94 research outputs found
Equations of Motion for Massive Spin 2 Field Coupled to Gravity
We investigate the problems of consistency and causality for the equations of
motion describing massive spin two field in external gravitational and massless
scalar dilaton fields in arbitrary spacetime dimension. From the field
theoretical point of view we consider a general classical action with
non-minimal couplings and find gravitational and dilaton background on which
this action describes a theory consistent with the flat space limit. In the
case of pure gravitational background all field components propagate causally.
We show also that the massive spin two field can be consistently described in
arbitrary background by means of the lagrangian representing an infinite series
in the inverse mass. Within string theory we obtain equations of motion for the
massive spin two field coupled to gravity from the requirement of quantum Weyl
invariance of the corresponding two dimensional sigma-model. In the lowest
order in we demonstrate that these effective equations of motion
coincide with consistent equations derived in field theory.Comment: 27 pages, LaTeX file, journal versio
Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling
A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems
On Harsanyi payoff vectors and the Weber set
The paper discusses the set of Harsanyi payoff vectors, also known as the Selectope. First, we reconsider some results on Harsanyi payoff vectors, published by Vasil'ev in the late 1970's, within a more general framework. In particular, these results state already that the set of Harsanyi payoff vectors is given by the core of an associated convex game, a result that recently has been proven by Derks et. al. (2000). The marginal contribution vectors are examples of..
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