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  • Springer  (62,697)
  • Blackwell Publishing Ltd  (7,137)
  • 1990-1994  (69,834)
  • 1980-1984
  • 1925-1929
  • 1992  (69,834)
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  • 1990-1994  (69,834)
  • 1980-1984
  • 1925-1929
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  • 1
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    Gold metallogeny in the Sino-Korean Platform: examples from Hebei province, NE China. (1992)
    Springer
    Details
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/book
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  • 2
    Electronic Resource
    Electronic Resource
    Editorial (1992)
    Springer
    Insectes sociaux 39 (1992), S. 1-1 
    Details
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01240526
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  • 3
    Electronic Resource
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    Queen condition and alate density affect pleometrosis in the antLasius pallitarsis (1992)
    Springer
    Insectes sociaux 39 (1992), S. 3-13 
    Details
    ISSN: 1420-9098
    Keywords: Ants ; colony founding ; competition ; Lasius pallitarsis ; pleometrosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ant queens often cooperate in starting colonies (pleometrosis), but not all foundresses are likely to achieve equal reproductive success. Therefore, joining decisions may be influenced by queens' perceptions of a partner's likelihood to be of mutualistic benefit or to be a successful competitor in eventually controlling reproduction. Large queen size (as measured by weight) was assumed to be a desired characteristic in a mutualistic partner, but to be avoided in a potential competitor. With respect to this variable,Lasius pallitarsis queens appeared to join others in a manner consistent with increasing their competitive advantage. When given a choice between joining another queen or nesting alone, only queens with a large weight advantage were significantly likely to join. When given a choice between joining either a light or a heavy queen, queens of all weights preferentially joined the lighter resident. Moreover, when queen condition was improved by feeding, changes in joining behavior were consistent with predictions of improved competitive ability. Finally, lighter queens were more likely to leave nest sites when joined by others. However, queens significantly aggregated when in high densities, which may be consistent with gaining mutualistic benefits. Pleometrosis appears to have an evolutionary dynamic between mutualistic group benefits and individual competition to monopolize those benefits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01240527
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  • 4
    Electronic Resource
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    Genetic differentiation of disjunct populations of the antsFormica aquilonia andFormica lugubris in Europe (1992)
    Springer
    Insectes sociaux 39 (1992), S. 15-29 
    Details
    ISSN: 1420-9098
    Keywords: Ants ; polygyny ; polydomy ; sibling species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The speciesFormica aquilonia andF. lugubris of the mound-building red wood ants have a disjunct boreoalpine distribution in Europe. The populations ofF. aquilonia in Finland, Switzerland and the British Isles show little genetic differentiation, whereas the populations ofF. lugubris show considerable differentiation. The Central European populations morphologically identified asF. lugubris can be genetically divided into two groups (here called types A and B). Type B is found in the Alps and the Jura mountains, and is genetically inseparable fromF. aquilonia. Type A lives sympatrically with type B in the Jura mountains and is also found in the British Isles. Sympatry of the two types in the Jura shows that these are separate species. It remains open whether type B is morphologically atypicalF. aquilonia or whether it is a separate species, perhaps with a past history of introgression betweenF. aquilonia andF. lugubris. The gene frequencies in the Finnish populations ofF. lugubris differ from those of both types A and B. Genetic differences withinF. lugubris indicate that the populations have evolved separately for a long time. The social structure ofF. lugubris colonies also shows geographic variation. The nests in Finland and the British Isles seem to be mainly monogynous and monodomous, whereas the nests in Central Europe are polygynous and form polydomous colonies.F. aquilonia has polygynous and polydomous colonies in all populations studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01240528
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  • 5
    Electronic Resource
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    Interspecific interference for nest sites betweenLeptothorax congruus andMonomorium intrudens (1992)
    Springer
    Insectes sociaux 39 (1992), S. 117-127 
    Details
    ISSN: 1420-9098
    Keywords: Competition ; community ; Leptothorax ; Monomorium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Interference competition for nest sites was studied in ant communities dominated byLeptothorax congruus in the suburbs of Tokyo, central Japan. At the two study plots located in a deciduous wood and in grassland,L. congruus constructed nests in dead branches or stems of dead grasses. Approximately 50% of the nests were physically broken within a year, suggesting that they were very fragile. Of totals of 67 and 91 nests ofL. congruus marked at the two sites, 12 (17.5%) and 53 (58.2%) nests, respectively, were replaced by other ant species (Monomorium intrudens,Crematogaster brunnea teranishii,Camponotus itoi andLasius sp.) which were common in both habitats. Field observation suggested that, among these ants,M. intrudens was a major competitor usurping the nests ofL. congruus by aggressive invasion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01249288
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  • 6
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    Growth-related changes in predation behavior in incipient colonies of the ponerine antEctatomma tuberculatum (Olivier) (1992)
    Springer
    Insectes sociaux 39 (1992), S. 129-143 
    Details
    ISSN: 1420-9098
    Keywords: Ants ; colony growth ; development of behavior ; predation strategy ; guarding behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We traced the development in the laboratory of 18 young colonies of the arboricolous ponerine antEctatomma tuberculatum. Colony foundation is of the partially-claustral type. During the early stages, when the colony is entirely dependent on the queen's behavior, the growth of the colony in terms of number of workers produced over time was relatively predictable. Afterwards, divergence in colony growth in function of the time increases as fast as the number of workers influences the efficiency of colony provisioning. Comparative analysis indicated clear changes in the predation behavior of foundresses and workers as colonies developed. For any stage of colony growth, all individuals provisioned the nest with dead prey or sugar-rich substances in the same way. However, prey hunting involves two different strategies. Foundresses and nanitic workers (originating from colonies with 9–15 workers) foraged actively, catching prey as the result of random encounters. Post-nanitic foragers (originating from colonies with 20–30 workers) and those from nature colonies developed an ambush strategy. Workers in these colonies gained experience at catching and handling prey during a period when they acted as nest guards, and so tended to be more efficient hunters than poorly experienced foundresses or nanitic foragers. The change in strategy was also positively correlated with an increase in the size of workers as the colony matured. A stable maximum in workers size is apparently reached only after the appearance of efficiently hunting foragers, presumably in numbers sufficient to provide adequate quantity and quality of larval food. Such a correlation between worker size and colony growth, assumed general for all ants, has not been demonstrated for Ponerinae before this work.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01249289
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  • 7
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    Seasonal cycles of growth, development and movement of the African honey bee,Apis mellifera scutettata, in Africa (1992)
    Springer
    Insectes sociaux 39 (1992), S. 167-179 
    Details
    ISSN: 1420-9098
    Keywords: African honey bee ; scutellata ; swarming ; absconding ; migration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The relationship between the annual colony cycle and seasonal patterns of forage availability was investigated for the African honey bee,Apis mellifera scutellata, in the Okavango River Delta, Botswana. The annual cycle occurred in three distinct periods. The swarming season occurred from October-November, following two to three months of intense brood production, and coincided with the end of peak forage abundance. The migration season occurred from November-May and coincided with reduced and variable floral resources. During the migration season, brood production and food storage were generally low but quite variable from month to month, and swarms passing over the study area at this time traveled in an easterly direction. The migration season was followed by the establishment period (June-September), in which large numbers of new colonies traveling from the west moved into the study area. The establishment period coincided with, and slightly preceded, the period of peak forage abundance, and colonies devoted resources collected at this time almost entirely to brood rearing, which culminated in swarm production. The data suggest that honey bee colonies in the Okavango are mobile and gear their reproduction and movement to seasonally shifting resource pattern.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01249292
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  • 8
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    Seasonal patterns of foraging activity in colonies of the African honey bee,Apis mellifera scutellata, in Africa (1992)
    Springer
    Insectes sociaux 39 (1992), S. 181-193 
    Details
    ISSN: 1420-9098
    Keywords: Apis mellifera scutellata ; African honey bee ; foraging ; brood rearing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Seasonal foraging patterns were investigated using six observation colonies maintained in the Okavango Delta, Botswana. Pollen collection, flight from the hive, and recruitment for pollen and nectar sources occurred throughout the 11 months of the study. However, the distribution of foraging activity throughout the day changed seasonally. Colonies emphasized recruitment for pollen sites throughout most of the year. Brood production occurred in all months except May, and there was a significant, positive correlation between the proportion of recruitment activity devoted to pollen sources and the amount of brood comb in the colonies. The seasonal foraging patterns ofscutellata in the Okavango were similar to those of Africanized honey bees in the neotropics. The extended foraging season and emphasis on pollen collection may be associated with the high swarming rates and migrational movements of tropical honey bees.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01249293
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  • 9
    Electronic Resource
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    Variation of ommatidia number as a function of worker size inCamponotus pennsylvanicus (DeGeer) (Hymenoptera: Formicidae) (1992)
    Springer
    Insectes sociaux 39 (1992), S. 233-236 
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    ISSN: 1420-9098
    Keywords: Camponotus pennsylvanicus ; compound eye ; ommatidia number ; Polymorphism ; caste development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The relation of worker size to ommatidia number was examined in the polymorphic antCamponotus pennsylvanicus (DeGeer). Linear regression described this relationship as:Y = 260.9 + 113.6×; whereYis ommatidia number andX is head width. A log-log regression described this relationship as:Y = 323.5 + 286.9*logX(r 2 = 0.98). This analysis indicated an allometric relation of ommatidia number to head width, where ommatidia numbers increase at a slower rate than head width. This relationship is discussed in terms of ethotypes associated with worker morphotypes, and the possible mechanisms regulating polymorphic development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01249297
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  • 10
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    On foraging, recruitment systems and optimum number of scouts in eusocial colonies (1992)
    Springer
    Insectes sociaux 39 (1992), S. 201-213 
    Details
    ISSN: 1420-9098
    Keywords: Foraging ; recruitment ; colonies ; social insects ; ants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A numerical model of an eusocial colony foraging for food showed that, for each set of values of resource density, resource size and recruitment system employed, a given optimal proportion of scouts in the colony maximize the amount of resources retrieved by a colony during a fixed period. The model predicts that ants using mass recruitment systems should have larger colonies with small foragers, and should forage on large food sources. Retrieval of small food sources by small colonies is best achieved with large workers using individual foraging strategies. For mass foragers, several food sources are best retrieved using democratic decision-making systems in recruitment, whereas for very large food sources at very low mean food patch density, autocratic decision-making systems are optimal. Some of the experimental evidence available is discussed in the light of these findings, as they confirm the prediction that large colonies with small workers have mass recruitment systems, whereas workers of small colonies with large workers are generally lone foragers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01249295
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  • 11
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    Adaptative properties of the chemical trail system of the African weaver antOecophylla longinoda Latreille (Hymenoptera, Formicidae, Formicinae) (1992)
    Springer
    Insectes sociaux 39 (1992), S. 341-346 
    Details
    ISSN: 1420-9098
    Keywords: Oecophylla longinoda ; orientation ; trail pheromones ; fæcal marking ; chemical communication ; tropics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Trail communication of the weaver antOecophylla longinoda is highly adapted to the African rain forests, insofar natural selection in the tropics might favour chemical trails which are durable in nature. A dry chemical trail can last over nine weeks, and over ten months when reinforced with fecal marking. The trail pheromones are resistant to rain, whether they are fresh or three months old, and whether they are reinforced or not with anal deposits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01323954
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  • 12
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    An environmentally determined polymorphism in malate dehydrogenase isozymes ofMyrmica rubra as revealed by isoelectric focusing (1992)
    Springer
    Insectes sociaux 39 (1992), S. 447-450 
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    ISSN: 1420-9098
    Keywords: Myrmica rubra ; isozymes ; isoelectric focusing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A polymorphism in the enzyme malate dehydrogenase in Dorset populations ofMyrmica rubra was detected using isoelectric focusing (IEF). The polymorphism was not detected on native polyacrylamide gels. Two forms, with pI values of 4.9 and 5.7, were resolved. Several lines of evidence show that the polymorphism has an environmental rather than a genetic basis. The cause of the change from one phenotype to the other may be related to a seasonally varying factor. The results indicate that whilst IEF has great potential for revealing isozyme polymorphisms in ants, care should be taken in interpreting results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01240627
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  • 13
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    Forager success increases with experience inPolybia occidentalis (Hymenoptera: Vespidae) (1992)
    Springer
    Insectes sociaux 39 (1992), S. 451-454 
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    ISSN: 1420-9098
    Keywords: Foraging ; reliability ; task performance ; wasps
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Foragers of the neotropical swarm-founding waspPolybia occidentalis showed improved task performance, as indicated by foraging success rate, with foraging age. Foragers also spent significantly more time in the field on foraging trips as they aged, while foraging rate did not change with age. These patterns were not explained by directional changes in resource availability or colony need over time. We compare these results to earlier findings on changes in task performance with experience in social insect foragers, and suggest that increases in forager persistence in the field explain improved foraging success with experience.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01240628
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  • 14
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    Fractal approach of the temporal earthquake distribution in the Hellenic arc-trench system (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 269-276 
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    ISSN: 1420-9136
    Keywords: Fractals ; earthquake clustering ; scale-invariant processes ; Hellenic Arc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The time clustering of earthquakes occurring in the Hellenic arc-trench system is quantitatively analyzed by means of the fractal dimension,D, of their time distribution in the time intervals of 1950–1985 (M s 〉-4.5) and 1964–1985 (M s ≥4.0). The results obtained imply that scale-invariant clustering holds over very large scale lengths of time,T, with 22–28≤T (in min) ≤220–222, depending on the seismotectonic segment considered. In all segments a common feature is the relation between theD 1,D 2 andD 3-values found for shallow, intermediate-depth and all-depth shocks, respectively:D 3〉D1〉D2. TheD-values found for shallow shocks range between 0.137 and 0.191 with the exception of the Ionian Islands and Cretan segments where anomalously high values (D=0.221–0.251) have been determined. We discuss possible seismotectonic interpretations of the results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876331
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  • 15
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    Triggered earthquakes and deep well activities (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 561-578 
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    ISSN: 1420-9136
    Keywords: Induced seismicity ; triggered earthquakes ; fluid injection ; fluid extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Earthquakes can be triggered by any significant perturbation of the hydrologic regime. In areas where potentially active faults are already close to failure, the increased pore pressure resulting from fluid injection, or, alternatively, the massive extraction of fluid or gas, can induce sufficient stress and/or strain changes that, with time, can lead to sudden catastrophic failure in a major earthquake. Injection-induced earthquakes typically result from the reduction in frictional strength along preexisting, nearby faults caused by the increased formation fluid pressure. Earthquakes associated with production appear to respond to more complex mechanisms of subsidence, crustal unloading, and poroelastic changes in response to applied strains induced by the massive withdrawal of subsurface material. As each of these different types of triggered events can occur up to several years after well activities have begun (or even several years after all well activities have stopped), this suggests that the actual triggering process may be a very complex combination of effects, particularly if both fluid extraction and injection have taken place locally. To date, more than thirty cases of earthquakes triggered by well activities can be documented throughout the United States and Canada. Based on these case histories, it is evident that, owing to preexisting stress conditions in the upper crust, certain areas tend to have higher probabilities of exhibiting such induced seismicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00879951
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  • 16
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    Observations of heterogeneous stope convergence behavior and implications for induced seismicity (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 639-656 
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    ISSN: 1420-9136
    Keywords: Rockburst ; stope convergence ; creep ; microseismicity ; fault stability models ; normal stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Analysis of stope convergence measurements in a burst-prone lead-zinc-silver mine is being used by the U.S. Bureau of Mines to study rock burst processes. Three convergence gages were installed in a 3-m wide stope of the Galena Mine with an inter-gage distance of approximately 8 m. The two-month period immediately after installation, during which the subsequent cut of the pillar was made, is the subject of the analysis described in this paper. Microseismicity rates and locations (local magnitude −5 and above) were also recorded during this period. Coseismic convergence steps within the 10-minute sample interval are observed at various times on all three gages. The convergences of the three gages do not track one another, indicating the blocky nature of deformation in this stope at a 10 meter or smaller size scale. The behavior of the three gages is different with respect to coseismic and interseismic convergence during the study period. For one of the gages, 82% of total closure occurs coseismically. The other two gages show much smaller percentages of coseismic convergence (30% and 35%), and proportionately higher percentages of interseismic steady creep. This heterogeneous convergence behavior may be indicative of the relative stability of the faults in the vicinity of each gage. An examination of stability models shows that the mine-geometry-related spatial variation in normal stress, acting on an existing set of faults, may explain the observed behavior.
