    Virtual reality 4 (1999), S. 260-264 
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    ISSN: 1434-9957
    Keywords: Haptic ; Peltier ; Tactile ; Virtual reality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In this report we describe an advanced virtual reality glove that we are developing, called the Peltier Haptic Interface (PHI), which will provide improved sensation of touch in virtual environments. PHI will provide force/pressure feedback that can be varied independently on each finger, as well as temperature sensation that can be varied non-uniformly over the whole hand. The combination of these sensations will provide a more realistic sense of touch and significantly increase the realism of virtual environments. PHI will find extensive applications in biomedical simulations, teaching, industrial line training, and many other areas.
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    URL: http://dx.doi.org/10.1007/BF01421809
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    Application of virtual reality in hospital facilities design (1999)
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    Virtual reality 4 (1999), S. 223-234 
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    ISSN: 1434-9957
    Keywords: Virtual reality ; CFD ; Building layout ; Hospital facilities design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract The airborne particles present in certain hospital environments, such as the tuberculosis isolation or operating rooms, can be extremely harmful for patients and/or hospital personnel. An important issue during the design of hospital facilities is an efficient airborne particle removal system. A near-optimal setup of the parameters that affect the airflow, and consequently the airborne particle trajectories within the room is desirable. Computational Fluid Dynamics (CFD) is an alternative to tedious and time-consuming experimental investigations during the design phase, when a large number of alternatives need to be evaluated. The main limitations of CFD application in building design are the high level of skill required, the complexity of the setup phase, and the difficulty of output data interpretation using common 2D (two-dimensional) display devices. A virtual reality (VR) environment can help in overcoming some of these limitations. A CFD/VR procedure for design of contaminant-free hospital facilities is presented in this paper. By means of a VR preprocessing step, inferior solutions can be discharged to drastically reduce the number of configurations to investigate. Then, a CFD/VR tool is used to explore the restricted set of room layouts. The 3D (three-dimensional), immersive visualisation of an indoor space and of the particle motion inside it allows the user to really see the particle flows and consequently understand the effects of room parameters on particle motion throughout the room. In this way a close-to-optimal configuration of the room layout and of the ventilation system can be achieved more speedily and more conveniently compared to traditional CFD investigations.
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    Analysis of programmed cell death in wheat endosperm reveals differences in endosperm development between cereals (1999)
    Springer
    Plant molecular biology 39 (1999), S. 915-926 
    Details
    ISSN: 1573-5028
    Keywords: programmed cell death ; wheat ; endosperm ; ethylene ; nucleases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although maize endosperm undergoes programmed cell death during its development, it is not known whether this developmental feature is common to cereals or whether it arose inadvertently from the selection process that resulted in the enlarged endosperm of modern maize. Examination of wheat endosperm during its development revealed that this tissue undergoes a programmed cell death that shares features with the maize program but differs in some aspects of its execution. Cell death initiated and progressed stochastically in wheat endosperm in contrast to maize where cell death initiates within the upper central endosperm and expands outward. After a peak of ethylene production during early development, wheat endosperm DNA underwent internucleosomal fragmentation that was detectable from mid to late development. The developmental onset and progression of DNA degradation was regulated by the level of ethylene production and perception. These observations suggest that programmed cell death of the endosperm and regulation of this program by ethylene is not unique to maize but that differences in the execution of the program appear to exist among cereals.
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    Seed treatment with growth regulators and crop productivity. I. 2,4-D as an inducer of salinity-tolerance in wheat (Triticum aestivum L.) (1999)
    Springer
    Plant and soil 210 (1999), S. 209-218 
    Details
    ISSN: 1573-5036
    Keywords: 2 ; 4-D ; germination ; growth ; salinity-tolerance ; seed treatment ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments were conducted under laboratory and greenhouse conditions to study the effect of 2,4-D on rooting and salinity tolerance of wheat. Seeds of one commercial wheat (Inqalab-91) and three salt-tolerant wheat lines (WL-41, WL-359, and WL-1073 developed through wide hybridization) were included in the study. Preliminary and short-term experiments were conducted to determine the level of 2,4-D (administered through seed soaking for 24.5 h. at 25 °C in the dark) at which the maximum number of roots emerged. Under hydroponic conditions, 2,4-D treatment of seeds caused an increase of 60 to 100% in the number of primary roots. The maximum increase in the number of roots was observed in one of the salt tolerant wheat lines (WL-41). The roots appeared in bunches but showed stunted growth at higher levels of 2,4-D. Dry matter accumulation decreased markedly; the effect was more pronounced in Inqalab-91 which is less tolerant to stress than other wheat lines. In all wheat types, allocation of dry matter to roots relative to shoot increased due to 2,4-D treatment. In soil, seeds treated with different levels of 2,4-D showed a germination delay of 1–3 days. Although the number of primary roots increased, 2,4-D treatment caused a decrease in total dry matter accumulation by plants grown for 40 days. In another experiment, conducted under greenhouse conditions, seed germination and growth of seedlings was significantly retarded in saline compared to that in non-saline (normal) soil. Initially, the pace of germination of treated seeds as well as seedling growth was slower in both soils, but after six weeks, the leaf area of seedlings raised from treated seeds was greater than those raised from untreated seeds. Towards maturity, plants arising from treated seeds developed wider and longer flag leaves leading to enhanced yield. Root biomass decreased in saline soil as compared to normal soil. However, 2,4-D treatment caused a substantial increase in root biomass in saline soil and the roots were harder in texture in wheats other than Inqalab-91. Seed treatment with 2,4-D led to a significant improvement in the number of productive tillers, yield of straw and grain, and grain protein content of all wheats grown in saline soil. Plants grown in normal soil did not show any marked effect of seed treatment on grain yield and other agronomic parameters. The four wheats showed substantial differences for different parameters but the salt tolerant wheat lines performed better compared to the commercial variety Inqalab-91.
