63 research outputs found
Prototypical similarity, selfâcategorization, and depersonalized attraction: A perspective on group cohesiveness
In contrast to traditional approaches that widely equate group cohesiveness with interpersonal attraction, selfâcategorization theoryargues that selfâcategorization depersonalizes perception in terms of the group prototype, and transforms the basis of interindividual attitude (liking) from idiosyncracy into prototypicality. An implication is that while attraction in interpersonal relationships relates to overall similarity, attraction among group members is based on prototypical similarity. To test this idea, subjects (N = 219) participated in an experiment in which they reported their attitude towards an individual who would be their partner, or a fellow group member (of either group âVisualâ or group âTactileâ) for a subsequent task. Subjectâtarget similarity varied on each of two dimensions: dimension âAâ was more prototypical of group âVisualâ, and dimension âFâ of group âTactileâ. The independent variables of social orientation (interpersonal, group âVisualâ, group âTactileâ), similarity on dimension A (A ±), and dimension F(F±) were manipulated in a 3 Ă 2 Ă 2 design. The three hypotheses tested in this experiment were generally supported. Subjects preferred prototypically similar group members to interpersonal partners, and downgraded prototypically dissisimilar group members (HI). Identification was positively related to target evaluation (H2), more strongly for prototypically similar than dissimilar targets (H3), and the identificationâattraction relationship was mediated by perceived prototypical similarity. Groupâbased effects were independent of perceptions of overall similarity. Copyrigh
Variable style of transition between Palaeogene fluvial fan and lacustrine systems, southern Pyrenean foreland, NE Spain
Two Palaeogene fluvial fan systems linked to the south-Pyrenean margin are
recognized in the eastern Ebro Basin: the CardonaâSuÂŽ ria and SolsonaâSanauš ja
fans. These had radii of 40 and 35 km and were 800 and 600 km2 in area
respectively. During the Priabonian to the Middle Rupelian, the fluvial fans
built into a hydrologically closed foreland basin, and shallow lacustrine
systems persisted in the basin centre. In the studied area, both fans are part of
the same upward-coarsening megasequence (up to 800 m thick), driven by
hinterland drainage expansion and foreland propagation of Pyrenean thrusts.
Fourteen sedimentary facies have been grouped into seven facies associations
corresponding to medial fluvial fan, channelized terminal lobe, nonchannelized
terminal lobe, mudflat, deltaic, evaporitic playa-lake and
carbonate-rich, shallow lacustrine environments. Lateral correlations define
two styles of alluvial-lacustrine transition. During low lake-level stages,
terminal lobes developed, whereas during lake highstands, fluvial-dominated
deltas and interdistributary bays were formed. Terminal lobe deposits are
characterized by extensive (100â600 m wide) sheet-like fine sandstone beds
formed by sub-aqueous, quasi-steady, hyperpycnal turbidity currents.
Sedimentary structures and trace fossils indicate rapid desiccation and subaerial
exposure of the lobe deposits. These deposits are arranged in
coarseningâfining sequences (metres to tens of metres in thickness)
controlled by a combination of tectonics, climatic oscillations and autocyclic
sedimentary processes. The presence of anomalously deeply incised
distributary channels associated with distal terminal lobe or mudflat
deposits indicates rapid lake-level falls. Deltaic deposits form progradational
coarsening-upward sequences (several metres thick) characterized by channel
and friction-dominated mouth-bar facies overlying white-grey offshore
lacustrine facies. Deltaic bar deposits are less extensive (50â300 m wide)
than the terminal lobes and were also deposited by hyperpycnal currents,
although they lack evidence of emergence. Sandy deltaic deposits
accumulated locally at the mouths of main feeder distal fan streams and
were separated by muddy interdistributary bays; whereas the terminal lobe
sheets expand from a series of mid-fan intersection points and coalesced to
form a more continuous sandy fan fringe
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The roles of olfaction and vision in host-plant finding by the diamondback moth, Plutella xylostella
The relative roles of olfaction and vision in the crepuscular host-finding process of a major lepidopteran pest of cruciferous crops, the diamondback moth Plutella xylostella are investigated in a series of laboratory and semi-field experiments. Flying female moths use volatile plant chemical cues to locate and to promote landing on their host, even in complex mixed-crop environments in large cages. Multiple regression analysis shows that both the plant position (front, middle or back rows) and the type of plant (host plant, nonhost plant) are needed to explain the distribution of insects in such a mixed-crop situation. This strong plant position effect indicates that, when host plants are present in a mixture, foraging P. xylostella are more likely to alight on the first row of the plants. The findings are discussed with regard to current theories of host-plant location by phytophagous insects and the possible implications for integrated pest management
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