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    URL: http://dx.doi.org/10.1007/BF00879956
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  • 17
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    Relation of fracture resistance to fabric for granitic rocks (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 657-677 
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    ISSN: 1420-9136
    Keywords: Granite ; subcritical crack growth ; stress corrosion ; double-torsion ; anisotropy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Double-torsion specimens of two granitic rocks were prepared in several directions with reference to microcracks fabric. Even for the same rock and at the same stress levels, the observed crack velocities in two granitic rocks were dependent on both the propagation direction and the opening direction. The maximum difference by several orders of magnitude was found for both rocks. The highest crack velocity was observed when the subcritical crack was parallel to most of the preexisting cracks. The maximum critical stress intensity factor was about twice as high as the minimum one in different directions. An analysis for a thin plate having anisotropic elasticity under torsional load showed that the observed difference in the crack velocity and the critical stress intensity factor was not an error due to conventional equations derived on the assumption of isotropic elasticity but the true material's property. As the preferred orientation of microcracks has been pointed out for many granitic rocks, we can conclude that the anisotropic nature of the fracture resistance of the two granitic rocks used in this study was not exceptional. A region of a transport-limited velocity was not found for rocks, even at the velocity of 10−2 m/s, that is almost equal to the theoretical limit of the stress corrosion cracking.
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    URL: http://dx.doi.org/10.1007/BF00876343
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  • 18
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    Use of the mantle magnitudeM m for the reassessment of the moment of historical earthquakes (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 59-85 
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    ISSN: 1420-9136
    Keywords: Deep seismicity ; historical seismicity ; seismic moment ; magnitudes ; mantle waves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We extend to the case of intermediate and deep earthquakes our application of the mantle magnitudeM m to historical events. Because of the general lack of quantitative studies of deep earthquakes before the initiation of the Centroid Moment Tensor databank in 1977, we regard as historical all non-shallow earthquakes up to and including 1976. An analysis of 57 records from 41 events, using the Uppsala Wiechert seismometer and various long-period instruments at Pasadena, yields new moment estimates for 28 events whose moments had not previously been published. Our results correlate poorly with available traditional magnitudes, as would be expected from early saturation effects for magnitude scales measured at relatively high frequencies. They also suggest that large events (1028 dyn-cm and greater) take place in the 100–200 km depth range, but that the depth interval 350–520 km features few if any large earthquakes.
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    URL: http://dx.doi.org/10.1007/BF00876826
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  • 19
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    Maximum Entropy Spectral Analysis of the geological time series of the oxygen isotope record from deep-sea cores (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 145-162 
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    ISSN: 1420-9136
    Keywords: Oxygen isotope ; geological time series
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A Maximum Entropy Spectral Analysis of the geological time series of the oxygen isotope 18 for the last 782,000 years showed 98,000 years as the most prominent periodicity, followed by 40,000 years of less than half the amplitude and still smaller peaks at 24,000, 67,000, 84,000, 107,000 and 786,000 years. Among the astronomical parameters, only eccentricity showed a similar periodicity viz. 96,000 years. Obliquity had a prominent periodicity at 41,000 years which was reflected in the oxygen isotope series also. Corresponding to the bimodal precession peaks (23,000 and 19,000 years), the oxygen isotope series showed a peak at 24,000 years and smaller peaks at 22,000 and 19,000 years. Our results compare well with those obtained byThomson (1990) with a more sophisticated method.
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    URL: http://dx.doi.org/10.1007/BF00876829
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  • 20
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    Coulomb constitutive laws for friction: Contrasts in frictional behavior for distributed and localized shear (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 195-214 
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    ISSN: 1420-9136
    Keywords: Friction ; Coulomb failure ; constitutive laws ; localized shear
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We describe slip-rate dependent friction laws based on the Coulomb failure criteria. Frictional rate dependence is attributed to a rate dependence of cohesionc and friction angle ϕ. We show that differences in the stress states developed during sliding result in different Coulomb friction laws for distributed shear within a thick gouge layer versus localized shear within a narrow shear band or between bare rock surfaces. For shear within gouge, shear strength is given by τ=c cosφ + σ n sinφ, whereas for shear between bare rock surfaces the shear strength is τ=c cosφ + σ n tanφ, where τ and σ n are shear and normal stress, respectively. In the context of rate-dependent Coulomb friction laws, these differences mean that for a given material and rate dependence of the Coulomb parameters, pervasive shear may exhibit velocity strengthening frictional behavior while localized shear exhibits velocity weakening behavior. We derive from experimental data the slip-rate dependence and evolution ofc and ϕ for distributed and localized shear. The data show a positive rate dependence for distributed shear and a negative rate dependence for localized shear, indicating that the rate dependence ofc and ϕ are not the same for distributed and localized shear, even after accounting for differences in stress state. Our analysis is consistent with the well-known association of instability with shear localization in simulated fault gouge and the observation that bare rock surfaces exhibit predominantly velocity weakening frictional behavior whereas simulated fault gouge exhibits velocity strengthening followed by a transition to velocity weakening with increasing displacement. Natural faults also exhibit displacement dependent frictional behavior and thus the results may prove useful in understanding the seismic evolution of faulting.
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    URL: http://dx.doi.org/10.1007/BF00876327
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  • 21
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    Statistical analysis of seismic data from north-western and western Argentina (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 277-292 
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    ISSN: 1420-9136
    Keywords: Large earthquake recurrence ; western Argentine seismicity ; earthquake risk ; Argentine seismic catalogue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Due to the process of subduction of the Nazca Plate, high seismic activity is observed near the Argentine Andean range between 21°S and 36°S. The new version of the Argentine Seismic Catalogue, which includes well-defined events during the period 1964–1989, allows us to perform an analysis of seismic risk. Earthquakes with epicenters in the provinces included in the north-western and western regions were studied using Gumbel III extreme value distribution. Modal extreme magnitudes and return periods were calculated for both regions and the results were compard with the ones obtained through the entire process techniques (both analytical and graphical). As a first study, we analyzed each province separately, after which mean values for each region were obtained. Modal values around 5–5.5 have been found and times of recurrence for events withm b 〉6 of approximately 25 years were obtained.
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    URL: http://dx.doi.org/10.1007/BF00876332
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    The bayesian probabilistic prediction of the next earthquake in the ometepec segment of the mexican subduction zone (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 309-329 
    Details
    ISSN: 1420-9136
    Keywords: Bayes' theorem ; Gaussian process ; maximization ; fault segment ; subduction ; prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A predictive equation to estimate the next interoccurrence time (τ) for the next earthquake (M≥6) in the Ometepec segment is presented, based on Bayes' theorem and the Gaussian process. Bayes' theorem is used to relate the Gaussian process to both a log-normal distribution of recurrence times (τ) and a log-normal distribution of magnitudes (M) (Nishenko andBuland, 1987;Lomnitz, 1964). We constructed two new random variablesX=InM andY=In τ with normal marginal densities, and based on the Gaussian process model we assume that their joint density is normal. Using this information, we determine the Bayesian conditional probability. Finally, a predictive equation is derived, based on the criterion of maximization of the Bayesian conditional probability. The model forecasts the next interoccurrence time, conditional on the magnitude of the last event. Realistic estimates of future damaging earthquakes are based on relocated historical earthquakes. However, at the present time there is a controversy between Nishenko-Singh and Gonzalez-Ruiz-Mc-Nally concerning the rupturing process of the 1907 earthquake. We use our Bayesian analysis to examine and discuss this very important controversy. To clarify to the full significance of the analysis, we put forward the results using two catalogues: (1) The Ometepec catalogue without the 1907 earthquake (González-Ruíz-McNally), and (2) the Ometepec catalogue including the 1907 earthquake (Nishenko-Singh). The comparison of the prediction error reveals that in the Nishenko-Singh catalogue, the errors are considerably smaller than the average error for the González-Ruíz-McNally catalogue of relocated events. Finally, using the Nishenko-Singh catalogue which locates the 1907 event inside the Ometepec segment, we conclude that the next expected damaging earthquake (M≥6.0) will occur approximately within the next time interval τ=11.82 years from the last event (which occurred on July 2, 1984), or equivalently will probably occur in April, 1996.
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    URL: http://dx.doi.org/10.1007/BF00876334
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    Sequential velocity imaging and microseismic monitoring of mining-induced stress change (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 421-447 
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    ISSN: 1420-9136
    Keywords: Sequential velocity imaging ; temporal velocity changes ; mining-induced seismicity ; velocity-seismicity association
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Sequential imaging of the temporal changes inP-wave velocity offers a practical tool to monitor a rock mass. Using established correlations between the location of seismic events and velocity structure, the temporal seismic potential characteristics of the rock may be monitored. Furthermore, the temporal velocity differences isolate the time dependent factors effecting velocity such as stress, while cancelling static factors such as lithology. Various sequential imaging techniques were compared with respect to accuracy. Differences between successive velocity images were found to have relatively high associated error estimates. However, images of velocity differences calculated from measured travel time delays between successive velocity surveys were found to have lower error estimates. In particular, travel time delays measured using cross-correlation techniques resulted in the most accurate sequential image. Two 3D sequential imaging studies were carried out at Strathcona Mine in Sudbury, Ontario, Canada. Results of the average static images indicated an association between the location of induced microseismicity and a zone of both high velocity and high gradient. Additional examples are described from the global seismology literature which also show a similar correlation between seismicity and velocity structure. We attribute this association to an interrelated stress and strength effect. The Strathcona Mine sequential images show zones of significantly decreased velocity in regions of concentrated microseismic activity, which are postulated to be indications of localized destressing and relaxation of the clamping forces resulting in the microseismicity. The zones of decreased velocity corresponded to an increase in the velocity gradient. One of the case studies also shows an increase in velocity in a zone of high static velocity, which is later the site of am N 2.5 mining-induced seismic tremor. The increase in velocity is believed to correspond to a region of stress concentration, resulting in the subsequent seismic tremor.
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    URL: http://dx.doi.org/10.1007/BF00879945
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    Thermal impact of salt: Simulation of thermal anomalies in the gulf of Mexico (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 181-192 
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    ISSN: 1420-9136
    Keywords: Salt ; thermal anomaly ; Gulf of Mexico
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Salt and related structures have played important roles in controlling hydrocarbon accumulations in the Gulf of Mexico. Using a two-dimensional fluid flow/compaction model, which allows for both conduction and convection of heat, an examination is given of the effects on thermal patterns of the combined influence of multiple salt features, including diapirs, pillows, sheets and wedges. The focusing and defocusing of heat due to the higher thermal conductivity of salt are accounted for in the modeling. The results show that there could be as much as a 30°C anomaly above multi-salt bodies due to the focusing of heat by salt, and as much as 50°C temperature contrast between internal salt positions and sediments external to the salt in the deep part of a section. The magnitude of the thermal anomaly depends on the size (or width) of the salt and on the depth of the rooted salt. The modeled results provide estimates of the influence of salt in expanding the oil generation window by approximately half of the salt thickness.
