Alejandro León

Provenance, age constraints and metamorphism of Ediacaran metasedimentary rocks from the El Triunfo Complex (SE Chiapas, México): evidence for Rodinia breakup and Iapetus active margin

ABSTRACT Metasedimentary rocks from the El Triunfo Complex (Jocote Unit) in the southern Chiapas Massif (SE México) are constituted mainly by sillimanite-rich micaschist, locally intercalated with marble and calc-silicate rocks. Mafic rocks (now amphibolite) intruded the sequence prior to deformation and folding. Peak metamorphic conditions are estimated by geothermobaromerty at ~6.0 kbar and ~650ºC. The timing of the metamorphic event is dated by LA-MC-ICPMS analysis on zircon rims at 438+23/–12 Ma. Furthermore, detrital zircon grains yield mainly Stenian–Tonian and minor early Mesoproterozoic ages, indicating provenance from Grenville-type orogens (such as Oaxaquia) and some older cratonic sources. The 87Sr/86Sr values of 0.70775–0.70777 and the δ13C values from +1.9‰ to +2.7‰ in associated calcite marble define the time of deposition between 600 and 580 Ma. Geochemical markers from metapelite samples (such as La/Th > 3.94, La/Sc > 3.72, Th/U > 8.19, Th/Co > 0.42 and CIA = 74 to 83), as well as Sm–Nd isotope data (εNdi = −8.1 to −4.0, TDM(Nd) = 1.65–1.32 Ga) suggest weathering of Mesoproterozoic felsic rocks during temperate to warm climate. Furthermore, Zr/Sc values (9.1–21.0), chondrite-normalized REE patterns [La/Yb]N = 10.3–23.3, Eu/Eu* < 0.64), and ΔHf values (1.98–10.02) are indicative of pelagic and zircon-depleted sediments of a passive margin. The results suggest that the Jocote Unit was deposited during the opening of the Eastern Iapetus Ocean in the Ediacaran Period. This is the first evidence for Rodinia breakup in southern México. Besides that, the Ordovician tectonothermal event is probably related to compression during subduction and accretion along the western margin of Gondwana.

Housing Stiffness Influence on Gearbox Dynamic Loading for Wind Turbine Applications

The design of wind turbine gearboxes must consider particular conditions such as wind speed variations, load changes, and they must be as light as possible. Although there are enough field data, their life prediction lacks of good estimation. It is common to find gearboxes with bearing or gear premature failures. The housing can dissipate noise and vibrations in a positive manner; but in wind turbines it can increase the synchronization among nonlinear elements. This phenomenon adds an additional dynamic load on the gears and rolling bearings.The work presented here is a method for estimating the influence of the housing stiffness on the dynamic synchronization of wind turbine gearbox elements. The analysis estimates a dynamic load factor that affects both gears and rolling bearings. The analysis takes into account the gearbox nonlinear elements, as well as the turbine blades excitations.Copyright

CONTACT MODE: EFFECT ON CONDITIONAL DISCRIMINATION ACQUISITION, TRANSFER AND RULE EMERGENCE

This study examined the effect of four contact modes (direct, morphology, linguistic, observational, and direct plus description) on the acquisition and transfer of conditional discrimination and the emergence of rules. Sixteen experimentally naive university students, aged between 18 and 21 years, participated in the study. A within-subject design that involved initial test, training, rule generation, and testing transfer (extra instance test, extra modal test, extra relational test) was used. A second order matching to sample task was used. The results suggest that: a) both the observational mode without instrumental components and the linguistic morphology without direct perceptual contact allow the acquisition and transfer of conditional discrimination and the emergence of rules; b) there is no consistent relationship between the rules and the effective extrarelational transfer. Results are discussed in terms of the need for: i) direct contact with contingencies for the transfer and emergence of rules,

MODO DE CONTATO: EFEITO SOBRE A AQUISIÇÃO E TRANSFERÊNCIA DE UMA DISCRIMINAÇÃO CONDICIONAL DE SEGUNDA ORDEM E A EMERGÊNCIA DE REGRAS

This study examined the effect of four contact modes (direct, morphology, linguistic, observational, and direct plus description) on the acquisition and transfer of conditional discrimination and the emergence of rules. Sixteen experimentally naive university students, aged between 18 and 21 years, participated in the study. A within-subject design that involved initial test, training, rule generation, and testing transfer (extra instance test, extra modal test, extra relational test) was used. A second order matching to sample task was used. The results suggest that: a) both the observational mode without instrumental components and the linguistic morphology without direct perceptual contact allow the acquisition and transfer of conditional discrimination and the emergence of rules; b) there is no consistent relationship between the rules and the effective extrarelational transfer. Results are discussed in terms of the need for: i) direct contact with contingencies for the transfer and emergence of rules,

MODO DE CONTACTO: EFECTO SOBRE LA ADQUISICIÓN Y TRANSFERENCIA DE UNA DISCRIMINACIÓN CONDICIONAL DE SEGUNDO ORDEN Y LA EMERGENCIA DE REGLAS

This study examined the effect of four contact modes (direct, morphology, linguistic, observational, and direct plus description) on the acquisition and transfer of conditional discrimination and the emergence of rules. Sixteen experimentally naive university students, aged between 18 and 21 years, participated in the study. A within-subject design that involved initial test, training, rule generation, and testing transfer (extra instance test, extra modal test, extra relational test) was used. A second order matching to sample task was used. The results suggest that: a) both the observational mode without instrumental components and the linguistic morphology without direct perceptual contact allow the acquisition and transfer of conditional discrimination and the emergence of rules; b) there is no consistent relationship between the rules and the effective extrarelational transfer. Results are discussed in terms of the need for: i) direct contact with contingencies for the transfer and emergence of rules,