Modern Physics Letters B

When femtosecond laser pulses pass through a trapped polystyrene bead, water breakdown is induced even though the energy of laser pulse is much lower compared to the threshold value of breakdown when the femtosecond laser directly irradiates in water. This mechanism is assigned to the secondary convergence of the laser by the trapped bead.

The entropy flows of Hurricane Katrina (2005) are calculated using the entropy flow formula appropriate for atmospheric dynamical systems based on the National Centre for Environmental Prediction/National Centre for Atmospheric Research reanalysis data. The results show that the intensification of net negative (positive) entropy flow entering into Katrina preceded the strengthening (weakening) of its intensity and the asymmetries of the entropy flow pattern around Katrina's centre contained some significant information on hurricane track prediction. These results imply that classical thermodynamic entropy may serve as an order parameter for an atmospheric system and that entropy flow analysis might provide a new insight into the mechanism responsible for the life cycle of the system.

The extension of the quantization rule approach to non-central potentials is investigated. The energy spectra for the generalized Coulomb and oscillator systems are presented. The results are in good agreement with those obtained before.

In this paper, we establish exact special solutions of the generalized nonlinear Schrödinger equation with nonlinear dispersion (called the GNLS(m,n,p,q) equation) by using a sn-cn method. Some new Jacobi elliptic, envelope compacton and solitary pattern solutions of GNLS(m,n,p,q) equations are obtained.

Total energies and electronic structures of rhombohedral lanthanum cobaltite (LaCoO₃) with both non-magnetic and magnetic states are calculated from generalized gradient approximation (GGA) with on-site Coulomb correlation corrections (GGA + U) method. It is found that only the non-magnetic ground state can be obtained for LaCoO₃ at 5 K, consistent with previous studies. When U = 4.0 eV is employed, the band gap is found to be 0.6 eV, in agreement with the result of ultraviolet photoemission spectroscopy (UPS). The ferromagnetic ground state can be obtained for LaCoO₃ at 100 K, but much larger on-site Coulomb interaction between Co 3d is found. Only when U = 7.8 eV is employed for the calculation of LaCoO₃ at 100 K can we find a band gap of 0.26 eV, consistent with the optical conductivity measurements. According to these results, we propose a probable mechanism for spin-state transition in LaCoO₃ at around 100 K. The transition is mainly due to the big change in the on-site Coulomb repulsion between Co 3d electrons.

Effects of confinement potential hω₀ on two- and four-electron quantum dots (QDs) subjected to an external magnetic field B are theoretically investigated. The energy spectra of low-lying states of the QDs as a function of B are obtained. The (L₀, S₀) phase diagrams are presented, indicating how the ground-state transitions of the QDs vary with B and hω₀, where L₀ denotes the total angular momentum and S₀ the total spin of the ground states. Arising from symmetry effect, L₀ and S₀ are matched with each other in a special way. Density functions are calculated, and information on electronic configurations is extracted from them. The ground states are found to have a regular-polygon configuration.

The properties of microscopic particles are studied using the linear Schrödinger equation in quantum mechanics and nonlinear Schrödinger equation, respectively. The results obtained show that the microscopic particles have only a wave nature in quantum mechanics, but a wave-corpuscle duality in nonlinear systems depicted by the nonlinear Schrödinger equation, no matter the form of external potentials. Thus we know that the kinetic energy term in dynamic equations determines the wave feature of the particles; the nonlinear interaction term determines the corpuscle feature; their combination makes the microscopic particles have a wave-corpuscle duality. However the external potential term can change the phase and group velocities of motion, phase, amplitude, frequency and form of wave for the particles in both quantum mechanics and the nonlinear quantum systems, although it cannot change these fundamental natures of particles, no matter the forms. Meanwhile, we find that the changes of positions of the microscopic particles by increasing the time under action of an external potential satisfy the Newton-type equation of motion in nonlinear quantum systems. Thus the investigations make us not only see the limits and approximations of quantum mechanics but also know the necessity and importance of developing nonlinear quantum mechanics on the basis of the nonlinear Schrödinger equation.

For hearing sense, the mechanoreceptors fire action potentials when their membranes are physically stretched. Based on the statistical physics, we analyzed the entropical aspects in auditory processes of hearing. We develop a model that connects the logarithm of relative intensity of sound (loudness) to the level of energy disorder within the system of cellular sensory system. The increasing of entropy and disorder in the system is connected to the free energy available to signal the production of action potentials in inner hair cells of the vestibulocochlear auditory organ.

This paper talks about obtaining an exact 1-soliton solution of the generalized Radhakrishnan, Kundu, Lakshmanan equation with nonlinear dispersion. The solitary wave ansatz will be used to carry out the integration. It will be proved that dark optical solitons can exist only when the power law nonlinearity reduces to Kerr law.