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    URL: http://dx.doi.org/10.1007/BF00878894
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    Moving salt sills and hydrocarbon maturity (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 471-487 
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    ISSN: 1420-9136
    Keywords: Salt motion ; hydrocarbon maturity ; thermal anomaly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Salt sills have been observed in the Gulf Coast. The contrast in the thermal conductivity between salt and detrital sediments means that a salt sill focuses heat around its leading edge, resulting in the devlopment of an anomalous temperature pattern in the vicinity of the salt sill. The consequent anomaly in thermal maturity pattern for hydrocarbons is related to four parameters: the salt sill thickness; the subsurface depth of the sill; the inclination of the sill; and the salt speed through the sediments. The excess maturity in the vicinity of the salt sill is shown to be dominantly dependent on the velocity of the salt sill. The positional influence of the hydrocarbon maturity relative to the salt is also examined and it is shown that the alteration of sedimentary burial paths by the inserted salt also causes a thermal anomaly. Both thermal focusing of heat by salt and sediment burial to a different thermal regime caused by passage of inserted salt produce thermal maturity effects comparable in magnitude, and neither may be ignored.
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    URL: http://dx.doi.org/10.1007/BF00876883
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    Remanent hysteresis study of dolerite dykes (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 489-499 
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    ISSN: 1420-9136
    Keywords: Coercive force ; grain size ; magnetics ; hysteresis ; granulometry ; domain wall ; relaxation time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Saturation remanent hysteresis studies were carried out on numerous dolerite dyke samples from the peninsular India. These studies result in four types of remanent hysteresis curves which indicate that the magnetic material is magnetite or titanomagnetite with variable grain-size having remanent coercive forces (H cr ) of 8 to 30 mT, requiring saturating fields (H s ) up to 250 mT. Two extreme types of samples with (1) low coercive forces requiring high saturating fields and (2) high coercive forces requiring low saturating fields are noticed along with the generally observed ones. The Granulometric and Lowrie-Fuller Tests on these samples indicated that the magnetic material i.e., magnetite or titanomagnetite in these rocks is in the form of Multi-Domain (MD), Cation Deficient (CD) and a mixture of these two forms (MD+CD) within.
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    Anisotropic radiation modelling of macroseismic intensities for estimation of the attenuation structure of the upper crust in Greece (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 445-469 
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    ISSN: 1420-9136
    Keywords: Attenuation structure ; macroseismic intensity ; quality factor ; geometrical spreading ; anisotropic radiation ; Aegean area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A method is suggested for the analysis of macroseismic intensity data in order to accurately determine an “average” attenuation structure of the upper part of the crust in an area. The method is based on a model which assumes that the observed intensities depend on source properties (radiation pattern, size, focal depth), geometrical spreading and anelastic attenuation. The method is applied to 13,008 intensity values, observed in corresponding sites of Greece and grouped (in 4228 groups), according to their spatial clustering in order to diminish observational errors and site effects. An average intensity attenuation coefficient,c=−0.0039±0.0016, corresponding to a quality factor, Q=350±140, is determined for the upper 20 km of the crust in this area. This value is relatively low, in good agreement with the relatively high heat flow and high seismic activity of this area. A byproduct of the present study is the determination, for each earthquake, of a macroseismic focal depth and of a “macroseismic size,” which is strongly correlatted with both the earthquake's magnitude and its seismic moment determined by independent methods.
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    URL: http://dx.doi.org/10.1007/BF00876882
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    The embryological œuvre of Laurent Chabry (1992)
    Springer
    Development genes and evolution 201 (1992), S. 125-127 
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    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00188709
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    The expression of PS integrins in Drosophila melanogaster imaginal disc cell lines (1992)
    Springer
    Development genes and evolution 201 (1992), S. 120-123 
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    ISSN: 1432-041X
    Keywords: Integrin ; Drosophila ; In vitro ; Imaginal disc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Drosophila imaginal disc cell lines show a characteristic pattern of aggregation in culture, which appears to be due to cell-cell rather than cell-substrate interactions. We have examined the distribution of PS integrins in wing and leg cell lines, and find that these integrin homologues are expressed preferentially in aggregates. Cell sheets, small cell clumps and chains of cells express antigen at points of cell-cell contact only.
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    Teratogenic effects of parthenogenetic cells from LTXBO mice, a strain which develops ovarian teratomas at high frequency (1992)
    Springer
    Development genes and evolution 201 (1992), S. 142-148 
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    ISSN: 1432-041X
    Keywords: Parthenogenesis ; Gametic imprinting ; Mouse chimeras
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary LTXBO mice develop ovarian teratomas at high frequency. The phenotype of tumour tissues is unusual in that most contain trophoblast elements. Since the tumours are derived from parthenogenetically activated oocytes, they would not be expected to produce trophoblast. The developmental potential of parthenogenetic cells from these mice was tested in aggregation chimeras. No contribution to trophoblast tissues was observed. However, a high incidence of morphological abnormalities was seen, suggesting that the parthenogenetic cells exerted a teratogenic effect.
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    Change in chromatin organization related to in vivo transcriptional activity and histone synthesis independent of DNA replication during differentiation (germination) of Physarum spherules (1992)
    Springer
    Development genes and evolution 201 (1992), S. 149-156 
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    ISSN: 1432-041X
    Keywords: Physarum polycephalum ; Chromatin ; Histories ; Differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During the germination of Physarum spherules, increases have been observed, at the same moment, in the level of in vivo transcriptional activity as measured by [3H] uridine incorporation, and the accessibility of DNA for ethidium bromide staining as shown by flow cytometric measurements. We suppose that the changes observed in these two processes are due to a difference in chromatin organization between the first and the second period of the premitotic germination stage. In the second period, the four nucleosome core histories are synthesized in the absence of DNA replication and may correspond to a replacement of spherulation histone variants by plasmodial histone types in nucleosomes. The synthesis of historic H4 clearly distinguishes the second period of the premitotic germination stage from a growing plasmodium G2 phase, though nuclei exhibit a G2 phase DNA content. The same pattern of histone synthesis has been found during the cell cycle following the first mitosis after germination and the growing plasmodium cell cycle, with a synthesis of two histories H2B and H2A and the high mobility group (HMG)-like protein AS3 during the G2 phase, i.e. in the absence of DNA synthesis.
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    Heat shock as inducer of metamorphosis in marine invertebrates (1992)
    Springer
    Development genes and evolution 201 (1992), S. 169-172 
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    ISSN: 1432-041X
    Keywords: Heat-shock proteins ; Metamorphosis ; Invertebrates ; Hydractinia echinata ; Ciona intestinalis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In most sessile marine invertebrates, metamorphosis is dependent on environmental cues. Here we report that heat stress is capable of inducing metamorphosis in the hydroid Hydractinia echinata. The onset of heat-induced metamorphosis is correlated with the appearance of heat-shock proteins. Larvae treated with the metamorphosis-inducing agents Cs+ or NH4 + also synthesize heat-shock proteins. In heat-shocked larvae, the internal NH4 +-concentration increases. This fits the hypothesis that methylation plays a central role in control of metamorphosis. In the tunicate Ciona intestinalis, a heat shock is able to induce metamorphosis too.
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    Whole-embryo culture of Drosophila : development of embryonic tissues in vitro (1992)
    Springer
    Development genes and evolution 201 (1992), S. 364-375 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Tissue culture ; In vitro ; Invertebrate embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have devised techniques to culture whole, dissected embryos of Drosophila melanogaster. We examine multiple aspects of the morphological and physiological development of the epidermis, musculature, nervous system, and internal organs in this cultured preparation, and show that in vitro development closely parallels normal embryogenesis. These techniques permit a wide range of experimental manipulations during embryogenesis and allow us to extend observations through late embryonic stages, after cuticle deposition. Applications of this technique are presented.
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    URL: http://dx.doi.org/10.1007/BF00365124
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    Precocious synthesis of a thyroid hormone receptor inXenopus embryos causes hormone-dependent developmental abnormalities (1992)
    Springer
    Development genes and evolution 201 (1992), S. 312-321 
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    ISSN: 1432-041X
    Keywords: Xenopus embryos ; Thyroid hormone ; Thyroid hormone receptor ; Gastrulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have investigated the effects of aXenopus alpha thyroid hormone receptor (TR) upon early development ofX. laevis. After deleting the 5′-untranslated region of a cloned TR cDNA, we synthesised TR transcripts that can be translated in oocytes and embryos. When embryos are supplied with this RNA by direct injection, functional TR can be detected through gastrula and neurula stage embryos, considerably in advance of the normal onset of TR expression in larval development. TR mRNA-injected embryos are precociously responsive to thyroid hormone (T3). In the absence of T3 such embryos develop completely normally, but addition of T3 to the medium bathing the embryos results in abnormal embryos with graded anterior (head) deficiencies, losing forehead, eyes and cement gland, progressively. The degree of abnormality is dependent upon the dose of T3 and the stage of development at which it is applied, embryos treated at stage 6 (32 cell) becoming more abnormal than those treated at stage 121/2 (late gastrula). Embryos injected with TR mRNA and treated with T3 are similar, but not identical, to embryos treated with retinoic acid in early development. As is the case with retinoic acid treatment, we show that the T3-dependent effects are due, at least in part, to effects on gastrulation movements.
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    Regulatory signals and signal molecules in early neurogenesis of Drosophila melanogaster (1992)
    Springer
    Development genes and evolution 201 (1992), S. 1-11 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Neurogenesis ; Signals ; Delta ; Notch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ectodermal germ layer of Drosophila melanogaster gives rise to two major cell lineages, the neural and the epidermal. Progenitor cells for each of these lineages arise from groups of cells, whose elements must decide between taking on either fate. Commitment of the progenitor cells to one of the developmental fates implies two factors. One is intrinsic to the ectodermal cells and determines a propensity to take on neural fate; this factor is probably represented by the products of the so-called proneural genes, which are differentially distributed throughout the ectoderm. The other factor in the cells' decision to adopt one of the two alternative fates is intercellular communication, which is mediated by the products of the so-called neurogenic genes. Two types of interactions, one inhibiting and the other stimulating neural development, have been inferred. We discuss here the assumed role of various neurogenic genes, in particular Notch and Delta, in these processes.
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    A quantitive evaluation of gap junctions and their morphological alteration during differentiation of amphibian notochord cells (1992)
    Springer
    Development genes and evolution 201 (1992), S. 12-17 
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    ISSN: 1432-041X
    Keywords: Gap junction ; Notochord ; Differentiation ; Amphibia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The early development of notochord cells may be divided into three phases according to the quantitative evaluation of gap junctions: late gastrula, neurula and from tailbud to tadpole. In late gastrula, the percentage of the area of gap junctions to total membrane is 0.054% and most of the gap junctions are small in size. During the stages of neurulation, the ratios of gap junctions to total membrane area increase and remain high (0.106–0.181 %), and the majority of the gap junctions are of medium and large size. The high ratios of gap junctions to membrane area during neurulation suggests that intercellular communication via gap junctions is important during this period. In the stages from tailbud to tadpole the ratios decrease and drop drastically to 0.001 % and most of the gap junctions found are small in size. It is in the last phase that gap junctions of altered configuration appear.
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    The formation of the mesoderm in urodelean amphibians VI. The self-organizing capacity of the induced meso-endoderm (1992)
    Springer
    Development genes and evolution 201 (1992), S. 18-29 
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    ISSN: 1432-041X
    Keywords: Mesoderm induction ; Self-organizing capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During the years 1973 and 1974, non-dorsal/ventral (non-d/v)-polarized blastulae were made of animal (upper) ectodermal caps and vegetal (lower) endodermal yolk masses by means of the destruction of the d/v polarity of the yolk mass endoderm by disaggregation, stirring and subsequent reaggregation. A simultaneous dis- and reaggregation of the upper ectodermal cap, as performed in the 1970 and 1971 experiments, led to the same results. The destruction of d/v polarity in the reconstituted blastulae, under maintenance of their animal-vegetal polarity, did not therefore prevent dorsal axis formation. The formation of single, double, triple or multiple dorsal axes in these reconstituted embryos must be based upon the self-organizing capacity of the induced meso-endoderm, since the alternative assumption of the re-establishment of mesoderm-inducing centre(s) in the reaggregated yolk mass endoderm seems very unlikely. The formation of single, double, triple or multiple axes must be the result of a competition between mesodermal aggregation centres arising in an initially evenly-induced zone of meso-endoderm. These initial centres which compete for like cells, attract each other, resulting, e.g. in their fusion into a single dorsal axis system, or in the survival of two, three or more centres in an initially balanced spatial configuration. Intensification of the meso-endoderm-inducing capacity, by using dorsal instead of entire yolk endoderm mass and by using two instead of one dorsal yolk mass, led to a more complete type of dorsal axis formation and to a higher number of axes formed (a higher percentage of triple and multiple axes than double and single ones) in one and the same reaggregate. The possible nature of the self-organizing capacity of the induced meso-endoderm has briefly been discussed, emphasizing the fundamental significance of the self-organizing capacity of embryonic anlagen in developmental processes.
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    Partial characterization of neural-inducing factors from Xenopus gastrulae Evidence for a larger protein complex containing the factor (1992)
    Springer
    Development genes and evolution 201 (1992), S. 30-35 
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    ISSN: 1432-041X
    Keywords: Neural induction ; Protein factors ; Xenopus laevis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary High (Mr ≈ 90–110 kDa) and low (Mr ≈ 15–30 kDa) molecular weight forms of neural-inducing factors have been found in the supernatant of Xenopus gastrula homogenate. The factors, which are protein in nature, have been partially purified by size exclusion high-performance liquid chromatography (HPLC) and sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis. The factor of smaller size, which could be derived from a precursor, is associated with other proteins in a larger complex. The neural-inducing factors are not irreversibly inactivated after chemical deglycosylation with trifluoromethansulfonic acid. The neural-inducing protein which is found in ribonucleoprotein (RNP)-particles was partially purified by hydrophobic chromatography. Possible relationships of the factors in different subcellular fractions and their physiological significance are discussed.
