Modern Physics Letters B

Tsallis entropy introduced in 1988 is considered to have obtained new possibilities to construct generalized thermodynamical basement for statistical physics expanding classical Boltzmann–Gibbs–Shannon thermodynamics for non-equilibrium states. During the last two decades this q-generalized theory has been successfully applied to a considerable amount of physically interesting complex phenomena. The authors would like to present a short rewiev, the applications and the elementary properties of some operators in deformed q-algebra derived from Tsallis definition of non-extensive entropy based on the definitions of the q-logarithm and the q-exponential. The new definition of the q-root is also introduced.

In this paper, large spin polarization and magnetoconductance in a ferromagnet (FM)/ferromagnetic insulator (FI)/two-dimensional electron gas (2DEG)/non-magnetic insulator (I)/FM hybrid structure are theoretically predicted by introducing a spin-filtering injector. In the framework of coherent tunneling model, the electron transmission probability, spin polarization and magnetoconductance in the hybrid structure all oscillate with the electron density within the 2DEG channel. A complete single-mode spin injection would be realized by designing a well-defined geometry to adjust the competition between the spin-dependent tunneling of the conductive electrons and spin-filtering effect of the FI barrier.

Identifying communities in complex networks has recently attracted considerable attention in different fields. The goal of community identification is to cluster vertices of a network into groups, which is the same as clustering in machine learning and data mining domains. A recent proposed clustering method called affinity propagation shows high performance in clustering data sets into groups, and it does not require that the number of clusters be pre-specified. In this paper, based on a new method for calculating similarity between pairs of vertices and a transforming method for a given similarity from likelihood to log-domain, we apply that affinity propagation clustering method to identify communities in complex networks. Extensive simulation results demonstrate that affinity propagation clustering algorithm is very effective for identifying community structures in both computer-generated and real-world network data.

We proposed a physical scheme to concentrate unknown non-maximally entangled atomic states via cavity quantum electrodynamics (QED) techniques. In this scheme, the unique advantage is that the effects of the cavity decay and thermal field have been eliminated by using a classical driving field. The discussion indicates that it can be realized by current technologies.

Bis(tetrabutylammonium)-Hg(dmit)₂ was synthesized and its sample solution's optical Kerr Effect (OKE) signal was measured by the femtosecond optical Kerr gate technique. With the concentration of 9.27 × 10^-4 M, the sample solution's third-order optical susceptibility was obtained to be 2.53 × 10^-14 esu by using the CS₂ OKE signal as reference signal measured under identical conditions. The second-order hyperpolarizability for the bis(tetrabutylammonium)-Hg(dmit)₂ molecular was estimated to be 1.7 × 10^-32 esu. Its response time was about 226 fs, which is believed to be the contribution from the delocalized electrons.

EPR and DSC studies were carried out on MgO–R₂O–B₂O₃–V₂O₅ glasses. The electron paramagnetic resonance spectra of V⁴⁺ ion in the ternary glass system xMgO–(30-x)R₂O–70B₂O₃ (R = Li, Na, K) were recorded at X-band frequencies at 303 K. The V⁴⁺ ions in the present glass system exists as VO²⁺ ions in octahedral coordination with tetragonal compression. The site symmetry of vanadyl is C_4v and the ground state of 3d¹ ion is d_xy. Tetragonality (Δg_‖/Δg_⊥) of V⁴⁺ ion sites show a nonlinear variation with MgO content in the glasses. The covalency rates indicate moderate covalency for σ and π-bonds. The optical basicity values were also reported. Glass transition temperatures (T_g) of the glasses were found to increase linearly with increasing MgO content.

We present our results on nonlinear optical (NLO) of chicago sky blue 6B doped polyvinyl alcohol (PVA) film. This film was studied at 633 nm and 532 nm using a continuous wave laser. We have evaluated the sign and magnitude of the third-order nonlinearity from the closed aperture Z-scan data while the nonlinear absorption properties were assessed using the open aperture data. The chicago sky blue 6B doped PVA film exhibited nonlinear saturated absorption and strong self-defocusing effect. The limiting effect of the sample was studied and the results indicate that the film possesses good characteristic of optical limiting.

A finite discretization method in two dimensions has been developed and used to model electron transport in wurtzite phase GaN MESFETs. The model is based on the solutions of the highly-coupled nonlinear hydrodynamic partial differential equations. These solutions allow us to calculate the electron drift velocity and other device parameters as a function of the applied electric field. This model is able to describe inertia effects which play an increasing role in different fields of micro and optoelectronics where simplified charge transport models like drift-diffusion model and energy balance model are no longer applicable. Results of numerical simulations are shown for a two-dimensional GaN MESFET device which are in fair agreement with other theoretical or experimental methods.