Cosmological perturbations in Horava-Lifshitz theory without detailed balance

In the Horava-Lifshitz theory of quantum gravity, two conditions -- detailed balance and projectability -- are usually assumed. The breaking of projectability simplifies the theory, but it leads to serious problems with the theory. The breaking of detailed balance leads to a more complicated form of the theory, but it appears to resolve some of the problems. Sotiriou, Visser and Weinfurtner formulated the most general theory of Horava-Lifshitz type without detailed balance. We compute the linear scalar perturbations of the FRW model in this form of HL theory. We show that the higher-order curvature terms in the action lead to a gravitational effective anisotropic stress on small scales. Specializing to a Minkowski background, we study the spin-0 scalar mode of the graviton, using a gauge-invariant analysis, and find that it is stable in both the infrared and ultraviolet regimes for $0 \le \xi \le 2/3$. However, in this parameter range the scalar mode is a ghost.Comment: Some typos were corrected. Verison appeared in Phys. Rev. D81, 024009 (2010

Decomposability for stable processes

We characterize all possible independent symmetric alpha-stable (SaS) components of an SaS process, 0<alpha<2. In particular, we focus on stationary SaS processes and their independent stationary SaS components. We also develop a parallel characterization theory for max-stable processes.Comment: Major revision. Section 4 of previous version removed due to a mistake in the proof. Remarks 3.2 and 3.3 adde

Efficiency Costs of Subsidy Rules for Crop Insurance

Participation in federal crop insurance programs has been encouraged through premium subsidies. The current subsidy depends on contract features as well as coverage levels. This type of subsidy rule causes farmers to choose contract designs and coverages that are not efficient for managing risk, in order to capture subsidy. Farmers are found to be as well off with a flat subsidy that is up to 25% less than the value of the current regressive proportional subsidy.crop insurance, futures, risk management, subsidy, Risk and Uncertainty,