We study the exact solutions of the cascade three-level atom interacting with a single mode classical and quantized field with different initial conditions of the atom. For the semiclassical model, it is found that if the atom is initially in the middle level, the time dependent populations of the upper and lower levels are always equal. This dynamical symmetry exhibited by the classical field ...

We examine a possible connection between the anisotropic distribution of satellite galaxies around giant spiral galaxies and the evolution of satellite systems. The observed polar anisotropy (Zaritsky et al. 1997) is either imprinted by initial conditions or develops from an initially symmetric distribution. We attempt to discriminate between these two possibilities by exploring the implication...

Since Lotka and Volterra’s seminal and pioneering works (see [10]) many decades ago, modeling of interacting, competing species have received considerable attention in the fields of biology, ecology, mathematics (for example, see [3, 9]). In their remarkably simple deterministic model, Lotka and Volterra considered two coupled nonlinear differential equations that mimic the temporal evolution o...

We study the spatiotemporal dynamics of a two-dimensional excitatory neuronal network with synaptic depression. Coupling between populations of neurons is taken to be nonlocal, while depression is taken to be local and presynaptic. We show that the network supports a wide range of spatially structured oscillations, which are suggestive of phenomena seen in cortical slice experiments and in vivo...

To assess the potential for enhancing an existing stand of native perennial grasses on a California Coast Range Grassland site, we experimentally manipulated the seasonal timing and presence of grazing for 3 years (1994 through 1996) and of autumn burning for 2 years (1994 and 1995) and measured species cover for 6 years (1993 through 1998). We subjected the species matrix to classification (TW...

Liu, J., 1993. Discounting initial population sizes for prediction of extinction probabilities in patchy environments. Ecol. Modelling, 70: 51-61. Extinction is a major concern in conscrvation. A most urgcnt necd is to prcdict thc rclationship of a population's initial sizc to its probability of extinction. Previous work has led to a widcly acceptcd conclusion that thc larger an initial populat...

This paper presents an efficient meta-heuristic algorithm for optimization of double-layer scallop domes subjected to earthquake loading. The optimization is performed by a combination of harmony search (HS) and firefly algorithm (FA). This new algorithm is called harmony search firefly algorithm (HSFA). The optimization task is achieved by taking into account geometrical and material nonlinear...