5,494 research outputs found

    Quantiles for Fractions and Other Mixed Data

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    This paper studies the estimation of quantile regression for fractional data, focusing on the case where there are mass-points at zero or/and one. More generally, we propose a simple strategy for the estimation of the conditional quantiles of data from mixed distributions, which combines standard results on the estimation of censored and Box-Cox quantile regressions. The implementation of the proposed method is illustrated using a well-known dataset.

    Transcurrent continental tectonics model

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    The Ossa-Morena Zone (SW Iberian Massif) was affected by continuous orogen-parallel transcurrent continental tectonics from the Neoproterozoic to the Carboniferous times, involving transtension (TT) and transpression (TP) processes that co-existed together, occurred separately in neighbouring regions by the means of strain partitioning or even worked diachronically. A first stage of transpression TP1 took place during the Late Neoproterozoic–Lower Cambrian as a result of Cadomian arc-continent collisional processes. Structures generated by transtension TT1 from Cambrian to Lower Devonian were related to strong lithosphere stretching responsible for the development of basins controlled by major detachments, tilting, rifting and important tectono–thermal diachronic processes. Denudation phenomena and inhibition of sedimentation related with thermal uplift (asthenosphere upwelling) and consequent subsidence caused by isostatic equilibrium, involving generalized transgressions, were processes responsible for major unconformities. The Variscan TP2-TT2 episodes that followed diachronically TP1-TT1, by maintaining the orogen- parallel transport direction, were concomitant with syntectonic deposition of continental basins in the OMZ and foreland basins in the SPZ. TT2 local transtension and tectonic exhumation of deep crustal rocks along major shear zones, favoured the opening of tectonic troughs filled up by sediments and volcanism. TP2 shortening have generated fold axes parallel to the orogen- strike and composite dissymmetric flower structures

    A new model for the Hercynian Orogen of Gondwanan France

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    The study by Shelley and BossieÁre (2000) is an important contribution to the discussion concerning the Ibero±Armorican arc (IAA) generation model. This model comes as one of a sequence of previous ideas already published in several papers (Bard, 1971; Matte and Ribeiro, 1975; Lefort and Ribeiro, 1980; Ribeiro et al., 1980; Burg et al., 1981; Brun and Burg, 1982; Julivert, 1987; Ribeiro et al., 1990; Dias and Ribeiro, 1995; Ribeiro et al., 1995; Silva, 1997). A common feature of the interpretations in these papers is the great importance attributed to two major transcurrent faults: the dextral Porto±Tomar shear zone (PTSZ) and the sinistral Tomar±Badajoz±Cordoba shear zone (BCSZ), to explain the extension of the Iberian structures into the Armorican Massif in the form of trace the arcuate shape of the IAA

    Superposition relations of microfabrics in the northern hanging-wall block

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    This study reports alternation of D2 extension-related and D3 contraction-related microfabrics in the northern hanging wall block of a gneiss dome-like structure recognized in the Évora Massif (Ossa-Morena Zone). In the Arraiolos – Santo Antonio de Alcorrego traverse high- to low-grade mylonites are dominant. Microfabrics related to D2 ductile deformation and M2 high-amphibolite to greenschist facies characterize an extensional shear zone with telescoping metamorphic isograds. D2 microstructures indicate shear sense with top-to-SE. Superposition of D3 contraction developed under greenschist facies (M3) producing folding of D2 microfabrics, mylonitization of granites along strike-slip shear zones and retrogression of M2 mineral assemblages

    Comment on ‘‘Geodynamic evolution of the SW Europe

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    Ribeiro et al. [2007] have presented a geodynamic view of the SW Iberia Variscides based on data from Portugal. Their treatment of already published data is commendable, and the knowledge gained will surely encourage the discussion of the SWEurope Variscides. However, in our opinion, Ribeiro et al.’s modeling and interpretation of the Ediacaran–Lower Ordovician ( 560–470 Ma) geodynamic evolution are of limited value. In this regard, they based their analysis of the Ossa-Morena Zone (OMZ) on assumptions which are contradicted by recent published data. Ribeiro et al. ignored recent progress in the OMZ Ediacaran-Ordovician stratigraphy and, as a consequence they misunderstood the structure of domains overprinted by strong Variscan (Carboniferous) deformation and metamorphism