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    Laurent Chabry (1855–1893) and the “Age d'or” of biology (1992)
    Springer
    Development genes and evolution 201 (1992), S. 61-61 
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    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1007/BF00420416
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    Developmental potential for tissue differentiation of fully dissociated cells of the ascidian embryo (1992)
    Springer
    Development genes and evolution 201 (1992), S. 81-87 
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    ISSN: 1432-041X
    Keywords: Ascidian embryos ; Autonomous development ; Blastomere isolation ; Blastomere dissociation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Initially, each tissue-progenitor blastomere of embryos of the ascidian Halocynthia was identified and isolated manually at the 110-cell (late-blastula) stage, the time at which most of the blastomeres have assumed a particular fate, such that each gives rise to a single type of tissue. The isolates were allowed to develop as partial embryos, then tissue differentiation was examined by monitoring the expression of specific molecular markers for differentiation of epidermis, endoderm, muscle and notochord. Essentially, all of the precursor blastomeres of these four kinds of tissue expressed the appropriate features of tissue differentiation in isolation, indicating that determination is already complete in most of the blastomeres by the 110-cell stage. Next, in order to evaluate the absolute capacity of cells for autonomous development, embryos were maintained continuously in a dissociated state from the first cleavage to the 110-cell stage, then the cells were allowed to develop into partial embryos. Tissue differentiation in the partial embryos was examined. The results showed the striking autonomy of the processes of segregation of developmental potential, as well as the autonomy of the processes of expression of differentiated phenotypes, namely those of epidermis and endoderm. Autonomous muscle differentiation was also observed; however, excess formation of “muscle” partial embryos occurred. The hypothesis that fate determination is mediated by localized maternal information in the egg cytoplasm is supported by the evidence of development of these tissues. By contrast, no evidence of notochord differentiation was observed in the partial embryos.
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    Analysis of pattern formation during embryonic development of Hydractinia echinata (1992)
    Springer
    Development genes and evolution 201 (1992), S. 95-104 
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    ISSN: 1432-041X
    Keywords: Hydractinia echinata ; Embryonic development ; Pattern formation ; Metamorphosis ; Proportioning altering factor (PAF)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Patterning processes during embryonic development of Hydractinia echinata were analysed for alterations in morphology and physiology as well as for changes at the cellular level by means of treatment with proportioning altering factor (PAF). PAF is an endogenous factor known to change body proportions and to stimulate nerve cell differentiation in hydroids (Plickert 1987, 1989). Applied during early embryogenesis, this factor interferes with the proper establishment of polarity in the embryo. Instead of normal shaped planulae with one single anterior and one single posterior end, larvae with multiple termini develop. Preferentially, supernumerary posterior ends, which give rise to polyp head structures during metamorphosis, form while anterior ends are reduced. The formation of such polycaudal larvae coincide with an increase in the number of interstitial cells and their derivatives at the expense of epithelial cells. Treatment of further advanced embryonic stages causes an increase in length, presumably due to the general stimulation of cell proliferation observed in such embryos. Also, the spatial arrangement of cells (i.e. cells in proliferation and RFamide (Arg-Phe-amide immunopositive nerve cells) is altered by PAF. Larvae that develop from treated embryos display altered physiological properties and are remarkably different from normal planulae with respect to their morphogenetic potential: (1) Larvae lose their capacity to regenerate missing anterior parts; isolated posterior larva fragments form regenerates of a bicaudal phenotype. (2) In accordance with the frequently observed reduction of anterior structures, the capacity to respond to metamorphosis-inducing stimuli decreases. (3) The morphogenetic potential to form basal polyp parts is found to be reduced. In contrast, the potential to form head structures during metamorphosis increases, since primary polyps with supernumerary hypostomes and tentacles metamorphose from treated animals.
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    Gradual acquisition of the developmental capacity to differentiate adult structures by the genital disc of Drosophila melanogaster (1992)
    Springer
    Development genes and evolution 201 (1992), S. 105-112 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Genital disc ; tra-2 ts ; Differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Diplo-X flies homozygous for the transform-er-2 ts (tra-2 ts) mutation develop into females at 16° C, while they develop into males at 29° C (Belote and Baker 1982). By means of this conditional mutation, we have carried out a detailed analysis of the development of the genital disc. Temperature shifts between 16 and 29° C, in both directions, and temperature pulses at 29° C, have been applied during the larval growth of tra-2 ts homozygous diplo-X flies, and the external derivatives of the genital disc have been analysed. Genital discs shifted from 16 to 29° C rapidly lose their capacity to differentiate female genital structures, while they become able to differentiate male genital structures whose inventory is more complete the earlier in larval development the temperature shift is carried out; moreover, duplicated male genital structures were observed. In the shift from 29 to 16° C, the genital disc loses its capacity to differentiate male genital structures, while it becomes able to differentiate female genital structures. The inventory of male structures is smaller, and the inventory of the female structures is more complete, the earlier in larval development the temperature is shifted. No duplicated female or male genital structures were observed in the downshift experiment. With respect to the analia, the shift from 16 to 29° C resulted in the quick formation of pure male anal plates, while in the opposite shift the formation of pure female anal plates occurred gradually. Moreover, the time course for the dorsal and ventral anal plates to show normal female phenotype was different: when the dorsal anal plates were completely normal, it was still possible to find incomplete ventral anal plates. In the pulse experiment at 29° C, the genital disc is able to differentiate both female and male genital structures, although the inventory of the latter ones was not complete. In addition, the capacity of the genital disc to differentiate male genital structures depended on the duration of the temperature pulse. The anal plates were always female, although they showed a reduction in their size, the ventral female anal plate being more affected than the dorsal one. No male anal plates were observed. The results have revealed that the genital disc follows a sequence in its capacity to differentiate female or male adult structures. We suggest that this sequence reflects the sequence of determination events occurring in the genital disc during its larval growth. In addition, results shown here provide evidence for the existence in the female genital primordium of a set of cells capable of giving rise either to female genital structures (ventral vaginal plates) or to male genital structures (hypandrium and penis apparatus). We also present evidence supporting the previous idea of two primordia for the anal plates.
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    Nerve-independent DNA synthesis and mitosis in regenerating hindlimbs of larval Xenopus laevis (1992)
    Springer
    Development genes and evolution 201 (1992), S. 128-133 
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    ISSN: 1432-041X
    Keywords: Xenopus laevis ; DNA synthesis ; Mitosis ; Limb regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Xenopus laevis larvae at stage 52–53 (according to Nieuwkoop and Faber 1956) were subjected to amputation of both limbs at the thigh level as well as to repeated denervations of the right limb. Results obtained in larvae sacrificed during wound healing (1 after amputation), blastema formation (3 days) and blastema growth (5 and 7 days) showed that denervated right limbs have undergone the same histological modifications observed in innervated left limbs and have formed a regeneration blastema consisting of mesenchymal cells with a pattern of DNA synthesis and mitosis very similar to that in presence of nerves. Also, the patterns of cellular density in regenerating right and left limbs were very similar. On the whole, the data here reported show a highly remarkable degree of nerve-independence for regeneration in hindlimbs of larval Xenopus laevis at stage 52–53 and lend some substance to the hypothesis that, in early limbs, there would exist trophic factors capable of replacing those released by nerves, promoting DNA synthesis and mitosis in blastemal cells.
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    Demonstration of sucrase immunoreactivity of the brush border induced by duodenal mesenchyme in chick stomach endoderm (1992)
    Springer
    Development genes and evolution 201 (1992), S. 389-392 
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    ISSN: 1432-041X
    Keywords: Sucrase-Brush border ; Mesenchymal induction ; Stomach endoderm ; Immunoelectron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary When stomach endoderm of chick embryos was recombined and cultured with duodenal mesenchyme, the endoderm developed a brush border structure over a large area and also differentiated into mucous cells in a small area according to its own developmental fate. In the present investigation, we examined whether the induced brush border structure expressed sucrase antigen by immunoelectron microscopy using the antiserum raised against chicken sucrase. Sucrase immunoreactivity could be detected as ferritin particles in the region where the brush border was induced, whereas it was never detected on microvilli of endodermal cells which differentiated into the mucous cells. Thus, almost all of the endodermal cells could be identified as either small intestine-type cells possessing the sucrase antigen or stomach-type cells possessing mucous granules but not the sucrase antigen. The results indicate that stomach endodermal cells of chick embryos can differentiate not only morphologically but also functionally into typical intestinal epithelial cells under the inductive influence of the duodenal mesenchyme.
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    Acknowledgement to refers (1992)
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    Development genes and evolution 201 (1992), S. 393-393 
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    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    Hans Driesch's “philosophy really ab ovo”, or why to be a vitalist (1992)
    Springer
    Development genes and evolution 202 (1992), S. 1-3 
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    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1007/BF00364590
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    Expression and distribution of SPARC in early Xenopus laevis embryos (1992)
    Springer
    Development genes and evolution 202 (1992), S. 4-9 
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    ISSN: 1432-041X
    Keywords: SPARC ; Osteonectin ; Xenopus ; Embryogenesis ; Extracellular matrix
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary SPARC (Secreted Protein, Acidic, Rich in Cysteine) is a highly conserved, calcium-binding, extracellular matrix protein. To investigate its role in early embryogenesis, we examined its tissue distribution in early Xenopus embryos. SPARC mRNA transcripts were detectable by Northern blot analysis beginning at the early neurula stage. SPARC transcripts then rapidly accumulated, reaching their highest embryonic level at the tailbud stage. The levels of SPARC mRNA were similar in dorsalized (LiCl-treated) and ventralized (UV-treated) embryos, indicating embryonic expression of SPARC mRNA was not obviously altered by changes in pattern formation. Immunofluorescence staining showed SPARC was an abundant protein in tissues of mesodermal and ectodermal origin in tailbud embryos, with the exception of the notochord. Of particular interest was the distribution of SPARC within the intersomitic clefts during somitogenesis. The widespread distribution of SPARC in early embryogenesis suggests it may play a role in the formation of a variety of tissues.
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    The role of eggshell and underlying vitelline membrane for normal pattern formation in the early C. elegans embryo (1992)
    Springer
    Development genes and evolution 202 (1992), S. 10-16 
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    ISSN: 1432-041X
    Keywords: Nematode ; Micromanipulation ; Laser microbeam ; Polarity ; Gastrulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The embryo of the nematode Caenorhabditis elegans is surrounded by an inconspicuous inner vitelline membrane and a prominent outer chitinous eggshell proper. We demonstrate that the complete removal of the chitinous eggshell does not interfere with successful development to yield a normal worm. The same result can be obtained when the vitelline membrane is penetrated with laser microbeam irradiation of only the eggshell proper, gently enough to permit its resealing after a while. However, when large holes are made into the eggshell the concomitantly penetrated vitelline membrane does not reseal. While early development is quite normal under these conditions, gastrulation is defective in that gut precursor cells do not migrate in properly, eventually leading to embryonic arrest. This suggests a crucial role for pattern formation of the “micro-environment” around the embryo preserved by the intact vitelline membrane. Removing both eggshell and vitelline membrane results in a string-like arrangement of founder cells and subsequent grossly abnormal cell patterns. Our experiments support the idea that the prominent eggshell proper just functions as a mechanical protection while the thin vitelline membrane directly or indirectly serves as a necessary control element affecting the positions of cells which to begin with are determined by the orientation of the cleavage spindle.
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    Embryogenesis in C. elegans after elimination of individual blastomeres or induced alteration of the cell division order (1992)
    Springer
    Development genes and evolution 202 (1992), S. 17-22 
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    ISSN: 1432-041X
    Keywords: Caenorhabditis ; Micromanipulation ; Cell cycle ; Cell-autonomous development ; Gastrulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Our earlier studies on embryonic arrest mutants of C. elegans had indicated that early deviations from the normal temporal and spatial pathway of development lead to monstrous terminal phenotypes with little resemblance to a hatched juvenile. To analyze more directly the roles of different parameters for cellular pattern formation, various experiments with a laser microbeam have now been performed and are described in this and the accompanying paper. By ablating early blastomeres we demonstrate here that the establishment of certain cell lineages is not necessary for the generation of a hatching juvenile. However, no replacement of missing cells was observed in these cases, and the resultant animals lacked those structures which are normally produced by the ablated cells. We found that retardation of cell cycle periods in certain cell lineages and thus a change in the normal order of cell divisions is compatible with development to a hatching juvenile. This is also true when, after irradiation of gut precursor cells, their inward migration is considerably delayed. Our results demonstrate that the invariant pattern of early nematode embryogenesis is not a necessary prerequisite for normal development. Studying parameters necessary for gastrulation we found that after irradiation leading to prolonged cell cycle periods the undivided gut founder cell itself rather than its two daughters moves into the center of the embryo. We removed individual early blastomeres and tested whether the typical inward movement of gut precursors still took place. Our results show that the presence of specific neighboring founder cells is not required, indicating that prospective gut cells reduce their cohesive contacts with adjacent blastomeres prior to the onset of gastrulation.
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    A new extracellular matrix protein of the sea urchin embryo with properties of a substrate adhesion molecule (1992)
    Springer
    Development genes and evolution 201 (1992), S. 173-178 
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    ISSN: 1432-041X
    Keywords: Pl-nectin ; Cell-substrate adhesion ; Sea urchin ; Embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A new embryonic extracellular matrix protein has been purified from eggs of the sea urchin Paracentrotus lividus. The molecule is a 210 kD dimer consisting of two 105 kD subunits that are held together by S-S bridges. In the unfertilized egg, the protein is found within granules uniformly distributed throughout the cytoplasm. After the egg is fertilized, the antigen is polarized to the apical surface of ectodermal and endodermal cells during all of the developmental stages examined, until the pluteus larva is formed. The protein promotes the adhesion of blastula cells to the substrate and is antigenically distinct from echinonectin, a well characterized substrate adhesion molecule. This report adds a new candidate to the list of known extracellular matrix molecules for the regulation of differentiation and morphogenesis in the sea urchin embryo.
