Modern Physics Letters B

We are focusing on the uncertainties of analytical and numerical analysis of AC losses in superconducting accelerator magnets working at a relatively high ramp rate. The loss experimental techniques are discussed as well as the source of error in the measurements. The correlation between the interstrand resistance of Rutherford cables and quench current behavior of superconducting magnets is addressed. The control of the critical current of full Rutherford cables by measuring the strands extracted from such cables is illustrated. The importance of cables curing temperature on microhardness and RRR of Cu-matrix of multifilamentary NbTi is pointed out.

The effect of a small amount of Sb doping (5%) on the formation of the high temperature superconducting phase has been investigated on the Bi_1.5Pb_0.5Sr₂Ca₂Cu₃O_y compound. It is observed that at 860°C the T_c zero value depends on the sintering time. It first increases to a maximum value of 96 K and then decreases to a stable lowest value of 88 K. The samples have been characterized by X-ray diffraction (XRD), four probe electrical resistance and current density measurements. The XRD revealed the presence of two phases: an orthorhombic high-T_c 2223 phases with lattice constants a = 5.395 Å, b = 5.508 Å, c = 37.0422 Å and another tetragonal low-T_c 2212 phase with lattice constants a = b = 5.419 Å, c = 30.832 Å.

In this work the two-dimensional Ising model with nearest- and next-nearest-neighbor interactions is revisited. We obtain the dynamic critical exponents z and θ from short-time Monte Carlo simulations. The dynamic critical exponent z is obtained from the time behavior of the ratio , whereas the non-universal exponent θ is estimated from the time correlation of the order parameter <M(0)M(t)> ~ t^θ, where M(t) is the order parameter at instant t, d is the dimension of the system and <(⋯)> is the average of the quantity (⋯) over different samples. We also obtain the static critical exponents β and ν by investigating the time behavior of the magnetization.

We investigate the interaction of two two-level atoms with a single mode cavity field. One of the atoms is exactly at resonance with the field, while the other is well far from resonance and hence is treated in the dispersive limit. We find that the presence of the non-resonant atom produces a shift in the Rabi frequency of the resonant atom, as if it was detuned from the field. We focus on the discussion of the evolution of the state purity of each atom.

The quantum statistical properties of a single mode of the radiation field, prepared in the coherent state, interacting with a nonlinear medium of inversion symmetry are studied with the help of the usual two photon correlation function for zero time delay. We report the photon antibunching and sub-Poissonian photon statistics in addition to the usual photon bunching and the super-Poissonian photon statistics for an input vacuum field. The manipulation of the phase of input coherent light gives rise to the well known self induced transparency. The possible physical explanations for these events are presented.

Results concerning the structural, optical and magnetic properties of xFe₂O₃ · (100 - x)[3Bi₂O₃ · 2PbO] glasses (0 = x = 20 mol%) are reported. The transparence in the infrared range was investigated. The homogeneous absorption cross section was determined from the optical absorption spectra using the density matrix formalism of the McCumber theoretical model. From the temperature dependence of reciprocal magnetic susceptibility, negative paramagnetic Curie temperatures have been found suggesting the antiferromagnetic nature of the magnetic interaction between the iron ions in the studied samples. The iron ions occur both in the (II) and (III) valence state. The Fe²⁺/Fe³⁺ ratio was determined from the experimental values of the magnetic moments for all samples. The glass transition temperature with increasing Fe₂O₃ content was also investigated.

The validity of complexity simplifications for proteins with different structural features may be different. In this paper, the simplification for proteins is studied using the ratios of successful prediction of structural class under a presumed amino-acid-grouping scheme with a composition-coupled method. It is found that for the α-class proteins, a two-letter alphabet may cover the degree of freedom to characterize the complexity of the class; for the β-class proteins, a 7-letter alphabet might indicate the minimal number of residue types to reconstruct the class feature of the natural proteins; for the α + β-class proteins and the α/β-class proteins, the redundancy of the compositions is weak and the simplification leads to a great loss of the information related to the corresponding structural classes.