Search results for "Polarization"
showing 10 items of 1884 documents
Design of a narrow-band filter based on the Brewster phenomenon for microwave applications
2017
A high-efficiency narrow-band filter based on a Dielectric Frequency-Selective Surface (DFSS) has been predicted theoretically for oblique plane-wave incidence. A DFSS showing total reflection at a frequency of 10.5 GHz, based on the Brewster phenomenon for TM polarization, has been designed with a single dielectric grating, showing extremely low-reflectance sidebands adjacent to the resonance peak. The angular and spectral response of the designed filter has been studied. In addition, dielectric ohmic losses have been accounted for in this structure. This work was supported by the Agencia Estatal de Investigación (AEI) and by the Unión Europea through the Fondo Europeo de Desarrollo Region…
Functional MR imaging of pulmonary ventilation using hyperpolarized noble gases.
2000
The current status of experimental and clinical applications for functional MR imaging of pulmonary ventilation using hyperpolarized noble gases are reviewed. 3-helium (3He) and 129-xenon (129Xe) can be hyperpolarized by optical pumping techniques such as spin exchange or metastability exchange in sufficient amounts. This process leads to an artificial, non-equilibrium increase of the density of excited nuclei which represents the source of the MR signal. Those hyperpolarized gases are administered mostly via inhalation, and will fill airways and airspaces allowing for ventilation imaging. Recent human studies concentrate on imaging the airways and airspaces with high spatial resolution. N…
Current-induced domain wall motion in nanoscale ferromagnetic elements
2011
The manipulation of a magnetic domain wall (DW) by a spin polarized current in ferromagnetic nanowires has attracted tremendous interest during the last years due to fundamental questions in the fields of spin dependent transport phenomena and magnetization dynamics but also due to promising applications, such as DW based magnetic memory concepts and logic devices. We comprehensively review recent developments in the field of geometrically confined domain walls and in particular current induced DW dynamics. We focus on the influence of the magnetic and electronic transport properties of the materials on the spin transfer effect in DWs. After considering the different DW structures in ferrom…
Ultrafast optics in coherently spinning molecules
2020
This thesis reports on the study of unidirectional rotation of molecules and focuses on the rotational Doppler effect occuring in the course of third-harmonic generation in coherently spinning molecules.The rotational Doppler effect appears when a circularly polarized wave interacts with an anisotropic rotating object. During the interaction, an exchange of angular momentum and energy between the field and the object occurs, leading to a frequency shift of the wave. In this work, the frequency shift of the third-harmonic generated in unidirectionaly rotating molecules has been observed. An anlytical model developped in the mansucript forsees four kinds of frequency shifts depending on the m…
HSP110 : role in colorectal cancer development and immunogenicity
2015
Our team studies HSPs, including HSP110. HSPs are chaperones involved in the folding of newly synthesized and denatured proteins. HSPs are overexpressed under stress conditions and are involved in cell survival thanks to their anti-apoptotic and anti-aggregation functions. HSP110 is overexpressed in colorectal cancer and is associated with a poor prognosis. The expression of a mutant HSP110, named HSP110DE9, has been shown in MSI colorectal cancer. This one was shown to act there as a dominant negative, by binding HSP110 and inhibiting its functions. Its expression sensitizes cancer cells to chemotherapy and is associated with a better prognosis for patients.I was first interested in HSP110…
Tuning the Pseudospin Polarization of Graphene by a Pseudomagnetic Field.
2016
One of the intriguing characteristics of honeycomb lattices is the appearance of a pseudo-magnetic field as a result of mechanical deformation. In the case of graphene, the Landau quantization resulting from this pseudo-magnetic field has been measured using scanning tunneling microscopy. Here we show that a signature of the pseudo-magnetic field is a local sublattice symmetry breaking observable as a redistribution of the local density of states. This can be interpreted as a polarization of graphene's pseudospin due to a strain induced pseudo-magnetic field, in analogy to the alignment of a real spin in a magnetic field. We reveal this sublattice symmetry breaking by tunably straining grap…
Magnetic Domain Imaging with a Photoemission Microscope
1997
ABSTRACTPhotoelectron emission microscopy (PEEM) has proven to be a versatile analytical technique in surface science. When operated with circularly polarized light in the soft x-ray regime, however, photoemission microscopy offers a unique combination of magnetic and chemical information. Exploiting the high brilliance and circular polarization available at a helical undulator beamline, the lateral resolution in the imaging of magnetic domain structures may be pushed well into the sub-micrometer range. Using a newly designed photoemission microscope we show that under these circumstances not only domains, but also domain walls can be selectively investigated. The high sensitivity of the te…
Panel Discussion Spin and Polarization Effects in Atomic Processes
1973
In view of all the present activity on spin and polarization effects in atomic processes, perhaps the best approach to my introduction is first to summarize some of the most important recent results and to restrict myself to some typical characteristics.
Polarization of τ in quasielastic (anti)neutrino scattering: The role of spectral functions
2019
We present a study of the $\tau$ polarization in charged-current quasielastic (anti)neutrino-nucleus scattering. The spectral function formalism is used to compute the differential cross section and the polarization components for several kinematical setups, relevant for neutrino-oscillation experiments. The effects of the nuclear corrections in these observables are investigated by comparing the results obtained using two different realistic spectral functions, with those deduced from the relativistic global Fermi gas model, where only statistical correlations are accounted for. We show that the spectral functions, although they play an important role when predicting the differential cross…
The complete experiment for photoproduction of pseudoscalar mesons in a truncated partial wave analysis
2013
The complete experiment problem in the truncated partial wave analysis of pseudoscalar meson photoproduction with suppressed t-channel exchanges is investigated. The focus is set to ambiguities of the group S observables with the unpolarized differential cross section, $\sigma_0$, and the three single-spin observables, $\Sigma$, $T$ and $P$. For this purpose, the approach and formalism already worked out by Omelaenko in 1981 is revisited in this work. A numerical study using multipoles of the PWA solution MAID2007 shows how only one additional double polarization observable can resolve all ambiguities. Therefore, the possibility emerges to perform a complete experiment with only five observ…