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    Effects of phosphorus nutrition on tiller emergence in wheat (1999)
    Springer
    Plant and soil 209 (1999), S. 283-295 
    Details
    ISSN: 1573-5036
    Keywords: leaf emergence ; phosphorus ; photosynthesis ; tillering ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus (P) deficiency limits the yield of wheat, particularly by reducing the number of ears per unit of area because of a poor tiller emergence. The objectives of this work were to (i) determine whether tiller emergence under low phosphorus availability is a function of the availability of assimilates for growth or a direct result of low P availability, (ii) attempt to establish a quantitative relation between an index of the availability of P in the plant and the effects of P deficiency on tiller emergence, and (iii) to provide a better understanding of the mechanisms involved in tiller emergence in field-grown wheat. Wheat (Triticum aestivum L., cv. INTA Oasis), was grown in the field under drip irrigation on a typic Argiudol, low in P (5.5 μg P g-1 soil Bray & Kurtz I) in Balcarce, Argentina. Treatments consisted of the combination of three levels of P fertilization 0, 60 and 200 kg P2O5 ha-1, and two levels of assimilate availability, a control (non-shaded) and 65% of reduction in incident irradiance from seedling emergence until the end of tillering (shaded). Phosphorus treatments significantly modified the pattern of growth and development of the plants. Shading reduced the growth and concentration of water-soluble carbohydrates in leaves and stems. Leaf photosynthetic rate at saturating irradiance was reduced by P deficiency, but was not affected by shading. At shoot P concentrations less than 4.2 g P kg-1 the heterogeneity in the plant population increased with respect to the number of plants bearing a certain tiller. At a shoot P concentration of 1.7 g P kg-1 tillering ceased completely. Phosphorus deficiency directly altered the normal pattern of tiller emergence by slowing the emergence of leaves on the main stem (i.e. increasing the phyllochron), and by reducing the maximum rate of tiller emergence for each tiller.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004690404870
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    Electronic Resource
    Electronic Resource
    Has yield stability changed with genetic improvement of wheat yield? (1999)
    Springer
    Euphytica 107 (1999), S. 51-59 
    Details
    ISSN: 1573-5060
    Keywords: wheat ; plant breeding ; yield stability ; environmental index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of plant breeding on yield and their physiological determinants has been widely studied in wheat. However, it is poorly understood how, and to what extent, yield stability has been modified. To attempt a direct analysis of changes in absolute and relative yield stability, data of yield of cultivars released in different eras in different environments were obtained from records from our lab and from the literature. Depending on the availability of data, effects of plant breeding on yield stability of cultivars released in Argentina, Australia, Italy and the United Kingdom were evaluated using a quantitative approach. In this paper it was assumed that the slope of yield vs. environmental index estimates the instability of the cultivars. In addition, a more qualitative approach for Mexico, and the former USSR complemented this analysis. There was a clear decrease in yield stability assessed in absolute terms as a consequence of wheat breeding. In Argentina, Australia, Italy and the UK this decrease was related to the magnitude of yield increases. However, the decrease in yield stability in Argentina and Australia was less than for Italy and the UK, particularly so during the last 30 years. Modern cultivars released in Argentina and Australia showed a trend to maintain yield stability as a percentage of their yield similar to that of their predecessors, while the two European countries analysed tended to a slight decrease in yield stability even in relative terms. The complementary, less quantitative evaluation of Mexico and the former USSR appeared to confirm the quantitative trends described for the other countries, i.e. a general decrease in yield stability (assessed in absolute terms) with genetic gains in yield potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003579715714
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