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  • 1
    ISSN: 1423-0127
    Keywords: Subarachnoid hemorrhage ; Spontaneously hypertensive rat ; Vasospasm ; Cerebral vasoconstriction ; Vascular casting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The purpose of the present study was to demonstrate, using a vascular casting technique, acute vasoconstrictive changes in the cerebral vasculature 1 h following whole-blood or plasma infusion into the subarachnoid space of conscious spontaneously hypertensive rats. Vascular casts from animals infused (over 20 min) with 0.45 ml of heparinized autologous arterial blood or plasma exhibited incomplete filling, while casts from saline-infused controls exhibited virtually no filling defects. Significant elevations in intracranial pressure were noted in blood, but not in plasma- or saline-infused rats. Two characteristic forms of constriction occurred, depending upon the vessel lumen diameter. Vessels with lumen diameters 〉100 µm were flattened longitudinally with deep endothelial nuclear imprints, while smaller vessels had focal circular constrictions resembling beads. Arterial cast filling terminated in vessels with lumen diameters from 70 to 20 µm with focal signs of constriction at or near the point of cast termination. The results indicate that the presence of both blood and plasma in the subarachnoid space produces acute small-artery constriction. This phenomenon is due to a noncellular blood component and does not correlate with increases in intracranial pressure.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biodiversity and conservation 5 (1996), S. 1545-1556 
    ISSN: 1572-9710
    Keywords: trampling ; impacts ; arthropods ; Game Park ; boundary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Seven grassland sites were sampled at South Africa's Hluhluwe-Umfolozi Game Park boundary with the surrounding land, to assess changes in arthropod diversity in response to land use. Epigaeic arthropods were sampled using pitfall traps and a sweep net. In all, 262 morphospecies were collected, but this is an underestimate of total local species richness. Fifty percent of the species caught were single occurrences. The number of species, families and orders represented at each of the seven sites was not significantly different, but the number of individuals was significantly different. Between-site comparisons, using multivariate statistics, did not reveal any strong site groupings, with all sites being unique. The conclusion is that the reserve boundary does not significantly divide arthropod diversity on a simple inside-versus-outside basis. A major factor influencing the arthropod assemblages was intensity of land use. Indigenous game animals and domestic cattle had the same effect, and it was the intensity of trampling that was important rather than the type of trampling. Human settlements had a major impoverishing effect. The Coleoptera families, Cicindelidae, Staphylindae and Carabidae, were particularly sensitive indicator taxa of land use Scarabaeidae species were the only group that were severely affected by the fence boundary, simply because their food source, the faeces of large native mammals, was inside, leaving them without resources outside the reserve.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 36 (1995), S. 91-100 
    ISSN: 1432-0762
    Keywords: Fallow ; Deer ; Mating ; Strategy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The rutting behaviour of bucks in an enclosed population was investigated between 1988 and 1990. A substantial proportion of the matings were observed. After preliminary observations in the 1987 rut we categorised bucks into one of four rutting strategies based mainly on their degree of territoriality. We investigate the effects of age, dominance and mating strategy on mating success. Territories were aggregated in an area of oak woods and mating success was highly skewed. Bucks of between 5 and 7 years old achieved the majority (over 90%) of observed matings. Mating success was highly correlated with dominance but only weakly related to fighting success. The possession of a territory was crucial to achieving high reproductive success, with a 38-fold difference between the most and least successful strategies. Bucks pursuing the different strategies also differed in the time they commenced groaning, timing of matings, mating interference and the locations where they achieved their matings. Although high-ranking males devoted considerable effort to obtaining and defending a territory only 36% of each buck's matings were achieved on his territory and males tended to abandon these sites when the tendency of females to visit them decreased.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 36 (1995), S. 91-100 
    ISSN: 1432-0762
    Keywords: Key words Fallow ; Deer ; Mating ; Strategy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The rutting behaviour of bucks in an enclosed population was investigated between 1988 and 1990. A substantial proportion of the matings were observed. After preliminary observations in the 1987 rut we categorised bucks into one of four rutting strategies based mainly on their degree of territoriality. We investigate the effects of age, dominance and mating strategy on mating success. Territories were aggregated in an area of oak woods and mating success was highly skewed. Bucks of between 5 and 7 years old achieved the majority (over 90%) of observed matings. Mating success was highly correlated with dominance but only weakly related to fighting success. The possession of a territory was crucial to achieving high reproductive success, with a 38-fold difference between the most and least successful strategies. Bucks pursuing the different strategies also differed in the time they commenced groaning, timing of matings, mating interference and the locations where they achieved their matings. Although high-ranking males devoted considerable effort to obtaining and defending a territory only 36% of each buck’s matings were achieved on his territory and males tended to abandon these sites when the tendency of females to visit them decreased.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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