Electron microscope study of peridotite xenoliths in kimberlites     

Arne Olsen  Tore Birkeland 《Contributions to Mineralogy and Petrology》1973,42(2):147-157

Dislocation structures in naturally deformed olivine from garnet peridotite xenoliths from South African kimberlites have been studied by electron microscopy. The substructure consists mainly of straight subboundaries of dislocations with Burgers vectors [001]. Most of the dislocations have both edge and screw components, and the slip planes are mainly (100). The dislocation density between the subboundaries is low.The slip planes in olivine are discussed in relation to the olivine structure. The observed dislocation structures seem to indicate that the large difference in strain rate between natural and experimental deformation will produce a difference in the slip mechanisms.The nature of the deformation lamellae visible in optical microscope is discussed.  相似文献   

Longitudinal Social Science Research in Natural Resource Communities: Lessons and Considerations     

Melanie Stidham  Christine Olsen  Eric Toman  Stacey Frederick  Sarah McCaffrey  Bruce Shindler 《社会与自然资源》2014,27(10):1104-1108

The majority of social science research is cross-sectional in nature, with data collected at a single point in time. However, social systems are dynamic and many of the variables of interest to social scientists may change over time. Longitudinal research methods enable data collection at two or more points in time among a population of interest to examine change in measured variables and influencing factors. Despite the opportunities it affords, longitudinal research is relatively uncommon in natural-resource-based social science research as compared to other fields (e.g., medical, criminal, education). We feel that the field of natural resource social science is ripe for a proliferation of longitudinal studies, now that a substantial body of cross-sectional data has been built. In the spirit of encouraging more of this type of research, we draw on our collective experiences in longitudinal studies to share lessons learned in research design, sampling, and data management.  相似文献   

The First Reported Pleistocene Beaver,Castor fiber (Castoridae,Rodentia), from the Gobi Altai Region of Mongolia     

Klementiev  A. M.  Khatsenovich  A. M.  Bazargur  D.  Tserendagva  Y.  Marchenko  D. V.  Rybin  E. P.  Gunchinsuren  B.  Olsen  J. W.  Krivoshapkin  A. I. 《Doklady Earth Sciences》2023,507(3):S420-S423

Doklady Earth Sciences - Here, we report a fragmentary Castor fiber (Linnaeus, 1758) proximal left ulna from Tsagaan Agui Cave (Gobi Altai Mountains, southern Mongolia). This constitutes the first...  相似文献