Quintessence Model and Observational Constraints

The recent observations of type Ia supernovae strongly support that the universe is accelerating now and decelerated in the recent past. By assuming a general relation between the quintessence potential and the quintessence kinetic energy, a general relation is found between the quintessence energy density and the scale factor. The potential includes both the hyperbolic and the double exponential potentials. A detailed analysis of the transition from the deceleration phase to the acceleration phase is then performed. We show that the current constraints on the transition time, the equation of state and the energy density of the quintessence field are satisfied in the model.Comment: update references,add acknowledgements and correct some errors, accepted for publication in class. and quant. gra

Review of the 9th international conference on the evolution of language (Evolang9)

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Child Care in the Postwelfare Reform Era: Analysis and Strategies for Advocates

Adequate child care is essential to enable poor women to support their families with work outside the home. In 1994 the U.S. General Accounting Office found that offering a child care subsidy to poor mothers increased the likelihood by 15 percent that the mothers would work. An Illinois study found that 20 percent of parents who left public assistance for work returned to assistance because of child care problems. In Minnesota a study found that lack of child care caused 14 percent of parents awaiting child care subsidies to leave their jobs and rely on public assistance. These studies confirm what advocates know: Poor parents, like other parents, cannot work without child care. The goal of this article is to assist advocates in helping their clients access quality child care and assuring that they do not lose needed public assistance when child care is unavailable

The Escape Problem in a Classical Field Theory With Two Coupled Fields

We introduce and analyze a system of two coupled partial differential equations with external noise. The equations are constructed to model transitions of monovalent metallic nanowires with non-axisymmetric intermediate or end states, but also have more general applicability. They provide a rare example of a system for which an exact solution of nonuniform stationary states can be found. We find a transition in activation behavior as the interval length on which the fields are defined is varied. We discuss several applications to physical problems.Comment: 24 page