Resonant nonlinear magneto-optical effects in atoms

In this article, we review the history, current status, physical mechanisms, experimental methods, and applications of nonlinear magneto-optical effects in atomic vapors. We begin by describing the pioneering work of Macaluso and Corbino over a century ago on linear magneto-optical effects (in which the properties of the medium do not depend on the light power) in the vicinity of atomic resonances, and contrast these effects with various nonlinear magneto-optical phenomena that have been studied both theoretically and experimentally since the late 1960s. In recent years, the field of nonlinear magneto-optics has experienced a revival of interest that has led to a number of developments, including the observation of ultra-narrow (1-Hz) magneto-optical resonances, applications in sensitive magnetometry, nonlinear magneto-optical tomography, and the possibility of a search for parity- and time-reversal-invariance violation in atoms.Comment: 51 pages, 23 figures, to appear in Rev. Mod. Phys. in Oct. 2002, Figure added, typos corrected, text edited for clarit

Cue-target contingencies modulate voluntary orienting of spatial attention: dissociable effects for speed and accuracy

Voluntary orienting of spatial attention is typically investigated by visually presented directional cues, which are called predictive when they indicate where the target is more likely to appear. In this study, we investigated the nature of the potential link between cue predictivity (the proportion of valid trials) and the strength of the resulting covert orienting of attention. Participants judged the orientation of a unilateral Gabor grating preceded by a centrally presented, non-directional, color cue, arbitrarily prompting a leftwards or rightwards shift of attention. Unknown to them, cue predictivity was manipulated across blocks, whereby the cue was only predictive for either the first or the second half of the experiment. Our results show that the cueing effects were strongly influenced by the change in predictivity. This influence differently emerged in response speed and accuracy. The speed difference between valid and invalid trials was significantly larger when cues were predictive, and the amplitude of this effect was modulated at the single trial level by the recent trial history. Complementary to these findings, accuracy revealed a robust effect of block history and also a different time-course compared with speed, as if it mainly mirrored voluntary processes. These findings, obtained with a new manipulation and using arbitrary non-directional cueing, demonstrate that cue-target contingencies strongly modulate the way attention is deployed in space

Politique internationale

SYL-001330 = Fascicule 1 ;SYL-001331 = Fascicule 2 ;SYL-001195 = Fascicule 3 ;SYL-001332 = Fascicule 4/5 ;SYL-001333 = Fascicule 6 ;SYL-001334 = Fascicule 7 ;SYL-001196 = Fascicule 8 ;SYL-001197 = Fascicule 9 ;SYL-001703 = Fascicule 10Fascicule 1 :(World Politics) / E. Philippart -- Fascicule 2 :World Economy / A. Gilles, E. Philippart, F. Raynaud -- Fascicule 3 :Transnational issues / T. Amzile, D. Delieux -- Fascicule 4/5 :USA and CIS / A. Gilles, F. Raynaud -- Fascicule 6 :Europe / D. Delieux, S. Macaluso -- Fascicule 7 :Maghreb & Middle East / T. Amzile, D. Delieux -- Fascicule 8 :Asia & Pacific Basin / A. Gilles, S. Macaluso -- Fascicule 9 :Latin America / D. Delieux, S. Macaluso -- Fascicule 10 :Sub-Saharan Africa / Ajar Djaimourzina, Eric Philippart et Ivan PrusinaFascicule 1-9 :5e édition 1995-1996/1 ;Fascicule 10 :5e édition 1998-1999/1Syllabus strictement réservé aux étudiants suivant les cours dans le cadre du CERISinfo:eu-repo/semantics/published

Clonidine Has a Paradoxical Effect on Cyclic Arousal and Sleep Bruxism during NREM Sleep

STUDY OBJECTIVE: Clonidine disrupts the NREM/REM sleep cycle and reduces the incidence of rhythmic masticatory muscle activity (RMMA) characteristic of sleep bruxism (SB). RMMA/SB is associated with brief and transient sleep arousals. This study investigates the effect of clonidine on the cyclic alternating pattern (CAP) in order to explore the role of cyclic arousal fluctuation in RMMA/SB. DESIGN: Polysomnographic recordings from a pharmacological study. SETTING: University sleep research laboratory. PARTICIPANTS AND INTERVENTIONS: Sixteen SB subjects received a single dose of clonidine or placebo at bedtime in a crossover design. MEASUREMENTS AND RESULTS: Sleep variables and RMMA/SB index were evaluated. CAP was scored to assess arousal instability between sleep-maintaining processes (phase A1) and stronger arousal processes (phases A2 and A3). Paired t-tests, ANOVAs, and cross-correlations were performed. Under clonidine, CAP time, and particularly the number of A3 phases, increased (P≤0.01). RMMA/SB onset was time correlated with phases A2 and A3 for both placebo and clonidine nights (P≤0.004). However, under clonidine, this positive correlation began up to 40 min before the RMMA/SB episode. CONCLUSIONS: CAP phase A3 frequency increased under clonidine, but paradoxically, RMMA/SB decreased. RMMA/SB was associated with and facilitated in CAP phase A2 and A3 rhythms. However, SB generation could be influenced by other factors besides sleep arousal pressure. NREM/REM ultradian cyclic arousal fluctuations may be required for RMMA/SB onset

Impact of blindness onset on the functional organization and the connectivity of the occipital cortex

status: publishe