140 research outputs found

    Effective field approach to the Ising film in a transverse field

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    We study the phase transitions of the spin-1/2 Ising film in a transverse field within the framework of the effective field theory. We evaluate the critical temperature of the film as a function of the exchange interactions, the transverse field and the film thickness. We find that, if the ratio of the surface exchange interactions to the bulk ones R=Js/J is smaller than a critical value Rc, the critical temperature Tc/J of the film is smaller than the bulk critical temperature Tc^B/J and approaches Tc^B/J as R increases further. On the other hand, if R>Rc, Tc/J is larger than both the bulk Tc^B/J and the surface Tc^S/J critical temperatures of the corresponding semi-infinite system, and approaches Tc^S as R increases further.Comment: 16 pages, 5 figures, elsart.cls (included

    Electronic Structure and X-Ray Photoemission Spectra of MPtSn (M = Ti, Zr, Hf)

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    The electronic structures of the half-Heusler isostructural compounds TiPtSn, ZrPtSn and HfPtSn were calculated and measured applying the X-ray photoemission spectroscopy. The (Ti, Zr, Hf)PtSn compounds have gaps between the occupied valence band and the empty conduction band, calculated as about 0.75, 1.12, and 1.09 eV, respectively. The calculations were done by the full-potential local orbitals method in the framework of the local spin-density approximation and partly also by the full-potential linear mu±n-tin orbitals method by the LmtART code. Experimental X-ray photoemission spectra were measured using photons of en- ergy of 1486.6 eV. The experimental and calculated spectra match quite well except a small shift in the energy scale

    Utilization of an Eilat Virus-Based Chimera for Serological Detection of Chikungunya Infection.

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    In December of 2013, chikungunya virus (CHIKV), an alphavirus in the family Togaviridae, was introduced to the island of Saint Martin in the Caribbean, resulting in the first autochthonous cases reported in the Americas. As of January 2015, local and imported CHIKV has been reported in 50 American countries with over 1.1 million suspected cases. CHIKV causes a severe arthralgic disease for which there are no approved vaccines or therapeutics. Furthermore, the lack of a commercially available, sensitive, and affordable diagnostic assay limits surveillance and control efforts. To address this issue, we utilized an insect-specific alphavirus, Eilat virus (EILV), to develop a diagnostic antigen that does not require biosafety containment facilities to produce. We demonstrated that EILV/CHIKV replicates to high titers in insect cells and can be applied directly in enzyme-linked immunosorbent assays without inactivation, resulting in highly sensitive detection of recent and past CHIKV infection, and outperforming traditional antigen preparations

    Proceedings of the XII National School "Correlated Electron Systems

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    In the lecture the theory of spin polarons is reviewed on the basis of its analogy with the theory of lattice polarons. The energy dispersion curve for a single polaron in a two-dimensional antiferromagnetic square lattice is calculated in the self-consistent Born approximation. Also in self-consistent Born approximation the energy of a pair of interacting spin polarons is calculated. The results of calculations for realistic values of parameters of the model lead to the conclusion that pairing of spin polarons is not a likely mechanism of superconductivity in cuprates

    Damping of the spin wave resonance by dislocations

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    The relaxation time of long-wavelength magnons is calculated for the mechanism involving two-magnon scattering by dislocations. The results could be used to study the broadening of the spin wave resonance spectrum by dislocations in thin ferromagnetic films.On a calculé le temps de relaxation des magnons aux grandes longueurs d'ondes en tenant compte du mécanisme de diffusion de deux magnons par les dislocations. On applique les résultats obtenus à l'étude de l'élargissement des raies du spectre de résonance des ondes de spin par les dislocations dans les couches minces ferromagnétiques
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