151 research outputs found
The age, origin and emplacement of the Tsiknias Ophiolite, Tinos, Greece
The Tsiknias Ophiolite, exposed at the highest structural levels of Tinos, Greece, represents a thrust sheet of Tethyan oceanic crust and upper mantle emplaced onto the AtticâCycladic Massif. We present new field observations and a new geological map of Tinos, integrated with petrology, THERMOCALC phase diagram modelling, UâPb geochronology and whole rock geochemistry, resulting in a tectonoâthermal model that describes the formation and emplacement of the Tsiknias Ophiolite and newly identified underlying metamorphic sole. The ophiolite comprises a succession of partially dismembered and structurally repeated ultramafic and gabbroic rocks that represent the Moho Transition Zone. A plagiogranite dated by UâPb zircon at 161.9 ± 2.8 Ma, reveals that the Tsiknias Ophiolite formed in a supraâsubduction zone setting, comparable to the âEastâVardar Ophiolitesâ, and was intruded by gabbros at 144.4 ± 5.6 Ma. Strongly sheared metamorphic sole rocks show a condensed and inverted metamorphic gradient, from partially anatectic amphibolites at PâT conditions of ca. 8.5 kbar 850â600 °C, downâstructural section to greenschistâfacies oceanic metasediments over ~250 m. Leucosomes generated by partial melting of the uppermost sole amphibolite, yielded a UâPb zircon protolith age of ca. 190 Ma and a highâgrade metamorphicâanatectic age of 74.0 ± 3.5 Ma associated with ophiolite emplacement. The Tsiknias Ophiolite was therefore obducted ~90 Myrs after it formed during initiation of a NEâdipping intraâoceanic subduction zone to the northeast of the Cyclades that coincides with Africa's plate motion changing from transcurrent to convergent. Continued subduction resulted in highâpressure metamorphism of the Cycladic continental margin ~25 Myrs later
Brain activity underlying negative self- and other-perception in adolescents: The role of attachment-derived self-representations
One of teenagers' key developmental tasks is to engage in new and meaningful relationships with peers and adults outside the family context. Attachment-derived expectations about the self and others in terms of internal attachment working models have the potential to shape such social reorientation processes critically and thereby influence adolescents' social-emotional development and social integration. Because the neural underpinnings of this developmental task remain largely unknown, we sought to investigate them by functional magnetic resonance imaging. We asked n = 44 adolescents (ages 12.01-18.84 years) to evaluate positive and negative adjectives regarding either themselves or a close other during an adapted version of the well-established self-other trait-evaluation task. As measures of attachment, we obtained scores reflecting participants' positive versus negative attachment-derived self- and other-models by means of the Relationship Questionnaire. We controlled for possible confounding factors by also obtaining scores reflecting internalizing/externalizing problems, schizotypy, and borderline symptomatology. Our results revealed that participants with a more negative attachment-derived self-model showed increased brain activity during positive and negative adjective evaluation regarding the self, but decreased brain activity during negative adjective evaluation regarding a close other, in bilateral amygdala/parahippocampus, bilateral anterior temporal pole/anterior superior temporal gyrus, and left dorsolateral prefrontal cortex. These findings suggest that a low positivity of the self-concept characteristic for the attachment anxiety dimension may influence neural information processing, but in opposite directions when it comes to self- versus (close) other-representations. We discuss our results in the framework of attachment theory and regarding their implications especially for adolescent social-emotional development and social integration
A metodologia de Lamarck
Neste artigo, o mĂ©todo cientĂfico de Jean-Baptiste Lamarck Ă© estudado sob o ponto de vista de seu discurso metodolĂłgico, bem como sob o ponto de vista de sua prĂĄtica cientĂfica. Essa metodologia Ă© comparada Ă preconizada por Condillac, assim como Ă dos "ideĂłlogos" (idĂ©ologues) grupo no qual se costuma incluir o prĂłprio Lamarck. Mostra-se que o discurso metodolĂłgico de Lamarck assemelha-se ao dos ideĂłlogos; no entanto, sua prĂĄtica cientĂfica nĂŁo se coaduna com esse enfoque. Em vez de seguir uma abordagem empirista, a obra de Lamarck se fundamenta em princĂpios metafĂsicos gerais sobre a natureza. Sob o ponto de vista dos ideĂłlogos, seu trabalho deveria ser rejeitado - o que de fato ocorreu - como um mero sistema (systĂšme) metafĂsico - no sentido pejorativo utilizado pelos seguidores de Condillac. No entanto, o presente artigo argumenta que esse Ă© justamente um importante e inovador aspecto da obra de Lamarck, que permitiu a eclosĂŁo do evolucionismo moderno
An 850â820Ma LIP dismembered during breakup of the Rodinia supercontinent and destroyed by Early Paleozoic continental subduction in the northern Tibetan Plateau, NW China
O estado do Rio de Janeiro como limite sul e norte de distribuição de algumas espécies de aves
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