Observation of a temperature dependent electrical resistance minimum above the magnetic ordering temperature in Gd2_2PdSi3_3

Results on electrical resistivity, magnetoresistance, magnetic Results on electrical resistivity, magnetoresistance, magnetic susceptibility, heat capacity and Gd Mossbauer measurements on a Gd-based intermetallic compound, Gd$_{2}$PdSi$_{3}$ are reported. A finding of interest is that the resistivity unexpectedly shows a well-defined minimum at about 45 K, well above the long range magnetic ordering temperature (21 K), a feature which gets suppressed by the application of a magnetic field. This observation in a Gd alloy presents an interesting scenario. On the basis of our results, we propose electron localization induced by s-f (or d-f) exchange interaction prior to long range magnetic order as a mechanism for the electrical resistance minimum.Comment: 4 pages, 4 figure

Pion parameters in nuclear medium from chiral perturbation theory and virial expansion

We consider two methods to find the effective parameters of the pion traversing a nuclear medium. One is the first order chiral perturbation theoretic evaluation of the pion pole contribution to the two-point function of the axial-vector current. The other is the exact, first order virial expansion of the pion self-energy. We find that, although the results of chiral perturbation theory are not valid at normal nuclear density, those from the virial expansion may be reliable at such density. The latter predicts both the mass-shift and the in-medium decay width of the pion to be small, of about a few MeV.Comment: 9 Pages RevTex, 3 eps figure

PT-symmetric supersymmetry in a solvable short-range model

The simplest purely imaginary and piecewise constant $\cal PT$-symmetric potential located inside a larger box is studied. Unless its strength exceeds a certain critical value, all the spectrum of its bound states remains real and discrete. We interpret such a model as an initial element of the generalized non-Hermitian Witten's hierarchy of solvable Hamiltonians and construct its first supersymmetric (SUSY) partner in closed form.Comment: 3 figures, 1 tabl

Magnetic behaviour of Eu_2CuSi_3: Large negative magnetoresistance above Curie temperature

We report here the results of magnetic susceptibility, electrical-resistivity, magnetoresistance (MR), heat-capacity and ^{151}Eu Mossbauer effect measurements on the compound, Eu_2CuSi_3, crystallizing in an AlB_2-derived hexagonal structure. The results establish that Eu ions are divalent, undergoing long-range ferromagnetic-ordering below (T_C=) 37 K. An interesting observation is that the sign of MR is negative even at temperatures close to 3T_C, with increasing magnitude with decreasing temperature exhibiting a peak at T_C. This observation, being made for a Cu containing magnetic rare-earth compound for the first time, is of relevance to the field of collosal magnetoresistance.Comment: To appear in PRB, RevTex, 4 pages text + 6 psFigs. Related to our earlier work on Gd systems (see cond-mat/9811382, cond-mat/9811387, cond-mat/9812069, cond-mat/9812365

HEVC based Multi-View Video Codec using Frame Interleaving technique

this paper presents a HEVC based multi-view video codec. The frames of the multi-view videos are interleaved to generate a monoscopic video sequence. The interleaving is conducted in a way to increase the exploitation of the temporal and inter-views correlations. The MV-HEVC standard codec is configured to work as a single layered codec, which functions as a monoscipic HEVC codec with AVC capabilities, and used to encode interleaved multi-view video frames. The performance of the codec is compared with the anchor standard MV-HEVC codec by coding the three standard multi-view video sequences: “Balloon”, “Kendo” and “Newspaper1”. Experimental results show the proposed codec out performs the anchor standard MV-HEVC codec in term of bitrate and PSNR

PT-symmetric square well and the associated SUSY hierarchies

The PT-symmetric square well problem is considered in a SUSY framework. When the coupling strength $Z$ lies below the critical value $Z_0^{\rm (crit)}$ where PT symmetry becomes spontaneously broken, we find a hierarchy of SUSY partner potentials, depicting an unbroken SUSY situation and reducing to the family of $\sec^2$-like potentials in the $Z \to 0$ limit. For $Z$ above $Z_0^{\rm (crit)}$, there is a rich diversity of SUSY hierarchies, including some with PT-symmetry breaking and some with partial PT-symmetry restoration.Comment: LaTeX, 18 pages, no figure; broken PT-symmetry case added (Sec. 6

Generating Complex Potentials with Real Eigenvalues in Supersymmetric Quantum Mechanics

In the framework of SUSYQM extended to deal with non-Hermitian Hamiltonians, we analyze three sets of complex potentials with real spectra, recently derived by a potential algebraic approach based upon the complex Lie algebra sl(2, C). This extends to the complex domain the well-known relationship between SUSYQM and potential algebras for Hermitian Hamiltonians, resulting from their common link with the factorization method and Darboux transformations. In the same framework, we also generate for the first time a pair of elliptic partner potentials of Weierstrass $\wp$ type, one of them being real and the other imaginary and PT symmetric. The latter turns out to be quasiexactly solvable with one known eigenvalue corresponding to a bound state. When the Weierstrass function degenerates to a hyperbolic one, the imaginary potential becomes PT non-symmetric and its known eigenvalue corresponds to an unbound state.Comment: 20 pages, Latex 2e + amssym + graphics, 2 figures, accepted in Int. J. Mod. Phys.

MIXED-RESOLUTION HEVC BASED MULTIVIEW VIDEO CODEC

Studies have shown that mixed resolution based video codecs, also known as asymmetric spatial inter/intra view video codecs are successful in efficiently coding videos for low bitrate trans-mission. In this paper a HEVC based spatial resolution scaling type of mixed resolution coding model for frame interleaved multiview videos is presented. The proposed codec is designed such that the information in intermediate frames of the center and neighboring views are down-sampled, while the frames still retaining the original size. The codec’s reference frames structure is designed to efficiently encode frame interleaved multi-view videos using a HEVC based mixed resolution codec. The multi-view test video sequences were coded using the proposed codec and the standard MV-HEVC. Results show that the pro-posed codec gives significantly higher coding performance over the MV- HEVC codec at low bitrates