Aggregate agricultural supply response in developing countries : a survey of selected issues

The authors review several studies of the aggregate agricultural supply response. Using both economic and econometric reasons, they argue that time series estimation typically generates a downward-biased estimate of the response to a credible reform. Even though time series estimates can provide an accurate picture of past behavoiral relations, they do not provide an adequate basis for forecasting the impact of policy reform. This is especially true in developing countries, where policy reforms involve large changes and have included agricultural price reform, industrial trade liberalization, financial sector reform, and macroeconomic stabilization. Under those circumstances, parameters values obtained under the former policy regime have little relevance in the new regime. The authors also argue that investment in public goods should be viewed as complementary to, not competitive with, price policy. They claim that to select the policy with the biggest impact on output makes no sense. They provide what they consider to be better criteria for choosing the best from alternative policies.Environmental Economics&Policies,Payment Systems&Infrastructure,Economic Theory&Research,Markets and Market Access,Labor Policies,Economic Theory&Research,Environmental Economics&Policies,Access to Markets,Markets and Market Access,Inequality

The Cosmological Kibble Mechanism in the Laboratory: String Formation in Liquid Crystals

We have observed the production of strings (disclination lines and loops) via the Kibble mechanism of domain (bubble) formation in the isotropic to nematic phase transition of a sample of uniaxial nematic liquid crystal. The probablity of string formation per bubble is measured to be $0.33 \pm 0.01$. This is in good agreement with the theoretical value $1/ \pi$ expected in two dimensions for the order parameter space $S^2/{\bf Z}_2$ of a simple uniaxial nematic liquid crystal.Comment: 17 pages, in TEX, 2 figures (not included, available on request

Gauge transformation through an accelerated frame of reference

The Schr\"{o}dinger equation of a charged particle in a uniform electric field can be specified in either a time-independent or a time-dependent gauge. The wave-function solutions in these two gauges are related by a phase-factor reflecting the gauge symmetry of the problem. In this article we show that the effect of such a gauge transformation connecting the two wave-functions can be mimicked by the effect of two successive extended Galilean transformations connecting the two wave-function. An extended Galilean transformation connects two reference frames out of which one is accelerating with respect to the other.Comment: 7 Pages, Latex fil

Corrections to Fermi's Golden Rule in ϕ→KKˉ\phi \to K\bar{K} Decays

We analyze the decays $\phi \to K\bar{K}$ utilizing a formulation of transition rates which explicitly exhibits corrections to Fermi's Golden Rule. These corrections arise in systems in which the phase space and/or matrix element varies rapidly with energy, as happens in $\phi \to K\bar{K}$, which is just above threshold. We show that the theoretical corrections resolve a puzzling $5\sigma$ discrepancy between theory and experiment for the branching ratio $R = \Gamma (\phi \to K^+K^-)/\Gamma(\phi \to K^0\bar{K}^0)$

The Hallmarks of a Good Test: A Proposal for Applying the Functional Equivalent Rule From County of Maui v. Hawaii Wildlife Fund

The Clean Water Act generally requires a federal permit for the discharge of pollutants “from any point source” to navigable waters. It is undisputed that permits are required for discharges of pollutants from point sources that proceed “directly” to regulated waters. But there is much disagreement over the extent to which indirect point-source discharges are regulated. In an attempt to clarify, the United States Supreme Court in County of Maui v. Hawaii Wildlife Fund ruled that permits are required not just for direct point-source discharges, but also for any point-source discharge that is the “functional equivalent” of a direct point-source discharge. Unfortunately, the Court did not define the term “functional equivalent,” other than to offer a non-exhaustive list of seven factors to consider (emphasizing time and distance), and to admonish lower courts to both respect the states’ traditional authority over water pollution and be mindful of avoiding decisions that would encourage evasion of the Act’s permitting requirements. To pick up where County of Maui left off, this Article proposes the “hallmark” interpretation of the functional equivalent test. According to this approach, a pollutant discharge is the “functional equivalent” of a direct discharge (and therefore requires a permit) if it bears the hallmarks of a direct discharge—in other words, if the discharged pollutants still betray the traces of having been emitted from a “discernible, confined and discrete conveyance” (the statutory definition of “point source”). In contrast, if the pollutants lack those hallmarks, and thus are indistinguishable from pollutants added by nonpoint sources, then their discharge is not a regulated “functional equivalent.” This “hallmark” approach is consistent not only with County of Maui’s articulation of the functional equivalent rule, but also with the Court’s expectation of how that rule should be implemented. In support of the proposed hallmark analysis, the Article defines the reference point (“direct discharge”) and its functions, then explains how to determine whether the hallmarks of the pollutants at issue are equivalent to the hallmarks of a direct discharge. Finally, it cautions that, consistent with County of Maui’s admonition, the functional equivalent analysis must include a “perspective” check to prevent the Act from being used to undercut the states’ traditional authority over water quality, while also respecting Congress’ intent that certain point-source discharges be federally regulated

Atomic quantum superposition state generation via optical probing

We analyze the performance of a protocol to prepare an atomic ensemble in a superposition of two macroscopically distinguishable states. The protocol relies on conditional measurements performed on a light field, which interacts with the atoms inside an optical cavity prior to detection, and we investigate cavity enhanced probing with continuous beams of both coherent and squeezed light. The stochastic master equations used in the analysis are expressed in terms of the Hamiltonian of the probed system and the interaction between the probed system and the probe field and are thus quite generally applicable.Comment: 10 pages, 9 figure