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  • 2015-2019
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  • 1988  (55,483)
  • 1
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary Colonies ofMessor barbarus are monogynous and closed. Tests on societies during foundation showed that their closure is not complete. As long as the gyne is alone, she attacks and kills any stranger. When she has eggs and larvae, she accepts foreign eggs and larvae. With young workers, she may accept foreign workers and tolerate another gyne. It is possible to form a colony with two queens by joining two young societies. Older workers become aggressive and attack foreign conspecific ants: the societies are then permanently closed. Explanations of these changes in aggression are discussed.
    Notes: Resume Les sociétés deMessor barbarus apparaissent monogynes et fermées. Des expériences sur des sociétés en cours de fondation ont montré que leur fermeture n'est pas totale. Tant que la femelle fondatrice est seule, elle attaque et tue tous les individus étrangers. Son agressivité diminue quand elle possède du couvain. Peu après la naissance des premières ouvrières, les individus étrangers sont adoptés et il est même possible d'obtenir des sociétés définitivement digynes en réunissant deux jeunes sociétés. Au bout de quelques semaines naissent des ouvrières agressives vis-à-vis des étrangers et les sociétés sont alors définitivement fermées. Des explications à ces changements de l'agressivité sont proposées et discutées.
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  • 2
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    Insectes sociaux 35 (1988), S. 153-166 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume On a déjà montré (Brian, 1986b) que la sociabilité des reines deMyrmica rubra L. variait de l'état solitaire à très sociable. On rapporte ici que dans la colonie, les reines sociables se trouvent à proximité des œufs. Ces reines sont, au moins dans leur seconde année, plus lourdes car leurs ovaires et les tissus adipeux sont plus développés et leur fécondité est supérieure à celle des reines solitaires. Les reines solitaires vivent à la périphérie de la colonie et sont plus légères; leurs ovaires sont plus petits soit parce qu'ils se sont moins développés, soit parce qu'ils ont dégénéré. La fécondité est faible. Il s'agit de jeunes reines, de reines très âgées ou parfois de reines blessées. Les populations d'ouvrières varient en fonction du degré avec lequel elles régulent la répartition des reines; celles qui empêchent leur regroupement diminuent également la fécondité. Ainsi l'aversion mutuelle des reines et la régulation de la caste par les ouvrières limitent le nombre des reines présentes au cœur de la société. Seules les reines en pleine maturité qui peuvent pondre des œufs bipotentiels et ainsi contribuer au développement de la colonie peuvent fréquenter le cœur du nid.
    Notes: Summary Queens ofMyrmica rubra L. living in natural groups of workers, have been shown to range from sociable to solitary (Brian, 1986b). More data are now presented to show that the sociable queens tend to inhabit the core near the eggs, to be heavier as a result of having a well developed ovary and fat-body, to be at least in their second year of age and to lay more eggs. The solitary queens live peripherally and are lighter, have shorter ovaries that are either undeveloped or degenerate and only lay a few eggs. They are a mixture of first-year queens, spent queens or infirm ones. Worker populations vary in the degree to which they regulate the dispersion of queens; those which oppose central clustering also reduce fecundity. Thus both the queens by their mutual aversion and the workers by their grading of queens restrict entry into the nest core. Only the mature queens that can lay sex-competent eggs and so contribute to the full development of the society are able to frequent the core.
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  • 3
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Der Lebensraum und die Nestbiologie der Afrikanischen Honigbiene,Apis mellifera scutellata, wurden an Völkern im natürlichen Verbreitungsgebiet im Delta des Okavango Flusses, Botswana, untersucht. Beobachtungen der Vegetation zeigten, daß den Völkern im Delta das ganze Jahr über reichlich Nahrung zur Verfügung steht. Die Koloniedichte betrug 7.8 Nester/km2. Nesthöhlen fanden sich gleich häufig in Bäumen wie in Termitenhügeln, sie hatten ein Volumen von ca. 17 L, waren nicht propolisiert und hatten nach Süden gerichtete, oben liegende Eingänge. Die Völker im Delta waren klein (ca. 6,500 Arbeiterinnen), sie bauten wenig Waben (ca. 3,000 cm2), speicherten wenig Nahrung, verwendeten 78% der Waben für die Brut und sie verfteidigten ihr Nest nur schwach; die Verlustrate durch Räuber betrug 48%. Die charakteristischen Eigenschaften, die fürscutellata in dieser Untersuchung beobachtet wurden, werden als Anpassungen an das heisse Klima, an die lange Trachtperiode und an die im Delta auftretende hohe Verlustrate diskutiert. Die Ergebnisse, die an Völkern im Delta gewonnen wurden, werden verglichen mit Ergebnissen anscutellata in anderen tropischen Gebieten und mit Ergebnissen anscutellata in anderen tropischen Gebieten und mit Ergebnissen an Honigbienen in gemäßigten Klimazonen.
    Notes: Summary The habitat and nesting biology were studied for naturally occurring colonies of the African honey bee,Apis mellifera scutellata, in the Okavango River Delta, Botswana. Vegetational surveys revealed that the forage available to Delta colonies was abundant and potentially available year round. Colonies had a density of 7.8 nests/km2. Nest cavities occurred with equal frequency in trees and termite mounds, had a volume of approximately 17 L, were unpropolized, and had south-facing, top-located entrances. Delta colonies were small (ca. 6,500 workers), constructed small amounts of comb (ca. 3,000 cm2), stored little food, devoted 78% of comb space to brood production, exhibited little nest defense, and experienced a 48% predation rate during the 5 month study period. The characteristics observed forscutellata in this study are discussed as adaptations to the hot climate, long foraging season, and high predation rate experienced in the Delta. Data for the Delta colonies are compared to those forscutellata in other tropical areas, and to honey bees in temperate climate regions.
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  • 4
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    Insectes sociaux 35 (1988), S. 209-213 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 5
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Arbeiterinnen vonCamponotus spp., die in weisellosen Gruppen aufgezogen wurden, erkennen nestfremde Verwandte anscheinend auf grund von genetisch bedingten chemischen Abzeichen oder “Diskriminatoren”, während Arbeiterinnen, die in Gegenwart einer Königen gehalten werden, von der Königin Abzeichen annehmen, die ein solches Verwandtenerkennen verhindern. Wir untersuchten, inwieweit diese von der Königin stammenden Abzeichen ebenfalls genetisch bedingte chemische Marken darstellen. Dazu wurdenC. floridanus Arbeitergruppen, bestehend aus genetischen Geschwistern, oder nicht verwandten Tieren, in Gegenwart jeweils einer nicht begatteten Königin aufgezogen. Die Königinnen waren entweder Schwestern oder stammten aus verschiedenen, weit entfernten Nestern. In neutralen Arenatests wurde geprüft, inwieweit sich Angehörige verschiedener Adoptionsgruppen als Geschwister erkennen können. Dabei zeigte sich, dass Arbeiterinnen aus Gruppen, deren Adoptions-Königinnen Schwestern waren, sich weniger aggressiv zueinander verhielten, als Arbeiterinnen deren Adoptions-Königinnen aus verschiedenen Nestern stammten. Das legt den Schluss nahe, dass die von Königinnen übertragenen Abzeichen echte Diskriminatoren darstellen.
    Notes: Summary Camponotus spp. workers reared in queenless groups recognize non-nestmate kin, apparently by shared heritable chemical cues or “discriminators”, while workers reared in the presence of mated queens acquire labels which superoede such recognition. Whether queen-derived labels are themselves discriminators has not been examined previously. Groups of sister or unrelated workers ofC. floridanus were adopted to sister or unrelated virgin queens, and recognition among non-nestmate adoptees was assayed in neutral arena encounters. Interactions were significantly less aggressive among workers whose queens were sisters than among those whose queens were not, indicating that their acquired recognition cues are queen discriminators.
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  • 6
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    Insectes sociaux 35 (1988), S. 206-208 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume On décrit un système économique, léger et stable pour héberger temporairement et pour expédier des colonies de fourmis vivantes, ou d'autres petits insectes (fig. 1). Seulement deux types de tubes transparents et flexibles de PVC, des bouchons de PVC et un morceau de gaze de cuivre sont nécessaires pour faire le système. Les insectes sont aspirés dans les tubes.
    Notes: Summary A cheap, light and stable system for temporary housing and mailing live ant colonies, or other small insects, is described (fig. 1). Only two sizes of transparent and flexible PVC-tube, PVC-stoppers and a piece of copper gauze are needed to make the system. The insects are aspirated into the tubes.
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  • 7
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    Insectes sociaux 35 (1988), S. 262-270 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Mit zunehmendem Alter durchlaufen die Arbeiterinnen der Honigbiene in gesetzmässiger Reihenfolge ihre Tätigkeiten: sie gehen von der Brutpflege zum Bauen, dann zur Sammeltätigkeit über. Wenn man den Arbeitsmarkt künstlich, aber nur mässig stört, dann passen sich die Bienen dadurch an, dass sie einige Tätigkeiten intensiver ausführen, ohne dass dabei aber das mittlere Alter für diese Tätigkeit geändert wird. Dies steht im Gegensatz zu anderen Untersuchungen, wo der Arbeitsmarkt drastisch gestört wurde, z. B. durch Entfernung der meisten oder aller alten oder jungen Arbeiterinnen. Durch solchen drastischen demographischen Stress wurde eine Umstellung in der Altersstufe für bestimmte Tätigkeiten erwirkt. Die in dieser Arbeit durchgeführten demographischen leichten Manipulationen lassen den Schluss zu, dass der Bienenstaat bei verschiedenen Anforderungen an den Arbeitsmarkt durchaus plastisch beweglich ist, aber nicht maximal sich umstellen kann.
    Notes: Summary Worker honey bees proceed through a sequence of tasks, passing from hive and guard duties to foraging activities. When presented with moderate demographic alterations in colony age structure, bees may work harder at some tasks but do not significantly alter median ages of task performance for many behaviour patterns. This is in contrast to other studies that have presented colonies with more drastic demographic stresses (i.e., removal of most or all old and/or young workers) and which have demonstrated dramatic changes in the ages of task performances. The additional efforts invoked by demographic manipulations are consistent with a viewpoint that considers honey bee colonies to be resilient rather than maximally efficient systems.
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  • 8
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary In the antCataglyphis cursor, the developement of alate forms in laboratory rearings occurs from late March to late June and needs adequate conditions of temperature and food. The queen inhibits worker egg laying; she prevents other queens from developing in small incipient colonies. Several years of experiments show the following: 1- Larvae moved from a society producing only workers to another society made apart from the same colony having just overwintered and producing alates, can grow into queens. This “sexualization” succeeds for brood originating from queens as well as for brood issued by thelytoky from orphaned workers. 2- Conversely, large larvae (alate biased), except the ones which are close to pupation, die when put into homocolonial societies which have been active for two month after overwintering and therefore only able to produce workers. 3- The period of maximum efficiency for the production of alates by workers occurs between 10 and 20 days after the end of overwintering. 4- Female larvae can develop into queens or workers until the early third and last instar. 5- By increasing the nurse/larvae ratio, up to 100% of sexuals can be obtained. 6- Young workers, eclosed the year before, are able to sexualize the female larvae and rear male larvae to imagoes. After the winter diapause, the fat body of young nurses is abundant; they exhibit high physiological activity in ovarioles, corpora allata and postpharyngeal salivary glands. Older workers are still able to oviposit but unable to rear their own offspring. 7- Development and sexualization of larvae transferred to alien colonies is possible if all the recipient colony's eggs are removed and if the two colonies originate from geographically close localities. Adopted larvae are rapidly abandoned and die if the native brood is left in the nest; the latter normally develops into alates. 8- Similarly, male larvae need to be reared by young vernalized nurses to develop. Male larvae seem to be relatively susceptible and rare in the brood. They suffer heavy mortality while developing. The physiological condition of nurse-workers seems to be determinant for development and survival of sexuals. The role of thelytoky in the field and its implications for population structure and worker control of the colony are briefly discussed.
    Notes: Resume Chez la fourmiCataglyphis cursor, le développement des sexués ailés a lieu au printemps; il nécessite en élevage, une température et une nourriture suffisantes. La reine inhibe la ponte des ouvrières et empêche la formation d'autres reines dans les jeunes colonies où la population est encore faible. Des expériences renouvellées durant plusieurs années ont permi de mettre en évidence les points suivants: 1- Des larves à devenir ouvrières, transférées dans des sociétés homocoloniales sortant d'hivernage, peuvent évoluer en reines. Cette «sexualisation» réussit avec des larves issues du couvain pondu par une reine comme avec du couvain issu d'ouvrières, par parthénogenèse thélytoque. 2- Inversement, des grosses larves d'ailés (sauf si elles sont très proches de la nymphose) avortent lorsqu'elles sont données à des sociétés homocoloniales sorties depuis longtemps d'hivernage. 3- La période optimale pour l'élevage des ailés se situe entre 10 et 20 jours après la sortie d'hivernage. 4- Les larves femelles restent bi-potentielles reine/ouvrière jusqu'au début du 3e stade. 5- En diminuant le nombre des larves par rapport au nombre d'ouvrières éleveuses, on peut obtenir jusqu'à 100% de reines. 6- Le couvain est sexualisé par les jeunes ouvrières, nées l'année précédente; après la diapause hivernale, leur corps gras est abondant, les ovaires, les corps allates et les glandes postpharyngiennes montrent des signes d'activité élevée. Les ouvrières âgées de plus d'un an peuvent encore pondre mais semblent incapables d'élever des larves jusqu'au stade adulte. 7- La sexualisation des larves par des ouvrières étrangères reste possible si l'on retire tous les œufs pondus par les ouvrières-hôtes et si le transfert de larves est tenté entre colonies d'une même localité ou de localités géographiquement proches. Des larves adoptées, dont la sexualisation est en cours, avortent lorsque le couvain indigène est laissé en place; celui-ci évolue normalement en produisant des ailés. 8- Pour se développer, les larves de mâles ont aussi besoin d'être soignées et nourries par des ouvrières sorties d'hivernage depuis peu. Les larves de mâles paraissent relativement fragiles et subissent une forte mortalité au cours de leur développement. Le rôle de la parthénogenèse dans la nature et ses implications sur la structure des populations et le contrôle de la colonie par les ouvrières sont brièvement discutés.
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  • 9
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary The life spans of femalesPolistes were influenced by the social environnement found at the emergence time, within the limits set by a probable larval predisposition. An early separation from the natal colony reduced the proportion of wasps able to overwinter and to found a nest the next spring. On the other hand, the removal of older larvae from the brood increased the proportion of long-lived wasps among the imago that undergo this situation. The functional consequences of these findings are discussed.
    Notes: Resume Cette étude montre que la durée de vie des femelles de poliste est influencée, dans les limites d'une probable prédisposition larvaire, par les conditions sociales rencontrées à l'émergence. La séparation précoce d'avec le guêpier d'origine diminue fortement la proportion des descendantes qui supportent l'hiver et fondent au printemps suivant. Par contre, la destruction, dans le couvain, des larves de grande taille provoque un accroissement de la proportion des descendantes à vie longue parmi les guêpes subissant cette situation à l'état imaginal. On discute la signification fonctionnelle de ces résultats.
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  • 10
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume Les ouvrières deLeptothorax unifasciatus utilisent des repères chimiques et des repères visuels au cours des activités de fourragement. Cependant, une orientation ménotactique (ampoule lumineuse de 60 watt) et reposant sur des repères visuels ambiants domient une orientation chimique. Un trajet effectué vers la nourriture suffit aux ouvrières pour s'orienter ensuite sur une ampoule lumineuse. Les ouvrières tracent une piste au cours du fourragement n'ayant pas fonction de recrutement, mais agissant comme repère orientationnel individuel. Ces pistes sont distinguées et préférées même lorsqu'elles sont superposées à plusieurs autres. Néanmoins, les ouvrières acceptent de suivre les pistes de leurs congénères en l'absence de leur propre piste. Les ouvrières nouvellement recrutées sont incapables de s'orienter sur les pistes chimiques.
