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Knut W. Vollset Oddbjrn Seljeset
yvind Fiksen Arild Folkvord 《Deep Sea Research Part II: Topical Studies in Oceanography》2009,56(21-22):1984
A replicated mesocosm experiment was carried out to evaluate differential effects of feeding conditions for larval Northeast Arctic (NA) cod and Norwegian coastal (NC) cod. The two populations were (1) reared together with a 6-day older NA cohort (mixed) in high (HC) and low prey concentration (LC; 2000 and 200 prey/L initially), and (2) reared separately in HC treatments (non-mixed) to be able to evaluate both the effect of feeding conditions and possible effects of size interaction within mesocosms. The larvae were fed natural zooplankton, and the two stocks were identified in the mixed mesocosms by otolith marking. NA larvae hatched at a larger size, had higher growth rates, and survived better than NC larvae in both mixed and non-mixed mesocosms in the HC treatment. The second cohort clearly survived better in the non-mixed than in the mixed mesocosms, indicating the presence of an interaction effect before cannibalism could occur. We found a significant higher weight-at-length between NC and NA larvae (<12 mm), which was bigger than the effect difference due to feeding conditions. Furthermore, a positive relation between survival and initial growth within mesocosms was found. We suggest that lower growth at early larval stages was accompanied by lower survival, and suggest that this was further enhanced when larvae interacted with older and larger larvae. 相似文献
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Arild Gulbrandsen 《Planetary and Space Science》1973,21(11):2003-2011
Attention is drawn to the great statistical material on geomagnetic storms and solar activity, published mainly before the space age. By analyses of this material in connection with established correlations between geomagnetic activity and the interplanetary sector struc- ture, valuable information might be obtained that would significantly contribute to an increased understanding of solar and interplanetary sector magnetism.As an illustration of this, different analyses of solar-geomagnetic correlations have been considered in relation to the paper by Wilcox and Colburn (1972) on the observed sector struc- ture. Indications are found that (a) the interplanetary and solar sector pattern in the years 1919–1969 consisted of mainly 2 or 4 sectors per solar rotation, and (b) sector boundaries are related to bipolar magnetic regions on the Sun. 相似文献
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Peter Kresten Erik åhman Arild O. Brunfelt 《International Journal of Earth Sciences》1981,70(3):1215-1231
Alkahne ultramafic lamprophyres and associated carbonatite dykes form north-south trending dyke swarms. The lamprophyres are sub-divided into micaceous, picritic and breccia varieties. Carbonatites sensu stricto (beforsites) occur very subordinate.The dykes of the Kalix area show great similarities to petrographically related rocks from other Scandinavian occurrences (Sokli, Alnö and Fen). Major differences are found in their tectonic setting (regularly striking dyke swarms) and the REE-pattern (distinctly negative cerium anomalies).The following petrogenetic model is advanced for the Kalix dykes: (1) partial melting of upper mantle material, (2) Intrusion into a crustal magma chamber, fractional crystallization, (3) Interactions between crystallized material and the volatile phase (light REE depletion, oxidation of cerium), (4) Intrusion in fracture zones under horizontal tension.
Zusammenfassung Alkalin-ultrabasiscbe Lamprophyre und begleitende KarbonatitgÄnge bilden nordsüdlidi streichende GangschwÄrme. Die Lamprophyre zeigen gewisse Ähnlichkeiten zu alnöitischen und kimberlitischen Gesteinen; sie wurden unterteilt in glimmerreiche und pikritische Lamprophyre sowie Brekzien. Karbonatite im engeren Sinn treten nur sehr untergeordnet auf; sie sind als Beforsite charakterisiert.Die Ganggesteine des Kalix-Gebiets weisen gro\e Ähnlichkeiten mit petrographiscb verwandten Gesteinen von anderen skandinavischen Vorkommen (Sokli, Alnö und Fen) auf. GrundsÄtzliche Unterschiede finden sich vor allem im tektonischen Auftreten (ziemlich konstant streichende GangschwÄrme) und im Verteilungsmuster der seltenen Erden (deutlich negative Cer-Anomalien).Die Bildung der Kalix-GÄnge wird folgenderweise erklÄrt: (1) Partielle Aufschmelzung des oberen Mantels, (2) Intrusion der Schmelze in eine krustale Magmakammer, gefolgt von fraktionierter Kristallisation, (3) Reaktion zwischen vorzugsweise kristallisiertem Material und der volatilen Phase (Entarmung an leichten seltenen Erden, Oxidation des Cers), (4) Intrusion in Bruchzonen, die horizonteller Dehnung ausgesetzt sind.
