5,831 research outputs found
Photonic potential for TM waves
We discuss the effective photonic potential for TM waves in inhomogeneous
isotropic media. The model provides an easy and intuitive comprehension of form
birefringence, paving the way for a new approach on the design of graded-index
optical waveguides on nanometric scales. We investigate the application to
nanophotonic devices, including integrated nanoscale wave plates and slot
waveguides.Comment: 4 pages, 7 figure
Documentation of clinical data and its transference from Ebola and Marburg wards: health care workers' experiences and preferences
Technique for experimental determination of radiation interchange factors in solar wavelengths
Process obtains solar heating data which support analytical design. Process yields quantitative information on local solar exposure of models which are geometrically and reflectively similar to prototypes under study. Models are tested in a shirtsleeve environment
Interplay between multiple scattering and optical nonlinearity in liquid crystals
We discuss the role played by time-dependent scattering on light propagation in liquid crystals. In the linear regime, the effects of the molecular disorder accumulate in propagation, yielding a monotonic decrease in the beam spatial coherence. In the nonlinear case, despite the disorder-imposed Brownian-like motion to the self-guided waves, self-focusing increases the spatial coherence of the beam by inducing spatial localization. Eventually, a strong enhancement in the beam oscillations occurs when power is strong enough to induce self-steering, i.e. in the non-perturbative regime.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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Value encoding in the globus pallidus: fMRI reveals an interaction effect between reward and dopamine drive
The external part of the globus pallidus (GPe) is a core nucleus of the basal ganglia (BG) whose activity is disrupted under conditions of low dopamine release, as in Parkinson's disease. Current models assume decreased dopamine release in the dorsal striatum results in deactivation of dorsal GPe, which in turn affects motor expression via a regulatory effect on other nuclei of the BG. However, recent studies in healthy and pathological animal models have reported neural dynamics that do not match with this view of the GPe as a relay in the BG circuit. Thus, the computational role of the GPe in the BG is still to be determined. We previously proposed a neural model that revisits the functions of the nuclei of the BG, and this model predicts that GPe encodes values which are amplified under a condition of low striatal dopaminergic drive. To test this prediction, we used an fMRI paradigm involving a within-subject placebo-controlled design, using the dopamine antagonist risperidone, wherein healthy volunteers performed a motor selection and maintenance task under low and high reward conditions. ROI-based fMRI analysis revealed an interaction between reward and dopamine drive manipulations, with increased BOLD activity in GPe in a high compared to low reward condition, and under risperidone compared to placebo. These results confirm the core prediction of our computational model, and provide a new perspective on neural dynamics in the BG and their effects on motor selection and cognitive disorders
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