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  • 1
    Call number: ZSP-201-93/11
    In: CRREL Report, 93-11
    Description / Table of Contents: A laboratory study of the behavior of snow under shock wave loading and unloading conditions was conducted using a 200-mm-diameter gas gun to generate loading waves in snow samples with initial densities of 100 to 520 kg m-3 at temperatures of -2 to -23 deg C. Stress levels were 2 to 40 MPa. The response of snow to shock wave loading was measured as a function of distance from the impact plane using embedded stress gauges. Large impedance differences between snow and the stress gauges produced complex stress histories. A finite element model, along with a simple analytical model of the experiment, was used to interpret the stress histories. Snow deformation was not affected by initial temperature, but was found to be rate dependent. The initial density of the snow determined its pressure-deformation path. The pressure needed to compact snow to a specific final density increases with decreasing initial density. The release moduli increased nonlinearly from 50 MPa at a snow pressure of about 15 MPa to 2700 MPa at a snow pressure of about 40 MPa.
    Type of Medium: Series available for loan
    Pages: iii, 150 Seiten , Illustrationen
    Series Statement: CRREL Report 93-11
    Language: English
    Note: CONTENTS Preface Introduction Experimental equipment and methods Gas gun Snow target assembly Data acquisition Experimental procedure Measured data Stress histories Snow characterization Data analysis Recommendations Experimental methods Experimental needs Summary Literature cited Appendix A : Stress-time data plots Appendix B: Tabulated stress-time data Abstract
    Location: AWI Archive
    Branch Library: AWI Library
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the World Aquaculture Society 23 (1992), S. 0 
    ISSN: 1749-7345
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The aquaculture of marine finfish in Newfoundland presents a challenge due to the cold-water (〈0 C) conditions which occur over a four to five month period. As part of a continuing research program on the culturing of cold-water marine finfish species we report on preliminary results of two “new” aquaculture species. The lumpfish and the Ocean pout both occur along the coast of Newfoundland and are adapted to a cold-water environment. Lumpfish have been reared from egg masses collected from the wild or from eggs stripped in the hatchery. Eggs and larvae are relatively large and larvae are well developed at hatch. Larvae will feed on day-old Artemia nauplii after four to six days. Survival over the first eight weeks is high but declines over the first year. Lumpfish cultured in the laboratory become sexually mature and produce eggs (roe) at the end of their second year. Ocean pout have been cultured only from egg masses collected from the wild. Eggs and larvae are extremely large compared to other marine finfish currently being cultured. Larvae hatch during the cold-water period, absorb the yolk-sac within 24 hours and are ossified at hatch. Juveniles feed on Artemia nauplii within two days at very low temperatures. Survival is comparatively high (75–80%) over the first year. Initial results are encouraging but more research is required before commercial production of these species would be feasible.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 4852-4861 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We conducted gas-gun impact experiments on snow, with initial densities of 100–520 kg m−3 and at temperatures from −2 to −23 °C and stress levels of 2–40 MPa. Carbon stress gauges were embedded in the snow to measure shock stress histories and arrival times. The unsteady and complex nature of the shock stresses necessitated the use of finite element and reverberation analysis techniques to determine the shock pressure-density (P-ρ) relationships for snow. Experimental results indicate that variations in initial snow density are reflected in differences in the P-ρ deformation path. The pressure needed to compact snow to a specific final density increases with lower initial density. Snow deformation was not affected by initial temperature, but was found to be strain rate dependent. Estimated release moduli increased nonlinearly from 50 MPa at a peak compression pressure of about 15 up to 2700 MPa at a peak pressure of about 40 MPa. Calculated stress histories and shock arrival times agreed with measured values within 20%.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 93 (1993), S. 31-37 
    ISSN: 1432-1939
    Keywords: Substrate selection ; Habitat ; Atlantic cod ; Predation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although predator avoidance has been proposed as one possible factor influencing the distribution of fish among substrate types, no study has addressed this question directly. Groups of juvenile Atlantic cod were offered a choice between pairs of the following three substrates: sand, gravel-pebble and cobble. Their distribution on these substrates was compared prior to, during and following exposure to a predator (i.e. a larger conspecific). With no apparent risk of predation, juvenile cod preferred sand or gravel-pebble. When cobble was present, juveniles hid in the interstitial spaces of this substrate in the presence of a predator. With no cobble present, juveniles showed no preference between sand and gravel-pebble, and did not seek refuge from predation in association with these substrates. Following exposure to a predator (i.e. 2.5 h later) larger juvenile cod again showed a preference for the finer-grained substrates, but smaller individuals continued to associated with the cobble. The presence of cobble resulted in fewer juveniles being captured and a significant increase in the latency until the first juvenile was captured by the predator. Results are discussed with respect to the effects of predation on the distribution and survival of fishes among substrate types.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-5133
    Keywords: mortality ; specific growth rate ; Newfoundland ; fish ; aquaculture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study examined the effects of body size and food ration on over-winter survival of age-0 Atlantic cod. Cod were divided into two groups based on standard length (large=76.95±1.10 mm SL; small=57.65±1.02 mm SL; mean±1 SE) and wet weight (large=4.02± 0.21 g; small=1.52±0.09 g). Replicate tanks (n=2) of 10 large and 10 small cod were exposed to one of two food rations (0.25% and 1.0% body weight day-1) for the entire experiment (December to June). Tanks were examined daily for mortalities and feeding was adjusted accordingly. The experiment was run under ambient light and seawater conditions. All but large age-0 cod exposed to the low food ration grew over the course of the experiment. The specific growth rate (SGR) of small cod was significantly higher (0.2425% wet weight day-1) than that of the large fish (0.0443% wet weight day-1). Food ration had no significant influence on SGR or over-winter survival. Significantly more of the large age-0 cod survived the winter (58.5% of those originally introduced) compared to the smaller fish (14%). Our results are consistent with those from studies of several other fish species, and are discussed in relation to the ecology of age-0 cod, and their potential use in aquaculture in Newfoundland.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Reviews in fish biology and fisheries 6 (1996), S. 201-219 
