ADM, Bondi mass, and energy conservation in two-dimensional dilaton gravities

We show how a stress-energy pseudotensor can be constructed in two-dimensional dilatonic gravity theories (classical, CGHS and RST) and derive the expression for the ADM mass in these theories from it. We define the Bondi mass for these theories by using the pseudotensor formalism. The resulting expression is the generalization of the expression for the ADM mass. The boundary condition needed for the energy conservation is also investigated. It is shown that under appropriate boundary conditions, our definition of the Bondi mass is exactly the ADM mass minus the matter radiation energy at null infinity.Comment: 11 pages, latex, no figure

Folding Mechanism of Small Proteins

Extensive Monte Carlo folding simulations for four proteins of various structural classes are carried out, using a single atomistic potential. In all cases, collapse occurs at a very early stage, and proteins fold into their native-like conformations at appropriate temperatures. The results demonstrate that the folding mechanism is controlled not only by thermodynamic factors but also by kinetic factors: The way a protein folds into its native structure, is also determined by the convergence point of early folding trajectories, which cannot be obtained by the free energy surface.Comment: 11 pages, 4 figure

Collapse transition of a square-lattice polymer with next nearest-neighbor interaction

We study the collapse transition of a polymer on a square lattice with both nearest-neighbor and next nearest-neighbor interactions, by calculating the exact partition function zeros up to chain length 36. The transition behavior is much more pronounced than that of the model with nearest-neighbor interactions only. The crossover exponent and the transition temperature are estimated from the scaling behavior of the first zeros with increasing chain length. The results suggest that the model is of the same universality class as the usual theta point described by the model with only nearest-neighbor interaction.Comment: 14 pages, 5 figure

A Stochastic Analysis of the Impact of Volatile World Agricultural Prices on European and UK Agriculture

Successive Common Agricultural Policy (CAP) reforms and trade liberalisation have led to a more market-orientated European agricultural sector, with EU commodity prices now more closely linked to world prices. As a consequence EU prices have become more volatile. Greater price volatility increases uncertainty and raises fresh challenges for projections of policy impacts in the EU. To take account of world price volatility stochastic modelling has been applied to the FAPRI-EU partial equilibrium model, which includes a UK modelling system. Stochastic modelling provides a means to capture some of the inherent uncertainty associated with agricultural production systems. By varying assumptions about certain exogenous variables, stochastic models can be used to examine the different ways markets may behave. Variable world prices are incorporated within the EU GOLD model. This process identifies the impact of a stochastic distribution of world prices on EU agriculture rather than the single point estimates in the conventional deterministic approach. The results outlined in this study demonstrate the impact of volatile world prices on EU and, in particular, UK prices and market control instrumentsAgricultural policy, Stochastic modelling, Agricultural and Food Policy,