Résumé Des lamprophyres alcalins ultrabasiques accompagnés de carbonatites forment des essaims de dykes de direction nord-sud. Les lamprophyres se subdivisent en variétés micacée, picritique ainsi que brÊchique. Les carbonatites sensu stricto sont rares et sont plutÔ des beforsites.Les dykes de la région de Kalix présentent de grandes similitudes avec des roches pétrographiquement apparentées d'autres localités Scandinaves (Sokli, Alnö et Fen). Les différences essentielles sont dues à leur situation tectonique (essaims de dykes de direction régulière) ainsi qu'à la distribution des Terres Rares (anomalie négative distincte de cérium).Le modèle pétrogénétique suivant est proposé pour les dykes de Kalix: (1) fusion partielle de matériau du manteau supérieur, (2) intrusion dans une chambre magmatique de l'écorce et cristallisation fractionnée, (3) interaction entre le material déjà cristallisé et la phase volatile (appauvrissement des éléments légers des Terres Rares, oxydation du cérium), (4) intrusion le long de zones de fracture dans des conditions d'extension horizontale.
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Arild Holt-Jensen 《GeoJournal》2000,51(4):281-291
Changes in the urban social geography; the development of urban neighbourhoods of multiple deprivation, in which different processes of social exclusion reinforce one another, is a grave challenge to the European society. Housing initiatives and local neighbourhood practices seem to be key factors in finding solutions in combating social exclusion and improving the quality of life in deprived urban neighbourhoods. The OECD-report `Integrating distressed urban areas' (Paris, 1998) states that a combination of policies focusing on specific urban areas and more general socio-economic measures are necessary to integrate such areas into the fabric of the cities. This evaluation of bottom-up neighbourhood solutions, within their national contexts, is the central focus of a European research project (NEHOM) involving housing researchers and providers in 8 European countries. Pilot case studies have been undertaken in United Kingdom, Norway and Hungary to test a common case study methodology. Using a range of indicators of improvements in the quality of life in case study areas, the research will seek to identify innovative housing initiatives and neighbourhood practices, as well as a toolkit for neighbourhood assessment and improvement. A special challenge for the research project is to assess and identify opportunities for and barriers to transferability of best practices and housing policies between European countries. 相似文献
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ABSTRACTThe article presents the changes in the discipline of geography over 60 years as experienced both in fieldwork and in practice by a Norwegian geographer. Based on diaries and collections of memoirs, the author, Arild Holt-Jensen, presents his life story and how it has been impacted by people, places and special events. His intention is to show how geography and his own work reflect social, political and intellectual changes since the late 1950s. Initially, a regional geography approach was adopted in the fieldwork for his master’s thesis but the approach was challenged by new ideas and methods from both the spatial science school and model thinking. As a young lecturer in 1968, the author was shocked by the positivism debate and critical philosophy, and his spatial science and quantitative approach in his PhD project had to be adapted. His political engagement and interest in planning led him to research social exclusion in European neighbourhoods. His need to trace the identity of geography as a discipline resulted in a textbook that throughout the years has been updated by following up on research trends to the present. Thus, the book and the article show Holt-Jensen’s shifts in disciplinary identity and research practice. 相似文献
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Modelling of AVO signatures for reservoir characterization requires V S estimation from other available logs when shear-wave data are not available. We tested various models for predicting V S from P-wave velocity, porosity and shale volume measured in well logs. Effective medium models which characterize the pore space in terms of ellipsoidal inclusions were compared with statistical V P – V S regressions. The inclusion models were calibrated by non-linear minimization of the difference between model-predicted velocities and actual measured velocities. The quality of the V S prediction was quantified in terms of the rms error by comparison with shear-wave data in wells where both V P and V S were measured. The linear regressions were found to be more robust and the rms error in the prediction was comparable to effective medium model-based predictions. 相似文献