Search results for "Anisotropy"
showing 10 items of 912 documents
Line coupling in Anisotropic Raman Branches
1994
Direct connection between collisional Raman cross sections and state‐to‐state rotational ones permits, within the sudden approximation, to evidence drastic decouplings from isotropic to anisotropic lines. These decouplings are consistent with the results obtained by using the strong collision model. Convenient energy corrections to the sudden approximation are used for N2 to calculate the resulting effects on the isotropic and anisotropic Q‐branch profiles in a large density range (several hundred bars). The comparison of the calculations with experimental coherent anti‐Stokes Raman scattering (CARS) and stimulated Raman (SRS) spectra of nitrogen exhibits a good agreement. Such effects coul…
Micron-precision in cleaving glass using ultrafast bessel beams with engineered transverse beam shapes
2017
International audience; Ultrafast lasers in association to beam shaping have shown to be excellent candidates for transparent material processing. Non-diffractive solutions such as Bessel beams allows for precise energy deposition since they are robust to undesired non-linear effects and as they do not distort along the propagation. This offers important opportunities in laser-assisted cleaving, i.e. mechanical medium separation after single-pass laser illumination. Here we break the Bessel beam cylindrical symmetry using a novel anisotropic and non-diffractive solutions to investigate both lateral intensity contributions on material response and induced processing effect for non-cylindrica…
Field-Induced Slow Magnetic Relaxation in a Six-Coordinate Mononuclear Cobalt(II) Complex with a Positive Anisotropy
2012
International audience; The novel mononuclear Co(II) complex cis-[Co-II(dmphen)(2)(NCS)(2)]center dot 0.25EtOH (1) (dmphen = 2,9-dimethyl-1,10-phenanthroline) features a highly rhombically distorted octahedral environment that is responsible for the strong positive axial and rhombic magnetic anisotropy of the high-spin Co-II ion (D = +98 cm(-1) and E = +8.4 cm(-1)). Slow magnetic relaxation effects were observed for 1 in the presence of a dc magnetic field, constituting the first example of field-induced single-molecule magnet behavior in a mononuclear six-coordinate Co(II) complex with a transverse anisotropy energy barrier.
Thermodiffusion anisotropy under a magnetic field in ionic liquid-based ferrofluids
2021
International audience; Ferrofluids based on maghemite nanoparticles (NPs), typically 10 nm in diameter, are dispersed in an ionic liquid (1-ethyl 3-methylimidazolium bistriflimide - EMIM-TFSI). The average interparticle interaction is found to be repulsive by small angle scattering of X-rays and of neutrons, with a second virial coefficient A2 = 7.3. A moderately concentrated sample at Φ = 5.95 vol% is probed by forced Rayleigh scattering under an applied magnetic field (up to H = 100 kA m-1) from room temperature up to T = 460 K. Irrespective of the values of H and T, the NPs in this study are always found to migrate towards the cold region. The in-field anisotropy of the mass diffusion c…
Correlation of the highest-energy cosmic rays with the positions of nearby active galactic nuclei
2008
Data collected by the Pierre Auger Observatory provide evidence for anisotropy in the arrival directions of the cosmic rays with the ighest-energies, which are correlated with the positions of relatively nearby active galactic nuclei (AGN) [Pierre Auger Collaboration, Science 318 (2007) 938]. The correlation has maximum significance for cosmic rays with energy greater than ~6 x 1019 eV and AGN at a distance less than ~75 Mpc. We have confirmed the anisotropy at a confidence level of more than 99% through a test with parameters specified a priori, using an independent data set. The observed correlation is compatible with the hypothesis that cosmic rays with the highest-energies originate fro…
Large-scale distribution of arrival directions of cosmic rays detected above 1018 eV at the Pierre Auger Observatory
2012
A thorough search for large-scale anisotropies in the distribution of arrival directions of cosmic rays detected above 1018 eV at the Pierre Auger Observatory is presented. This search is performed as a function of both declination and right ascension in several energy ranges above 1018 eV, and reported in terms of dipolar and quadrupolar coefficients. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Assuming that any cosmic-ray anisotropy is dominated by dipole and quadrupole moments in this energy range, upper limits on their amplitudes are derived. These upper limits allow us to test the origin of cosmic rays above 1018 eV from stationary Galactic …
Elastic Geobarometry for Anisotropic Inclusions in Anisotropic Host Minerals: Quartz-in-Zircon
2021
Current models for elastic geobarometry have been developed with the assumption that the host and/or inclusion minerals are elastically isotropic. This assumption has limited applications of elastic thermobarometry to mineral inclusions contained in cubic quasi-isotropic host minerals (e.g., garnet). Here, we report a new elastic model that takes into account the anisotropic elastic properties and relative crystallographic orientation (RCO) of a host-inclusion system where both minerals are noncubic. This anisotropic elastic model can be used for host-inclusion elastic thermobarometric calculations provided that the RCO and elastic properties of both the host and inclusion are known. We the…
Monte Carlo dosimetric study of Best Industries and Alpha Omega Ir-192 brachytherapy seeds
2004
Ir-192 seeds are widely used in the USA for low dose rate interstitial brachytherapy. There are two commercially available models: those manufactured by Best Industries filtered with stainless steel, and those manufactured by Alpha-Omega seeds filtered with Pt. Newly developed 3D correction algorithms for brachytherapy are based on dosimetry data obtained on unbounded phantom size, allowing corrections for heterogeneities and actual tissue boundaries. Published dosimetric datasets for both seeds have been obtained under bounded conditions. The aim of the present study is to obtain dosimetric datasets for these seeds under full scatter conditions. The Monte Carlo GEANT4 code has been used to…
Diffuse ultraviolet erythemal irradiance on inclined planes: a comparison of experimental and modeled data.
2009
Values of measured and modeled diffuse UV erythemal irradiance (UVER) for all sky conditions are compared on planes inclined at 40 degrees and oriented north, south, east and west. The models used for simulating diffuse UVER are of the geometric-type, mainly the Isotropic, Klucher, Hay, Muneer, Reindl and Schauberger models. To analyze the precision of the models, some statistical estimators were used such as root mean square deviation, mean absolute deviation and mean bias deviation. It was seen that all the analyzed models reproduce adequately the diffuse UVER on the south-facing plane, with greater discrepancies for the other inclined planes. When the models are applied to cloud-free con…
Azimuthal anisotropy of charged jet production in √sNN = 2.76 TeV Pb–Pb collisions
2016
We present measurements of the azimuthal dependence of charged jet production in central and semicentral √sNN = 2.76 TeV Pb–Pb collisions with respect to the second harmonic event plane, quantified as vch jet 2 . Jet finding is performed employing the anti-kT algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero vch jet 2 is observed in semi-central …