Is charity a homogeneous good?

In this paper I estimate income and price elasticities of donations to six different charitable causes to test the assumption that charity is a homogeneous good. In the US, charitable donations can be deducted from taxable income. This has long been recognized as producing a price, or taxprice, of giving equal to one minus the marginal tax rate faced by the donor. A substantial portion of the economic literature on giving has focused on estimating price and income elasticities of giving as the received wisdom suggests that a price elasticity greater than unity is indicative of the ‘treasury efficiency’ of the tax deductibility of charitable contributions, as the loss to tax revenue is less than the increase in giving. However, a major limitation of nearly all the previous attempts to identify such effects has been the implicit assumption that charity is a homogeneous good, meaning giving to one type of charity is a perfect substitute for any other and that the causespecific responsiveness of giving to changes in price and income is equal across those causes. If this assumption is violated, then estimates may be biased and policies designed to increase charitable contributions may be sub-optimal. Results suggest that the tax-price of giving only affects giving to religious organisations and that the income effect is invariant over charitable causes

Isotropic probability measures in infinite dimensional spaces: Inverse problems/prior information/stochastic inversion

Let R be the real numbers, R(n) the linear space of all real n-tuples, and R(infinity) the linear space of all infinite real sequences x = (x sub 1, x sub 2,...). Let P sub n :R(infinity) approaches R(n) be the projection operator with P sub n (x) = (x sub 1,...,x sub n). Let p(infinity) be a probability measure on the smallest sigma-ring of subsets of R(infinity) which includes all of the cylinder sets P sub n(-1) (B sub n), where B sub n is an arbitrary Borel subset of R(n). Let p sub n be the marginal distribution of p(infinity) on R(n), so p sub n(B sub n) = p(infinity)(P sub n to the -1(B sub n)) for each B sub n. A measure on R(n) is isotropic if it is invariant under all orthogonal transformations of R(n). All members of the set of all isotropic probability distributions on R(n) are described. The result calls into question both stochastic inversion and Bayesian inference, as currently used in many geophysical inverse problems

Completeness of Inertial Modes of an Incompressible Non-Viscous Fluid in a Corotating Ellipsoid

Inertial modes are the eigenmodes of contained rotating fluids restored by the Coriolis force. When the fluid is incompressible, inviscid and contained in a rigid container, these modes satisfy Poincar\'e's equation that has the peculiarity of being hyperbolic with boundary conditions. Inertial modes are therefore solutions of an ill-posed boundary-value problem. In this paper we investigate the mathematical side of this problem. We first show that the Poincar\'e problem can be formulated in the Hilbert space of square-integrable functions, with no hypothesis on the continuity or the differentiability of velocity fields. We observe that with this formulation, the Poincar\'e operator is bounded and self-adjoint and as such, its spectrum is the union of the point spectrum (the set of eigenvalues) and the continuous spectrum only. When the fluid volume is an ellipsoid, we show that the inertial modes form a complete base of polynomial velocity fields for the square-integrable velocity fields defined over the ellipsoid and meeting the boundary conditions. If the ellipsoid is axisymmetric then the base can be identified with the set of Poincar\'e modes, first obtained by Bryan (1889), and completed with the geostrophic modes.Comment: 19 pages, 1 figure, to appear in Physical Review

Modeling currents at satellite altitudes

A mathematical formalism for modeling the poloidal magnetic field and current density at satellite altitudes is presented

Comparing hard and soft prior bounds in geophysical inverse problems

In linear inversion of a finite-dimensional data vector y to estimate a finite-dimensional prediction vector z, prior information about X sub E is essential if y is to supply useful limits for z. The one exception occurs when all the prediction functionals are linear combinations of the data functionals. Two forms of prior information are compared: a soft bound on X sub E is a probability distribution p sub x on X which describeds the observer's opinion about where X sub E is likely to be in X; a hard bound on X sub E is an inequality Q sub x(X sub E, X sub E) is equal to or less than 1, where Q sub x is a positive definite quadratic form on X. A hard bound Q sub x can be softened to many different probability distributions p sub x, but all these p sub x's carry much new information about X sub E which is absent from Q sub x, and some information which contradicts Q sub x. Both stochastic inversion (SI) and Bayesian inference (BI) estimate z from y and a soft prior bound p sub x. If that probability distribution was obtained by softening a hard prior bound Q sub x, rather than by objective statistical inference independent of y, then p sub x contains so much unsupported new information absent from Q sub x that conclusions about z obtained with SI or BI would seen to be suspect

Ban on castration of boars in the Netherlands: modeling economic consequences of options

As a result of social criticism on castration, the Netherlands intend to start fattening boars. The great obstacle to a ban on castration is the expected negative effect on international trade because of the fear of boar taint. Consumers’ perception of boar taint is investigated, and a summary is presented of the knowledge gained up to the present to reduce boar taint. Advantaged and drawbacks of several alternatives are assessed. An economic chain- and import/export model has been developed to estimate economic consequences. The total added value of the pig farmers' chain will significantly reduce, but there is much uncertainty of the estimation of market acceptance and prices. A further elaboration of the model is proposed, with an assessment of the optimal mix of alternative

Moving towards boar taint-free meat: an overview of alternatives to surgical castration from a chain perspective

The objective of this study is to review important issues in boar taint prevention without surgical castration, namely alternatives to surgical castration, factors influencing boar taint development and economic considerations associated with the presently feasible alternatives to surgical castration. The paper looks at these issues from the pig production chain perspective and suggests a framework for the analysis of boar taint prevention without surgical castration within the whole-chain contex