Results 1 - 10 of 11
Results 1 - 10 of 11. Search took: 0.015 seconds
|Sort by: date | relevance|
[en] We present the analytical results at the mean-field level for the asymmetrical fermion system with attractive contact interaction at zero temperature. The results can be expressed in terms of linear combinations of the elliptic integrals of the first and second kinds. In the limit of small gap parameter, we discuss how the asymmetry in fermion species affects the phases of the ground state of the system. In the limit of large gap parameter, we show that two candidate phases are competing for the system's ground state. The Sarma phase containing a pure Fermi fluid and a mixed condensate is favored at a large degree of asymmetry. The separated phase consisting of a pure Fermi fluid and a boson condensate supports the system at a small degree of asymmetry. The two phases are degenerate in the limit of infinite pairing gap
[en] Within the framework of supersymmetric quantum mechanics, we obtain a class of solvable potentials of shape invariance in two steps, where the parameters a1 and a2 of partner potentials are related to each other by translation a2 = a1 + α. It is found that discontinuity at some x-points is a characteristic of the two-step superpotentials, therefore giving rise to Dirac delta-function singularities to the corresponding potentials
[en] The simplified algebraic structure of the shape invariance condition in two steps is developed by imposing an extra relation on the two superpotentials of the corresponding two-step potentials. This simplified version of potential algebra is found to be similar to that of the shape invariance condition in one step. The solvable potentials of shape invariance in two steps, with a translation change of parameters a1 = a0 + δ, are shown to possess such a simplified version of potential algebra. The condition under which the potential algebra of shape invariance in more than two steps becomes simplified is also discussed
[en] Within the framework of supersymmetric quantum mechanics, we study the simplified version of the potential algebra of the shape invariance condition in k steps, where k is an arbitrary positive integer. The associated potential algebra is found to be equivalent to the generalized deformed oscillator algebra that has a built-in Zk-grading structure. The algebraic realization of the shape invariance condition in k steps is therefore formulated by the method of the Zk-graded deformed oscillator. Based on this formulation, we explicitly construct the general algebraic properties for shape invariant potentials in k steps, in which the parameters of partner potentials are related to each other by the translation a1 = a0 + δ. The obtained results include the cyclic shape invariant potentials of period k as a special case.
[en] We present a variational method to study the ground state of the newly realized 52Cr dipolar Bose-Einstein condensate. Besides the usual contact potential term in the mean-field equation, there is an additional long-range and anisotropic dipole-dipole interaction potential. We develop an efficient Newton-Raphson's scheme to solve the condensate state. The solution shows a double-peak feature in the loosely confined dimension. Compared to the existing single-peak calculations, the double-peak solution has lower energy and reflects the distinct property of the dipole-dipole interaction. Our method is easy and efficient to use for future investigations of the dipolar systems
[en] In this paper, pure and MnO added (1 - x)Pb(Fe2/3W1/3)O3-xPbTiO3 [(1 - x)PFW-xPT] ceramics are synthesized by using the conventional solid state oxide reaction method. The temperature dependence of the freezing processes is investigated by using the modified-Landau theory. This result is compared with the spin-glass phenomenon. According to the experimental data and the fitting results, the temperature-dependent local order parameters are derived from the modified-Landau theory and the spin-glass model with the experimental data separately and show similar tendencies. Furthermore, the derived local order parameters by using these two models show higher thermal stability by doping MnO additives and decreasing PbTiO3 contents. In conclusion, the ordering degree of B-site cations is enhanced by increasing PbTiO3 compositions and is reduced by doping MnO additives. This result is the main mechanism that induces the changes of the temperature-dependent local ordering parameters.
[en] In this paper, the low-field dielectric behaviors of 0.7PbFe2/3W1/3O3-0.3PbTiO3 (0.7PFW-0.3PT) relaxor ferroelectrics sintered at various temperatures have been investigated. The X-ray diffraction detector, the diffusion phase transition model and the spin glass model are used to analyze the dielectric characteristics. According to our experimental results and the theoretical analysis, it is found that the structure is changed from cubic to tetragonal and the diffusion phase transition characteristics and the spin glass behavior is weakened as the sintering temperature increases. In conclusion, the normal ferroelectric characteristics are more obvious as the sintering temperature increases in this system
[en] In this paper, 0.75Pb(Fe2/3W1/3)O3-0.25PbTiO3-0.15 wt% MnO (0.75PFW-0.25PT-0.15 wt% MnO) ceramics are synthesized by two different methods, the conventional direct oxide synthesized (DS) method and two-step indirect synthesized (IS) method. The low-field dielectric responses are investigated by using the empirical law, the Curie-Weiss law, the modified-Landau theory and the spin-glass model. Due to the IS method, the lattice structure and the grain structure of the samples are changed. Furthermore, the dielectric properties are evidently modified. It is suggested that the ordering degree of B-site cations is enhanced by using the IS synthesized method
[en] Purpose: To investigate the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in cervical cancer and their association with clinical outcome in patients treated with radical radiotherapy. Methods and Materials: One hundred sixty-seven consecutive patients with FIGO Stages IB-IVA squamous cell cervical cancer underwent radical radiotherapy, including external-beam radiotherapy or high-dose-rate brachytherapy, or both, between 1989 and 2002. Immunohistochemical studies of their formalin-fixed, paraffin-embedded tissues were performed. Univariate and multivariate analyses were performed to identify and evaluate the effects of the factors affecting patient survival. Results: Positive immunostainings of iNOS and COX-2 were observed in 58.7% and 64.1% of the participants, respectively. The expression of both iNOS and COX-2 was positively correlated (Spearman correlation coefficient = 0.49, p < 0.01), and their overexpression provided independent predictors of distant metastasis (odds ratio = 5.22 and 10.07, respectively; p < 0.01 for all). iNOS- and COX-2-expressing patients had significantly shorter disease-free survival (p < 0.01, both) and cause-specific overall survival (p = 0.01, p < 0.01, respectively). Patients with iNOS-positive/COX-2-positive tumors had the poorest survival rates. Coexpression of iNOS/COX-2, together with bulky tumor and advanced stage were independent prognostic factors for disease-free survival. Conclusion: Overexpression of iNOS or COX-2 or both was associated with decreased survival and a greater propensity to metastasize in cervical cancer patients treated with radiotherapy. Coexpression of iNOS and COX-2 may represent a useful biologic marker in patients receiving radical radiotherapy for cervical cancer
[en] A comprehensive totally aqueous phase synthesis of nickel-nitrilotriacetate (Ni-NTA) modified superparamagnetic Fe3O4 nanoparticles is presented. The Fe3O4-NTA-Ni nanoparticles are able to perform efficient and specific purification of 6-His tagged proteins from crude cell lysates, as evidenced by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis. The average binding capacity, as demonstrated by streptopain (MW 42 kDa), is 0.23 mg/mg (protein/Fe3O4-NTA-Ni). Considering the high affinity and specificity of the binding between hexahistidine motif and Ni-NTA, Ni-NTA modified nanoparticles could act as a module to carry 6-His tagged proteins on the particle surface with molecular orientation control, since only the 6-His domain could be attached. These modularly designed functional nanoparticles enhance cancer cell targeting, as supported by the in vitro receptor mediated targeting assay using RGD-4C-6-His fusion peptide. The nanoparticles show no significant hemolysis for human blood and could be investigated further for their in vivo functional imaging applications