    The role of bedding in the formation of fault–fold structures,

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    Fold-fault structures within a major transpressional shear zone of the SW Iberian Massif were investigated by combining geological mapping, cross-section analysis and microtectonic studies. A significant example of contractional deformation is displayed in the Portalegre-Esperanc¸a Shear Zone (PESZ) where a heterogeneous Ordovician stratigraphic sequence, showing a strong competence contrast between quartzites, slates and quartzo-feldspathic rocks favoured strain localization and fault nucleation that controlled fold formation. The presence of pelitic layers within the thick-bedded quartzites had probably provided weakness zones that were more favourable for the strain localization than the previous foliation present in the quartzites. The quartzites and the quartzo-feldspathic rocks (granites and volcaniclastic rocks) accommodated heterogeneous high strain developing different degrees of mylonitization. The quartzites with protomylonitic textures are dominant and represent coarse-grained siliciclastic sediments that suffered metamorphism and partial dynamic recrystallization. Ultramylonites occur within discrete high-strain shear zones. It is probable that the strain localization in the PESZ involved both the effect of having layers of different competence and layers or stratigraphic contacts with rocks that experienced grain size reduction dominated by cataclasis and dislocation creep. Folds within quartzites with sub-horizontal to gently plunging hinges vary from closed to open in thick-bedded quartzites and from tight to closed in thin-bedded quartzites. Observed changes in structural style of deformed quartzites, slates and quartzo-feldspathic rocks are interpreted to result from the constraints imposed by the mechanical properties of the different lithologies. As the folds tightened during shortening, the alternating zones of contrasting competence favoured the disruption of the bedding. The deformation history in the PESZ was dominated by thrusting and strike-slip faulting along incompetent layers that locally developed staircase geometry and transected the lower Ordovician stratigraphic sequence. The kinematic model proposed for the PESZ is consistent with the models of transpressional shear zones stretched along strike with the development of coeval strike-slip and low angle oblique-slip faults associated to active buckle folds with axes parallel to the principal extension directio

    The effect of loss aversion and entitlement on cheating: An online experiment

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    We investigate how loss aversion and entitlement influence lying. We conduct an online experiment with a cheating task in which participants draw and report a number. Participants can cheat by reporting a different number to earn a higher payoff. We vary whether participants perform (or not) a real effort task to generate their endowment before the cheating task to evoke a sense of entitlement, and whether participants can cheat for an additional gain or to avoid a loss using a 2 (earned/not earned endowment) × 2 (loss/gain) design. We find no effect of loss aversion on cheating and only weak evidence of a prior stage of real effort on lying behavior. Furthermore, we find a correlation between real effort task performance and lying, but only in the gain domain. This is the first study to look at how entitlement affects cheating behavior in both the gain and loss domains

    NACA0012 benchmark model experimental flutter results with unsteady pressure distributions

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    The Structural Dynamics Division at NASA Langley Research Center has started a wind tunnel activity referred to as the Benchmark Models Program. The primary objective of this program is to acquire measured dynamic instability and corresponding pressure data that will be useful for developing and evaluating aeroelastic type computational fluid dynamics codes currently in use or under development. The program is a multi-year activity that will involve testing of several different models to investigate various aeroelastic phenomena. This paper describes results obtained from a second wind tunnel test of the first model in the Benchmark Models Program. This first model consisted of a rigid semispan wing having a rectangular planform and a NACA 0012 airfoil shape which was mounted on a flexible two degree of freedom mount system. Experimental flutter boundaries and corresponding unsteady pressure distribution data acquired over two model chords located at the 60 and 95 percent span stations are presented
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