Who Killed the Rule Against Perpetuities?

During the last two decades more than half the states have either abolished or substantially weakened the traditional rule against perpetuities. The increased demand for perpetual trusts is widely attributed to the ability of such trusts to avoid federal wealth transfer taxes. Furthermore, recent empirical studies confirm a correlation between repeal of the rule against perpetuities (coupled with favorable state income tax treatment) and increased personal trust assets and average account size. This symposium article discusses the asymmetric benefits and drawbacks of perpetual trusts and concludes that the decline of the rule against perpetuities cannot be explained solely in terms of rational tax planning

Social Security Reform: Lessons from Private Pensions

Widespread concerns about the long-term fiscal gap in Social Security have prompted various proposals for structural reform, with individual accounts as the centerpiece. Carving out individual accounts from the existing system would shift significant risks and responsibilities to individual workers. A parallel development has already occurred in the area of private pensions. Experience with 401(k) plans indicates that many workers will have difficulty making prudent decisions concerning investment and withdrawal of funds. Moreover, in implementing any system of voluntary individual accounts, it will be important to design default settings that provide appropriate guidance for workers with heterogeneous levels of financial sophistication and risk tolerance. The central goal of Social Security reform should be to close the fiscal gap in a way that preserves rather than undermines the existing system of mandatory defined benefits for all workers

Nanometer-scale sharpness in corner-overgrown heterostructures

A corner-overgrown GaAs/AlGaAs heterostructure is investigated with transmission and scanning transmission electron microscopy, demonstrating self-limiting growth of an extremely sharp corner profile of 3.5 nm width. In the AlGaAs layers we observe self-ordered diagonal stripes, precipitating exactly at the corner, which are regions of increased Al content measured by an XEDS analysis. A quantitative model for self-limited growth is adapted to the present case of faceted MBE growth, and the corner sharpness is discussed in relation to quantum confined structures. We note that MBE corner overgrowth maintains nm-sharpness even after microns of growth, allowing the realization of corner-shaped nanostructures.Comment: 4 pages, 3 figure

Smoothing a Rock by Chipping

We investigate an idealized model for the size reduction and smoothing of a polygonal rock due to repeated chipping at corners. Each chip is sufficiently small so that only a single corner and a fraction of its two adjacent sides are cut from the object in a single chipping event. After many chips have been cut away, the resulting shape of the rock is generally anisotropic, with facet lengths and corner angles distributed over a broad range. Although a well-defined shape is quickly reached for each realization, there are large fluctuations between realizations.Comment: 7 pages, 10 figures, 2-column revtex4 format; version 2: final published form in PRE; contains minor changes in response to referee comment