Homogenization of lateral diffusion on a random surface

We study the problem of lateral diffusion on a static, quasi-planar surface generated by a stationary, ergodic random field possessing rapid small-scale spatial fluctuations. The aim is to study the effective behaviour of a particle undergoing Brownian motion on the surface viewed as a projection on the underlying plane. By formulating the problem as a diffusion in a random medium, we are able to use known results from the theory of stochastic homogenization of SDEs to show that, in the limit of small scale fluctuations, the diffusion process behaves quantitatively like a Brownian motion with constant diffusion tensor $D$. While $D$ will not have a closed-form expression in general, we are able to derive variational bounds for the effective diffusion tensor, and using a duality transformation argument, obtain a closed form expression for $D$ in the special case where $D$ is isotropic. We also describe a numerical scheme for approximating the effective diffusion tensor and illustrate this scheme with two examples.Comment: 25 pages, 7 figure

Ancestry versus ethnicity: the complexity and selectivity of Mexican identification in the United States

Using microdata from the 2000 U.S. Census, we analyze the responses of Mexican Americans to questions that independently elicit their “ethnicity” (or Hispanic origin) and their “ancestry.” We investigate whether different patterns of responses to these questions reflect varying degrees of ethnic attachment. For example, those identified as “Mexican” in both the Hispanic origin and the ancestry questions might have stronger ethnic ties than those identified as Mexican only in the ancestry question. How U.S.-born Mexicans report their ethnicity/ancestry is strongly associated with measures of human capital and labor market performance. In particular, educational attainment, English proficiency, and earnings are especially high for men and women who claim a Mexican ancestry but report their ethnicity as “not Hispanic.” Further, intermarriage and the Mexican identification of children are also strongly related to how U.S.-born Mexican adults report their ethnicity/ancestry, revealing a possible link between the intergenerational transmission of Mexican identification and economic status

Intermarriage and the intergenerational transmission of ethnic identity and human capital for Mexican Americans

Using microdata from the 2000 U.S. Census and from recent years of the Current Population Survey (CPS), we investigate whether selective intermarriage and endogenous ethnic identification interact to hide some of the intergenerational progress achieved by the Mexican-origin population in the United States. First, using Census data for U.S.-born youth ages 16-17 who have at least one Mexican parent, we estimate how the Mexican identification, high school dropout rates, and English proficiency of these youth depend on whether they are the product of endogamous or exogamous marriages. Second, we analyze the extent and selectivity of ethnic attrition among second-generation Mexican-American adults and among U.S.-born Mexican-American youth. Using CPS data, we directly assess the influence of endogenous ethnicity by comparing an “objective” indicator of Mexican descent (based on the countries of birth of the respondent and his parents and grandparents) with the standard “subjective” measure of Mexican self-identification (based on the respondent’s answer to the Hispanic origin question). For third-generation Mexican-American youth, we show that ethnic attrition is substantial and could produce significant downward bias in standard measures of attainment which rely on ethnic self-identification rather than objective indicators of Mexican ancestry

An examination of the fraud liability shift in consumer card-based payment systems

Identity theft ; Fraud ; Payment systems

Treaty Self-Execution as “Foreign” Foreign Relations Law?

This contribution to the Oxford Handbook on Comparative Foreign Relations considers how a state’s approach to foreign relations problems may have an external origin, or what we call “foreign” Foreign Relations Law (FFRL). Using the distinction between self-executing and non-self-executing treaties as a case study, we find close parallels between manifestations of this distinction in various states and how it evolved in the United States, where the distinction was first articulated. The chapter explores whether these parallels reflect the distinction’s transplantation from one legal system to another or the organic development of similar doctrines to address similar problems within the states involved. The chapter then addresses the utility of differentiating the exogenous/endogenous origins of particular foreign relations doctrines. We argue that consideration of a doctrine’s exogenous origins raises questions that can deepen and develop the nascent field of comparative foreign relations law. Why do states accept (or reject) FFRL? How does FFRL enter a state’s system? Who is doing the transporting? What happens to FFRL in its new site(s) – i.e., how static or dynamic does the concept prove in different settings? Further research on such questions may, in turn, set the table for more normative questions such as when states should seek (or resist) the importation of foreign relations law

Editorial: choosing new targets for rheumatoid arthritis therapeutics: too interesting to fail?

No abstract available