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    Spatial and temporal localization of FGF receptors in Xenopus laevis (1992)
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    Development genes and evolution 201 (1992), S. 334-339 
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    ISSN: 1432-041X
    Keywords: Mesoderm ; FGF receptors (flg) ; Growth factors ; Embryonic induction ; Competence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mesoderm formation is a result of cell-cell interactions between the vegetal and animal hemisphere and is thought to be mediated by inducing peptide growth factors including members of the FGF and TGFβ superfamilies. Our immunochemical study analyses the distribution of FGF receptors coded by the human flg gene during embryogenesis of Xenopus laevis. Immunostaining was detected in the dorsal and ventral ectoderm and also in the marginal zone of early cleavage, blastula and gastrula stages. Signals were very strong in the mid and late blastula (stage 8 and 9) and declined slightly in the early gastrula (stage 10). A dramatic decrease was observed up to the late gastrula (stage 11+). In stage 13 embryos, immunostaining was only found in cells around the blastopore. Isolated ectoderm cultured in vitro showed a similar temporal expression and decrease of the signal as the normal embryos. These results indicate that receptor expression is independent of the interaction of the animal cells with the vegetal part of the embryo. Of interest is the fact that the signal cannot only be found at or near the cell surface but also within the cell. This suggests the presence of an intracellular isoform of the receptor resulting from the endogenous expression of splice variants and the internalization of transmembrane receptor. Taken together our results suggest that the loss of competence (for bFGF around stage 10) is not directly correlated with the presence of receptors. The possible roles of heparan sulphate glucosaminoglycans (low affinity receptors) and control mechanisms in the intracellular signalling pathway downstream of the receptor level should be taken into consideration.
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    Outgrowth dependency of forelimb regeneration on nerves in adult African clawed frog, Xenopus laevis (1992)
    Springer
    Development genes and evolution 201 (1992), S. 376-382 
    Details
    ISSN: 1432-041X
    Keywords: Heteromorphic limb regeneration ; Nerve supply augmentation ; Denervation ; Xenopus laevis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The relationship between the size and shape of regenerative outgrowth and the quantity of innervation was studied in adult Xenopus laevis. The forelimbs, of which the nerve supply was artificially altered, were amputated midway through the stylopodium and were kept for 1 year. The regenerative outgrowths that formed in normal limbs with an intact nerve supply were mainly spike-shaped and occasionally rod-shaped. However, when the nerve supply to the distal part of the forelimb was augmented by surgically diverting ipsilateral sciatic nerve bundles, the quantity of innervation was increased to about two and a half times that of the normal limb. These hyperinnervated outgrowths were somewhat larger than those of the normally innervated outgrowths and the majority of them were oar-shaped, a type hardly ever encountered in normal regeneration. In contrast, when partial denervation was performed concomitantly with limb amputation, by ablation of the N. radialis at the shoulder joint, the quantity of innervation decreased to about one half that of the normal limb. The outgrowths obtained were spike-shaped in all cases, with their size being about half that of the normally innervated outgrowths. Furthermore, when both the N. radialis and N. ulnaris were ablated in the same way, the amputated limbs were mostly non-regenerative, but some of them regenerated small conical outgrowths. Based on these results, a discussion is presented concerning the relationship between a regenerative outgrowth and the innervation of the forelimb in Xenopus.
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    The insertion of mesenchyme cells into the ectoderm during differentiation in Sea urchin embryos (1992)
    Springer
    Development genes and evolution 201 (1992), S. 383-388 
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    ISSN: 1432-041X
    Keywords: Ectodermal wall ; Mesenchyme cells ; Differentiation ; Larval skeleton ; Primitive gut
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During the course of sea urchin development, from early blastula to pluteus larva, there are two major visible processes toward which all activities seem to be focused. They are the differentiation of the larval skeleton by the primary mesenchyme cells and the differentiation of the primitive gut by the secondary mesenchyme cells. These activities take place within the shell-like layer of epithelial cells, or ectodermal wall. The interactive role of the ectodermal wall with the mesenchyme cells is not yet clearly understood. A number of earlier studies have proposed that the ectoderm may have an inductive influence on the mesenchyme cells and that its inner surface forms a molecular template for guiding the mesenchyme cells. In this report, we suggest an additional role for the ectodermal wall. We show that some primary mesenchyme cells and secondary mesenchyme cells insert between the cells of the ectodermal wall in order to firmly anchor the anlage of the larval skeleton and primitive gut during differentiation. This mechanism may provide a physical basis for maintaining the stable positional relationship of the anlage during development.
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    The response of Drosophila imaginal disc cell lines to ecdysteroids (1992)
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    Development genes and evolution 202 (1992), S. 23-35 
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    ISSN: 1432-041X
    Keywords: Ecdysteroid ; Imaginal disc ; Drosophila ; Cell line
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have investigated the action of the moulting hormone 20-hydroxy ecdysone (20-HOE) on our leg and wing imaginal disc cell lines. At the morphological level, cells stop dividing and there is some cell death. The remaining cells elongate and aggregate, often producing long processes which form connections between different aggregates. 20-HOE acts within the first one or two days of a passage, at an optimum concentration of 10 ng/ml, this being about 1/100 of the optimum for ecdysone. One cloned wing cell line, C9, has been found to be relatively insensitive to the action of 20-HOE. We have been able to select for resistance to 20-HOE by growing cells in gradually increasing concentrations of hormone followed by passages in hormone-free medium. This has enabled us to isolate a wing cell line C1.8R from its parent cloned line C1.8+. This shows no response to 20-HOE, and cell growth continues even at hormone concentrations as high as 150 ng/ml. We have measured chitin synthesis by the incorporation of radioactive glucosamine into a cell fraction resistant to extensive alkali hydrolysis. The residue was incubated with chitinase, which resulted in a 50% reduction in labelled product. Treatment with 10 ng/ml of 20-HOE dramatically increased chitin synthesis in line C1.8+, but had no effect in the line C1.8R, selected for resistance to hormone.
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    Second-site modifiers of the Delta wing phenotype in Drosophila melanogaster (1992)
    Springer
    Development genes and evolution 202 (1992), S. 49-60 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Delta ; Enhancers ; Suppressors ; Neurogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have screened for dominant enhancers and suppressors of the wing phenotype associated with two Delta alleles: Dl 9P39, an amorphic allele, and Dl FE32, an antimorphic allele. The interactions of some of the modifiers with Delta are due to haplo-insufficient expression of the corresponding genes. Although not explicitly shown for the remaining cases, we assume that haploin-sufficiency is also the basis for the relationships of these genes to Delta, since no allele specific interactions were observed. The modifiers found define 22 genes with pleiotropic expression, which can be classified into two groups: genes required for wing vein pattern formation and for neurogenesis, and genes which are not required for neurogenesis. Among the genes of the first group, Hairless and Star were previously known to participate in neural development. One further modifier was found which may correspond to a new neurogenic gene. The second group of genes is larger and includes already known loci, e.g., Plexate, blistered, plexus, etc, as well as other previously unidentified genes, which function during wing morphogenesis.
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    Cell lineage studies in the crayfish Cherax destructor (Crustacea, Decapoda) : germ band formation, segmentation, and early neurogenesis (1992)
    Springer
    Development genes and evolution 202 (1992), S. 36-48 
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    ISSN: 1432-041X
    Keywords: Cell lineage ; Segmentation ; Neuroblasts ; Crayfish ; Crustacea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The cell division pattern of the germ band of Cherax destructor is described from gastrulation to segmentation, limb bud formation, and early neurogenesis. The naupliar segments are formed almost simultaneously from scattered ectoderm cells arranged in a V-shaped germ disc, anterior to the blastopore. No specific cell division pattern is recognisable. The post-naupliar segments are formed successively from front to rear. Most post-naupliar material is budded by a ring of about 39 to 46 ectoteloblasts, which are differentiated successively and in situ in front of the telson ectoderm. The ectoteloblasts give rise to 15 descendant cell rows by unequal divisions in an anterior direction, following a mediolateral mitotic wave. Scattered blastoderm cells of non-ectoteloblastic origin in front of the ectoteloblast descendants and behind the mandibular region are also arranged in rows. Despite their different origins, teloblastic and non-teloblastic rows cleave twice by mediolateral mitotic waves to form 4 regular descendant rows each. Thereafter, the resulting grid-like pattern is dissolved by stereotyped differential cleavages. Neuroblasts are formed during these differential cleavages and segmentation becomes visible. Each ectoderm row represents a parasegmental unit. Therefore, the segmental boundary lies within the area covered by the descendants of 1 row. Segmental structures (limbs, ganglia) are composed of derivatives of 2 ectoderm rows. The results are compared with the early development of other crustaceans and insects in relation to mechanisms of germ band formation, segmentation, neurogenesis, and evolution.
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    Differential susceptibility of early steps in carp (Cyrinus carpio) development to α-amanitin (1992)
    Springer
    Development genes and evolution 202 (1992), S. 61-65 
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    ISSN: 1432-041X
    Keywords: Fish ; Development ; Epiboly ; α-amanitin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Carp embryos were dechorionated and their early development was studied in the presence or absence of a-amanitin. Cleavage and the formation of the enveloping layer and yolk syncytial layer were not influenced by the drug. However, a-amanitin largely blocked epiboly which started 6 h after fertilization in controls. Involution of deep cells, taking place during gastrulation movements, appeared to be blocked to a lesser degree. This might reflect differences in the degree to which maternal transcripts influence these developmental steps.
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    Morphometry of cellular protrusions of mesodermal cells and fibrous extracellular matrix in the primitive streak stage chick embryo (1992)
    Springer
    Development genes and evolution 201 (1992), S. 36-44 
    Details
    ISSN: 1432-041X
    Keywords: Mesodermal cell ; Locomotion ; Filopodia ; Extracellular matrix ; Orientation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chick mesodermal cells, having become invaginated and beginning to locomote prior to the formation of the mesodermal cell layer at an early primitive streak stage, extend many filopodia and flatten themselves against the basal surface of the epiblast. Morphometry on scanning electron micrographs of chick mesodermal cells revealed two statistically significant tendencies. Each cell took an extended form and protruded filopodia, preferably along its major axis, suggesting that the force extending the cell body was generated by both ends rich in filopodia. The cells also tended to protrude filopodia most frequently in a direction away from Hensen's node. The orientation of the fibrous extracellular matrix (fECM), running on the basal surface of the epiblast, was assessed quantitatively, and it was proved statistically that the orientation of the fECM was radial around the primitive streak: With an immunogold staining technique, fECM, to which the filopodia of the mesodermal cells attached frequently and closely, was confirmed to be rich in fibronectin (FN). These results lead us to conclude that the mesodermal cells in chick gastrula were guided to locomote towards the periphery of the area pellucida by FN-rich fECM laid on the basal surface of the epiblast, and that this movement was due to an in vivo locomotive mechanism using filopodia.
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    Intermediate filament protein expression and mesoderm formation in the rabbit embryo (1992)
    Springer
    Development genes and evolution 201 (1992), S. 45-60 
    Details
    ISSN: 1432-041X
    Keywords: Gastrulation ; Cytokeratins ; Vimentin ; Immunofluorescence ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This study aims to describe the regulation of vimentin and cytokeratin expression during differentiation of primary mesenchymal cells in the 7 day old rabbit embryo; unusual intermediate filament protein expression patterns have already been found in this species at later embryonic stages. Double-labelling indirect immunofluorescence assays with a panel of monoclonal intermediate filament antibodies are performed on frozen sections and compared with aldehyde-fixed plastic-embedded tissues. The histological part of the study, serving as a basis for the topographical orientation in the immunostained frozen sections, emphasises many similarities between the primitive streak embryos of the rabbit and the chick. The immunohistochemical analysis reveals cytokeratin expression to varying degrees in all germ layers. Vimentin expression, always in combination with cytokeratin expression, is found in a few cells of the ectoderm, endoderm and lateral mesoderm, but not in the primary mesenchymal cells of either the primitive node or the primitive streak. The results are discussed in relation to recent experimental findings on differentiation and morphogenetic processes in the primitive streak embryo. While these complex expression patterns make it seem unlikely that intermediate filament protein subtypes are expressed independently of cellular function during development, no indication can be found for a relation between vimentin expression and the morphogenetic changes thought to be important during mesoderm formation.
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    Spatial and temporal expression of an Antennapedia/lac Z gene construct integrated into the endogenous Antennapedia gene of Drosophila melanogaster (1992)
    Springer
    Development genes and evolution 201 (1992), S. 65-80 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Homeotic gene regulation ; Antennapedia ; Development ; β-galactosidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In order to study the regulation of spatial and temporal expression of the homeotic gene Antennapedia (Antp) in Drosophila melanogaster, we have constructed fusion genes which contain Antp sequences linked to the reporter gene lac Z of Escherichia coli. In one case of P-element transformation, a fusion gene construct integrated into the endogenous Antp gene close to one of the two promoters (P1). The spatial expression from the reporter gene in this transformant line, as analysed by the detection of β-galactosidase activity, was found to exactly mimic the normal expression from the P1 promoter of the Antp gene. We have used this unique transformant as a tool for studying the expression of the P1 promoter in embryonic, larval and adult development. Parallel lines transformed with the same fusion gene construct did not confer a correct P1 pattern of expression. The position in the genome was, therefore, crucial for the expression pattern of the reporter gene. Experiments aiming at the detection of autoregulatory control of Antp gene expression were designed. The results did not, however, support models of positive or negative autoregulation of P1 expression by Amp protein.