    Notes: Summary Leptothorax unifasciatus workers use both chemical and visual cues when foraging. A visual orientation based on menotactical cues (60 watt light-bulb) and environmental cues (laboratory surroundings) dominate over a chemical orientation. The learning response to a 60 watt light-bulb cue occurs after a single trip to the food source. Workers lay down a trail when foraging which helps them to orient themselves but does not recruit other nestmates. Such trails are distinguished and preferred even when superposed by several other nestmates' trails. Nevertheless, the foragers are able to follow their nestmates' trails if their own is somehow missing. Newly recruited ants are unable to orient along chemical trails.
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  • 11
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    Pure and applied geophysics 126 (1988), S. 103-121 
    ISSN: 1420-9136
    Keywords: instability ; overreflection ; Orr mechanism ; wave-mean flow interaction ; Orr-Sommerfeld problem ; shear instability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This paper reviews work done over the last twelve years on wave overreflection in shear flows, and on the development of a mechanical picture of how overreflection and instability work. It is argued that the wave geometry of a flow configuration is the primary determinant of its stability. It is also argued that the primary mechanism for wave amplification is the Orr mechanism.
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  • 12
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
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  • 13
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    Pure and applied geophysics 126 (1988), S. 279-318 
    ISSN: 1420-9136
    Keywords: Earthquake prediction ; precursory quiescence ; quiescence ; seismicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Precursory seismic quiescence has played a major role in most of the succesful earthquake predictions made to date. In addition to these successes, the number of detailed post-mainshock documentations of precursory quiescence is steadily growing. These facts suggest that precursory quiescence will play an important role in earthquake prediction programs of the future. For this reason it is important to critically evaluate the present state of knowledge concerning this phenomenon. The history of observations of precursory seismic quiescence includes work on seismic gaps and ‘seismic preconditions’ as well as actual studies of temporal quiescence. These papers demonstrated the importance of quantitative evaluation of seismicity rates and the benefits of systematic analysis. During the early 1980's the impact of man-made effects on seismicity rates was demonstrated for the first time. Despite progress in catalog understanding, the identification and correction of man-made seismicity changes remains as the major barrier to earthquake prediction using these data. Effects of man-made changes are apparent in many past studies of seismicity patterns, making the results difficult to evaluate. Recent experience with real-time anomalies has demonstrated the necessity of determining the false alarm rates associated with quiescence precursors. Determination of false alarm rates depends on quantitative definitions of anomalies and statistical evaluations of their significance. A number of successful predictions, which have been made on the basis of seismic quiescence, provide important lessons for present and future work. There are many presently unanswered questions regarding seismic quiescence which must be answered before we can determine the reliability of this phenomena as a precursor.
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  • 14
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    Pure and applied geophysics 126 (1988), S. 141-151 
    ISSN: 1420-9136
    Keywords: atmospheric tides ; vector statistics ; lunar and solar effects ; South-west Pacific
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Lunar and solar atmospheric tidal oscillations have been determined with reasonable accuracy from a ten-year record of hourly mercury-barometer readings, corrected to mean-sea-level, at Rarotonga (Cook Islands), 21.2°S. For the lunar semidiurnal tide, the annual determination shows an amplitude (56 μb) slightly lower and a phase (51°) much smaller than the values (58 μb, 72°) that would be derived, for the position of Rarotonga, from the spherical harmonic analysis given byHaurwitz andCowley (1969). The seasonal variation of this oscillation, as given by the monthly and J, E, D values, shows most of the characteristic features found in world-wide determinations. In particular, the near equality of the J, D amplitudes at Rarotonga tends to support theHaurwitz andCowley (1969) suggestion of negative J-D values in southern middle latitudes. For the solar tides, the semidiurnal and terdiurnal oscillations at Rarotonga are similar to those found at other stations in the south-west Pacific region. However, for the diurnal oscillation, the annual amplitude (232 μb) is only about half the value (∼465 μb) indicated for the position of Rarotonga by the world maps of theS 1(p) annual harmonic coefficients given byHaurwitz (1965). It thus seems likely that the relatively small area of lowS 1(p) annual amplitude in the eastern part of the south Pacific, as indicated by these maps, is much more extensive than formerly supposed.
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  • 15
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    Pure and applied geophysics 126 (1988), S. 333-356 
    ISSN: 1420-9136
    Keywords: Earthquake prediction ; seismic quiescence ; San Andreas fault
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The Stone Canyon earthquake sequence started during August 1982 and lasted for about four months. It contained four mainshocks withM L ≥4, each with an aftershock zone about 4 km long. These mainshocks, progressing from southeast to northwest, ruptured a segment of the fault approximately 20 km long leaving two gaps, which were later filled by theM L =4.6 mainshocks of January 14, and May 31, 1986. The equivalent magnitude of the sequence isM L =5.0. Precursory seismic quiescence could be identified in: (1) the northernmost 10 km of the aftershock zone which contained three of the mainshocks; and (2) the southern gap in the aftershock zone. The fault segment containing the first mainshock and its aftershocks did not show quiescence. This pattern of precursory quiescence is very similar to two cases in Hawaii where the rupture initiation points of the mainshocks (M S =7.2 and 6.6, respectively) were located in volumes of constant seismicity rate, surrounded by volumes with pronounced precursory quiescence. The precursory quiescence before the August 1982 Stone Canyon earthquakes lasted for 76 weeks, amounted to a reduction in rate of about 60%, and could be recognized without any false alarms. That is, the anomaly was unique within the 60 km study segment of the fault and in the years 1975 through August 1982. Eighteen foreshocks occurred between July 27 and August 7, 1982. We conclude that the August 1982 mainshocks could have been predicted, based on seismic quiescence and foreshocks.
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  • 16
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    Pure and applied geophysics 126 (1988), S. 447-463 
    ISSN: 1420-9136
    Keywords: Intermediate-term precursor ; downward migration ; seismic gap ; doughnut pattern ; subduction zone ; Tonankai earthquake ; Tokachi-oki earthquake ; Tokai earthquake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Before the 1944 Tonankai earthquake along the Nankai Trough, seismic activity increased in the shallow depths, and then the activity gradually migrated downwards. When it reached its limit (a depth of approximatelty 70 km), the main shock occurred. Several deep earthquakes, including one ofM5.3, occurred several months prior to the Tonankai earthquake. A similar downward migration pattern also can be recognized regarding the 1952 Tokachi-oki earthquake. In this case the deepest earthquakes reached about 400 km. This may be one of the intermediate-term precursory phenomena of great thrusttype earthquakes in subduction zones. Recent observations in the Tokai district along the Suruga Trough, where a large earthquake is expected to occur in the future, suggest a similar downward migration pattern in the land area.
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  • 17
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    Pure and applied geophysics 126 (1988), S. 589-617 
    ISSN: 1420-9136
    Keywords: Earthquake prediction ; foreshocks ; aftershocks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Current methods for calculation of long-term probabilities for the recurrence of large earthquakes on specific fault segments are based upon models of the faulting process that implicitly assume constant stress rates during the interval separating earthquakes and instantaneous failure at a critical stress threshold. However, observations indicate that the process of stress recovery following an earthquake involves rate variations at all time scales in addition to stress steps caused by nearby earthquakes. Additionally, the existence of foreshocks, aftershocks and possible precursory processes suggest that there may be significant time dependence of the earthquake nucleation process. A method for determining the conditional probabilities for earthquake occurrence under conditions of irregular stressing is developed that could be useful at all time scales including those pertinent to short-and intermediate-term prediction. Used with models for earthquake occurrence at a stress threshold, the addition of variable stressing introduces a simple scaling of the conditional probabilities by stress level and stress rate. A model for the time-dependent nucleation of earthquake slip has been proposed recently that is based upon laboratory observations of fault strength. This failure criterion results in large but relatively short duration changes in the probability of earthquake recurrence particularly following stress steps. Applied to populations of earthquakes the models predicts a 1/t decay of seismicity following stress steps as observed for aftershocks and for frequency of foreshock-mainshock pairs. The model suggests that variations of seismicity rates of small earthquakes in the nucleation zone of the expected earthquake directly indicate variations in probability of recurrence of the large earthquake.
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  • 18
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    Pure and applied geophysics 127 (1988), S. 33-61 
    ISSN: 1420-9136
    Keywords: Seismic ; image ; reservoirs ; hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This paper examines those aspects of reflection seismology which require special consideration when imaging deeper hydrocarbon reservoirs, including the constraints imposed by vertical resolution, lateral resolution, and velocity analysis. We derive quantitative expressions relating the uncertainties in stacking velocities and in interval velocities derived from stacking velocities to acquisition parameters, as well as expressions for the lateral resolution which can theoretically be achieved for migrated seismic images. This analysis shows that the most significant limitations of seismic imaging at depth involve the finite lateral resolution of the seismic method, and the proper lateral positioning of seismic images. These difficulties are overcome in large measure through the proper migration of a seismic dataset, which becomes more critical as deeper horizons are imaged. If these horizons are suspected of having significant 3-D structure, a strong argument may be made for acquiring a 3-D seismic survey over the prospect. Migration of this dataset will then generate an image of the subsurface with good lateral resolution in both the X and Y directions.
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  • 19
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    Pure and applied geophysics 126 (1988), S. 373-406 
    ISSN: 1420-9136
    Keywords: Earthquake prediction ; quiescence ; seismic quiescence ; statistics
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    Topics: Geosciences , Physics
    Notes: Abstract Numerous cases of precursory seismic quiescence have been reported in recent years. Some investigators have interpreted these observations as evidence that seismic quiescence is a somewhat reliable precursor to moderate or large earthquakes. However, because failures of the pattern to predict earthquakes may not, in general, be reported, and because numerous earthquakes are not preceded by quiescence, the validity and reliability of the quiescence precursor have not been established. We have analyzed the seismicity rate prior to, and in the source region of, 37 shallow earthquakes (M 5.3–7.0) in central California and Japan for patterns of rate fluctuation, especially precursory quiescence. Nonuniformity in rate for these pre-mainshock sequences is relatively high, and numerous intervals with significant (p〈0.10) extrema in rate are observed in some of the sequences. In other sequences, however, the rate remains within normal limits up to the time of the mainshock. Overall, in terms of an observational basis for intermediate-term earthquake prediction, no evidence is found in the cases studied for a systematic, widespread or reliable pattern of quiescence prior to the mainshocks. In earthquake sequences comprising full seismic cycles for 5 sets of (M 3.7–5.1) repeat earthquakes on the San Andreas fault near Bear Valley, California, the seismicity rates are found to be uniform. A composite of the estimated rate fluctuations for the sequences, normalized to the length of the seismic cycle, reveals a weak pattern of a low rate in the first third of the cycle, and a high rate in the last few months. While these observations are qualitative, they may represent weak expressions of physical processes occurring in the source region over the seismic cycle. Re-examination of seismicity rate fluctuations in volumes along the creeping section of the San Andreas fault specified by Wyss and Burford (1985) qualitatively confirms the existence of low-rate intervals in volumes 361, 386, 382, 372 and 401. However, only the quiescence in volume 386 is found by the present study to be statistically significant.
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  • 20
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    Pure and applied geophysics 127 (1988), S. 93-115 
    ISSN: 1420-9136
    Keywords: Water vapour ; atmospheric models
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    Topics: Geosciences , Physics
    Notes: Abstract Two sets of radiosounding measurements, taken at different hours from some stations in the Po Valley area, were examined in order to obtain the values of precipitable waterw and determine the shapes of the vertical distribution curves of absolute humidity. From these curves, we calculated the bestfit values of scale heightsH 1 andH 2 in the 0÷5 km and 5÷10 km altitude intervals, respectively. The analysis of the radiosounding data clearly shows that parametersw andH 1 are closely related to the evolutionary features of the meteorological conditions on synoptic scale and are influenced, to a lesser extent, by the diurnal variations in the atmospheric ground layer. Seasonal average curves of temperature and absolute humidity, as functions of altitude, were also defined from the radiosounding measurements taken at various hours of the day. Moreover, interpolation methods in time (applied to a 12-hour range) and in space (range of about 300 km) were proposed for determining parametersw andH 1 from the radiosounding measurements taken at different hours from the same station or from different stations at the same hour. Reliability tests, made by comparing the same station or from different stations at the same hour. Reliability tests, made by comparing the values given by the interpolation methods with those directly obtained from the radiosounding measurements, show that these evaluations ofw andH 1 are affected by standard errors of estimate, which are comparable to the errors usually made in analyzing the radiosounding data.
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  • 21
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    Pure and applied geophysics 127 (1988), S. 155-160 
    ISSN: 1420-9136
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  • 22
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  • 23
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    Pure and applied geophysics 127 (1988), S. 447-471 
    ISSN: 1420-9136
    Keywords: Interhemispheric coupling ; ionosphere ; plasmasphere ; nighttime winter anomaly ; thermal ion fluxes ; numerical modelling
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    Topics: Geosciences , Physics
    Notes: Abstract The nighttime winter anomaly (NWA) effect was observed during solar minimum conditions at the American sector by means of ionospheric electron content and vertical sounding measurements in Havana (Cuba). An effective interhemispheric transport of plasma is suggested to explain enhanced northern nighttime ionization during winter solstice. To elucidate this effect, an adequate physicalnumerical model of the coupled system ionosphere-plasmasphere is presented and applied to a corotating tube of plasma at L=1.5 in the American sector. The NWA can be explained by theoretically derived higher tube content during the December solstice and accordingly by more intense nighttime fluxes from the plasmasphere, compared to the June solstice.
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  • 24
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    Pure and applied geophysics 127 (1988), S. 607-625 
    ISSN: 1420-9136
    Keywords: Physical properties of rocks ; permeability
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    Topics: Geosciences , Physics
    Notes: Abstract Permeability, resistivity formation factor, and pore volume change were simultaneously measured on samples of Chelmsford granite subjected to confining pressure and pore pressure cycles. Using a technique described in a previous paper, the tangent coefficients of the effective pressure law for permeability α k and for formation factor α F were determined. α k and α F did not differ significantly from one another. They showed a strong stress history dependence as has already been observed for α k in several crystalline rocks. According to the definition of the effective pressure law used here, two physical properties with identical α's must be related through a one-to-one functional relationship. Hence, the observation above suggests that such a relationship may be empirically found between permeability and formation factor. Indeed, analysis of the data revealed that, to a good approximation, permeability was inversely proportional to the formation factor. The same relation has previously been observed in other crystalline rocks. This relationship was included in a recent version of the so-called equivalent channel model. Using this model, the specific surface area of the cracksA c/VS, the standard deviation of the distribution of asperities heightsh and the hydraulic radiusm o were evaluated. The following values were respectively found: 850 cm−1, 0.008 μm and 0.14 μm. The specific surface area of the cracks was independently estimated on micrographs of polished sections using a standard quantitative stereology method. The result was in good agreement with the values estimated from the transport properties data.
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  • 25
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    Pure and applied geophysics 128 (1988), S. 101-118 
    ISSN: 1420-9136
    Keywords: Reflection ; transmission ; plane waves ; compact inhomogeneities ; cracks
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    Topics: Geosciences , Physics
    Notes: Abstract Reflection and transmission of elastic wave motion by a layer of compact inhomogeneities has been analyzed. For identical inhomogeneities whose geometrical centers are periodically spaced, the problem has been formulated and solved rigorously. The reflected and transmitted longitudinal and transverse wave motions have been expressed as superpositions of wavemodes, where each wavemode has its own cut-off frequency. At its cut-off frequency a mode converts from a standing into a propagating wavemode. The standing wavemodes decay exponentially with distance to the plane of the centers of the inhomogeneities. At small frequencies only the lowest order modes of longitudinal and transverse wave motion are propagating. Reflection and transmission coefficients have been defined in terms of the coefficients of the zeroth-order scattered wavemodes. These coefficients have been computed by a novel application of the Betti-Rayleigh reciprocal theorem. They are expressed as integrals over the surface of a single inhomogeneity, in terms of the displacements and tractions on the surface of the inhomogeneity. The system of singular integral equations for the surface fields has been solved numerically by the boundary integral equation method. Curves show the reflection and transmission coefficients for the reflected and transmitted longitudinal and transverse waves as functions of the frequency. Some results are also presented for planar distributions of cracks whose spacing and size are random variables. Finally, dispersion relations are discussed for solids which are completely filled with periodically spaced inhomogeneities.