    ISSN: 1573-5184
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The data presented here suggest that significant selection pressures towards kin discrimination behaviour patterns result from kin-biased territorial defence behaviour patterns. Salmonids employ a phenotype matching recognition mechanism allowing individuals to discriminate unfamiliar kin. Kin discrimination abilities allow individuals to reduce the levels of aggression associated with territorial defence towards related conspecifics and to defend smaller territories near kin versus non-kin. This kin-biased territorial defence behaviour is observed in at least one species under a wide range of territorial quality conditions. Within kin groups, subordinate individuals obtain a greater number of foraging attempts, resulting in kin-biased foraging within the social group. As a result of this kin-bias, individuals within kin groups show significantly higher mean weight increases (increased direct fitness benefits) and reduced variance in these increases (increased indirect benefits). Since all individuals within the kin groups obtained higher, less variable weight increases, we can argue that individuals are increasing their inclusive fitness as a result of these kin-biased behaviour patterns. Based on these results, and on what is known about the life history of a variety of salmonid and non-salmonid species, we can formulate a number of testable predictions. By testing these predictions, we may be better able to understand both the proximate and ultimate causation of kin discrimination abilities in a variety of fishes.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Environmental biology of fishes 13 (1985), S. 25-34 
    ISSN: 1573-5133
    Keywords: Behaviour development ; Life-history ; Feeding ; Predator-avoidance ; Social Behaviour ; Sunfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Studies on the ontogeny of behaviour in fish have seldom considered the adaptive significance of the order of appearance of the behaviours. Results of laboratory studies and field observations on the ontogeny of feeding, predator-avoidance, and agonistic behaviour in largemouth bass, Micropterus salmoides, rock bass, Ambloplites rupestris, and pumpkinseed, Lepomis gibbosus, young indicate that the order of appearance of the various behavioural systems enhances the survival of the young. In the laboratory, all species spend significantly more time feeding during the first weeks of free-swimming than the later weeks. During a corresponding period in the field the young are either occupying an offshore area low in predators (rock bass, pumpkinseed) or are being guarded by a parent (largemouth bass); thus the risk of predation is low. When the young are in a predator-rich environment (inshore) both the predator-avoidance response and agonistic behaviour are well developed. Agonistic behaviour is the last to appear and may serve to disperse the young. Dispersal may relate to the feeding mode of the various species and may also reduce the probability of predation. It is apparent that the sequential onsets of the behavioural systems are in concert with ecological events and selective pressures confronting centarchid young.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 33 (1993), S. 225-231 
    ISSN: 1432-0762
    Keywords: Territorial behaviour ; Kin discrimination ; Rainbow trout
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effects of territory quality on kin-biased territorial defence behaviour and fitness of juvenile rainbow trout (Oncorhynchus mykiss) were examined by manipulating food and predation risk levels in an artificial stream channel. Groups of related (full sibling) or unrelated fry were observed in the channel under one of four treatments: (1) high food-low predator (high territory quality); (2) high food-high predator; (3) low food-low predator; and (4) low food-high predator (low territory quality). Fish within kin groups always initiated fewer aggressive interactions, defended smaller territories, exhibited higher proportions of ‘threat’ type territorial defence behaviours (as opposed to ‘overtly aggressive’ behaviours) and had a higher mean weight increase than non-kin groups. Within both kin and non-kin groups, decreasing territory quality significantly increased the frequency of aggressive interactions, the size of territories and decreased growth. It is argued that while kin-biased territorial defence behaviours are always present, decreased availability of resources and increased predation risk serve to reduce the magnitude of this kin bias. However, even in low-quality territories, the benefit of associating with kin may increase the probability of overwintering survival (increased fitness) of the young fish by increasing body size.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 31 (1992), S. 133-138 
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The threat-sensitive predator avoidance hypothesis predicts that prey can assess the relative threat posed by a predator and adjust their behaviour to reflect the magnitude of the threat. We tested the ability of larval threespine sticklebacks to adjust their foraging in the presence of predators by exposing them to conspecific predators of various sizes and recording their foraging and predator avoidance behaviours. Larvae (〈30 days post-hatch) displayed predator escape behaviours only towards attacking predators. At 3 weeks post-hatch larvae approached the predator after fleeing, a behaviour which may be the precursor to predator inspection. Larvae reduced foraging and spent less time in the proximity of large and medium-sized predators compared to small predators. The reduction in foraging was negatively correlated to the predator/larva size ratio, indicating that larvae increased their foraging as they increased in size relative to the predator. We conclude that larval sticklebacks can assess the threat of predation early in their ontogeny and adjust their behaviour accordingly.
    Type of Medium: Electronic Resource
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