Search results for "Polarization"
showing 10 items of 1884 documents
Quantitative microscopy of magnetic domains in Fe(100) by core-level x-ray photoelectron spectroscopy
2005
We present an experimental technique for imaging of magnetic domain patterns based on element-specific core-level photoemission using polarized soft-x-ray radiation. It is applied to the measurement of domain patterns at the Fe(100) surface and at the surface of polycrystalline Fe. Different from well established imaging techniques that use a photoemission electron microscope to measure the secondary electron intensity at the Fe absorption threshold, we have investigated the photoemission intensity contrast on the the Fe $2{p}_{3∕2}$ core level using circularly polarized x-ray light. The linear and circular dichroism characteristics of the identical domain pattern are extracted by linear co…
Exchange coupling in the correlated electronic states of amorphous GdFe films
2013
The bulk sensitivity of hard x-ray photoelectron spectroscopy in combination with circularly polarized radiation of the P09 beamline at PETRA III enables the investigation of the magnetic properties of capped films. We have determined the temperature dependence of the magnetic circular dichroism in the Fe 2$p$ and in the Gd 3$d$ states in amorphous GdFe films. The magnetic dichroism reflects the stronger temperature dependence of Gd moments compared to Fe moments in agreement with mean-field models. We resolved the exchange split Gd 3${d}_{5/2}$ substates and found a significant temperature dependence of the splitting which is attributed to a temperature dependent part of the exchange energ…
Investigations of Chl a aggregates cross-linked by dioxane in 3-methylpentane
1997
In this work, dioxane-bound aggregates of chlorophyll a are prepared in 3-methylpentane. The properties of the aggregates are studied by using steady-state and time-resolved spectroscopies. The Q -region absorption spectrum of the y chlorophyll a-dioxane aggregate shows four clearly resolvable narrow bands with comparable intensities. The band maxima are located at 683, 689, 698 and 702 nm. The emission spectrum consists of two emission bands centred at 699 and 702 nm suggesting the presence of two types of aggregates. High degree of fluorescence polarization is detected yielding the angles between the absorption transition moments with respect to the 702 nm emission transition moment. The …
Electrohydrodynamic instabilities and orientation of dielectric ellipsoids in low-conducting fluids.
2000
We study the dynamics of an ellipsoidal particle in a weakly conducting dielectric liquid when submitted to a dc electric field. At low field intensities, the particle long axis is aligned in the field direction. When the field strength is increased, we show that, depending on the initial orientation of the particle, there exist two stable orientations: the one with the long axis parallel to the field direction remains possible while a spinning state with the long axis perpendicular to the field appears. This last striking orientation is due to the finite Maxwell-Wagner polarization relaxation time. For sufficiently high field intensities, each state loses its stability and the particle dyn…
Cellular Mechanisms of Subplate-Driven and Cholinergic Input-Dependent Network Activity in the Neonatal Rat Somatosensory Cortex
2008
Early coordinated network activity promotes the development of cortical structures. Although these early activity patterns have been recently characterized with respect to their developmental, spatial and dynamic properties, the cellular mechanisms by which specific neuronal populations trigger coordinated activity in the neonatal cerebral cortex are still poorly understood. Here we characterize the cellular and molecular processes leading to generation of network activity during early postnatal development. We show that the somatosensory cortex of newborn rats expresses cholinergic-driven calcium transients which are synchronized within the deeply located subplate. Correspondingly, endogen…
Conduction band polarization in some CMR materials
2000
First principles electronic structure calculations reveal certain important common features in the conduction band polarization of many of the newly examined colossal magnetoresistance (CMR) materials. Most CMR compounds seem to possess a localized, magnetic band slightly below the Fermi energy. This localized band transfers polarization to a relatively broad conduction band. The nature of the two bands in different systems can be quite distinct. In the perovskite-derived manganese oxides, the magnetic band is derived from $Mn t_{2g}$ states while the conduction band is derived from Mn e states. In the chalcospinel $Fe_{^0.^5}$ $Cu_{^0.^5}$ $Cr_{2}$$ S_{4}$ , the $Crt_{2g}$ states which are…
Mucosal immunology and probiotics.
2013
The cross-talk between the mucosa-associated immune system and microbiota is critical in mucosal tissue homeostasis as well as in protection against infectious and inflammatory diseases occurring at mucosal sites. This recent evidence has paved the way to therapeutic approaches aimed at modulating the mucosa-associated immune system using probiotics. Different strains of probiotics possess the ability to finely regulate dendritic cell (DC) activation, polarizing the subsequent T cell activity toward Th1 (e.g. Lactobacillus (Lb) acidophilus), Th2 (Lb.reuteri and Bifidobacterium bifidum) or, as more recently demonstrated, Th17 responses induced by specific strains such as Lb.rhamnosus GG and …
The Politicization of European Union Trade Policy: Radical-Left Euroskeptic Opposition to the Transatlantic Trade and Investment Partnership
2021
This study aims to analyze the correlation between radical-left Euroskeptic (RLE) activity and European Union (EU) trade policy by focusing on the Transatlantic Trade and Investment Partnership (TTIP). At the beginning of TTIP negotiations, the agreement was not high on political agendas and was not a major concern within European society. Thus, its salience was low. This initial lack of interest stemmed from the fact that the TTIP, as an economic and technical issue, did not draw public attention. This study shows that RLEs profoundly affected public opinion on the TTIP by increasing its salience during the European parliamentary elections in 2014 in France and Germany. Second, RLEs involv…
Polarization and Spectacle in the Spanish Political Talk Show ‘La Sexta Noche’ During the 2019 European Elections
2021
This article analyses how in the main political talk show on television in Spain, La Sexta Noche, the main themes of the European agenda were silenced or conditioned by the themes of the national, regional and local agenda during the last European elec-tions. The media debate was oriented towards an analysis of the results of national elections and the campaign for regional and local elections that al-lowed for a greater spectacle, thanks to the shock effect of such polarized ideol-ogies and the trivialization of national politics. This research has studied all the shows of the programme broad-cast as of the national elections on 28th April 2019 up until the European elections held on 26th …