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    URL: http://dx.doi.org/10.1007/BF00420417
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    Cell lineage of flight muscle fibers in Drosophila: a fate map of the induced shibire phenotype in mosaics (1992)
    Springer
    Development genes and evolution 201 (1992), S. 88-94 
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    ISSN: 1432-041X
    Keywords: Fate map ; Drosophila ; Flight muscle ; Mosaics ; Cell lineage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A blastoderm fate map has been prepared for Drosophila, using mosaics of a temperature-sensitive mutation, shibire (shi). The mutation can cause abnormal flight muscle morphology, inducible only by a short heat pulse in early metamorphosis. Thus muscle lineage and development are unperturbed until the heat pulse in the early pupa. The developmental focus of the shi muscle phenotype maps to the ventral thorax at the expected site of thoracic mesoderm, and probably indicates the blastoderm progenitors of the adult flight muscle. The fate map provides greater detail than previously available for the dorsolongitudinal fibers (DLM) of flight muscle, showing wide separation of the fibers of flight muscle. DLM fibers a and b map close together, and far anterior to fibers e and f, which also map together. On a fate map, common developmental focus indicates a common blastoderm origin. Thus, the observed pattern for DLM fibers suggests that the blastoderm progenitors for each of these syncytial fiber pairs (a, b; e, f) include only one or two cells. It follows that there is usually a single genotype within each fiber pair (a, b; e, f), and that this genotype is directly reflected in the fiber phenotype. In a large number of cases, DLM fibers a and b differ in phenotype from other DLM fibers, in parallel with their other differences (e.g., timing of development in pupa, innervation, motor activity). The separation of fate map locations of the developmental focus for DLM fibers within mesoderm suggests that specific fibers of flight muscle may, in normal development, originate in all three thoracic mesodermal parasegments.
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    Isolation and developmental expression of an oogenesis-specific Xenopus cDNA clone (1992)
    Springer
    Development genes and evolution 201 (1992), S. 113-119 
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    ISSN: 1432-041X
    Keywords: cDNA ; Oogenesis ; Xenopus development ; Gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have characterized a cDNA clone designated XSYO, complementary to a transcript that is highly expressed during Xenopus oogenesis. XSYO is expressed as a maternal mRNA in oocytes and early embryos at a level up to 3 × 108 copies per mature oocyte. This level is 100-fold higher than the concentration of an average maternal RNA in the oocyte and close to the value found for the stockpiled maternal histone mRNA. This level remains constant thoughout the first rapid cleavage stages until the midblastula transition (MBT). After this stage, the XSYO RNA is degraded within 2 h and, after the blastula stage, a very weak expression was detected. This gene is not expressed in Xenopus proliferative somatic cultured cells, suggesting that it is not a simple housekeeping gene. The presence of a potential metal-binding domain in the XSYO sequence suggests that this gene might code for a protein involved in nucleic acid binding or gene regulation specific to oogenesis or early development.
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    Bovine embryonic stem cell-like cell lines cultured over several passages (1992)
    Springer
    Development genes and evolution 201 (1992), S. 134-141 
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    ISSN: 1432-041X
    Keywords: Bovine demi-blastocysts ; In vitro culture ; Chromosomes ; Stem cells ; Nuclear transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A total of 14 microsurgically produced zona pellucida-free bovine demi-blastocysts were cultured for 3 days in tissue culture medium (TCM) 199 supplemented with 10% heat-inactivated newborn calf serum (NBCS). Developing embryos were continuously cultured in TCM 199 plus 10% NBCS on a feeder-layer of murine embryonic fibroblasts, that had been incubated with mitomycin C (10 μg/ml) for 3 h prior to the onset of embryo cultivation to block mitotic activity of the fibroblasts. After 2 days, 3 expanded blastocysts were attached to the feeder-layer and both trophoblastic cells and inner cell mass (ICM) cells became apparent on the 9th day of culture in 2 out of the 3 expanded blastocysts. Five days later, the ICM cells were disaggregated by a short-term trypsin treatment. The resulting dissociated clumps were seeded on a new murine embryonic fibroblast feeder-layer and covered with modified minimum essential medium (MEM)-Alpha with 10% fetal calf serum (FCS), 0.1 mm mercaptoethanol, 4.5 g/l glucose and 20 mm HEPES-buffer (=passage 0). To prevent differentiation of the cells, approximately 1/3 of the MEM-Alpha was replaced by MEM previously incubated on cell line 5637 containing leucaemia inhibitory factor (LIF) for 3 days. Colonies of embryonic stem cell (ES)-like cells were observed 5 days after the 1st passage. These colonies were repeatedly passaged at approximately 2-week intervals. Two bovine ES-like cell lines were established, which grew considerably slower than murine ES cells, but were lost after the 4th passage, possibly because of toxic effects of a new FCS batch. After cytogenetic analysis, 16 out of 18 metaphase plates contained an euploid number of chromosomes with 2 X-chromosomes and 58 autosomes. Distribution of G-banding on the chromosomes of ES-like cells was in accordance with the diploid set of the bovine genome. ES-like cells were fused to in vitro matured bovine oocytes and, upon successful fusion, cultured in vitro over 5 days. Successful fusion was observed in 79.8% (67/84), 31.3% initiated cleavege and 10.4% reached the 8–16 cell stage at termination of culture.
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    Expression of gooseberry-proximal in the Drosophila developing nervous system responds to cues provided by segment polarity genes (1992)
    Springer
    Development genes and evolution 201 (1992), S. 157-168 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Pattern formation ; Segment polarity genes ; gooseberry ; Cell interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Segment polarity genes define the cell states that are required for proper organization of each metameric unit of the Drosophila embryo. Among these, the gooseberry locus has been shown to be composed of two closely related genes which are expressed in an overlapping single-segment periodicity. We have used specific antibodies raised against the protein product of the gooseberry proximal (gsb-p) gene to determine the spatial distribution of this antigen in wild type embryos, and to monitor the effects of segment polarity mutants on the pattern of the gsb-p protein distribution. We find that the gsb-p protein accumulates beneath each posterior axonal commissure in the progeny of neuroblasts deriving from the epidermal compartments of wingless (wg) and engrailed (en) expression. The results of this analysis support the idea that gsb-p has a specific role in the control of cell fates during neurogenesis, and indicate that en and wg provide critical positional cues to define the domain in which gsbp will be activated. Furthermore, these data suggest that, in order to be expressed in the embryonic CNS, gsb-p may preliminarily require activity of the gooseberry-distal gene in the epidermis.
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    How to dart ascidian blastomeres: The embryological micro-tools of Laurent Chabry (1855–1893) (1992)
    Springer
    Development genes and evolution 201 (1992), S. 191-193 
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    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00188751
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    A quantitative method for separation of livingHydra cells (1992)
    Springer
    Development genes and evolution 201 (1992), S. 296-300 
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    ISSN: 1432-041X
    Keywords: Cell separation ; Counterflow centrifugation elutriation ; Cell type specific gene expression ; Hydra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We describe a rapid method for the isolation of large numbers of livingHydra cells of defined cell type in an isotonic cell medium (Gierer et al. 1972). Intact animals are enzymatically dissociated into a single cell suspension and the various cell types separated in less than one hour by counterflow centrifugation elutriation. Cell loss is minimal. RNA isolated from various fractions can be probed with cell type specific cDNA-clones.
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    A study on cell lineage, especially the germ cell line, in embryos of the teleost fish,Barbus conchonius (1992)
    Springer
    Development genes and evolution 201 (1992), S. 275-283 
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    ISSN: 1432-041X
    Keywords: Cell lineage ; Primordial germ cell ; Fish development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Lucifer Yellow-Dextran labelling of lower layer cells (LLC), sometimes together with upper layer cells (ULC), of the 64-cellBarbus conchonius embryo resulted in labelled primordial germ cells (PGCs) at 12 h after fertilization (a.f.) in about 25% of cases. The presence of labelled PGCs was independent of the location of the injected blastomere with respect to the later orientation of the embryonic axis. After injection of an ULC alone, however, labelled PGCs were never found. Also, the distribution of labelled somatic cells differed between the ULC- and LLC-injected embryos. When we found fluorescent PGCs, only a few of them were labelled, suggesting that either a single predecessor exists earlier than the 64-cell stage or that the formation of germ cells is a polyclonal process. Tracing the fluorescent cells at successive stages of development shows an extensive mixing with unlabelled cells during the epiboly stage, which might well be the cause of partly unpredictable cell lineages. The chance of being committed to a specific fate is different for the ULC and LLC descendants. This might be due to relatively limited cell mixing between these two cell populations.
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    Hans Driesch the critical mechanist: “Analytische Theorie der organischen entwicklung” (1992)
    Springer
    Development genes and evolution 201 (1992), S. 331-331 
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    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1007/BF00365119
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    Extreme queen-worker dimorphism inRopalidia ignobilis, a small-colony wasp (Hymenoptera: Vespidae) (1992)
    Springer
    Insectes sociaux 39 (1992), S. 31-43 
    Details
    ISSN: 1420-9098
    Keywords: Caste ; eusocial ; Polistinae ; morphology ; reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ropalidia ignobilis dwells in small colonies of 100 or fewer contemporaneous adults, founded by one or a few females. Variation in size is continuous when a number of colonies are combined, yet each colony produces females in two discrete morphological castes. Nest architecture shows that workers abruptly switch from producing small to large larvae. Large females apparently fulfill the role of the dominant reproductive, but small females are not obligatorily sterile. Castes differ in size, allometric relationships between body parts, number of hamuli per mm. wing length, and coloration in a fashion consistent with what is known for more advanced dimorphic species of social wasps. This dimorphism, rare in Polistinae and previously unknown in small-colony, independent-founding species, challenges our understanding of the evolution of advanced insect sociality.
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    Development of the embryo nest ofVespa affinis (Hymenoptera: Vespidae) in Southern Japan (1992)
    Springer
    Insectes sociaux 39 (1992), S. 45-57 
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    ISSN: 1420-9098
    Keywords: Vespa ; embryo nest ; development ; ovarian index ; Japan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The aerial nests ofVespa affinis on Ishigaki Island, Japan, were found mainly within 1 m of the ground, attached to a twig roughly 4 mm in diameter. These are probably adaptations to survive adverse weather conditions. The favoured nesting habitat was in open farmland areas rather than in the natural forest. The entire envelope and more than half of the comb of the embryo nest is constructed during the first 10–12 days. The first workers emerge around 34 days after nest initiation. The duration of larval development was found to be linked to the number of larvae present in the nest, with the earlier progeny developing faster. The changes in the ovarian index of the mother queen during the early stages of nesting are described.
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    Trail laying behaviour during food recruitment in the antLasius niger (L.) (1992)
    Springer
    Insectes sociaux 39 (1992), S. 59-72 
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    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.
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    Relations entre la fourmi parasiteFormicoxenus provancheri et son hôteMyrmica incompleta. Données biologiques et éthologiques (Hym. Formicidae) (1992)
    Springer
    Insectes sociaux 39 (1992), S. 81-97 
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    ISSN: 1420-9098
    Keywords: Parasite ant ; grooming ; appeasement behaviour ; nestmate recognition ; species recognition ; polycalism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary Information on the biology and the behaviour ofFormicoxenus provancheri, a parasite ofMyrmica incompleta, is presented.F. provancheri forms large polycalic societies whith each unit maintaining some independance: movements from one unit to another are not frequent and there is brood discrimination between different units. Adoption ofFormicoxenus ergates byMyrmica societies is easy, the mortality is very low among the parasites, even if the adoptiveMyrmica were previously completely parasite free. The larvae ofFormicoxenus can be eaten by the host Myrmica', this explains the necessity for theFormicoxenus to keep their brood apart from the host. Grooming of the host is very frequent. This might enable the parasite to acquire the species-specific odour of the host colony. Grooming might also be a way of obtaining some nutricious substances from the host body. Appeasement behaviour presented by theFormicoxenus is described. New small units of colonies, at the periphery of the host society, are probably founded by budding of any fecundated female leaving the nest with some ergates. This leads to the formation of super-societies by the parasite. The probleme of how the parasite spreads is not answered by this study because it was shown that newly fecundated gynes suffer strong aggression when they enter an alien host society.
    Notes: Résumé La biologie et le comportement deFormicoxenus provancheri, fourmi parasite de Myrmica incompleta, sont précisées. Cette espèce forme de grandes sociétés polycaliques où chaque unité conserve une certaine autonomie (mise en évidence par le faible taux de passage d'une unité à l'autre et la discrimination du couvain de chaque unité). L'adoption desFormicoxenus par lesMyrmica est facile et n'entraîne qu'une mortalité très faible parmi les parasites, même lorsqu'il s'agit deMyrmica totalement indemnes de parasites. Nous décrivons deux comportements importants dans les interactions entre les deux espèces: le léchage de l'hôte et le comportement d'apaisement envers l'hôte. Les larves deFormicoxenus sont consommées par l'hôteMyrmica, ce qui explique la nécessité pour lesFormicoxenus de garder leur couvain à l'écart de l'hôte. Il est probable que la formation des supercolonies s'effectue par bouturage d'une gyne (ou d'une ergate fécondée) accompagnée d'ergates, qui va fonder une nouvelle calie à la périphérie de la société hôte. Le problème de la dissémination du parasite est posé: les gynes après fécondation sont fortement agressées si on tente de les introduire dans une société étrangère.