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  • 26
    ISSN: 1420-9136
    Keywords: Separation of scattering and absorption ; multiple scattering ; coda envelopes ; crustal heterogeneities
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    Notes: Abstract In order to separate the scattering effect from intrinsic attenuation, we need a multiple scattering model for seismic wave propagation in random heterogeneous media. In paper I (Wu, 1985), radiative transfer theory is applied to seismic wave propagation and the energy density distribution (or the average intensity) in space for a point source is formulated in the frequency domain. It is possible to separate the scattering effect and the absorption based on the measured energy density distribution curves. In this paper, the data from digital recordings in the Hindu Kush region are used as an example of application of the theory. We also discuss two approximate solutions of coda envelope in the time domain: the single scattering approximation and the diffusion approximation and discuss the relation with the frequency domain solution. We point out that in only two cases can the apparent attenuation be expressed as an exponential decay form. One is thedark medium case, i.e., whenB 0≪0.5, whereB 0 =η s /(η s +η a ) is the seismic albedo,η s is the scattering coefficient,η a is the absorption coefficient. In this case the absorption is dominant, the apparent attenuationb can be approximated by the coherent wave attenuationb =η s +η a . The other case is thediffuse scattering regime, i.e., whenB 0≫0.5 (bright medium) andR≫L s ,t ≪ τ s , whereR andt are the propagation distance and lapse time,L s and τ s are the scattering lengths (mean free path) and scattering time (mean free time), respectively. However, in this case the envelope decays with a rate close to the intrinsic attenuation, while the intensity decreases with distance with a coefficientb ≈d 0(η s +η a ) ≈d s η s , whered 0 andd s are the diffusion multipliers (0〈d 0,d s 〈1). For the Hindu Kush region, by comparing the theory with data from two digital stations of 53 events distributed up to depths of 350 km, we find that the scattering is not the dominant factor for the measured apparent attenuation ofS waves in the frequency range 2–20 Hz. From the observation on high frequency (f〉20 Hz) seismograms, we suggest the existence of a stron-scattering surface layer with fine scale heterogeneities in the crust, at least for this region.
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  • 27
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    Pure and applied geophysics 128 (1988), S. 157-193 
    ISSN: 1420-9136
    Keywords: Scattering ; finite difference ; Kirchhoff integration ; NTS
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    Topics: Geosciences , Physics
    Notes: Abstract A new method for interfacing numerical and integral techniques allows greater flexibility in seismic modeling. Specifically, numerical calculations in laterally varying structure are interfaced with analytic methods that enable propagation to great distances. Such modeling is important for studying situations containing localized complex regions not easily handled by analytic means. The calculations involved are entirely two-dimensional, but the use of an appropriate source in combination with a filter applied to the resulting seismograms produces synthetic seismograms which are point-source responses in three dimensions. The integral technique is called two-dimensional Kirchhoff because its form is similar to the classical three-dimensional Kirchhoff. Data from Yucca Flat at the Nevada Test Site are modeled as a demonstration of the usefulness of the new method. In this application, both local and teleseismic records are modeled simultaneously from the same model with the same finite-difference run. This application indicates the importance of locally scattered Rayleigh waves in the production of teleseismic body-wave complexity and coda.
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  • 28
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    Pure and applied geophysics 128 (1988), S. 231-249 
    ISSN: 1420-9136
    Keywords: Scattering ; coda ; underground explosions ; yield estimation ; wave propagation
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    Topics: Geosciences , Physics
    Notes: Abstract The earlyP wave coda (5–15 sec after the first arrival) of underground explosions at the Nevada Test Site is studied in the time domain using 2082 teleseismic short-period recordings, with the intent of identifying near-source contributions to the signals in the frequency range 0.2–2.0 Hz. Smaller magnitude events tend to have relatively high coda levels in the 0.4–0.8 Hz frequency band for both Yucca Flat and Pahute Mesa explosions. Coda complexity in this low-frequency passband is negatively correlated with burial depth for Pahute Mesa events but is only weakly correlated with depth for Yucca Flat events. Enhanced excitation of relatively long-period scattered waves for smaller, less deeply buried events is required to explain this behavior. Coda complexity in the 0.8–1.1 Hz band is positively correlated with magnitude and depth for Pahute Mesa events, but has no such dependence for Yucca Flat events. This may result from systematic variations between the spectra of direct signals and coda arrivals caused bypP interference for the largest events, all of which were detonated at Pahute Mesa. Another possible explanation is a frequency-dependent propagation effect on the direct signals of the larger events, most of which were located in the center of the mesa overlying strong lateral velocity gradients in the crust and upper mantle. Event average complexity varies spatially for both test sites, particularly in the 0.8–1.1 Hz band, providing evidence for frequency-dependent focussing or scattering by near-source structure. Both the direct arrivals and the early coda have strong azimuthal amplitude patterns that are produced by defocussing by mantle heterogeneity. The direct arrivals have stronger coherent azimuthal patterns than the early coda for Pahute Mesa events, indicating more pronounced deep crustal and shallow mantle defocussing for the direct signals. However, for Yucca Flat events the direct arrivals have less coherent azimuthal patterns than the coda, suggesting that a highly variable component of near-source scattering preferentially affecting the downgoing energy is superimposed on a pattern produced by mantle heterogeneity that affects the entire signal. This complicated behavior of the direct arrivals may be the result of triplications and caustics produced by the complex basement structure known to underlie the Yucca Flat test site. The presence of strong azimuthal patterns in the early coda indicates that source strength estimates based on early coda are subject to biases similar to those affecting estimates based on direct arrivals.
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  • 29
    ISSN: 1420-9136
    Keywords: Autoregressive modeling ; nonstationary time-frequency variations ; seismic-Q ; coda waves
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    Topics: Geosciences , Physics
    Notes: Abstract A technique to detect spectrum variations versus time along seismic signals is applied to coda waves of local earthquakes (Friuli, Northern Italy). The technique consists of an autoregressive modeling and utilizes nonlinear spectral analysis where the spectrum of stochastic processes is estimated as the transfer function of the filter that whitens the process under analysis. This approach appears to be particularly well suited to those investigations where automatic measurements of the instantaneous frequency have to be carried out on digital data. The detection of variations of the instantaneous frequency along the coda allows computation of seismic-Q in the lithosphere and its frequency dependence: the result obtained is $$Q = 100f^{0.4} $$ which appears to be strongly consistent with that, based on the estimate of the coda amplitude decay in the band including the most significant frequencies of the signals under analysis.
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  • 30
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    Pure and applied geophysics 128 (1988), S. 333-363 
    ISSN: 1420-9136
    Keywords: Information content ; high-frequency seismograms ; hard rock ; f max ; site resonance ; fractures
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    Topics: Geosciences , Physics
    Notes: Abstract Due to hardware developments in the last decade, the high-frequency end of the frequency band of seismic waves analyzed for source mechanisms has been extended into the audio-frequency range (〉20 Hz). In principle, the short wavelengths corresponding to these frequencies can provide information about the details of seismic sources, but in fact, much of the “signal” is the site response of the nearsurface. Several examples of waveform data recorded at “hard rock” sites, which are generally assumed to have a “flat” transfer function, are presented to demonstrate the severe signal distortions, includingf max, produced by near-surface structures. Analysis of the geology of a number of sites indicates that the overall attenuation of high-frequency (〉1 Hz) seismic waves is controlled by the whole-path-Q between source and receiver but the presence of distinctf max site resonance peaks is controlled by the nature of the surface layer and the underlying near-surface structure. Models of vertical decoupling of the surface and nearsurface and horizontal decoupling of adjacent sites on hard rock outcrops are proposed and their behaviour is compared to the observations of hard rock site response. The upper bound to the frequency band of the seismic waves that contain significant source information which can be deconvolved from a site response or an array response is discussed in terms off max and the correlation of waveform distortion with the outcrop-scale geologic structure of hard rock sites. It is concluded that although the velocity structures of hard rock sites, unlike those of alluvium sites, allow some audio-frequency seismic energy to propagate to the surface, the resulting signals are a highly distorted, limited subset of the source spectra.
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  • 31
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    Pure and applied geophysics 128 (1988), S. 423-432 
    ISSN: 1420-9136
    Keywords: Seismic attenuation ; porous media ; permeability ; local flow
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    Topics: Geosciences , Physics
    Notes: Abstract Contrary to the traditional view, seismic attenuation in Biot's theory of fluid-saturated porous media is due to viscous damping of local (not global) pore-fluid motion. Since substantial inhomogeneities in fluid permeability of porous geological materials are to be expected, the regions of highest local permeability contribute most to the wave energy dissipation while those of lowest permeability dominate the fluid flow rate if they are uniformly distributed. This dichotomy can explain some of the observed discrepancies between computed and measured attenuation of compressional and shear waves in porous earth. One unfortunate consequence of this result is the fact that measured seismic wave attenuation in fluid-filled geological materials cannot be used directly as a diagnostic of the global fluid-flow permeability.
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  • 32
    ISSN: 1420-9136
    Keywords: Attenuation ; spectral ratio ; peridotite ; partial melting ; high pressure and temperature
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    Topics: Geosciences , Physics
    Notes: Abstract A technique has been developed to determine attenuation in rocks at high temperature using a gas-media, high-pressure apparatus. A pulse transmission technique and a spectral ratio method are used to study compressional seismic properties of rocks. Seismic waves are transmitted to and from the sample through buffer rods of mullite. The effect of seismic wave reflections within the sample assembly are cancelled out by taking ratios of the spectra measured at different temperatures. In order to obtain good signal-to-noise ratio for resolving the attenuation at high pressure and temperature, special care is taken in the sample assembly and the ultrasonic coupling between the sample, buffer rods and transducers. A very tight connection of the sample-buffer rod-transducer is essential for obtaining high frequency signals (〉300 kHz) at high temperature. A small mass is attached to each outside end of the transducer to drive low frequency signals (〈250 kHz) into the sample. Before attenuation measurements, the sample and the buffer rods are tightly compacted in a platinum tube at high pressure and room temperature to ensure pressure seal of the sample assembly. The frequency range of measurement covers 50 to 450 kHz for the sample. Attenuation is very small in the buffer rod compared to the sample for the entire temperature range of the study. Because of the small attenuation, a wide frequency band of 50 kHz to 3.2 MHz can be covered for investigating the attenuation in the buffer rod. The technique has been used to measure attenuation at high confining pressure, and temperatures including sub- and hyper-solidus of upper mantle rocks. Therefore, effects of partial melting on attenuation can be studied. The method is applied to the attenuation measurement in a peridotite as a function of temperature to 1225°C at 200 MPa confining pressure. At high temperature, signal amplitude decays more rapidly at high frequency than at low frequency, from which attenuation (andQ) can be determined using a spectral ratio method. No frequency dependence ofQ is resolved for both the sample and the buffer rod over the entire temperature and frequency ranges of the measurement. The results show thatQ decreases rapidly with increasing temperature even in the temperature range below the solidus of peridotites. Such temperature sensitivity ofQ is probably more useful to probe thermal structure in the upper mantle than that of conductivity at temperatures below the solidus. The results in this study are compared with available seismic velocity, electrical conductivity and solidus data for peridotites, suggesting that there is no discontinuous change in both mechanical and electrical properties of peridotites at the solidus temperature. Even at hypersolidus temperatures, it appears that velocity drops and conductivity increases continuously (not abruptly) with increasing melt fraction. This implies that mechanical and electrical properties of the upper mantle will gradually change at the boundary where the geotherm crosses the solidus.
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  • 33
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    Pure and applied geophysics 128 (1988), S. 547-624 
    ISSN: 1420-9136
    Keywords: Geodynamics ; seismotectonics ; global seismicity ; subduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary The pattern of seismicity as a function of depth in the world, and the orientation of stress axes of deep and intermediate earthquakes, are explained using viscous fluid models of subducting slabs, with a barrier in the mantle at 670 km. 670 km is the depth of a seismic discontinuity, and also the depth below which earthquakes do not occur. The barrier in the models can be a viscosity increase of an order of magnitude or more, or a chemical discontinuity where vertical velocity is zero. LongN versus depth, whereN is the number of earthquakes, shows (1) a linear decrease to about 250–300 km depth, (2) a minimum near that depth, and (3) an increase thereafter. Stress magnitude in a subducting slab versus depth, for a wide variety of models, shows the same pattern. Since there is some experimental evidence thatN is proportional toe κσ, where κ is a constant and σ is the stress magnitude, the agreement is encouraging. In addition, the models predict down-dip compression in the slab at depths below 400 km. This has been observed in earlier studies of earthquake stress axes, and we have confirmed it via a survey of events occurring since 1977 which have been analysed by moment tensor inversion. At intermediate depths, the models predict an approximate but not precise state of down-dip tension when the slab is dipping. The observations do not show an unambiguous state of down-dip tension at intermediate depths, but in the majority of regions the state of stress is decidedly closer to down-dip tension than it is to down-dip compression. Chemical discontinuities above 670 km, or phase transitions with an elevation of the boundary in the slab, predict, when incorporated into the models, stress peaks which are not mirrored in the profile of seismicity versus depth. Models with an asthenosphere and mesosphere of appropriate viscosity can not only explain the state of stress observed in double Benioff zones, but also yield stress magnitude profiles consistent with observed seismicity. Models where a nonlinear rheology is used are qualitatively consistent with the linear models.
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    Pure and applied geophysics 128 (1988), S. 683-724 
    ISSN: 1420-9136
    Keywords: Continental crust ; crustal evolution ; isotopes ; mantle ; recycling ; sediment ; subduction
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    Topics: Geosciences , Physics
    Notes: Abstract In order to understand the evolution of the crust-mantle system, it is important to recognize the role played by the recycling of continental crust. Crustal recycling can be considered as two fundamentally distinct processes: 1) intracrustal recycling and 2) crust-mantle recycling. Intracrustal recycling is the turnover of crustal material by processes taking place wholly within the crust and includes most sedimentary recycling, isotopic resetting (metamorphism), intracrustal melting and assimilation. Crust-mantle recycling is the transfer of crustal material to the mantle with possible subsequent return to the crust. Intracrustal recycling is important in interpreting secular changes in sediment composition through time. It also explains differences found in crustal area-age patterns measured by different isotopic systems and may also play a role in modeling crustal growth curves based on Nd-model ages. Crustal-mantle recycling, for the most part, is a subduction process and may be considered on three levels. The first is recycling with only short periods of time in the mantle (〈10 m.y.). This may be important in explaining the origin of island-arc and related igneous rocks; there is growing agreement that 1–3% recycled sediment is involved in their origin. Components of recycled crustal material, with long-term storage (up to 2.5 b.y.) in the mantle as distinct entities, has been suggested for the origin of ocean island and ultrapotassic volcanics but there is considerably less agreement on this interpretation. A third proposal calls for the return of crustal material to the mantle with efficient remixing in order to swamp the geochemical and isotopic signature of the recycled component by the mantle. This type of recycling is required for steady-state models of crustal evolution where the mass of the continents remains constant over geological time. It is unlikely if crust-mantle recycling has exceeded 0.75 km3/yr over the past 1–2 Ga. Good evidence exists that selective recycling is an important process. Sedimentary rocks preserved in different tectonic settings are apparently recycled at different rates, resulting in a bias in the sediment types preserved in the geologic record. Selective recycling has important implications for the interpretation of Nd model ages of old sedimentary rocks and in the analysis of accreted terranes. Although there is evidence that continental crust was formed prior to 3.8 Ga, the oldest preserved rocks do not exceed this age. It is likely that the intense meteorite bombardment, which affected the earth during the period 4.56–3.8 Ga, coupled with rapid mantle convection, which resulted from greater heat production, caused the destruction and probable recycling into the mantle of any early formed crust. Although crust-mantle recycling is seen as a viable process, it is concluded that crustal growth has exceeded crust-mantle recycling since at least 3.8 Ga. Intracrustal recycling has not been given adequate consideration in models of crustal growth based on isotopic data (particularly Nd model ages). It is concluded that crustal growth curves based on Nd model ages, while vastly superior to those based on K/Ar or Rb/Sr, tend to underestimate the volume of old crust, due to crust-mantle and/or intracrustal recycling.
