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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Theoretical Biology 159 (1992), S. 397-415 
    ISSN: 0022-5193
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-8889
    Keywords: Lasius niger ; trail following ; trail laying ; pheromone evaporation ; mathematical model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Foragers of the ant Lasius nigerexploiting a 1 Msugar source were found to lay 43 %more trail marks than those exploiting a 0.05 or a 0.1 Msource. The trail laying per forager decreased during the course of individual recruitment episodes, and the mean lifetime of the trail pheromone was estimated to be 47 min. A mathematical function describing the probability that a forager chooses one of two paths in relation to the amount of trail pheromone on them closely fitted experimental data. These results were incorporated into a model describing the recruitment dynamics of L. niger.Simulations of this model showed that the observed modulation of trail laying with respect to food source quality is sufficient in itself to account for the systematic selection of the richer source seen in the experiments.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 37 (1990), S. 258-267 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume Nous présentons une série d'expëriences qui montrent comment la fourmiLasius niger peut utiliser son système des recruitement par piste afin de sélectionner une dfes deux sources de nourriture. Sil on leur offire simultanément deux solution 1M de saccharose, la sojciét'e concentre son activité sur l'une des deux. Si l'on offre deux solutions, une de 1M et l'autre de 0.1M, elle sélectionne la plus riche, à mons que la piste qui mène à la source 0.1M soit déjà bien développée au moment où l'on introduit la source 1M. Face à la même situation, la fourmiTetramorium caespitum, qui recrute par groupe/masse, utilise son mode de transmission d'information plus, individuel pour changes son exploitation vers la source 1M. Un modèle mathématique décrit ces processus, dont la dynamique correspond bien aux observations expérimentales.
    Notes: Summary A series of experiments shows how the andLasius niger uses its trail recruitment system to select between two food sources. Simultaneously presented with to 1M sucrose solution it concentrates on one of them. When offered a 1M solution together with a 0.1M solution it selects the richer source, unless the trait to the 0.1M source had become well-developed before the 1M source was introduced. In the same situation, however, the group/mass recruiting antTetramorium caespitum uses its more individual transmission of information to switch to the 1M source. A mathematical model describes these processes and its dynamics reflect the experimental results.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 39 (1992), S. 59-72 
    ISSN: 1420-9098
    Keywords: Hymenoptera ; Formicidae ; Lasius niger ; food recruitment ; trail laying behaviour ; collective decision making
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The trail-laying behaviour of foragers of the antLasius niger was observed in the laboratory on a 20 cm bridge between the nest and the food source. We measured both the frequency of trail laying, as defined by the proportion of trips during which trail laying occurred, and its intensity, as defined by the number of marks laid during one bridge crossing. Foragers do not exhibit trail-laying behaviour until a food source is discovered. Trail laying then occurs more or less equally both to and from the nest, and both its frequency and intensity decrease as the recruitment proceeds. Foragers from very small colonies less than a year old appear to have quantitatively the same trail laying behaviour as those from older and much larger colonies. Groups of recruiters and recruits were individually marked. Their trail laying intensity was similar, both for trips to and from the nest, and for an ant's first, second, third and fourth trip. The frequency diminished rapidly with the number of trips made by each individual, and was 2–3 times higher for recruiters than for recruits, for trips both to and from the nest. Even though foragers stop marking after a variable number of passages, they continue to move between the nest and the food source, and other ants start marking. Different foragers appear to have widely different levels of trail laying, although we cannot say whether these differences are stable between different recruitments. Trail laying is strongly affected by the foragers' position on the bridge, especially for ants returning to the nest which lay up to five times more on the segment closest to the source than that closest to the nest. Foragers on a weakly marked trail appear to mark more than those on a well-marked trail. However, this effect is weak and could partly be attributed to their lower speed. Finally, a model using the experimental data gathered on the individuals' trail-laying behaviour reproduced satisfactorily the colony's overall trail laying.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1420-9098
    Keywords: Orientation ; individual memory ; chemical communication ; Formicidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The relative contribution of visual and chemical components in the orientation ofLasius niger andIridomyrmex humilis (Argentine ant) workers during mass recruitment to newly discovered food sources is analyzed over short time intervals. While both species orient in response to the trail pheromone, a large number ofL. niger foragers rapidly switch to a more individual orientation, based on their memory of environmental cues.I. humilis workers, on the other hand, predominantly use collective chemical cues. The effect of the number of reinforcements on visual learning and its interference with chemical communication show that olfactory cues always prevail in the Argentine ant. InL. niger, the proportion of ants orienting to visual cues is independent of the trail concentration. Detailed observations of the trail-laying behavior of individually marked foragers show that nearly all theI. humilis workers initially lay a trail, whereas only half theL. niger foragers do so. This proportion decreases considerably with the number of trips performed byL. niger workers, while remaining constant for the Argentine ants. These results are interpreted with respect to the species' behavioral ecology.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1076
    Keywords: Screening ; Neonatal mass screening ; Metabolic disorders ; Hypothyroidism ; Hyperphenylalaninaemia ; Galactosaemia ; Maple syrup urine disease ; Adrenogenital syndrome ; Cystic fibrosis ; Duchenne's muscular dystrophy ; Histidinaemia ; Hypermethioninaemia ; Tyrosinaemia ; Haemoglobinopathies ; Glucose-6-phosphate dehydrogenase deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The present situation of neonatal mass screening for metabolic disorders in eleven European countries is presented. The only disease screened for on a population wide basis in almost all countries is phenylketonuria. Screening for congenital hypothyroidism has been started in most countries or is under active consideration. A priority list of disorders that should be screened for routinely in all newborns comprises congenital hypothyroidism, hyperphenylalaninaemia, galactosaemia and maple syrup urine disease. Other disorders, like adrenogenital syndrome, cystic fibrosis. Duchenne's muscular dystrophy, histidinaemia, or tyrosinaemia cannot be recommended for mass screening at present because of an unsatisfactory test procedure or lack of effective treatment.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1041
    Keywords: ketanserin ; intermittent claudication ; Doppler velocimetry ; capillary microscopy ; macro/microcirculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of ketanserin on macrocirculatory and microcirculatory blood flow was investigated in a placebo-controlled, double-blind trial in 11 patients suffering from intermittent claudication using Doppler velocimetry and intravital skin capillary microscopy, respectively. After 1 year of treatment no significant change was observed either in the ketanserin or the placebo group. It appears that ketanserin has no significant effect on macrocirculatory blood flow and microcirculatory nutritional skin blood flow in patients with intermittent claudication.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-7284
    Keywords: Rubella ; Malformation ; Europe ; Epidemiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Twenty-five cases of congenital rubella syndrome were recorded in 1,458,126 live births in 19 EUROCAT birth defects registries from 1980 to 1986. During the study period, the incidence declined steadily from 3.50 to 0.41 per 100,000 births. Rubella infection occurred in 12 multiparous women indicating failure in immunization programme.
    Type of Medium: Electronic Resource
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