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    Colony defence against ants inVespa (1992)
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    Insectes sociaux 39 (1992), S. 99-111 
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    ISSN: 1420-9098
    Keywords: Vespa ; sternal glands ; colony defence ; ants ; embryo nest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary On Ishigaki Island in southern Japan, despite the prevalence of ants in the study area, none of the failures of 54Vespa affinis (L.) colonies located could be directly attributed to attacks from ants. The long vestibule of theV. affinis embryo nest was not effective in preventing access to the nest by small species of ants.V. affinis andV. tropica (L.) females produce a substance which is repellent to ants. The substance is produced by the 6th and 7th abdominal sternal glands and is thought to be applied to the embryo nest petiole via the sternal brush. As the substance is produced by workers and queens during the entire life of the colony, it probably has a dual function.
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    Development of non-reproductive castes in the neotropical termite generaCornitermes, Embiratermes andRhynchotermes (Isoptera, Nasutitermitinae) (1992)
    Springer
    Insectes sociaux 39 (1992), S. 313-324 
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    ISSN: 1420-9098
    Keywords: Isoptera ; Termitidae ; Nasutitermitinae ; caste differentiation ; phylogeny ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The developmental pattern of the neuter castes was studied in the mandibulate nasute generaCornitermes, Embiratermes andRhynchotermes. InCornitermes walkeri, all the workers and soldiers are male. There are two larval and a single worker instar. Workers can molt into presoldiers. InEmbiratermes chagresi andRhynchotermes perarmatus, both sexes are present among the neuters. A slight sexual dimorphism (males 〉 females) is discernible among both larval instars and among workers ofE. chagresi; female workers can molt into presoldiers. InR. perarmatus, the sexual dimorphism is conspicuous from the first larval instar on. Male larvae go through two instars, then give rise to workers, which do not molt. InR. perarmatus, there is no worker stage in females, but a third larval instar, preceding the presoldier. Hypotheses are proposed as to the evolution of these caste patterns, attempting to conciliate present knowledge of Nasutitermitinae phylogeny and known evolutionary trends affecting termite caste patterns, according to the species' ecology.
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    Intra- and inter-nest variation in mitochondrial DNA in the polygynous antLeptothorax acervorum (Hymenoptera; Formicidae) (1992)
    Springer
    Insectes sociaux 39 (1992), S. 335-340 
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    ISSN: 1420-9098
    Keywords: Leptothorax acervorum ; mtDNA ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 27 nests ofLeptothorax acervorum were analysed for restriction fragment-length polymorphism (RFLP) in mitochondrial DNA (mtDNA), using four endonucleases. A substantial degree of variation was found between nests in the population (13 composite haplotypes). Intra-nest variation was detected in 15 % of the nests. The presence of occasional alien inseminated females indicates that polygyny in this species is caused by adoption of mated females. The occasional acceptance of alien females is difficult to explain, but interesting, since this behaviour could have given rise to inquilinism. Our results suggest that analysis of mtDNA RFLP is a method well suited for investigations of the population structure of ants.
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    Patterns of colonization and incipient nest survival inAcromyrmex niger andAcromyrmex balzani (Hymenoptera: Formicidae) (1992)
    Springer
    Insectes sociaux 39 (1992), S. 347-350 
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    ISSN: 1420-9098
    Keywords: Colonization ; survivorship ; Brazil ; Acromyrmex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Patterns of colonization by queens and incipient nest survival of the leaf-cutting antsAcromyrmex niger andAcromyrmex balzani were studied by means of belt transects and individually marked incipient nests. No relation was found between colony density and the number of colonization attempts. Both species are not claustral, and high rates of queen mortality were attributed to conspecific executions and predation. Of other discernable mortality factors, failure of fungal garden establishment was the most important. Only 34 of 296A. balzani and 13 of 154A. niger marked colonies were alive at the end of one year. These figures are higher than those reported for species ofAtta. These results are contrasted with those of claustral-foundingAtta species. Small colonies are occasionally raided by larger colonies which robbed brood.
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    The labial gland in the termiteSchedorhinotermes lamanianus (Isoptera: Rhinotermitidae): Morphology and function during communal food exploitation (1992)
    Springer
    Insectes sociaux 39 (1992), S. 373-384 
    Details
    ISSN: 1420-9098
    Keywords: Polymorphism ; exocrine secretion ; aggregation pheromone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary InSchedorhinotermes lamanianus, size and cellular differentiation of the labial gland exhibit a caste-specific polymorphism. The acini of workers are composed of three distinct types of secretory cells, one of which is absent in soldiers and alates. The labial gland of workers releases a chemical signal for intraspecific communication. During the communal exploitation of a food source, labial gland secretion makes workers aggregate at gnawing sites where this signal is deposited. A newly developed bioassay is demonstrated.
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    Nest structure and colony cycle of the Allegheny mound ant,Formica exsectoides Forel (Hymenoptera: Formicidae) (1992)
    Springer
    Insectes sociaux 39 (1992), S. 385-402 
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    ISSN: 1420-9098
    Keywords: Formica exsectoides ; nests ; colony cycle ; temperature ; brood ; reproductives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nest structure and colony cycle of a population of Allegheny mound ants,Formica exsectoides, were examined in central Michigan. The dispersion pattern of mounds was random. Nest structure and presence of brood were primarily determined by excavation of twenty-three nests over three intervals from June through September. Additional excavations of five nests in 1990 and ten nests in 1991 provided further details on nest structure and colony cycle. Most galleries occurred within the mound and upper 30 cm of soil, but some activity reached depths of 100 to 270 cm. Depth of nests showed little correlation with external measurements of height and diameter. Immature stages were recovered from two strata: the upper 20 cm of nest and mound and the lowest nest depths. Alate sexual forms were found in or near the mound in July, and numerous dealate queens were collected in September from peripheral galleries near the soil surface.
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    Comparative biological data in two closely related eusocial species:Evylaeus calceatus (Scop.) andEvylaeus albipes (F.) (Hym., Halictinae) (1992)
    Springer
    Insectes sociaux 39 (1992), S. 351-364 
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    ISSN: 1420-9098
    Keywords: Castes ; delayed eusociality ; non-delayed eusociality ; polygyny ; social flexibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Following a brief review of the similarities and differences between the two closely related species,Evylaeus calceatus andE. albipes, a description of certain biological features common to both species is given: the occasional presence of workers among the first-emerged sexuals of the second brood; a short summer collecting phase by the queen which sometimes appears to initiate foraging by the workers; the possibility of a few queens surviving a second overwintering and possibly digging a second-year nest; a trigynous society is described, composed of a second-year egg-layer associated with two first-year auxiliaries, illustrating a case of delayed eusociality. Attention is drawn to the social flexibility of the two species and the influence of environmental factors on the social organization.
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    URL: http://dx.doi.org/10.1007/BF01240620
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    Book reviews (1992)
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    Pure and applied geophysics 139 (1992), S. 163-163 
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    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
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    URL: http://dx.doi.org/10.1007/BF00876830
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    EM induction in the Vancouver Island region: 3D numerical, analogue model, and field site results (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 193-206 
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    ISSN: 1420-9136
    Keywords: Analogue modelling ; thin sheet modelling ; induction arrows ; coast effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Electromagnetic induction in the Vancouver Island region for a uniform inducing source field for 300 s period is investigated with the aid of three-dimensional (3-D) numerical and analogue model results and field site measurements. The thin sheet numerical model, based on the subducting Juan de Fuca plate analogue model ofDosso et al., consists of a 5km thick non-uniform thin sheet (comprising the lateral conductivity contrasts arising from the land, the varying depth ocean, and the sediment) underlain by a four-layer conductive structure. The four-layer conductive structure beneath the non-uniform thin sheet simulates the effect of the Juan de Fuca plate subducting Vancouver Island. To examine the effects of the ocean channel depth between Vancouver Island and the British Columbia (Canada) mainland, numerical results were obtained for two channel depths (0 and 600 m). The results indicate that the channel plays an important role in the geomagnetic response in the central and inner coastal regions of Vancouver Island. The general agreement of the 3-D numerical model induction arrows with the analogue model and field site induction arrows for 300 s supports the premise of a layered conductive substructure dipping at a small angle, at most, beneath Vancouver Island.
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    Comparison of observed and theoretically calculated seiches of Heda Bay, Japan (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 309-322 
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    ISSN: 1420-9136
    Keywords: Seiche ; supersonic tide gauge ; tsunami
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We carried out observations of sea-level fluctuations simultaneously at three stations on the coast of Heda Bay, Honshu, Japan, using supersonic-type water level gauges controlled by a personal computer. Analyses of the obtained data showed predominant spectral peaks at periods of 7.6, 2.0 and 1.3 minutes for all three stations. Comparison of the observed data with numerically calculated normal oscillation modes of the bay indicates that these three spectral peaks correspond to the theoretical first, third and seventh normal modes of the basin respectively, judging from the results of cross-spectral analyses. The reason for the absence of the remaining normal modes, especially of the second or the lateral first mode of the basin, is briefly considered.
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    URL: http://dx.doi.org/10.1007/BF00878901
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    Love-Rayleigh wave incompatibility and possible deep upper mantle anisotropy in the Iberian peninsula (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 429-444 
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    ISSN: 1420-9136
    Keywords: Iberian Peninsula ; Love-Rayleigh discrepancy ; ILIHA ; anisotropy ; surface waves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Love and Rayleigh wave phase velocities are analyzed with the goal of retrieving information about the anisotropic structure of the Iberian lithosphere. The cross-correlation method is used to measure the interstation phase velocities between diverse stations of the ILIHA network at periods between 20 and 120 s. Despite the 2-D structure of the network, the Love wave data are too few to enable an analysis of phase velocity azimuthal variations. Azimuthal averages of Love and Rayleigh wave phase velocities are calculated and inverted both in terms of isotropic and anisotropic structures. Realistic isotropic models explain the Rayleigh wave and short-period Love wave phase velocities. Therefore no significant anisotropy needs to be introduced in the crust and down to 100 km depth in the upper mantle to explain our data. A discrepancy is observed only at long periods, where the data are less reliable. Love wave data at periods between 80 and 120 s remain 0.15 km/s faster than predicted by isotropic models explaining the long-period Rayleigh wave data. Possibilities of biases in the measurements due to interferences with higher modes are examined but seem unlikely. A transversely isotropic model with 8% of S-wave velocity anisotropy in the upper mantle at depths larger than 100 km can explain the whole set of data. In terms of a classical model of mantle anisotropy, this corresponds to 100% of the crystals perfectly oriented in the horizontal plane in a pyrolitic mantle. This is a rather extreme model, which predicts at time delay between 0 and 2 seconds for split SKS.
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    Introduction (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 529-529 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
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    URL: http://dx.doi.org/10.1007/BF00876336
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    Book reviews (1992)
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    Pure and applied geophysics 138 (1992), S. 507-527 
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    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
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    URL: http://dx.doi.org/10.1007/BF00876886
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    Fractures: Finite-size scaling and multifractals (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 679-706 
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    ISSN: 1420-9136
    Keywords: Fractures ; fractals ; multifractals ; scaling ; percolation ; geohydrology ; rock mechanics ; permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The distributions of contact area and void space in single fractures in granite rock have been determined experimentally by making metal casts of the void spaces between the fracture surfaces under normal loads. The resulting metal casts on 52 cm diameter core samples show a complex geometry for the flow paths through the fracture. This geometry is analyzed using finite-size scaling. The spanning probabilities and percolation probabilities of the metal casts are calculted as functions of observation scale. Under the highest stresses of 33 MPa and 85 MPa there is a significant size-dependence of the geometric flow properties for observation scales smaller than 2 mm. Based on this data, the macroscopic percolation properties of the extended fracture can be well represented by relatively small core samples, even under normal stresses larger than 33 MPa. The metal casts also have rich multifractal structure that changes with changing stress.
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    Stress-induced crack path in Aji granite under tensile stress (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 641-656 
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    ISSN: 1420-9136
    Keywords: Stress-induced crack ; granite ; tensile strength ; fractal ; double-torsion test ; stress corrosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The double-torsion test using Aji granite was carried out to investigate the interaction between stress-induced crack path and mineral grains. Crack velocities were controlled at range 10−7 m/s to 10−1 m/s. After the stressed specimens were dyed, we checked the crack path by thin section analysis, using an optical microscope. The stress-induced crack path was divided into two types, transgranular and intergranular cracks, and each path was subdivided with respect to mineral grains. In spite of the extensive range of crack velocities, the ratios between the transgranular and intergranular crack lengths did not change. The crack paths were all jagged, and often showed detour around the grain boundary when faced with obstacles like hard grains or preexisting cracks. That is to say, quartz grain played an important role as an obstacle. Feldspar grain could change the crack path because of its cleavage plane. Biolite grain had a serious effect on the path even if its constitution ratio is very small. Fractal dimensions of the crack paths were calculated by three methods, as indicators of surface roughness. The fractal dimensions were shown in a slight trend with the change of crack velocity. This trend can be explained from the point of limited cracking rate in stress corrosion.
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    Coda-Q before and after the 1986 Andreanof Islands earthquake (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 1-16 
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    ISSN: 1420-9136
    Keywords: Coda-Q ; subduction earthquakes ; Aleutian Islands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Coda-Q values before and after the May 7, 1986 Andreanof Islands earthquake in the central Aleutian subduction zone were calculated from microearthquake seismograms on the basis of Aki's single backscattering model. Digital waveforms from 329 microeathquakes in 5.4 years before the mainshock and 40 aftershocks recorded by 11 stations of the Central Aleutians Seismic Network were utilized. Before the mainshock, coda-Q in the rupture zone west of the mainshock epicenter was 15% higher than theQ outside the rupture zone to the west. A lowQ in the region east of the mainshock epicenter is inferred, but lacks solid evidence. The highQ region accords with the part of the rupture zone where most seismic moment was released. During approximately two months after the mainshock, coda-Q in the rupture zone decreased about 10%. PrecursoryQ changes were not found in the 5.4 years before the mainshock. It is deduced that a coda-Q precursor, if it existed, was of small magnitude (〈10%), or its duration was either shorter than one year or longer than four years.