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    Development genes and evolution 197 (1988), S. 10-18 
    ISSN: 1432-041X
    Keywords: Monensin ; Mesoderm ; Determination ; Extracellular matrix ; Mollusca
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    Topics: Biology
    Notes: Summary In embryos of the equally cleaving marine gastropod Patella vulgata, the mesodermal stem cell is determined during the interval between the fifth and sixth cleavage by means of cellular interactions between one of the four vegetally located macromeres with the overlying animal micromeres. Shortly before and during this interaction phase an extracellular matrix (ECM) is present between the interacting cells. In this study the glycosylation-perturbing ionophore monensin was used to investigate the possible morphogenetic significance of the ECM. Incubation of 32-cell-stage Patella embryos in 10−6 M monensin results in radialized embryos in which none of the four macromeres interacts with the overlying animal micromeres. None of the macromeres is determined, therefore, to form mesoderm in such embryos. Trochophore larvae reared from these embryos retain their radial symmetry, as is indicated by the presence of four shell glands and four blastopore- or stomodeum-like invaginations in these larvae. The monensin-treated embryos probably secrete abnormal ECM that does not provide the proper conditions for the blastomeres to stretch and interact with the micromeres. Changes in intracellular ionic concentrations may also be involved.
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    Development genes and evolution 197 (1988), S. 40-48 
    ISSN: 1432-041X
    Keywords: Drosophila ; Homeosis ; Tumorous-head ; Bithorax-complex mutant ; Morphology
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    Topics: Biology
    Notes: Summary Transformations of tumorous-head Drosophila melanogaster were examined in order to investigate whether head structures were replaced by specific abdominal structures. Heads selected for the presence of genital structures were analyzed in detail. Female abnormalities included any combination of vaginal teeth, vulvar papillae, sensilla trichodea, abdominal tergites 6 (T6), 7 (T7), 8 (T8) and anal plate. Anal plate was observed in the prefrons and rostral membrane, while all other genital structures were intimately associated with modified shingle cuticle. Male abnormalities included transformation of antennal structures to penis, clasper teeth, lateral plate, anal plate and eye to T6. The distribution of each type of homeotic structure was confined to general regions of the eye-antenna, with no precise dividing lines between them. However, the spatial sequence of homeotic structures in the eye-antenna was generally the same as the sequence of the same structures in the posterior abdomen.
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  • 37
    ISSN: 1432-041X
    Keywords: Avian hereditary muscular dysgenesis ; Skeletal/non-skeletal musculature ; Ubiquitous ultrastructural effects
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    Topics: Biology
    Notes: Summary Muscular dysgenesis in trunk and limb regions of the crooked neck dwarf (cn/cn) fowl is characterized by a complete disorganization of the muscles, starting at 7.5 days of incubation and resulting, at the end of the incubation period, in a profound muscular atrophy. It has previously been attributed to progressively extending defects of the myotubes. In this paper, embryonic cn/cn head and neck muscles were subjected to histological and ultrastructural analysis. The mononucleated myoblasts of the skeletal muscles are not diseased. Pathology is only expressed in the multinucleated cells, mainly by impaired sarcomerogenesis and distension of the sarcoplasmic reticulum. In the non-skeletal (cardiac or smooth) muscles, the connective tissue scaffolding and the ultrastructural features are similar to those of normal muscles at the same age. The present report confirms that the cn defect is confined to the skeletal muscle cells. All of them belong to the same lineage, which is contained in the somitic mesoderm, whether the latter becomes segmented or not during embryogenesis.
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    Development genes and evolution 197 (1988), S. 63-65 
    ISSN: 1432-041X
    Keywords: Chimeras ; In situ hybridization ; Mice ; Transgenic
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    Topics: Biology
    Notes: Summary We describe the construction of aggregation chimeras between normal and transgenic embryos containing multiple copies of mouse β-globin genes. The transgenic component of the chimeras is then detected in tissue sections by a DNA-DNA in situ hybridization technique, using a biotinylated DNA β-globin probe and an avidin-linked alkaline phosphatase detection system. The general advantages of transgenic markers for chimeras are discussed.
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  • 39
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    Development genes and evolution 197 (1988), S. 56-62 
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    Keywords: Epithelial-mesenchymal interaction ; Pepsinogen expression ; Differentiation potency ; Stomach ; Gizzard
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The avian stomach is subdivided into two parts, the proventriculus and the gizzard. It has been shown that the gizzard epithelium can express embryonic chick pepsinogen (ECPg) antigen, a marker protein of the proventricular epithelium, as well as normal proventricular epithelium, under the appropriate experimental conditions. To study the possible mechanisms involved in the suppression of ECPg synthesis in the gizzard epithelium during normal development, we carried out heterotypic and heterochronic recombination experiments of the epithelium and mesenchyme of these two organ rudiments. When recombined and cultured with 6-day proventricular mesenchyme, gizzard epithelium of 3.5- to 12-day embryos expressed pepsinogen at all stages tested. However, the ratio of ECPg-positive cells to total epithelial cells in the gizzard epithelium decreased rapidly when epithelium older than 7 days was cultured with proventricular mesenchyme. In contrast to proventricular mesenchyme, 6-day gizzard mesenchyme did not allow ECPg expression in associated proventricular epithelium of 3.5- to 7-day embryos. These results indicate that gizzard epithelium does not express pepsinogen in normal development because of both a decrease in ability to express the enzyme in itself in the course of development and a repressive influence of gizzard mesenchyme.
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  • 40
    ISSN: 1432-041X
    Keywords: Salivary glands ; Protein synthesis ; Larval development ; Drosophila gibberosa, Drosophila melanogaster
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    Notes: Summary The late larvae of Drosophila gibberosa Patterson and Mainland choose different pupariation sites than the larvae of Drosophila melanogaster Meigen. Since the larvae of D. gibberosa do not attach themselves to the substratum, the salivary glands contain only a small amount of the “glue” proteins before pupariation. Proteins comprising the salivary gland secretions of late larvae of these two species were compared and found to be qualitatively quite different. Only five polypeptides with the same molecular masses were identified in both species. The rate of protein synthesis in the salivary glands of D. gibberosa continued to increase through the late larval stage and pupariation. As a consequence, the total amount of protein contained in the salivary glands also continued to increase after pupariation. To demonstrate temporal changes in protein synthesis from 48 h before pupariation to 28 h after pupariation, newly synthesized polypeptides were pulse labeled by culturing salivary glands in vitro. The patterns of polypeptide synthesis fell into four major groups depending upon whether the synthesis of a protein stopped shortly after pupariation, stopped during late pupariation, increased at pupariation, or was initiated after pupariation. Changing patterns of protein synthesis are correlated with the known changes in gene puffing during this developmental period.
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  • 41
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    Development genes and evolution 197 (1988), S. 75-91 
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    Keywords: Drosophila ; Maternal effect mutation ; Pattern formation ; Gastrulation
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    Topics: Biology
    Notes: Summary The gastrulation defective (gd) locus is a maternally expressed gene in Drosophila required for normal differentiation of structures along the embryonic dorso-ventral axis. Cuticular defects of the offspring from females with different combinations of gd alleles comprised a phenotypic continuum. Complementation among several alleles produced normal offspring while progressively more severe mutations produced a graded loss of structures from ventral, and then lateral, blastoderm cells. The most severely affected embryos consisted entirely of structures derived from dorsal blastoderm cells. Histological examination of staged siblings from selected allelic combinations showed that internal tissues were similarly affected. The tissues observed in amorphic embryos support new, more dorsal, assignments of fate map positions for blastoderm precursors of the cephalopharyngeal apparatus, hindgut and ventral nerve cord. The loss of ventral and lateral structures did not occur through cell death and appeared to involve a change in blastoderm cell fate. A direct effect of the mutations on blastoderm cell determination, however, was insufficient to explain the development of the dorsalized embryos. Intermediate phenotypes suggested that cell interactions or movements associated with morphogenesis are required for the determination of some cell fates in the dorsoventral axis. Thus, the developmental fate of all blastoderm cells may not be fixed at the time of blastoderm formation.
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  • 42
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    Development genes and evolution 197 (1988), S. 92-100 
    ISSN: 1432-041X
    Keywords: Chick blastoderm serum proteins ; Extraembryonic endoderm
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    Topics: Biology
    Notes: Summary The pattern of serum protein synthesis and secretion in aggregates of extraembryonic endoderm cells (EEC) from the area opaca of primitive streak chick embryos was studied. EEC aggregates were cultured for various time intervals and serum proteins were detected using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and fluorography. Serum proteins were identified based on their comigration with reference proteins from 4 day chick embryo serum and with reference proteins from egg white albumen and chicken serum. A number of serum proteins were detected in EEC aggregates including: two variants of immunoglobulin (IgG), four variants of transferrin, a protein with a molecular weight of 66 500 which may correspond to α globulins, prealbumin, and a protein with a molecular weight of 38 600 (serum protein 11) which remains unidentified. These proteins were also detected in the culture medium. The banding profiles of EEC extracts and culture medium were compared over various time intervals of culture (6, 18 and 30 h). The IgGs, transforms and serum protein 11 decreased in concentration in EEC extracts over the culture interval. These proteins as well as prealbumin, were detected in the culture medium. A number of proteins were synthesized by EEC, as determined by radiolabelled amino acid incorporation. All of the labelled serum proteins were detected in the culture medium, not in EEC extracts. These results suggest that serum proteins are synthesized by EEC then rapidly released into the medium. Labelled serum proteins detected in the culture medium include prealbumin and an unidentified serum protein (serum protein 14) which migrates with the tracking dye, both synthesized early in culture (6 h), and transferrin which was synthesized later (18 h) during culture.
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  • 43
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    Development genes and evolution 197 (1988), S. 141-147 
    ISSN: 1432-041X
    Keywords: Cell proliferation ; Embryonic ectoderm ; Explants ; Xenopus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Dissociated prospective ectoderm cells from Xenopus laevis embryos divide autonomously up to the 17th division cycle of the embryo. To examine the requirements for the further proliferation of these cells, the continuation of cell division in compact ectodermal explants beyond the 17th division cycle has been studied. Such explants develop into aggregates of epidermal cells, as can be shown immunohistochemically with an anti-serum against Xenopus epidermal cytokeratin. Cell division in these explants is comparable to the in vivo proliferation rate at least during the first 24 h of cultivation, that is, well beyond the 17th division cycle. Thus, epidermal cells are provided with all the factors necessary for continued proliferation, but these can be effective only when the cells form tight aggregates. The long-term changes in cell number are complex. Mitotic figures are present until the explants disintegrate after 3–4 days. However, the total cell number per explant does not increase during later development. The production of cells by mitotic divisions is likely to be countered by the loss of cells due to cell death, which is indicated by the presence of pyknotic nuclei.
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  • 44
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    Development genes and evolution 197 (1988), S. 148-156 
    ISSN: 1432-041X
    Keywords: Bufo bufo ; Pancreatic morphogenesis ; Pancreatic endocrine cell ; Immunocytology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Bufo bufo at stage III6 the first endocrine islets appear in the part of the pancreas corresponding to the dorsal anlage. At stage IV2, 5 days later, the pancreatic duct develops and new islets arise by budding off from the ductal epithelium. The ultrastructural study of the secretory granules morphology of endocrine cells has distinguished four different cell types: B-cells (stage III9), A-cells (stage IV3), D-cells (stage IV3) and a fourth type not yet identified (stage IV3). By immunocytology insulin and corticotropin-releasing factor (CRF) cells have been demonstrated at stage III9, and glucagon and somatostatin cells at stage IV1. Lastly, endocrine islets can be homogeneous (predominantly containing insulin cells, rarely glucagon cells) or heterogeneous (insulin cells at the centre and glucagon or somatostatin cells at the periphery). Hypotheses are put forward for the origin and the constitution of the different generations of endocrine islets and isolated cells.
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  • 45
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    Development genes and evolution 197 (1988), S. 190-192 
    ISSN: 1432-041X
    Keywords: Xenopus laevis ; Free lens ; Crystallin ; Indirect immunofluorescence ; Antigen ; Antiserum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ontogeny and localization of crystallins during free lens development (i.e. lens development without the optic vesicle) were investigated in Xenopus laevis using the indirect immunofluorescence staining method with an antiserum raised against homologous total lens soluble proteins. Since the developing free lenses pass through stages similar to those of the lenses regenerated from the inner cell layer of the outer cornea following lentectomy in the same species Freeman's classification was used to identify the stages of free lens development. The first appearance of a positive reaction occurred at early stage IV in a number of cells in an area where future lens fibre cells would develop. With further differentiation of the free lens more and more cells in the fibre area started to show a positive reaction and the first positive reaction in the epithelium was observed late in stage V. Histological examination revealed that a fully differentiated free lens and a normally developed lens are similar but that the free lens is smaller.
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  • 46
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    Development genes and evolution 197 (1988), S. 307-320 
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    Keywords: Parascaris ; Nematoda ; Chromatin diminution ; Cleavage pattern ; Local presomatic activation (LPA)
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    Topics: Biology
    Notes: Summary In Parascaris developmental commitment to the germ line and somatic lineages is indicated by the orientation of the mitotic spindle in blastomeres, the topology of cells in the embryo, and chromatin diminution in presomatic blastomeres. Using three different experimental techniques: transient pressure treatment, application of cytochalasin B, and isolation of blastomeres, we have succeeded in uncoupling several developmental processes during cleavage of P. univalens. The following results were obtained: (1) Following mitotic nondisjunction we observed identical behavior of all chromatids in each blastomere. Thus chromosome differentiation by differential replication does not occur. (2) Chromosome fragments obtained by pressure treatment of egg cells underwent chromatin diminution. Thus this process does not require an intact germ-line chromosome. However, chromosomes immobilized on a monopolar spindle did not undergo chromatin diminution. Thus diminution appears to require segregation of chromatids. (3) Blastomeres that completely lacked chromosomes as a result of mitotic nondisjunction underwent normal early cleavage divisions. (4) Pressure treatment or prolonged treatment with cytochalasin B caused egg cells or germ line blastomeres to lose their germ line quality, as deduced from the coincident occurrence of symmetrical (presomatic-like) cleavage and chromatin diminution. (5) Isolated blastomeres from 2-cell embryos, i.e. 1/2 blastomeres, usually cleaved according to their prospective fates in the whole embryo. However, in some partial embryos derived from such blastomeres, chromatin diminution was delayed for either one or two cleavage mitoses. An “activation” model as an alternative to a prelocalization model is presented, which can account for early blastomere topogenesis and chromatin diminution.
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  • 47
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    Development genes and evolution 197 (1988), S. 339-344 
    ISSN: 1432-041X
    Keywords: Protein kinases ; Neural induction ; Amphibia
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    Notes: Summary Ectoderm explants from early gastrula stages of Xenopus laevis were induced with a neutralizing factor. The factor was isolated from Xenopus gastrulae and partially purified by chromatography on DEAE cellulose. The ectoderm was cultured for different periods of time and then homogenized. Protein kinase activity was determined in the homogenates from induced and control explants with histone H 1 or C-terminal peptide derived from histone H 1 as substrates. The C-terminal peptide is a more specific substrate for protein kinase C, whereas histoneH 1 is a substrate for cAMP/cGMP-dependent protein kinases as well protein kinase C. With both substrates the enzyme activity increases after induction. With the C-terminal peptide as the substrate the protein kinase activity is lower, but its relative increase after induction higher. This suggests that besides cAMP/cGMP dependent protein kinases protein kinase C or related enzymes are involved in the neural induction and differentiation processes. This corresponds to previous experiments which have shown that treatment of ectoderm with phorbol myristate acetate, an activator of protein kinase C and protein kinase C related enzymes, initiates neural differentiation. Endogeneous substrates, which are more intensively phosphorylated after induction are proteins with apparent molecular weights 21 kDa and 31 kDa. Addition of protein kinase C to the induced and control homogenates abolishes the difference in the phosphorylation rate of these proteins.
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  • 48
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    Development genes and evolution 197 (1988), S. 355-359 
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    Keywords: Determination ; Pattern formation ; Histoblasts ; Housefly
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    Notes: Summary Using a novel grafting procedure for histoblasts, we have transplanted the fifth dorsal or ventral histoblast nests to heterotopic positions in the abdomen of the prepupa of the housefly to find out how rigid are these imaginai cells in their commitment to form their respective segmental pattern. Our results clearly show that these histoblasts survive in their new positions and form patterns according to their original determined state.
