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561.
Hÿtch MJ Dunin-Borkowski RE Scheinfein MR Moulin J Duhamel C Mazaleyrat F Champion Y 《Physical review letters》2003,91(25):257207
A detailed understanding of the formation of magnetic vortices in closely spaced ferromagnetic nanoparticles is important for the design of ultra-high-density magnetic devices. Here, we use electron holography and micromagnetic simulations to characterize three-dimensional magnetic vortices in chains of FeNi nanoparticles. We show that the diameters of the vortex cores depend sensitively on their orientation with respect to the chain axis and that vortex formation can be controlled by the presence of smaller particles in the chains. 相似文献
562.
Yannick Petit Simon Joly Patricia Segonds Benoît Boulanger 《Laser \u0026amp; Photonics Reviews》2013,7(6):920-937
This article is mainly devoted to the modeling and measurement of the absorption and fluorescence angular distributions in polarized light of monoclinic crystals. Up to now theoretical crystal optics were mostly devoted to crystals having a high crystallographic symmetry. In these crystals belonging to the cubic, hexagonal, tetragonal, trigonal or orthorhombic lattice classes, the tensor properties related to the real part of the dielectric permittivity and to its imaginary part can be described in the same frame which orientation does not vary as a function of wavelength. The situation is much more complicated in the case of monoclinic crystals because it is necessary to define a specific frame for each property and each wavelength that are considered. The main features of monoclinic crystal optics are described in detail, followed by a review of monoclinic materials and the consequence of these features on their related optical properties. 相似文献
563.
Youness Kaddar Wei Zhang Hanna Enriquez Yannick J. Dappe Azzedine Bendounan Gérald Dujardin Omar Mounkachi Abdallah El kenz Abdelilah Benyoussef Abdelkader Kara Hamid Oughaddou 《Advanced functional materials》2023,33(21):2213664
2D materials beyond graphene and in particular 2D semiconductors have raised interest due to their unprecedented electronic properties, such as high carrier mobility or tunable bandgap. Blue phosphorene is an allotrope of black phosphorene that resembles graphene as it presents a honeycomb structure. However, it is known to have semiconductor character and the crucial point is to determine whether this hexagonal phase of phosphorene presents Dirac fermions as in graphene. Here, the first compelling experimental evidence of Dirac fermions in blue phosphorene layer grown on Cu(111) surface is presented. The results highlight the formation of a highly ordered blue phosphorene sheet with a clear Dirac cone at the high symmetry points of the Brillouin Zone. The charge carriers behave as massless relativistic particles. Therefore, all the expectations held for graphene, such as high-speed electronic devices based on ballistic transport at room temperature, may also be applied to blue phosphorene. 相似文献
564.
We demonstrate low-threshold supercontinuum generated in a highly nonlinear arsenic selenide chalcogenide nanowire with tailored dispersion. The tapered submicrometer chalcogenide fiber exhibits an ultrahigh nonlinearity, n(2) approximately 1.1x10(-17) m(2)/W and an effective mode area of 0.48 mum(2), yielding an effective nonlinearity of gamma approximately 93.4 W/m, which is over 80,000 times larger than standard silica single-mode fiber at a wavelength of approximately 1550 nm. This high nonlinearity, in conjunction with the engineered anomalous dispersion, enables low-threshold soliton fission leading to large spectral broadening at a dramatically reduced peak power of several watts, corresponding to picojoule energy. 相似文献
565.
Alain Hdoux Jeong‐Ah Seo Yannick Guinet Laurent Paccou 《Journal of Raman spectroscopy : JRS》2012,43(1):16-23
Cold‐ and heat‐induced β‐lactoglobulin (BLG) transformations have been analyzed in the presence of 4 M urea, from Raman spectroscopy investigations carried out simultaneously in the low wavenumber range (10–400 cm−1) and in the amide I region (1500–1800 cm−1). These investigations show common features between the denaturation processes at low and high temperatures. The denatured states are reached via an intermediate state characterized by a soft tertiary structure without detectable conformational changes. This intermediate is intimately connected with a tetrahedral hydrogen‐bond structure of water which extends over a limited range. It is shown that the disruption of the hydrogen‐bond network of D2O has an important consequence on the solvent dynamics, which controls protein dynamics and is characterized by an anharmonic behavior. By monitoring the amide I mode, conformational changes are detected at low temperature (below 5 °C) and determined to be similar to those detected at high temperature in the presence of urea near 65 °C, and in the absence of urea near 80 °C. The conformational changes are described as a loss of α‐helix structures and a concomitant formation of β‐sheets. The temperature dependence of the amide I wavenumber in BLG dissolved in the 4 M urea aqueous solution was interpreted on the basis of a two‐state model, leading to the protein stability curve related to its molecular conformation. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
566.