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    MAGSAT data and Curie-depth below Deccan flood basalts (India) (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 61-75 
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    ISSN: 1420-9136
    Keywords: MAGSAT ; Deccan traps ; spectral analysis ; Curie-depth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Ground and airborne magnetic data are severely disturbed due to random susceptibility variations in Deccan flood basalts. However, Magnetic Satellite (MAGSAT) data over the Deccan flood basaltic region of the Indian subcontinent exhibit filtering of surficial noise. Three passes over Deccan traps show a “low” at about 20°N latitude and a “high” at about 23°N latitude. Spectral analysis of these passes and an available 2-D MAGSAT vertical intensity map indicate a deep (40±4 km) magnetic interface. It is interesting to note that the determination of Curie-depth from MAGSAT matches and confirms the geothermal data model. The estimates correspond to the Moho depth derived from gravity and deep seismic sounding studies. The study suggests a continental shield-like geothermal gradient of about 14°C/km below the area.
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    Network properties of a two-dimensional natural fracture pattern (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 95-114 
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    ISSN: 1420-9136
    Keywords: Rock fracture ; fracture network ; clusters ; connectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The influence that fractures exert on the permeability of a fractured rock is, to a large extent, controlled by the nature of the network formed by the fracture system. Here, the network properties of a two-dimensional natural pattern, mapped from the surface of a sandstone layer, are investigated and compared to those of realizations of spatially randomly distributed line segments with similar orientation and length distributions and line segment density (line length per unit area) to the natural pattern. These patterns are composed of clusters of varying size and shape, made up of interconnected fracture traces or line segments. Comparing the natural pattern with the realizations, the natural pattern was found to contain roughly half the number of clusters while the mass (total line length) of the largest cluster is approximately double that of the realizations. The size of the largest cluster controls the connectivity of the patterns, as can be seen by comparing the largest cluster of the natural pattern, which connects all four sides of the region, with those of the realizations, which are unconnected or connect only two sides. Cluster scaling characteristics were found to be similar in the natural pattern and the realizations and show a crossover from a dimension of one (their topological dimension) to two (the dimension of the embedding medium) at a point that corresponds to the fracture spacing. An investigation of the self-similarity dimension, using the box-counting method, showed similar characteristics with a broad transition zone between one- and two-dimensional behaviour at smaller box sizes. The patterns are therefore found to be non-fractal. The effect of the spatial distribution shown by the natural pattern is thus to modify the manner in which fractures are distributed among clusters, increasing connectivity (and permeability in the case of open fractures), but does not affect the cluster scaling characteristics or the self-similarity dimension of the fracture patterns.
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    Case history of a slip-type rockburst (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 627-637 
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    ISSN: 1420-9136
    Keywords: First motion ; rockburst ; full waveform ; double-couple ; macroseismic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract First-motion analyses of digital seismic records and an assessment of damage provided conclusive evidence that a fault-slip source mechanism was responsible for a Richter magnitude 2 that occurred at the Lucky Friday Mine on April 13, 1990. This event was the first time that movement along an argillite bed had been observed after the macroseismic monitoring system had been installed. The physical evidence of a shear-slip type failure established confidence in using double-couple, first-motion analyses for the macroseismic system. The U.S. Bureau of Mines is conducting this research as part of its mission to enhance safety by reducing rockburst hazards in mines.
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    Note on fault-slip motion inferred from a study of micro-cataclastic particles from an underground shear rupture (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 677-695 
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    ISSN: 1420-9136
    Keywords: Rockburst ; micro-cataclasis ; faulting process ; shock rebound ; rhombic dodecahedra ; source mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Mining of a highly-stressed remnant in a deep South African gold mine was accompanied by considerable seismic activity and some significant rockbursts. The larger seismic events were registered some 60 km away at a WSSN station and several shear ruptures corresponding to these events were encountered during mining operations. A careful study based on detailed exploration of two of these ruptures proved them to be the source of two of the larger rockbursts. Certain striking features revealed by a scanning electron microscopic study of some of the fresh cataclastic ‘rock-flour’ forming part of the comminuted filling of these ruptures provide strong evidence of violent ’shock rebound’ phenomena in the faulting process. This interpretation could provide useful insight into earthquake source mechanisms and also has practical significance in the understanding of mine rockbursts.
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    The three-dimensional dynamic displacement discontinuity method: Theory and applications (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 763-779 
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    ISSN: 1420-9136
    Keywords: Three-dimensional ; elastodynamic ; boundary element method ; displacement discontinuity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A boundary element technique has been developed for solving three-dimensional elastodynamic problems in rock mechanics, such as joint slip and the sudden advance of excavations. Both implicit and explicit versions of the technique have been implemented. Comparisons of accuracy and computational efficiency are made for a simple verification problem. Examples in which the technique has been used to investigate the dynamic response of supported and unsupported excavations in tabular orebodies are presented.
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    Periodicities in the time series of annual minimum temperatures for the United States Gulf Coast region (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 323-333 
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    ISSN: 1420-9136
    Keywords: Minimum temperatures ; USA Gulf Coast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The minimum winter temperature series for the United States Gulf Coast for 1799–1988 (190 values) was subjected to Maximum Entropy Spectral Analysis. Significant periodicities in the QBO region (T-2–3 years) and atT=∼3.7, 4.5, 5.5, 6.5, 7.5, 12.9, 15.5 and 22 years were detected. Some of these were present in the first half only (1799–1893) while others in the latter half only (1894–1988), indicating a transient nature. Also, more than 50% of the variance was random. Many of the significant periodicities are seen in other geophysical parameters. Some may be harmonics of the 11-year sunspot cycle and the 22-year Hale magnetic sunspot cycle.
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    Fresnel zone inversion for lateral heterogeneities in the earth (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 391-406 
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    ISSN: 1420-9136
    Keywords: Velocity inversion ; finite wavelength ; Fresnel zone ; Rytov approximation ; paraxial ray approximation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We propose a different kind of seismic inversion from travel-time or waveform inversion for lateral heterogeneities in the earth: Fresnel zone inversion. Amplitude and phase delay of data in several frequency ranges are inverted for model space around ray paths with a width corresponding to the considered frequency so that primary effect of finiteness of wavelength be included. For vertically heterogeneous media, Fréchet derivatives for inversion are obtained very efficiently using the paraxial ray approximation, with nearly similar amounts of computation compared to travel-time inversion. As an example, Fréchet derivatives are computed for a teleseismic observation system for a three-dimensional structure in the lithosphere beneath an array of seismic stations. Even if the used frequency is around 2 Hz, the width of Fréchet derivatives cannot be neglected, particularly near the bottom of the lithosphere. Sensitivity of model parameters to observations is, moreover, different in our approach from conventional travel-time inversion: it is zero along ray paths but large slightly away from them. Some model calculations show that travel-time inversion, particularly with models divided into very fine meshes or blocks, might give misleading results. An example of inversion for a simple Camembert model, in the event that travel-time inversion gives no reliable results, shows how this technique works with much smaller data sets and computation than waveform inversions.
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    Chaotic seismic faulting with a mass-spring model and velocity-weakening friction (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 569-589 
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    ISSN: 1420-9136
    Keywords: Seismicity ; slide-blocks ; chaos ; earthquakes ; fractals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We present a systematic analysis of the dynamical behavior introduced by fault zone heterogeneities, using a simple mass-spring model with velocity-weakening friction. The model consists of two sliding blocks coupled to each other and to a constant velocity driver by clastic springs. The state of this system can be characterized by the positions of the two blocks relative to the driver. Symmetry stabilizes the system and generates only cyclic behavior. For an asymmetric system where the frictional forces for the two blocks are not equal, the solutions exhibit chaotic behavior. The transition from stable cyclic behavior to chaos is characterized by the period-doubling route to chaos. Lyapunov exponents are computed to quantify the deterministic chaos and to locate the onset of the chaotic evolution in parameter space. In many examples of deterministic chaos, chaotic behavior of a low-order system implies chaos in similar higher order systems. Thus, our results provide substantial evidence that crustal deformation is an example of deterministic chaos.
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    Multifractal analysis of earthquakes (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 591-610 
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    ISSN: 1420-9136
    Keywords: Multifractal ; generalized dimension ; earthquakes ; epicenter and hypocenter distribution ; energy distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Multifractal properties of the epicenter and hypocenter distribution and also of the energy distribution of earthquakes are studied for California, Japan, and Greece. The calculatedD q-q curves (the generalized dimension) indicate that the earthquake process is multifractal or heterogeneous in the fractal dimension. Japanese earthquakes are the most heterogeneous and Californian earthquakes are the least. Since the earthquake process is multifractal, a single value of the so-called fractal dimension is not sufficient to characterize the earthquake process. Studies of multifractal models of earthquakes are recommended. Temporal changes of theD q-q curve are also obtained for Californian and Japanese earthquakes. TheD q-q curve shows two distinctly different types in each region; the gentle type and the steep type. The steeptype corresponds to a strongly heterogeneous multifractal, which appears during seismically active periods when large earthquakes occur.D q for smallq or negativeq is considerably more sensitive to the change in fractal structure of earthquakes thanD q forq≥2. We recommend use ofD q at smallq to detect the seismicity change in a local area.
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    An asperity model to simulate rupture along heterogeneous fault surfaces (1992)
    Springer
    Pure and applied geophysics 138 (1992), S. 549-567 
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    ISSN: 1420-9136
    Keywords: Asperity ; earthquake ; fracture mechanics simulation ; seismicity ; characteristic earthquakes ; b-value
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A model has been developed to simulate the statistical and mechanical nature of rupture on a heterogeneous strike-slip fault. The model is based on the progressive failure of circular asperities of varying sizes and strengths along a fault plane subjected to a constant far-field shear displacement rate. The basis of the model is a deformation and stress intensity factory solution for a single circular asperity under a unidirectional shear stress. The individual asperities are unified through the fault stiffness and the far-field stress and displacement. During fault deformation asperities can fail and reheal, resulting in changes in the local stresses in the asperities, stress drops, and changes in the stiffness of the fault. Depending on how the stress is redistributed following asperity failure and on the strenghts of the neighboring asperities an earthquake event can be the failure of one or more asperities. Following an earthquake event seismic source parameters such as the stress drop, energy change, and moment magnitude are calculated. Results from the model show a very realistic pattern of earthquake rupture, with reasonable source parameters, the proper magnitude-frequency behavior, and the development of characteristic earthquakes. Also the progression ofb-values in the model gives some insight into the phenomenon of ‘self-organized criticality.’
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    Use of the mantle magnitudeM m for the reassessment of the moment of historical earthquakes (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 17-57 
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    ISSN: 1420-9136
    Keywords: Historical earthquakes ; magnitudes ; mantle waves ; tsunamis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The mantle magnitudeM m is used on a dataset of more than 180 wavetrains from 44 large shallow historical earthquakes to reassess their moments, which in many cases had been previously estimated only on the basis of the earthquake's rupture area. We provide 27 new or revised values ofM o, based on the spectral amplitudes of surface waves recorded at a number of stations, principally Uppsala and Pasadena. Among them, and most significantly, we document a large low-frequency component to the source of the 1923 Kanto earthquake: the low-frequency seismic moment is 2.9×1028 dyn-cm, in accord with geodetic observations. On the other hand, we revise downwards the seismic moment of the 1906 Ecuador event, which did not exceed 6×1028 dyn-cm. Finally, the study of the 1960 Chilean and 1964 Alaskan earthquakes whose exceptionally large moments are properly retrieved throughM m measurements, serves proof that this approach performs flawlessly even for the very greatest earthquakes, and is therefore successful in its goal to avoid the saturation effects plaguing any magnitude scale measured at a fixed period.
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    Scattering of elastic waves by a fracture zone containing randomly distributed cracks (1992)
    Springer
    Pure and applied geophysics 139 (1992), S. 121-144 
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    ISSN: 1420-9136
    Keywords: Fracture zone ; cracks ; scattering ; friction ; attenuation ; phase velocity ; transmitted and reflected waves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We theoretically study the scattering ofP, SV andSH waves by a zonal distribution of cracks, which simulates a fault fracture zone. An investigation is conducted how the geometrical properties of the crack distribution and the frictional characteristics of the crack surface are reflected in the attenuation and dispersion of incident waves, as well as in the amplitudes of the transmitted and reflected waves from the zone. If the crack distribution within the fault zone changes temporally during the preparation process of the expected earthquake, it will be important for earthquake prediction to monitor it, utilizing the scattering-induced wave phenomena. We consider the two-dimensional problem. Aligned cracks with the same length are assumed to be randomly distributed in a zone with a finite width, on which elastic waves are assumed to be incident. The distribution of cracks is assumed to be homogeneous and sparse. The crack surface is assumed to be stress-free, or to undergo viscous friction; the latter case simulates fluid-filled cracks. The opening displacement of the crack is assumed to be negligibly small. The idea of the mean wave formalism is employed in the analysis, and Foldy's approximation is assumed. When the crack surface is stress-free, it is commonly observed for every wave mode (P, SV andSH) that the attenuation coefficientQ −1 peaks aroundka∼1, the phase velocity is almost independent ofk in the rangeka〈1 and it increases monotonically withk in the rangeka〉1, wherek is the intrinsicS wavenumber anda is the half length of the crack. The effect of the friction is to shift the peak ofQ −1 and the corner of the phase velocity curve to the low wavenumber range. The high wavenumber asymptote ofQ −1 is proportional tok −1 independently of model parameters and the wave modes. If the seismological observation thatQ −1 ofS waves has a peak at around 0.5 Hz in the earth's crust is combined with our results, the upper limit of crack size within the crust is estimated about 4 km. The information regarding the transmitted and reflected waves, such as the high wavenumber limit of the amplitude of the transmitted wave etc., allows estimation of the strength of the friction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876828
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