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  • 49
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    Development genes and evolution 197 (1988), S. 441-446 
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    Keywords: Mesoderm ; Tail ; Xenopus ; Interspecific grafts
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    Notes: Summary We have used interspecific grafts between Xenopus borealis and Xenopus laevis to study the signalling system that produces tail mesoderm. Early gastrula ectoderm grafted into the posterior neural plate region of neurulae responds to a mesodermal inducing signal in this region and forms mainly tail somites; this signal persists until at least the early tail bud stage. Ventral ectoderm grafted into the posterior neural plate loses its competence to respond to this signal after stage 10 1/2. We have established the specification of anterior and posterior neural plate ectoderm. In ectodermal sandwiches or when grafted into unusual positions, anterior regions gave rise to mainly nervous system and posterior regions to large amounts of muscle, together with some nervous system. Thus it was impossible to assess the competence of posterior neural plate ectoderm to form further mesoderm and hence to establish if mesodermal induction continues during neurulation in unmanipulated embryos.
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  • 50
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    Development genes and evolution 197 (1988), S. 457-470 
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    Keywords: Neurogenesis ; Neurogenic genes ; Achaetescute complex ; Daughterless ; Genetic interactions ; Drosophila
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    Notes: Summary In Drosophila melanogaster the neuroblasts separate from epidermoblasts to give rise to the neural primordium. This process is under the control of several genes. The group of the so-called neurogenic genes is required for epidermal development; other genes, comprising those of the achaete-scute complex and daughterless, are required for neural development. We have studied the relationships between both groups of genes in two different ways. We have analyzed the phenotype of double-mutant embryos and our results show that the neural hyperplasia caused by neurogenic mutations can be partially prevented if a mutation in one of the other genes is present in the same genome. Only the neural cells that do not require the function of a particular gene of the achaete-scute complex in the wild-type seem to develop to a neural fate in the double mutant embryos. At least some of the genetic interactions affect the transcriptional level, as shown by in situ hybridization, since the territories of transcription of the achaetescute genes are expanded in neurogenic mutants. All cells of the neurogenic region of the double mutants apparently initiate neural development. However, during later development some of these cells switch their fate either to epidermogenesis or to cell death and this leads to the final phenotype of the double mutants. We discuss these results with respect to the events of early neurogenesis.
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  • 51
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    Keywords: Phorbol ester ; Muscarinic receptor ; Calcium ; Chick embryo ; Morphogenesis
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    Notes: Summary A muscarinic cholinergic receptor is present on undifferentiated cells of the chick embryo. Stimulation of the muscarinic receptor with muscarinic agonists triggers intracellular Ca2#x002B; mobilization. Here, we investigate the effect of phorbol 12-myristate 13-acetate (PMA) on the muscarinic receptor-mediated Ca2#x002B; mobilization, which is monitored in cell suspensions of chick embryos of stage 24 by chlorotetracycline fluorescence. PMA inhibits the Ca2#x002B; mobilization in a time-dependent and concentration-dependent manner without changing the ED50 of acetylcholine. The concentration of PMA that gives halfmaximal inhibition is 3.1×10−9 M PMA.
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  • 52
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    Development genes and evolution 197 (1988), S. 129-129 
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  • 53
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    Keywords: Flow cytometry ; DNA-content ; Differentiation ; Spherulation ; Physarum
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    Notes: Summary Using flow cytometry, spherulating nuclei of Physarum isolated at the beginning of spherule wall formation were found to exhibit a DNA content corresponding to the G2 phase of the cell cycle, although 8% lower. Before the first mitosis after spherule germination, a very slight incorporation of 3H thymidine into DNA was observed that was too weak to correspond to S phase, strongly suggesting that nuclei are stopped in G2 phase inside the spherules. The lower value of nuclear DNA content found using flow cytometry of germinating spherules may not be related to DNA quantity, but may be due to a difference in chromatin organization during growth or spherulation, resulting in interference with the staining.
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  • 54
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    Keywords: Bithorax complex ; Drosophila ; Abdominal-B mutations ; Genetic mosaics
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    Notes: Summary The phenotypic effects in imaginal hypodermal tissue of a number of Abdominal-B mutations of the bithorax complex are described. Evidence is given from complementation analysis that the phenotypic heterogeneity in both the spatial limits and the nature of the homeotic transformations produced is not an arbitrary classification of allelic differences that we find. We have used genetic mosaic analysis to support the interpretation that the Abdominal-B genetic unit can exist in a number of alternative functional states of expression during development and that individual Abdominal-B mutations may abolish some states whilst leaving others unaffected.
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  • 55
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    Keywords: cAMP ; Oocyte maturation ; Germinal vescle ; Calcium channels ; Hydrozoa
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    Notes: Summary Externally applied membrane permeable cAMP derivatives and the injection of cAMP induce oocyte maturation in several species of hydrozoans. This technique for inducing oocyte maturation has been used to study ion permeability changes, maturation promoting factor activity and surface tension changes during maturation. Oocyte membrane potential remains constant during maturation. Cyclic AMP induced maturation proceeds in the absence of external Ca2+, K−, Mg2+ or Na+. Cytoplasm from maturing oocytes that induces oocyte maturation when it is injected into untreated oocytes is produced during cAMP induced maturation. Surface tension, as measured by the application of a standardized force that mechanically deforms individual oocytes, declines during the first part of maturation. This is followed by a sharp rise and fall of surface tension at first and second polar body formation that accompanies a slow rise in the resistance of oocytes to deformation during the last part of maturation. The production of maturation promoting factor activity and some of the changes in surface tension during maturation can occur in the absence of germinal vesicle material. Two early developmental events that follow oocyte maturation are the production of sperm chemoattractant and calcium channel function. Neither of these events occurs in eggs that have undergone maturation in the absence of germinal vesicle material. The addition of germinal vesicle contents from oocytes to eggs that have undergone maturation in the absence of germinal vesicle material initiates calcium channel function. This experiment indicates that the germinal vesicle contains factors that are necessary for post-maturation developmental events.
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  • 56
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    Keywords: Odontoblast ; Ameloblast ; Matrix ; Cytoskeleton ; Immunofluorescence
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    Notes: Summary Several extracellular matrix components (procollagen type III, fibronectin, collagen type IV, laminin and nidogen) and microfilament constituents (actin, α-actinin and vinculin) were localized by indirect immunofluorescence microscopy in frozen sections of embryonic mouse molars. Nidogen was present at the epithelio-mesenchymal junction during polarization and initial steps of functional differentiation of odontoblasts. Nidogen disappeared at a stage where direct contacts between preameloblasts and predentin were required to allow the initiation of ameloblast polarization. Our observations concerning the distribution of procollagen type III and fibronectin during odontoblast differentiation add to current knowledge. Procollagen type III and fibronectin surrounding preodontoblasts accumulated at the apical part of polarizing and functional odontoblasts secreting “initial” predentin. Procollagen type III, but not fibronectin, disappeared in front of functional odontoblasts synthesizing “late” predentin and dentin. Fibronectin, present in “initial” predentin, was no longer detected in “late” predentin and dentin but was found between odontoblasts secreting “late” predentin and dentin. Actin, α-actinin and vinculin were concentrated in the peripheral cytoplasm of preameloblasts and accumulated at the apical and basal poles of functional ameloblasts. During differentiation of odontoblasts, the three proteins accumulated at the apical pole of these cells. Time and space correlations between matrix and microfilament modifications during odontoblast and ameloblast differentiation are documented. The possibility is discussed that there is transmembranous control of the cytoskeletal activities of odontoblasts and ameloblasts by the extracellular matrix.
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  • 57
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    Keywords: Cell surface antigens ; Antibody ; Differentiation ; Epidermis ; Pleurodeles waltlii
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    Notes: Summary A polyclonal antibody (SP-2) has been produced, which recognizes antigens expressed in epidermal cells of Pleurodeles waltlii embryos. The antigens appear first at the end of gastrulation in the external surface of the embryo and are selectively expressed in ectodermally derived epidermal structures. Ectodermal commitment was investigated using cell cultures and blastocoel graft experiments. The four animal blastomeres of the 8-cell stage as well as the animal cap explants of the early gastrula stage cultured in vitro differentiate into epidermis, and SP-2 antigens are expressed. The expression of SP-2-defined antigens is inhibited both in vivo and in vitro by the inductive interaction of chordomesoderm. Once dissociated, ectodermal cells do not react with SP-2. Conversely, the aggregation of ectodermal cells may restore the expression of SP-2 antigens. Transplantation of animal cap explants or isolated ectodermal cells into the blastocoel of a host embryo at the early gastrula stage shows that only cells integrated into the epidermis express the marker antigens. When vegetal cells were dissociated from donor embryos before the mid-blastula stage and implanted into the blastocoel of host embryos at the early gastrula stage, their progeny were found in all germ layers, cells that were found in the host epidermis were stained with SP-2, whereas those contributing to mesoderm and endoderm were not. Thus the acquisition of cell polarity in epidermal differentiation and the organization of cells into epithelial structures are essential for SP-2-defined antigen expression.
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  • 58
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    Keywords: Apis mellifera ; Homeobox genes ; Dfd ; In situ hybridization ; Blastoderm
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    Topics: Biology
    Notes: Summary We have isolated and characterized a homeoboxcontaining gene from the honeybee Apis mellifera. Its homeobox region shows a high degree of sequence similarity to the homeobox of the Drosophila gene Deformed (Dfd). At the DNA level 82% of the basepairs are the same, whereas the putative amino acid sequences are identical between the bee and the fruitfly genes. Similarity is also present 5′ and 3′ to the homeobox. Using this isolate as a probe we have performed in situ hybridization on sections from blastoderm-stage embryos of the honeybee Apis mellifera. In early blastoderm stages we found a rather irregular pattern of labelled nuclei. In middle stages we found silver grains over each nucleus and also over the cytoplasm in a belt of blastoderm cells in the prospective gnathal region. These results indicate that the Deformed genes from honeybee and fruitfly are homologous both with respect to their DNA sequence and their spatial and temporal pattern of expression during embryogenesis.
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  • 59
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    Development genes and evolution 197 (1988), S. 275-281 
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    Keywords: Regional protein production ; Cell fate ; Dorsalized embryos ; Ventralized embryos ; Embryonic pattern formation
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    Topics: Biology
    Notes: Summary The proteins synthesized before the 512-cell stage by Xenopus blastomeres with different fates were compared by one dimensional PAGE. Blastomeres that contributed more progeny to antero-dorsal axial structures produced proportionately more of two proteins of 225000 and 245000 daltons. Additionally, these proteins were reversibly increased in ventralized embryos and were decreased in dorsalized embryos. These observations indicate that some proteins that are synthesized during cleavage stages are expressed to different degrees in different regions of the embryo, that their expression can be correlated to cell fate in the normal embryo, and that their expression is altered quantitatively in dorsalized and ventralized embryos. The inverse relationship between the production of these proteins and the potential to produce dorsal structures in the normal and in dorsalized/ventralized embryos is consistent with a model in which cell fate is influenced by a gradient of particular proteins.
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    Development genes and evolution 197 (1988), S. 298-301 
    ISSN: 1432-041X
    Keywords: Morula ; Gene expression ; Heat-shock proteins ; α-Amanitin ; Chick embryo
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    Topics: Biology
    Notes: Summary The polypeptides synthesized during the morula stage in the chick embryo are insensitive to transcriptional inhibition by α-amanitin. Protein synthesis seems to depend predominantely, if not exclusively, on the recruitment of maternal mRNA, rather than on embryonic gene expression in chick morula. The morula embryo expresses the heatshock polypeptides when stressed at 43°C. The heat-induced polypeptides are isoforms of polypeptides that are synthesized normally. These polypeptides are α-amanitin sensitive and appear to mark the first major expression of the embryonic genome in the chick embryo.
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  • 61
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    Development genes and evolution 197 (1988), S. 282-293 
    ISSN: 1432-041X
    Keywords: Caenorhabditis ; Embryogenesis ; Laser microbeam ; Cleavage pattern ; Germline
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    Topics: Biology
    Notes: Summary Early embryogenesis of the nematode Caenorhabditis elegans is characterized by the continuous visibility of a germline and the stepwise separation of all somatic cells from it. Germline and somatic cells exhibit different cleavage patterns. Typical for the germline is a series of stemcell-like, unequal cleavages generating blastomeres, which differ in size, cell cycle periods, and fate. Typical for members of somatic cell lineages during early development are their equal and synchronous cleavages generating cells of similar appearance. Using a laser microbeam various experiments have been carried out to investigate the conditions that lead to the two different types of cleavage. Development of partial embryos demonstrates that the potential for germline-like cleavage is localized in the posterior region of the fertilized egg prior to both the formation of pronuclei and the posterior aggregation of germline-specific granules. Experimental alteration of the cleavage plane can result in a switch from unequal to equal cleavage, with an apparent correlation between the orientation of the mitotic spindle and the type of cleavage. Nuclear transfer experiments indicate that nuclei and centrioles are not involved in the decision as to which type of cleavage will be executed. Cytoplasmic transfer from soma-like to germline-like cleaving cells and vice versa does not alter the cleavage type in the recipient cell. But if separation of germline from soma is delayed after the removal of a centrosome, germline-like cleavage may be completely suppressed, all cells thereafter dividing soma-like.
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    Development genes and evolution 197 (1988), S. 294-297 
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    Keywords: Chicken otocyst ; In vitro culture ; Protein kinase C activation ; DNA synthesis ; Cell proliferation
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    Notes: Summary The role of protein kinase C (PKC). during the early development of the inner ear was investigated using organ culture techniques. Otocysts isolated from chick embryos were made quiescent by culturing in the absence of serum for 24 h. The normal process of development could be reactivated by restoration of serum and other growth factors. Addition of phorbol ester (TPA) or synthetic diacylglycerol (OAG) to serum-free medium was also effective in reactivating development and stimulation of DNA synthesis was 41% and 52% of that of serum, respectively. Insulin potentiated the effects of TPA and OAG but had no effect when present alone. Morphogenesis and the associated cell proliferation stimulated by either serum or PKC activation were both inhibited by sphingosine, an in vitro inhibitor of PKC. Inhibition by sphingosine was dose-dependent with a half-maximal inhibitory concentration of about 10 μM. The results suggest that PKC activation is an essential step in controlling proliferative growth during early stages of the development of the inner ear.
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    Development genes and evolution 197 (1988), S. 305-305 
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  • 64
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    Keywords: Mouse egg ; Maternal effect ; X irradiation ; Cell cycle ; Phosphorylation
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    Notes: Summary In some strains of mice, eggs when X irradiated during the pronuclear stage, undergo a mitotic block in the G2 phase of the first cell cycle and cleave when the second division takes place in controls. The importance of this effect varies considerably with the strain and depends exclusively on the maternal genotype. In previous work, two-dimensional electrophoresis showed that eggs blocked at the one-cell stage after irradiation, undergo the same modifications in polypeptide synthesis as two-cell controls of the same age, except at the time of normal first mitosis, where three polypeptide sets of 30, 35 and 45 kDa appear only in cleaving controls. In the present study, we have found phosphorylations in dividing controls, on polypeptides of 30, 35 and 45 kDa. These phosphorylations are not seen in blocked irradiated eggs.
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    Development genes and evolution 197 (1988), S. 328-338 
    ISSN: 1432-041X
    Keywords: Cell communication ; Trans-regulatory genes ; Pattern formation ; Cell differentiation
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    Notes: Summary Phenotypic analyses of genetic combinations involving the gene extramacrochaetae (emc) reveal its participation in the differentiation of both sensory elements and wing veins. The study of near-amorphic alleles of emc in mitotitc recombination clones indicates that it also affects cell proliferation. These clones show abnormal sizes, shapes and spatial distribution. They differentiate extra sensory elements as well as extra veins. A gain of function mutation in the gene causes opposite phenotypes in both differentiation systems. The effects of the mutant on proliferation and patterning are consistent with the emc gene being involved in the transfer of information between neighbouring cells, which leads to the spatial expression of the achaetescute gene complex and genes involved in vein formation.