Sana Hraiech Anis Jouini Kyoung Jin Kim Yannick Guyot Akira Yoshikawa Georges Boulon 《Radiation measurements》2010,45(3-6):323-327
Yb3+ and M+ monovalent alkali ions (M+ = Li+, Na+, K+)-co-doped CaF2 cubic laser crystals were grown by the micro-pulling-down method (μ-PD) under CF4 atmosphere. Structural and spectroscopic characterizations of Yb3+ in substitution of Ca2+ (absorption, emission and decay curves) were carried out to study the effect of M+ ions as charge compensators. 相似文献
567.
Yannick Henrio 《manuscripta mathematica》2001,106(2):131-150
Let R be a complete discrete valuation ring of mixed characteristics, with algebraically closed residue field k. We study the existence problem of equivariant liftings to R of Galois covers of nodal curves over k. Using formal geometry, we show that this problem is actually a local one. We apply this local-to-global principle to obtain
new results concerning the existence of such liftings.
Received: 10 February 2000 / Revised version: 13 September 2000 相似文献
568.
We consider the so-called Encrypted Davies–Meyer (EDM) construction, which turns a permutation P on \(\{0,1\}^n\) into a function from \(\{0,1\}^n\) to \(\{0,1\}^n\) defined as \(P(P(x)\oplus x)\). A similar construction using two independent permutations, namely \(P'(P(x)\oplus x)\), was previously analyzed by Cogliati and Seurin (Advances in cryptology—CRYPTO 2016 (Proceedings, Part I). LNCS, vol 9814, pp. 121–149, 2016) who showed that when P and \(P'\) are secret and random, then any black-box adversary needs at least roughly \(2^{2n/3}\) queries to distinguish the construction from a uniformly random function from \(\{0,1\}^n\) to \(\{0,1\}^n\). In this paper, we focus on the single-permutation variant of the construction. Our main result is that the PRF-security of the single-permutation EDM construction is also (at least) roughly \(2^{2n/3}\), in the sense that any black-box adversary needs at least this number of queries to distinguish the construction from a uniformly random function. This yields the first PRP-to-PRF conversion method which uses a single permutation, does not shrink the original domain nor range of the permutation, and provides security beyond the birthday bound. 相似文献
569.
We study the Γ-convergence of the following functional (p > 2)
$F_{\varepsilon}(u):=\varepsilon^{p-2}\int\limits_{\Omega}
|Du|^p d(x,\partial \Omega)^{a}dx+\frac{1}{\varepsilon^{\frac{p-2}{p-1}}}
\int\limits_{\Omega}
W(u) d(x,\partial \Omega)^{-\frac{a}{p-1}}dx+\frac{1}{\sqrt{\varepsilon}}
\int\limits_{\partial\Omega}
V(Tu)d\mathcal{H}^2,$F_{\varepsilon}(u):=\varepsilon^{p-2}\int\limits_{\Omega}
|Du|^p d(x,\partial \Omega)^{a}dx+\frac{1}{\varepsilon^{\frac{p-2}{p-1}}}
\int\limits_{\Omega}
W(u) d(x,\partial \Omega)^{-\frac{a}{p-1}}dx+\frac{1}{\sqrt{\varepsilon}}
\int\limits_{\partial\Omega}
V(Tu)d\mathcal{H}^2, 相似文献
570.
In this article, we investigate a non-localization property of the eigenfunctions of Sturm–Liouville operators with Dirichlet boundary conditions, where runs over the bounded nonnegative potential functions on the interval with . More precisely, we address the extremal spectral problem of minimizing the -norm of a function on a measurable subset ω of , where runs over all eigenfunctions of , at the same time with respect to all subsets ω having a prescribed measure and all potential functions having a prescribed essentially upper bound. We provide some existence and qualitative properties of the minimizers, as well as precise lower and upper estimates on the optimal value. Several consequences in control and stabilization theory are then highlighted. 相似文献
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