Classical O(N) nonlinear sigma model on the half line: a study on consistent Hamiltonian description

The problem of consistent Hamiltonian structure for O(N) nonlinear sigma model in the presence of five different types of boundary conditions is considered in detail. For the case of Neumann, Dirichlet and the mixture of these two types of boundaries, the consistent Poisson brackets are constructed explicitly, which may be used, e.g. for the construction of current algebras in the presence of boundary. While for the mixed boundary conditions and the mixture of mixed and Dirichlet boundary conditions, we prove that there is no consistent Poisson brackets, showing that the mixed boundary conditions are incompatible with all nontrivial subgroups of $O((N)$.Comment: revtex4, 7pp, bibte

Housing over time and over the life cycle: a structural estimation

We estimate a structural model of optimal life-cycle housing and consumption in the presence of realistic labor income and house price uncertainties. The model postulates constant elasticity of substitution between housing service and nonhousing consumption, and explicitly incorporates a house adjustment cost. Our estimation fits the cross-sectional and time-series household wealth and housing profiles from the Panel Study of Income Dynamics quite well, and suggests an intra-temporal elasticity of substitution between housing and nonhousing consumption of 0.33 and a housing adjustment cost that amounts to about 15 percent of house value. Policy experiments with estimated preference parameters imply that households respond nonlinearly to house price changes with large house price declines leading to sizable decreases in both the aggregate homeownership rate and aggregate non-housing consumption. The average marginal propensity to consume out of housing wealth changes ranges from 0.4 percent to 6 percent. When lending conditions are tightened in the form of a higher down payment requirement, interestingly, large house price declines result in more severe drops in the aggregate homeownership rate but milder decreases in nonhousing consumption.

Relativistic Ab initio Study On PtF and HePtF

The electronic structures and spectroscopic constants of the first three low-lying electronic states (Omega = 1/2, 3/2, and 5/2) of the linear HePtF complex were investigated by highly accurate relativistic ab initio methods, in which the spin-orbit coupling was taken into account, and compared with the results of PtF. It shows that the complex is significantly different from the typical van der Waals systems because of short He-Pt bond distances (1.80 similar to 1.87 angstrom), large He-Pt stretching frequencies (500 similar to 600 cm(-1)), considerable binding energies (1400 similar to 2500 cm(-1) with corrections), and a small electron transfer from helium (about 0.06). However, the topological analysis of the electron density distribution indicates that there is strong van der Waals interaction in the He-Pt bond instead of weak covalent one.Welch Foundation F-100Chemistr