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    Development genes and evolution 197 (1988), S. 1-9 
    ISSN: 1432-041X
    Keywords: Ammonia ; Tetraethylammonium ; Amiloride ; Metamorphosis ; Hydractinia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Hydractinia metamorphosis from the swimming larval stage to the sessile polyp stage has been found to be inducible by several agents, including Li+, K+, Cs+, Rb+, diacylglycerol (DG), tetradecanoyl-phorbol-acetate (TPA) and some other tumour-promoting phorbol esters. Induction is antagonized by ouabain and compounds which are able to increase the internal level of S-adenosylmethionine (SAM). Based on the finding that Hydractinia larvae contain such compounds in a stored form, including N-methylpicolinic acid, N-methylnicotinic acid and N-trimethylglycine, as well as on the results of experiments with antagonists of SAM production and transmethylation, it has been argued that regulation of the internal SAM level plays a key role in the control of metamorphosis. However, it remains to be clarified whether the inducing agents act by decreasing the SAM level or by via different pathways. In the present study, substances chemically related to the substances known to induce or inhibit metamorphosis were tested for their metamorphosis-inducing abilities. Some were found to be effective, including NH4 +, methylamine, tetraethylammonium ions (TEA+), ethanolamine, Ba2+, Sr2+ and the diuretic, amiloride. It is of particular interest that in many organisms TPA and DG increase cytoplasmic pH while amiloride prevents a rise in pHi. Several of the substances known to trigger metamorphosis may increase the internal NH4 + concentration by hindering the export of the constantly produced NH4 + through K+ channels or through the Na+-H+ antiport. Treatment with Cs+ for 1 h increases the internal level of NH4 +. Produced and applied ammonia, as well as applied methylamine and ethanolamine, may act by accepting methyl groups, thus reducing the SAM level.
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    Development genes and evolution 197 (1988), S. 19-26 
    ISSN: 1432-041X
    Keywords: Drosophila ; Morphogenesis ; Appendages
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    Notes: Summary The phenotype of rotund (rn) null alleles is described, and compared to wild type. The mutants are expressed zygotically and cause position specific defects in certain imaginal discs (antenna, legs, wing, haltere and proboscis) and their corresponding adult derivatives. In the discs, specific folds are absent in rn mutants compared to wild type. Clonal analysis shows that the rn + gene is partially autonomous in its expression in cells destined to form certain distal parts of the adult appendages. The results are consistent with the idea that the rn + gene is required for normal morphogenesis of specific distal parts of the adult appendages.
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    Development genes and evolution 197 (1988), S. 27-36 
    ISSN: 1432-041X
    Keywords: Chick embryo ; Retinoids ; Phocomelia ; Limb development
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    Topics: Biology
    Notes: Summary Two retinoids, all-trans-retinoic acid and a synthetic analog, TTNPB, were locally applied to different positions along the proximo-distal axis of embryonic chick wing buds using controlled release carriers. Truncations or limbs with duplicated structures across the antero-posterior axis develop after retinoid application to distal positions in buds from stage 20–24 embryos. Phocomelic limbs develop when the retinoids are applied more proximally to buds of stage 23–24 embryos. Duplications of the pattern of structures along the proximo-distal axis never occur. Using TTNPB that is relatively stable, the amount of retinoid in the wing tissue when phocomelia is induced was measured. There is twice as much retinoid per cell in the proximal half of the bud as in the distal half of the bud. The concentration of TTNPB in proximal tissue is estimated to be three times higher than in distal tissue in which pattern formation and cartilage morphogenesis are relatively normal. At early stages in the development of phocomelia, the shape of the bud changes and the indentation that marks the elbow does not arise. Neither retinoid-induced cell killing nor effects on the pattern of programmed cell death were detected. The induction of phocomelia by retinoids appears to be based on effects on proximal cells, whereas retinoids produce pattern changes by acting on distal cells. Furthermore, compared with pattern changes, higher concentrations of retinoid in the bud tissue are required to produce phocomelia.
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    Development genes and evolution 197 (1988), S. 193-196 
    ISSN: 1432-041X
    Keywords: Newt ; limb regeneration ; transferrin ; cell culture
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    Notes: Summary In order to study mitogenic control during axolotl limb regeneration, we have developed a primary blastema cell culture as a very sensitive bioassay for blastema mitogens. Transferrin, an iron-binding glycoprotein which has been shown to be the neurotrophic factor for muscle cells, is the mitogen which has been analysed in the present report. Addition of approximately 2 μg human transferrin/ ml of serum-free culture medium enhances blastema cell proliferation 11-fold over control levels and 2-fold over that produced by the addition of nerve extracts or purified growth factors extracted from nerve tissues (basic and acidic fetal growth factor, FGF). At a higher concentration (20 μg/ml), transferrin alone has no mitogenic effect unless the medium is also supplemented with FeCl3 (100 μM). The results are discussed with regard to the sensitivity of the blastema cell culture bioassay and in the context of the neurotrophic theory of urodele limb regeneration.
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    Development genes and evolution 197 (1988), S. 375-375 
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  • 71
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    Keywords: Drosophila ; Injection of embryo ; Daudi conditioned medium ; Rudimentary ovaries ; Mean number of ovarioles
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    Notes: Summary Drosophila melanogaster embryos were injected before the blastoderm stage with conditioned media from several male Burkitt's lymphoma human cell lines and the Daudi cell line. Such injections do not have any effect on the male genital apparatus or on the female tract. The Daudi conditioned medium modifies the ovarian morphogenesis of the flies and the rudimentary ovaries obtained look like nymphal gonads. Moreover, they have a drastically reduced number of germ cells. The ovaries that looked functional contain numerous necrotic germ cells and the mean number of ovarioles per fly is significantly smaller than that of the controls. The abnormalities observed resemble the results of experimental and genetic lack of germ cells. They disappear at very high dilution (1×10−6).
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    Development genes and evolution 197 (1988), S. 447-456 
    ISSN: 1432-041X
    Keywords: Micromeres ; Sea urchin embryo ; Primary mesenchyme ; Spiculogenesis ; Cell lineage
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    Topics: Biology
    Notes: Summary In embryos of the “modern” sea urchin species, subclass Euechinoidea, primary mesenchyme cells are derived from the progeny of micromeres formed at the sixteen cell stage of embryogenesis. The micromeres reside within the vegetal plate epithelium and later ingress into the blastocoel as primary mesenchyme cells which form the larval skeleton. Embryos of Eucidaris tribuloides, a member of the “primitive” subclass Perischoechinoidea, exhibit several noteworthy differences from euechinoid primary mesenchyme cell lineage including variable numbers and sizes of micromeres, the absence of mesenchyme ingression, and the lack of any detectable primary mesenchyme although a larval skeleton forms. In the present study, the cell lineage of the spiculogenic mesenchyme has been studied in Eucidaris tribuloides and in the euechinoid Lytechinus pictus by microinjecting the fluorescent tracer, Lucifer Yellow, into individual blastomeres of the embryo. In addition, wheat germ agglutinin, a lectin which binds only to primary mesenchyme cells of the early euechinoid embryo, was injected into the blastocoel of embryos of both species in order to examine the distribution of cells which possess primary mesenchyme-specific cell surface markers. The results of these experiments demonstrate that the spiculogenic mesenchyme of both Lytechinus and Eucidaris arise from descendants of micromeres formed at the sixteen cell stage, although the temporal and spatial distribution of these mesenchyme cells varies considerably between species. Furthermore, the evidence obtained suggests that the information necessary for spicule formation is already segregated to the vegetal pole by the eight cell stage. The results also suggest that there are no gap junctions present between the blastomeres of the early sea urchin embryo.
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    Development genes and evolution 197 (1988), S. 476-489 
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    Keywords: Cell surface patterns ; Double mutant analysis ; Ciliate development ; Tetrahymena thermophila
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    Topics: Biology
    Notes: Summary An analysis of bcd, janA; bcd, janB; and bcd, janC double-mutant phenotypes in Tetrahymena thermophila has allowed us to examine patterning processes affected by two different classes of mutations. bcd brings about a broadening of the oral and contractile vacuole pore domains in the ciliate cortex, while the janus mutations generate a mirror-image duplication of the ventral cortical pattern. We observed both bcd and janus characteristics expressed in the double mutants, as well as features unique to the double-mutant. Temperature-shift experiments employing the temperature-sensitive janB mutation in a double-mutant (bcd, janB) combination allowed us to observe the changes in pattern as a mirror-image geometry was brought into expression and subsequently removed within the bcd, janB double homozygote. These experiments suggest that there are multiple pattern-mechanisms at work with differing kinetics of expression in the ciliate cortex. We discuss how the bcd mutation could influance expression of the janus mutations in light of a model previously proposed to account for the janus phenotype.
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    Development genes and evolution 197 (1988), S. 507-512 
    ISSN: 1432-041X
    Keywords: Drosophila ; Reporter gene ; hairy ; Segmentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Random insertions of a promotor fused to a reporter gene, such as Lac-Z, reveal regulatory sequences that confer temporal and spatial patterns of gene expression in eukaryotes. These patterns may reflect the activity of a neighbouring gene and thus lead to the isolation of new genes essential for normal development. Here, we demonstrate that this hypothesis is true for an insertion into the well characterized segmentation gene, hairy, in Drosophila. The insertion is homozygous lethal and fails to complement other hairy alleles, giving the phenotype described for hairy mutations. The insertion is located at 66D on the polytene chromosome map, is within 300–600 bp 5′ to the first hairy exon, and is orientated in the same sense (5′-3′) as the hairy transcription unit. Expression of β-galactosidase (β-gal), deriving from the insertion, follows closely the spatio-temporal patterns of expression of hairy gene product during embryogenesis. In addition, other sites of β-galactosidase expression are shown in the third larval instar stage and in the adult ovary. The results show that some insertions, giving restricted patterns of reporter gene expression, will reflect the temporo-spatial activity of a nearby gene.
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    Development genes and evolution 197 (1988), S. 496-502 
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    Keywords: Larval hemolymph proteins ; Gene regulation ; Juvenile hormone ; 20-hydroxyecdysone
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    Topics: Biology
    Notes: Summary Developmental Northern analysis of larval hemolymph protein gene transcripts in Galleria mellonella showed that Lhp76 is expressed all through the larval life, while Lhp82 is expressed only during the last larval stadium. Neither transcript was detectable in pharate adults and adult moths. In addition, these transcripts were not detectable during the first 48 h of the last larval stadium. Experimental analyses of the effects of the nutritional state and the hormonal levels of the last instar larvae on LHP gene expression suggests that the nutritional state of the larva has no direct effect, but nutrition acts through its effect on the hormone titers. Larvae starved after the first 24 h of the stadium and those fed on a non-protein diet produced both the transcripts on schedule on day 3. However, starvation during the first 24 or 48 h or feeding them on agar caused a marked delay in activation of Lhp82. These starved larvae pupated 4 to 12 days later than controls. Furthermore, JH titers in the starved larvae remain high even 5 days after ecdysis into the last instar. Prothorax-ligation of the starved and the starved-refed larvae accelerated production of the transcripts, thereby suggesting that the nutritional state does not directly affect LHP gene expression. Application of JH 1 to the ligated preparations resulted in selective blocking of Lhp82, while 20-OH ecdysone affected both the genes, thereby supporting the view that the insect hormones play an important role in stage-specific expression of LHP genes.
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    Development genes and evolution 197 (1988), S. 518-518 
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    Development genes and evolution 197 (1988), S. 519-519 
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    Development genes and evolution 197 (1988), S. 513-517 
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    Keywords: Cell adhesion ; Condensation ; Mechanism ; Somitogenesis ; Traction
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    Topics: Biology
    Notes: Summary This paper suggests that chick somites form because presomitic cells exert tractional forces on one another. These forces derive from the increase in cell adhesion and density that occurs as N-CAM and N-cadherin are laid down by the motile cells of the presomitic mesoderm, well before the somites form. Harris et al. (1984) have shown that adhesive and motile cells in an appropriate environment in vitro can spontaneously form aggregates under the influence of the tractional forces that they exert. Presomitic mesodermal cells may behave similarly: as CAM production increases local adhesivity, the tractional forces between the cells should become sufficiently strong for groups of cells to segment off the mesenchyme as somites. The successive expression of CAMs down the presomitic mesoderm will thus lead to the formation of an anterior-posterior sequence of somites. This mechanism can explain several aspects of somitogenesis that models generating a repetitive pre-pattern through gating cohorts of cells find hard to explain: first, mesodermal segregation occurs among highly adherent cells; second, that multiple rows of somites can form in embryos cultured on highly adherent substrata; third, that stirred mesoderm will still form normal somites; and, fourth, how somite size can be altered in heat-shocked embryos and elsewhere. Suggestions are given as to how the mechanism may be tested and where else in the embryo it could apply.
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    Insectes sociaux 35 (1988), S. 47-60 
    ISSN: 1420-9098
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    Topics: Biology
    Description / Table of Contents: Resume Les caryotypes de 16 taxa de la fourmi moissonneuse du genrePogonomyrmex ont été étudiés. Des espèces représentatives des deux sous-genres de l'Amérique du Nord ont été examinées, incluant des membres des quatre complexes du sous-genrePogonomyrmex. Le sous-genrePogonomyrmex est caractérisé par un nombre diploide de 32, alors que les espèces du sous-genreEphebomyrmex possèdent 2n=36 (P. (E.) huachucanus) et 2n=58−62 (P. (E.) imberbiculus). Un polymorphisme chromosomique n'a été identifié qu'avecP. (E.) imberbiculus.
    Notes: Summary Karyotypes of 16 taxa of the New World harvester ant genusPogonomyrmex are presented. Species representing both North American subgenera are examined, including members of all four complexes of the nominate subgenus. The nominate subgenus is characterized by a diploid number of 32, whereasEphebomyrmex species have 2n=36 (P. (E.) huachucanus) and 2n=58−62 (P. (E.) imberbiculus). Chromosome polymorphism was identified only in the latter species.
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    Description / Table of Contents: Resume Plusieurs espèces de fourmis ponérines n'ont pas de caste royale, et il n'est pas établi si cette modification de la structure sociale a un effet sur l'habilité à discriminer parmi les compagnes du nid et les ouvrières provenant de nids étrangers. Des fourrageuses deRhytidoponera espèce 12 ont été prélevées de 15 nids adjacents, et ont été testées immédiatement deux à deux. Suite à 179 tests, l'attaque a eu lieu dans 84 % des cas, et dans 5 % des cas il y avait une hostilité évidente. Egalement, des batailles entre fourmis étrangères marquées préalablement ont été observées près des nids. Il y a plusieurs ouvrières fécondées et pondeuses dans les colonies deR. 12, donc les habitantes d'un même nid ont une similarité génétique moins élevée qu'ailleurs (le résultat est tel que leurs odeurs endogènes de reconnaissance peuvent varier considérablement). Puisqu'il n'y a pas l'influence d'une odeur royale, l'existence du phénomène de fermeture de la société révèle que les ouvrières sont capables d'apprendre la gamme d'odeurs individuelles des habitantes de leurs nids. Dans certains cas où les ouvrières provenant de deux nids différents ne se sont pas attaquées, chacune d'elles a été testée à nouveau avec d'autres fourmis étrangères (provenant du même nid ou d'un autre nid). Elles étaient alors parfois capables de discriminer, mais pas dans tous les cas. Ceci donne à penser qu'une odeur «gestalt» n'existe pas dans ces colonies, mais davantage de résultats sont nécessaires pour confirmer ceci. Les colonies deR. 12 ne sont pas polycaliques, contrairement à ce qui avait été suggéré auparavant. Le transport d'ouvrières qui a lieu entre les nids est équivalent à des épisodes de déménagement du nid.
    Notes: Summary Various ponerine ants do not have a queen caste, and it is not known whether this modification in the eusocial structure affects the ability to recognize between nestmates and non-nestmates. Foragers ofRhytidoponera sp. 12 were collected from 15 adjacent nests, and were immediately tested in pairwise introductions between nests. Out of 179 tests, 84 % resulted in fighting, and in another 5 % there were unambiguous signs of hostility. Furthermore, natural aggression between marked foreign workers was observed near the nests. There are many mated laying workers in the colonies ofR. sp. 12, and this leads to nestmates being less genetically-similar (whereupon their genotypically-correlated recognition odours may vary considerably). Since there is no influence of a queen odour, the existence of a distinct colony identity reveals that workers are able to learn the spectrum of individual odours of their nestmates. In instances where workers from two foreign nests did not fight, each of them was again tested with other foreign ants (from the same or a different nest). They could discriminate in some cases but not others. This suggests that a gestalt odour does not exist in these colonies, but larger samples are needed to confirm this. Colonies ofR. sp. 12 are not polydomous, as had been previously suggested. The transfer of workers which sometimes occurs between nests represents episodes of nest emigration.
