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An increasing body of research has investigated the effect of emotions on judgments concerning moral transgressions. Yet, few studies have controlled for arousal levels associated with the emotions. High arousal may affect moral processing by triggering attention to salient features of transgressions, independently of valence. Therefore previously documented differences in effects of negative and positive emotions may have been confounded by differences in arousal. We conducted two studies to shed light on this issue. In Study 1 we developed a questionnaire including vignettes selected on the basis of psychometrical properties (i.e., mean ratings of the actions and variability). This questionnaire was administered to participants in Study 2, after presenting them with selected pictures inducing different valence but equivalent levels of arousal. Negative pictures led to more severe moral judgments than neutral (p = .054, d = 0.60) and positive pictures (p = .002, d = 1.02), for vignettes that were not associated with extreme judgments. In contrast, positive pictures did not reliably affect judgments concerning such vignettes. These findings suggest that the observed effects of emotions cannot be accounted for by an increase in attention linked to the arousal which accompanies these emotions

We have investigated the influence of the electronic band structure on the exciton dynamics in GaAsP tensile-strained quantum wells. We have found that the exciton cooling time is notably reduced when the heavy- and light-hole excitons are degenerate. The lifetime of the heavy-hole exciton is approximately 300 ps whereas it is approximately 500 ps for the light-hole exciton. Furthermore, we have determined, from the initial degree of polarization of the emission, the valence-band mixing as a function of the energy splitting between the heavy-hole and light-hole subbands. The degree of mixing is in qualitative agreement with tight-binding calculations.

We have studied the exciton dynamics and spin-flip processes in tensile strained GaAs1-yPy/Ga0.65Al0.35As quantum wells as a function of phosphorous composition and well width. The strain introduced by the presence of phosphorous modifies the valence band structure. This strongly affects the characteristic times of exciton formation and polarization decay. However, the recombination time is essentially determined by the light-or heavy-character of the excitonic ground state.

We have investigated exciton dynamics and spin relaxation in a GaAs/AlAs multiple quantum well and in tensile-strained GaAs1-x/Al0.35Ga0.65As quantum wells. The studies have been done by picosecond time-resolved photoluminescence spectroscopy. The strain introduced by the presence of phosphorous in the GaAs1-xPx/Al0.35Ga0.65As quantum wells modifies the subband dispersions, permitting access to new structures that include the possibility of the light-hole exciton's being the first excited state of the system. Our studies have focused on the influence of the different subband dispersions on exciton dynamics and spin relaxation. We have found that the exciton formation and the spin relaxation times decrease for the quasi-degenerate heavy-hole-light-hole excitonic ground state and that the recombination time depends essentially on the character of the excitonic ground state. © 1996 Optical Society of America.

We have observed the strong dependence of the in-plane effective masses of the heavy-hole and light-hole valence bands in quantum wells on their coupling. The magnitude of this interaction, which is a function of the energy separation of the two bands, was tuned by adjusting the magnitude of tensile strain and well width in GaAs1−yPy/Al0.35Ga0.65As quantum wells. A distinct increase of both the heavy- and light-hole masses is observed when the bands merge at k=0, consistent with theoretical predictions.

We have investigated the magneto-optical properties of GaAs1-xPx/Ga1-yAlyAs quantum wells (QW's) as a function of biaxial strain using photoluminescence excitation spectroscopy. The fan diagrams of the electronic transitions, for fields applied in the Faraday configuration, are analyzed in terms of two-dimensional exciton, using an hydrogenic model. We extract from the analysis the excitonic binding energies and their reduced effective masses. The polarization of the heavy- and light-hole excitons are compared with a theory of the spin relaxation of the photocreated carriers. © 1992.

Memoria de las prácticas en las minas "Cabezo Rajado"

An increasing body of research has investigated the effect of emotions on judgments concerning moral transgressions. Yet, few studies have controlled for arousal levels associated with the emotions. High arousal may affect moral processing by triggering attention to salient features of transgressions, independently of valence. Therefore previously documented differences in effects of negative and positive emotions may have been confounded by differences in arousal. We conducted two studies to shed light on this issue. In Study 1 we developed a questionnaire including vignettes selected on the basis of psychometrical properties (i.e., mean ratings of the actions and variability). This questionnaire was administered to participants in Study 2, after presenting them with selected pictures inducing different valence but equivalent levels of arousal. Negative pictures led to more severe moral judgments than neutral (p = .054, d = 0.60) and positive pictures (p = .002, d = 1.02), for vignettes that were not associated with extreme judgments. In contrast, positive pictures did not reliably affect judgments concerning such vignettes. These findings suggest that the observed effects of emotions cannot be accounted for by an increase in attention linked to the arousal which accompanies these emotions