Raising household energy prices in Poland : who gains? who loses?

The authors examine the welfare effects of increasing household energy prices in Poland. Their main finding is that the policy of subsidizing household energy prices, common in the transition economies of Eastern Europe and the former Soviet Union, is regressive. Such programs do help the poor by providing them with lower-cost energy, but they are more useful to the rich, who consume more energy. What is surprising is the extent to which Poland's nonpoor have benefited from lower energy prices. Non only do the wealthy consume more energy in absolute terms than the poor, but they also spend a larger portion of their income on energy. Their analysis allowed the authors to rule out the oft-used social welfare argument for delaying increases in household energy prices, but they do not try to recommend a dynamically efficient pricing path. The first-best response would be to raise energy prices while targeting cash relief to the poor through a social assistance program. This is far more efficient than the present go-slow price adjustment policies, which imply energy subsidies that provide across-the-board relief to all consumers. But if governments want to provide some relief for consumers to ease the adjustment, several options are available: in-kind transfers to the poor, vouchers, cash transfers, and lifeline pricing for a small block of electricity combined with significant price increases. Simulations show that if raising prices to efficient levels for all consumers is not now politically feasible, it may be socially better to use lifeline pricing and a large price increase rather than an overall (but smaller) price increase. Lifeline pricing for electricity in combination with an 80 percent price increase has better distributional effects than a 50 percent across-the-board price increase. Ideally, the public utility would be compensated from the budgtet for any reduced-price sales, rather than having to finance them through internal cross-subsidies. In-kind transfers to poor households are also effective in terms of efficiency, but may be harder to administer in some countries than lifeline pricing.Engineering,Environmental Economics&Policies,Economic Theory&Research,Markets and Market Access,Payment Systems&Infrastructure,Environmental Economics&Policies,Economic Theory&Research,Markets and Market Access,Access to Markets,Energy Demand

Supergeometry and Arithmetic Geometry

We define a superspace over a ring $R$ as a functor on a subcategory of the category of supercommutative $R$-algebras. As an application the notion of a $p$-adic superspace is introduced and used to give a transparent construction of the Frobenius map on $p$-adic cohomology of a smooth projective variety over the ring of $p$-adic integers.Comment: 14 pages, expanded introduction, more detail

Some exact results for the velocity of cracks propagating in non-linear elastic models

We analyze a piece-wise linear elastic model for the propagation of a crack in a stripe geometry under mode III conditions, in the absence of dissipation. The model is continuous in the propagation direction and discrete in the perpendicular direction. The velocity of the crack is a function of the value of the applied strain. We find analytically the value of the propagation velocity close to the Griffith threshold, and close to the strain of uniform breakdown. Contrary to the case of perfectly harmonic behavior up to the fracture point, in the piece-wise linear elastic model the crack velocity is lower than the sound velocity, reaching this limiting value at the strain of uniform breakdown. We complement the analytical results with numerical simulations and find excellent agreement.Comment: 9 pages, 13 figure

Statistical Mechanics of Linear and Nonlinear Time-Domain Ensemble Learning

Conventional ensemble learning combines students in the space domain. In this paper, however, we combine students in the time domain and call it time-domain ensemble learning. We analyze, compare, and discuss the generalization performances regarding time-domain ensemble learning of both a linear model and a nonlinear model. Analyzing in the framework of online learning using a statistical mechanical method, we show the qualitatively different behaviors between the two models. In a linear model, the dynamical behaviors of the generalization error are monotonic. We analytically show that time-domain ensemble learning is twice as effective as conventional ensemble learning. Furthermore, the generalization error of a nonlinear model features nonmonotonic dynamical behaviors when the learning rate is small. We numerically show that the generalization performance can be improved remarkably by using this phenomenon and the divergence of students in the time domain.Comment: 11 pages, 7 figure

Finite-distance singularities in the tearing of thin sheets

We investigate the interaction between two cracks propagating in a thin sheet. Two different experimental geometries allow us to tear sheets by imposing an out-of-plane shear loading. We find that two tears converge along self-similar paths and annihilate each other. These finite-distance singularities display geometry-dependent similarity exponents, which we retrieve using scaling arguments based on a balance between the stretching and the bending of the sheet close to the tips of the cracks.Comment: 4 pages, 4 figure

Supersonic crack propagation in a class of lattice models of Mode III brittle fracture

We study a lattice model for mode III crack propagation in brittle materials in a stripe geometry at constant applied stretching. Stiffening of the material at large deformation produces supersonic crack propagation. For large stretching the propagation is guided by well developed soliton waves. For low stretching, the crack-tip velocity has a universal dependence on stretching that can be obtained using a simple geometrical argument.Comment: 4 pages, 3 figure

Screening of charged singularities of random fields

Many types of point singularity have a topological index, or 'charge', associated with them. For example the phase of a complex field depending on two variables can either increase or decrease on making a clockwise circuit around a simple zero, enabling the zeros to be assigned charges of plus or minus one. In random fields we can define a correlation function for the charge-weighted density of singularities. In many types of random fields, this correlation function satisfies an identity which shows that the singularities 'screen' each other perfectly: a positive singularity is surrounded by an excess of concentration of negatives which exactly cancel its charge, and vice-versa. This paper gives a simple and widely applicable derivation of this result. A counterexample where screening is incomplete is also exhibited.Comment: 12 pages, no figures. Minor revision of manuscript submitted to J. Phys. A, August 200