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    Insectes sociaux 35 (1988), S. 19-33 
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    Description / Table of Contents: Resume L'objectif de ce travail est de fournir des données concernant la production des mâles au laboratoire. Chez cette espèce les ouvrières sont incapables de pondre des œufs reproducteurs; en conséquence tous les mâles sont les descendants des reines. Dans les grosses sociétés stocks maintenues au laboratoire, les mâles sont élevés avec une périodicité de 3 à 4 mois. Dans l'intervalle, le couvain transféré des sociétés stocks dans des unités standardisées pourvues ou non de reines (1 à 5 reines) est à l'origine de nouveaux mâles. Il paraît donc raisonnable de penser que des œufs mâles sont pondus en permanence par les reines tout au long de la période d'activité. Cette observation est différente de celle que l'on fait habituellement chez la plupart des autres fourmis où il est généralement admis que les œufs mâles sont pondus à un moment déterminé du cycle annuel. On peut dès lors se demander pourquoi le développement des œufs mâles n'est pas continu mais au contraire intervient périodiquement. Des expériences comparatives suggèrent que l'élevage du couvain mâle jusqu'au stade nymphal dépend de plusieurs paramètres reliés entre eux. Le ratio ouvrières/larves: nous avons enregistré la production des mâles dans des unités standardisées où le ratio ouvrières/larves varie de 0,25 à 25. Plus la valeur du ratio est élevée, plus on obtient de larves mâles. Le contrôle royal: dans des unités standardisées où le ratio ouvrières/larves est élevé, la présence des reines n'est pas un obstacle à l'élevage des mâles. Ces données suggèrent l'absence d'une phéromone royale inhibitrice contrôlant la production des mâles. Il semble plutôt que les reines entravent le développement des mâles par le biais d'une appropriation de nourriture. Le régime alimentaire: des sociétés expérimentales soumises à un jeûne protidique cessent de produire des mâles. Il semble donc bien que le développement des mâles soit essentiellement contrôlé par la quantité de nourriture disponible. Si cette quantité vient à baisser à cause d'une diminution de l'approvisionnement, d'un couvain trop abondant ou d'un nombre de reines trop élevé, les ouvrières réagissent en cessant d'élever les larves mâles.
    Notes: Summary The influence of various social factors on the production of males was investigated in the Argentine ant,Iridomyrmex humilis. In this polygynous species, the workers which are monomorphic are unable to lay reproductive eggs, so all the males are the progeny of the queens. Although male eggs appear to be laid by mated queens throughout the year, in large stock colonies males are reared periodically (every 3 or 4 months); males develop from brood taken from these colonies at any point in the cycle and given queenless or queenright (1 to 5 queens) units. This is in striking contrast to many other species of ants where it is generally assumed that male eggs are laid seasonnally. Comparative experiments suggest that several related factors influence the rearing of males as far as the pupal stage. •Worker/larva ratio: The proportion of male larvae developing in standardized units in which the worker/larva ratio was varied from 0.25 to 25 demonstrated that low ratios inhibit male production. •Queen influence: In standardized units where the worker/larva ratio was high the presence of queens did not inhibit the rearing of males suggesting that there is no queen inhibitory pheromone controlling male experimental production. Data suggest evidence that queens prevent male production by means of appropriation of food. •Diet: Male larvae failed to pupate in experimental societies deprived of protein. Thus, the production of males appears to be controlled by the amount of food available to larvae. This depends on foraging activity, the quantity of brood in relation to the number of workers and the number of queens in the society.
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    Insectes sociaux 35 (1988), S. 1-18 
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    Topics: Biology
    Description / Table of Contents: Resume On décrit ici la recherche de nourriture chez la fourmi moissonneuseMessor wasmanni sur des pistes de 2 à 15 m. de long, en terrain plat et découvert, en Grèce. Ces fourmis recherchent leur nourriture pendant la journée, environ tous les trois jours; lorsqu'elles sont inactives, l'entrée du nid est bouchée avec des débris de matière végétale. Elles commencent leur activité vers l'aube, et travaillent jusqu'à ce que la température à la surface du sol atteigne un peu plus de 40°C. Environ 5000 fourmis d'un nid participent à ces expéditions, dont le nombre par nid est de l'ordre de 20 à 30000 par jour. Les fourmis se dispersent là où la piste se termine, chacune fourrageant sur quelques pieds carrés seulement (10 pieds carrés=environ 1 m2). Les nids, d'une densité d'environ 70 par hectare, ne sont pas répartis aléatoirement. Si le terrain sur lequel les fourmis d'un nid fourragent empiète sur celui d'un autre, il est rare que les pistes s'entrecroisent. Celles-ci rayonnent à partir de chaque nid, une seule piste par jour étant ordinairement utilisée. Sur environ 500, partant d'une douzaine de nids examinés, on n'a vu qu'un seul croisement: les deux pistes se rencontraient à angle droit, la plus courte s'arrêtant à la jonction. Les fourmis qui l'utilisaient poursuivaient leur chemin après la jonction, dans la même direction, mais en se dispersant. Toutes les colonies tendaient à fourrager après la pluie, mais le résultat de cet effet synchronisateur était minime, les expéditions de différents nids ayant lieu à des moments différents. Etant donné la possibilité que des expéditions de nids voisins aient lieu le même jour, et en supposant l'orientation des pistes choisie au hasard-leur longueur étant déduite par observation-la probabilité de l'intersection de deux pistes était faible (7). On n'a pas trouvé d'interactions agressives entre fourmilières, et des individus marqués et transférés près d'un nouveau nid ont survécu et ont participé au fourragement aux côtés des fourmis de ce nid. A trois reprises on a trouvé de petits nids secondaires dont les fourmis circulaient sur une piste menant à la fourmilière principale (des fourmis ont été vues transférant des œufs et des larves). Il était fréquent que des fourmis creusent de petits trous à côté d'une piste-trous qu'on peut interpréter comme des débuts de nids secondaires.
    Notes: Summary Foraging behaviour ofMessor wasmanni, a seed collecting ant, foraging along trails up to 15m long in open flat ground in Greece, is described. These ants foraged in daytime on about one day in three, the nest entrance being otherwise closed with discarded remains of the plant material. They started approximately at dawn and material. They started approximately at dawn and continued until the ground surface temperature reached 40–43°C. Of the order of 20–30,000 individual foraging expeditions were made from the nest per day involving about 5,000 individual ants. They dispersed from the end of the trail and searched individually in limited areas of a few square feet (say half m2). Nests at a density of about 70 to the hectare were spaced in a pattern which was not random. Trails go out radially from each nest, usually a single trail in any day. Foraging areas for different nests overlapped but the chance of trails intersecting was low. An intersection was seen only once in approximately 500 trails from about a dozen nests examined in detail. The two trails met at right angles and the shorter one broke up at the junction, the ants from it going on across the other trail in the same general direction but more dispersed than before. All nests tended to forage after rain but the net synchronizing effect of this tendency was small, the nests in general foraging independently of one another in time. Calculation of the probability of trail intersection, allowing for the chance of adjacent nests having trails on the same day, and assuming a random trail direction together with the observed distribution of trail length gave a low value (7) for the expected number of intersections. No evidence of aggressive behaviour between different nests was found. Individuals, marked with paint and transferred artificially to a new nest, survived and foraged among those of their new nest. On three ocasions small subsidiary nests were found from which ants went to and fro along a trail to the main nest and on one occasion eggs and larval stages were transferred. On many occasions groups of ants dug small holes in the ground adjacent to a trail, which are most easily explained as incipient subsidiary nests.
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    Insectes sociaux 35 (1988), S. 61-69 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Für die Haltung von Ameisen wurde eine künstliche Diät (Bhatkar andWhitcomb, 1970) empfohlen. Vergleichende Untersuchungen an einer sklavenhaltenden Ameise,Harpagoxenus sublaevis, und einer ihrer Sklavenarten,Leptothorax acervorum, zeigten, daß diese Diät für eine normale Brutproduktion der unabhängigen ArtL. acervorum nicht ausreicht. In Völkern der Sklavenhalterart, die mit der Diät gefüttert werden, werden nach Raubzügen viel mehr von den neu geraubten Sklavenart-Puppen gefressen als in Völkern, die mit einer natürlicheren Diät aus Insektenstücken und Honig versorgt werden. Diese Versuche zeigen, daß die Ernährung die Ergebnisse von Zucht- und Verhaltensversuchen stark beeinflussen kann, und damit auch die daraus abgeleiteten Schlüsse. Die B.—W.—Diät ist wahrscheinlich ungeeignet für viele Ameisenarten, die sowohl Insektenbeute als auch Honigtau benötigen.
    Notes: Summary An artificial diet (Bhatkar andWhitcomb, 1970) was recommended for maintaining ant colonies. Comparative studies with a slave-making ant,Harpagoxenus sublaevis, and one of its slave species,Leptothorax acervorum, have shown that this diet is not sufficient for normal brood production in the independent speciesL. acervorum. In colonies of the slavemaker species fed with the diet, much more of the slave species pupae captured during raids are consumed than in colonies supplied with a more natural diet of insect tissue and honey. These experiments demonstrate that diet can seriously influence the results of breeding experiments, and we suggest that diet may be very important for certain behavioral studies as well. We conclude that the B.—W.—diet is probably inappropriate for many ant species which utilize both insect prey and honeydew.
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    Insectes sociaux 35 (1988), S. 70-81 
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    Topics: Biology
    Description / Table of Contents: Zusammenfassung In Laborkolonien der Argentinischen Ameise wird durch die Anwesenheit von Königinnen die Aufzucht von Jungköniginnen völlig verhindert, die von Männchen verringert. Die gesteigerte Aufzucht von Männchen in weisellosen Völkern ist nicht auf die Ablage von Eiern durch Arbeiterinnen zurückzuführen. Diese Ergebnisse bestätigen frühere Arbeiten vonGiraud (1983a, 1983b) und anderen. Die Mechanismen der Kontrolle durch die Königinnen wurden untersucht. Ein Experiment, in dem Königinnen und Larven voneinander getrennt gehalten wurden, zeigte, daß direkter Kontakt zwischen beiden erforderlich ist um die Hemmung der Larvalentwicklung zu bewirken. In Anwesenheit von Königinnen war der Verzehr von Arbeiterinnen gelegter trophischer Eier durch Larven signifikant verringert. Diese Form von Nahrungsentzug als hemmender Mechanismus wird hiermit erstmalig wahrscheinlich gemacht. An einem weiteren Mechanismus könnte das Verschmieren von Königinnen-Eiern auf den Larven beteiligt sein. Dieses einzigartige Verhalten der Königinnen wird beschrieben.
    Notes: Summary The presence of queens in laboratory colonies of Argentine ants completely inhibited new queen production, and decreased male production. Increased male production in queenless colonies did not result from worker oviposition. These findings support previous work ofGiraud (1983a, 1983b) and others. Mechanisms of queen control were investigated. A queen-larvae segregation experiment demonstrated that direct contact between queens and larvae was required for larval inhibition, and worker produced trophic egg consumption by larvae was significantly reduced in the presence of queens. This is the first documentation of this form of nutritional deprivation as an inhibitory mechanism. A second mechanism may include the smearing of queen produced eggs on the larvae. This unique queen behavior is described.
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    Insectes sociaux 35 (1988), S. 82-91 
    ISSN: 1420-9098
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    Topics: Biology
    Description / Table of Contents: Resume La reconnaissance des partenaires du nid a été souvent rapportée chez les Hyménoptères sociaux quoique les données publiés sur ce phénomène chez les fourmis particulièrement concernent les ouvrières. Les raisonnements utilisant l'«inclusive fitness» suggèrent que les femelles reproductrices (reines et ailées) devraient être acceptées dans les nids étrangers moins souvent que les ouvrières; les mâles peuvent ou non entraîner moins de réponses agressives. Les reines désailées provenant d'une paire d'espèces voisines, l'une monogyne (Formica argentea), l'autre polygyne (F. podzolica), et les ailés des deux sexes de l'espèce polygyne ont été expérimentalement combinés avec des partenaires de nids familiers et peu familiers, des ouvrières étrangères de la même espèce, et des ouvrières de l'autre espèce. Dans l'espèce polygyne les ouvrières ont été moins promptes à rejeter des reines étrangères homospécifiques que dans l'espèce monogyne. Dans tous les cas, à l'exception des témoins et des introductions inter-espèces, les mâles étrangers ont été acceptés plus facilement que les femelles ailées étrangères.
    Notes: Summary Nestmate recognition has been frequently reported in the social Hymenoptera though published reports of this phenomenon in ants typically involve workers. Arguments involving inclusive fitness suggest that reproductive females (queens and alates) should be accepted less often than workers in foreign colonies; males may or may not elicit fewer aggressive responses. Dealate queens from a monogynous/polygynous sibling species pair (Formica argentea andF. podzolica) and alates of both sexes from the polygynous species were tested with familiar and unfamiliar nestmates, foreign conspecifics, and heterospecific workers. Workers from the polygynous species were less likely to reject foreign conspecific queens than workers of the monogynous species. In all cases except controls and between species introductions, foreign males were accepted more readily than foreign alate females.
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    Insectes sociaux 35 (1988), S. 92-105 
    ISSN: 1420-9098
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    Topics: Biology
    Description / Table of Contents: Resume Afin de comprendre comment les fourrageuses deFormica lugubris s'orientent en milieu naturel dans la végétation arborescente, des ouvrières ont été induites à fourrager dans un système tridimensionnel simple installé au laboratoire. Le système a été conçu pour étudier le rôle respectif des repères chimiques, visuels et kinaesthésiques à la fois sur l'axe vertical et sur le plan horizontal dans des conditions expérimentales contrôlées. Les résultats indiquent que sur l'axe vertical les fourmis peuvent utiliser simultanément divers types d'informations comme par exemple des repères chimiques et une source de lumière directionnelle avec une préférence pour cette dernière en cas d'ambiguité dans la direction indiquée par les deux types d'informations. Les expériences montrent que les repères chimiques sont hautement impliqués dans l'orientation sur le plan horizontal et ils semblent de plus avoir pour les fourmis une fiabilité plus importante que les autres types de repères. Cependant, quand les repères chimiques sont absents, les fourrageuses sont toujours capables de localiser la source de nourriture en se basant uniquement sur la direction des rayons lumineux. En outre, en dépit de nos précautions méthodologiques, des repères visuels non identifiés semblent également intervenir, au moins en tant qu'information secondaire, dans l'orientation sur le plan horizontal.
    Notes: Summary In order to understand howFormica lugubris foragers orient in the vegetation, we used a simple three dimensional foraging system set-up in controlled laboratory conditions. The system was designed to investigate the respective role of chemical, visual (directional light) and kinaesthetic cues both on the vertical axis and the horizontal plane. The results indicate that on the vertical axis, ants are able to utilize simultaneously various types of directional information e.g. chemical cues and directional light, with a preference for the latter in case of conflicting information. On the horizontal plane, the orientation was found to be essentially based on external references. Amongst the latter, chemical cues have been shown to be highly implicated and seem to have a greater reliability than any other orientating information available. However, when the scent trail is removed, ants are still able to relocate the food source by using the direction of the light rays. In addition, in spite of our methodological precautions, unidentified visual landmarks were unexpectedly found to intervene as auxiliary cues in the orientation on the horizontal plane.
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  • 87
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    Description / Table of Contents: Resume Afin d'étudier l'orientation de fourmis fourrageant dans les trois dimensions de l'espace, des ouvrières deFormica nigricans ont été observées dans leur milieu naturel alors qu'elles s'alimentaient spontanément, de jour et de nuit, sur un arbre artificiel. Les repères célestes ne semblent pas intervenir dans les directions prises par les insectes. Par contre le rôle des repères visuels terrestres et du marquage chimique des pistes est prépondérant aussi bien lors déplacements sur l'axe vertical que sur le plan horizontal. En cas de différences provoquées expérimentalement entre les directions indiquées par ces deux types de repères, les fourmis se basent préférentiellement sur les indices visuels terrestres. De plus l'utilisation de repères idiothétiques assure aux insectes une information complémentaire aux points de carrefour. D'autre part, l'orientation nocturne est essentiellement assurée par un repérage chimique. L'ensemble des résultats accrédite l'hypothèse d'une utilisation simultanée de tous les reprères disponibles au moment où se déroule l'orientation. Mais lors de situations conflictuelles, les fourmis se guident sur le repère spatialement le plus constant. L'organisation hiérarchique des repères, fréquemment rapportée dans la littérature, doit donc être largement relativisée.
    Notes: Summary In order to investigate the orientational mechanisms involved in the ants' three dimensional movements workers of the red wood antFormica nigricans were enticed to forrage, both during the day and in night, in an artifical tree set up in their natural environment. Celestial cues were found to be irrelevant in the ants' directionnality. In contrast, the results stress the importance of terrestrial and chemical landmarks both in the orientation on the vertical axis and on the horizontal plane. When a discrepancy was experimentally induced in the directional information provided by the two types of landmarks, terrestrial cues were preferred over the chemical ones. In addition, kinaesthetic information is used as a back-up orientating system at the cross-road. On the other hand, nocturnal orientation was found to be essentially based on chemical cues. These results support therefore the assumption of a simultaneous utilization of all the available directional information apart from alternative use of single cues during competitive situations and rule out the concept of an absolute hierarchie of cues.
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  • 88
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    Description / Table of Contents: Resume Une série d'expériences a été effectuée tester l'effet des boules de nourriture roulées par le bousierCanthon cyanellus cyanellus LeConte sur des individus de même sexe ou de sexe différent. Les résultats montrent que seuls les mêles mûrs imprègnent la boule avec des sécrétions attractive abdominales durant le roulage. Le marquage chimique de la boule est un moyen pour attirer une femelle a courte distance et, après, la reteinir dans le nid.
    Notes: Summary An experimental analysis was performed to test the effect of food balls rolled by the dung beetleCanthon cyanellus cyanellus LeConte on conspecific individuals of the same and different sex. The results show that only the mature males impregnate the foodballs with abdominal secretions during rolling. The chemical labelling of the ball is a means to attract a female over short distance and after retain it in the nest.
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    Insectes sociaux 35 (1988), S. 133-143 
    ISSN: 1420-9098
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    Topics: Biology
    Description / Table of Contents: Resume Parischnogaster jacobsoni, qui a été étudiée en Malaisie, a de longs nids linéaires et présente une fondation du nid haplométrotique. Dans les colonies mûres on retrouve communément plus d'une femelle fertilisée et au moins une femelle qui peut pondre. Les interactions de dominance-subordination sont liées au potentiel reproductif des femelles et à la division du travail. La biologie, l'architecture du nid et l'organisation sociale de cette espèce ressemblent à celles deParischnogaster nigricans serrei, qui a été étudiée à Java.
    Notes: Summary Parischnogaster jacobsoni, studied in Malaysia, presents long linear nests and haplometrotic nest foundation. In mature colonies more than one fertilized female and at least one potential egg layer can be found. Dominance-subordinance interactions are correlated with the reproductive potential of the females and with the division of labour. This species resemblesParischnogaster nigricans serrei, studied in Java, in its biology, nest architecture and social organization.
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    Insectes sociaux 35 (1988), S. 144-152 
    ISSN: 1420-9098
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    Topics: Biology
    Description / Table of Contents: Resume Les soldats de termites chez beaucoup d'espèces sont produits au cours des saisons chaudes, et les proportions de soldats sont connues pour varier selon la saison aussf bien chez les termites inférieurs que chez les supérieurs. Les paramètres du milieu qui peuvent stimuler la production saisonnière de soldats englobent la température et la nourriture. Nous avons examiné l'importance de ces facteurs dans la différenciation des soldat chez le termite souterrain de FormoseCoptotermes formosanus Shiraki (Rhinotermitidae). Nous avons trouvé qu'un nombre significativement supérieur de soldats était produit à 30° C et 31° C par rapport à 25°C et 27.5°C respectivement. Les termites consomment plus de bois et grossissent davantage à des températures plus élevées de sorte que la différenciation associée à la température a pu être liée a une meilleure nutrition. Il n'y a pas eu de difference significative dans la production de soldats sur le bois de pin par rapport au cyprès.
    Notes: Summary Termite soldiers are produced only in warm seasons in many species, and soldier ratios have been reported to vary seasonally in both lower and higher termites. Environmental parameters that may stimulate seasonal soldier production include temperature and diet. We examined the importance of these factors in soldier differentiation in the Formosan subterranean termite,Coptotermes formosanus Shiraki (Rhinotermitidae). We found that significantly more soldiers were produced at 30 °C and 31° C than at 25° C and 27.5° C, respectively. Termites consumed more wood and weighed more at higher temperatures, so that temperature-associated differentiation may have been related to better nutrition. There was no significant difference in soldier production on pine versus baldcypress diets.
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    Pure and applied geophysics 127 (1988), S. 73-77 
    ISSN: 1420-9136
    Keywords: Mean sea level ; climatic changes
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    Topics: Geosciences , Physics
    Notes: Abstract Sea level data from Stockholm, with the initial year 1774, have been recalculated using old information hitherto not taken into account. Since the resultant series of annual mean sea levels is the longest continued one in the world, and of very good reliability, it is published here. Also some results on eustatic changes of sea level, due to changes of climate, are given.
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    Pure and applied geophysics 127 (1988), S. 183-187 
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    Pure and applied geophysics 127 (1988), S. 415-446 
    ISSN: 1420-9136
    Keywords: Active experiments ; chemical releases ; ionospheric modification
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    Topics: Geosciences , Physics
    Notes: Abstract This paper discusses a mathematical model which is aimed at the interpretation of the effects by injections of chemically active gases into the ionosphere. A study is made of neutral-gas expansion processes as well as of processes associated with the formation of decreased plasma density regions, ionospheric ‘holes’. The spatial-temporal distribution of particles released during the transition to the diffusion regime is constructed using an approximate, analytic solution of the Boltzmann equation with the collision integral in the form of BGK, with proper allowance for gravitation and atmospheric inhomogeneity. The investigation of processes associated with the formation of ionospheric ‘holes’ is carried out using a numerical model of ionosphere-plasmasphere coupling, in which the transfer equations for charged components are integrated along geomagnetic field lines. The purpose of the model is to calculate the electron density and temperature, ion composition and emission of a disturbed region in the 6300 Å line at ionospheric and plasmaspheric heights.
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    Pure and applied geophysics 127 (1988), S. 573-579 
    ISSN: 1420-9136
    Keywords: b value ; magnitude uncertainties
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    Topics: Geosciences , Physics
    Notes: Abstract The maximum likelihood estimation of theb parameter in the Gutenberg-Richter relation is extended to the case of uncertain magnitude. An interval which contains the real unknown magnitude is used rather than the uncertain magnitude itself. The proposed approach is very flexible, it allows for the combination of the parts of a catalog of different quality into a single minimally biased set of recurrence parameters.
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    Pure and applied geophysics 126 (1988), S. 267-278 
    ISSN: 1420-9136
    Keywords: Earthquake prediction ; radon ; groundwater ; geochemical precursor
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    Topics: Geosciences , Physics
    Notes: Abstract Detection of precursory phenomena in observation data is essential to earthquake prediction studies. Continuous monitoring of radon concentration in groundwater in Japan in one case showed a short-term anomaly related to a nearby earthquake. With the exception of the 1978 Izu-Oshimakinkai earthquake (M7.0), however, no abnormal change has been noted. This may be due partially to difficulty in detecting insignificant precursory signals from observation data, which ordinarily contains a noise-induced fluctuations, and partially to lack of understanding of the mechanism controlling the appearance of precursory phenomena. In order to increase our knowledge of the variation pattern of precursory changes in radon concentration of groundwater, hydrologic precursors with significant features are examined in this paper. Complexity of appearance of precursory phenomena and problems in assignment of the specific earthquake are discussed.
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    Pure and applied geophysics 126 (1988), S. 465-497 
    ISSN: 1420-9136
    Keywords: Attenuation ; scattering ; coda ; cracks ; inhomogeneities ; heterogeneities ; seismograms ; earthquake prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The study of coda waves has recently attracted increasing attention from seismologists. This is due to the fact that it is viewed as a new means by which the stress accumulation stage preceding a large earthquake can be measured, since the scattering paths nearly uniformly cover a fairly large region around the focus and observation stations, compared with the direct ray paths. To date, we have had many reports on the temporal variation of the relation between coda duration and amplitude magnitude, and that of the coda attenuationQ c −1 which is estimated from coda amplitude decay. Some of these have shown a precursor-like behavior; however, others seem to have shown a coseismic change. We have critically reviewed these reports, and discussed what these observational facts tell us about the change in the heterogeneous crust. We found significant temporal variations, not only in the mean but also in the scatter ofQ c −1 , associated with the mainshock occurrence. The formation of new cracks, the reopening and growing of existing cracks, the interaction of these cracks, and the pore water movement through these cracks might correspond to such variations. In addition, we may expect an inhomogeneous distribution of crack clusters in a fairly large region, compared with the aftershock region. The gradual appearance of such crack clusters seems to be the most plausible mechanism by which coda decay gradients are caused to largely scatter in the stress accumulation stage.
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    Pure and applied geophysics 126 (1988), S. 555-588 
    ISSN: 1420-9136
    Keywords: Rock friction ; constitutive behavior ; earthquake prediction ; fault mechanics ; fault creep ; strainmeters ; creepmeters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Laboratory experiments show that the frictional resistance of rocks depends on the velocity of sliding and the state of the sliding surface as well as on the normal stress. Although the dependence on velocity is small in magnitude, and consequently difficult to measure with high accuracy, this dependence plays a major role in whether frictional sliding is stable or unstable. Constitutive descriptions of laboratory results involve a characteristic distance of sliding, over which the frictional resistance evolves following a step change in sliding velocity. Interactions occur between the elastic response of laboratory testing machines and the change in resistance with slip resulting from this evolution and these interactions are responsible for the stability of sliding. In most situations, materials that show an increase in steady state resistance with increases in sliding velocity (velocity strengthening) will slide stably, while the opposite velocity dependence (velocity weakening) can result in either stable or unstable sliding. The laboratory results suggest that changes in strain and velocity should occur prior to earthquakes. Extrapolation of laboratory results to the earth requires knowledge of how to scale the laboratory constitutive parameters. Use of laboratory constitutive laws to aid in understanding natural fault behavior also requires numerical models to deal with spatial variations of constitutive parameters on fault surfaces and of elastic strain in the adjacent rock. The model of strike slip faulting presented byTse andRice (1986) employs laboratory based constitutive laws and is used in this paper to explore the implications of laboratory results for designing a field monitoring program for earthquake prediction. The results of one of their model simulations are used to calculate the temporal and spatial variation of displacement and strain during an entire model earthquake cycle, with emphasis on the changes that occur in the time period imminent to an earthquake. The premonitory changes in strain that occur are quite small in magnitude near the earth's surface and although detectable with existing shallow borehole instruments, they may only be distinguishable from environmental noise within one month of the earthquake. Strain changes at focal depths of several kilometers would be at detectable levels for a longer time if measurements in suitably deep drill holes could be made. Premonitory changes in velocity of points at the earth's surface are predicted to be of sufficient magnitude that they should be measurable with two-color geodimeters and useful for earthquake prediction, especially if points at distances from a fault equal to focal depths are included. Predicted premonitory displacements at depth are significant; thus it would be valuable to develop techniques for precise surveying of deep drill holes.
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    ISSN: 1420-9136
    Keywords: Earthquake related stress changes ; San Andreas fault ; Tres Pinos earthquake ; Coalinga earthquake ; dislocation models ; creepmeters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Rates of shallow slip on creeping sections of the San Andreas fault have been perturbed on a number of occasions by earthquakes occurring on nearby faults. One example of such perturbations occurred during the 26 January 1986 magnitude 5.3 Tres Pinos earthquake located about 10 km southeast of Hollister, California. Seven creepmeters on the San Andreas fault showed creep steps either during or soon after the shock. Both left-lateral (LL) and right-lateral (RL) steps were observed. A rectangular dislocation in an elastic half-space was used to model the coseismic fault offset at the hypocenter. For a model based on the preliminary focal mechanism, the predicted changes in static shear stress on the plane of the San Andreas fault agreed in sense (LL or RL) with the observed slip directions at all seven meters; for a model based on a refined focal mechanism, six of the seven meters showed the correct sense of motion. Two possible explanations for such coseismic and postseismic steps are (1) that slip was triggered by the earthquake shaking or (2) that slip occurred in response to the changes in static stress fields accompanying the earthquake. In the Tres Pinos example, the observed steps may have been of both the triggered and responsive kinds. A second example is provided by the 2 May 1983 magnitude 6.7 Coalinga earthquake, which profoundly altered slip rates at five creepmeters on the San Andreas fault for a period of months to years. The XMM1 meter 9 km northwest of Parkfield, California recorded LL creep for more than a year after the event. To simulate the temporal behavior of the XMM1 meter and to view the stress perturbation provided by the Coalinga earthquake in the context of steady-state deformation on the San Andreas fault, a simple time-evolving dislocation model was constructed. The model was driven by a single long vertical dislocation below 15 km in depth, that was forced to slip at 35 mm/yr in a RL sense. A dislocation element placed in the seismogenic layer under XMM1 was given a finite breaking strength of sufficient magnitude to produce a Parkfield-like earthquake every 22 years. When stress changes equivalent to a Coalinga earthquake were superposed on the model running in a steady state mode, the effect was to make a segment under XMM1, that could slip in a linear viscous fashion, creep LL and to delay the onset of the next Parkfield-like earthquake by a year or more. If static stress changes imposed by earthquakes off the San Andreas can indeed advance or delay earthquakes on the San Andreas by months or years, then such changes must be considered in intermediate-term prediction efforts.
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  • 100
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 126 (1988), S. 701-718 
    ISSN: 1420-9136
    Keywords: Earthquake prediction ; earthquake mechanism ; dilatancy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In the past decade there have been major advances in understanding the seismic cycle in terms of the recognition of characteristic patterns of seismicity over the entire tectonic loading cycle. The most distinctive types of patterns are seismic quiescences, of which three types can be recognized:post-seismic quiescence, which occurs in the region of the rupture zone of an earthquake and persists for a substantial fraction of the recurrence time following the earthquake,intermediate-term quiescences, which appear over a similar region and persist for several years prior to large plate-rupturing earthquakes, andshort-term quiescences, which are pronounced lulls in premonitory swarms that occur in the hypocentral region hours or days before an earthquake. Although the frequency with which intermediate-term and short-term quiescences precede earthquakes is not known, and the statistical significance of some of the former has been challenged, there is a need, if this phenomena is to be considered a possibly real precursor, to consider physical mechanisms that may be responsible for them. The characteristic features of these quiescences are reviewed, and possible mechanisms for their cause are discussed. Post-seismic quiescence can be readily explained by any simple model of the tectonic loading cycle as due to the regional effect of the stress-drop of the previous principal earthquake. The other types of quiescence require significant modification to any such simple model. Of the possibilities considered, only two seem viable in predicting the observed phenomena, dilatancy hardening and slip weakening. Intermediate-term quiescences typically occur over a region equal to or several times the size of the rupture zone of the later earthquake and exhibit a relationship between the quiescence duration and size of the earthquake: they thus involve regional hardening or stress relaxation and agree with the predictions of the dilatancy-diffusion theory. Short-term quiescences, on the other hand, are more likely explained by fault zone dilatancy hardening and/or slip weakening within a small nucleation zone. Because seismicity is a locally relaxing process, seismicity should follow a behaviour known in rock mechanics as the Kaiser effect, in which only a very slight increase in strength, due to dilatancy hardening or decrease in stress due to slip weakening, is required to cause quiescence. This is in contrast to other precursory phenomena predicted by dilatancy, which require large dilatant strains and complete dilatancy hardening.
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