A Differentiation Theory for It\^o's Calculus

A peculiar feature of It\^o's calculus is that it is an integral calculus that gives no explicit derivative with a systematic differentiation theory counterpart, as in elementary calculus. So, can we define a pathwise stochastic derivative of semimartingales with respect to Brownian motion that leads to a differentiation theory counterpart to It\^o's integral calculus? From It\^o's definition of his integral, such a derivative must be based on the quadratic covariation process. We give such a derivative in this note and we show that it leads to a fundamental theorem of stochastic calculus, a generalized stochastic chain rule that includes the case of convex functions acting on continuous semimartingales, and the stochastic mean value and Rolle's theorems. In addition, it interacts with basic algebraic operations on semimartingales similarly to the way the deterministic derivative does on deterministic functions, making it natural for computations. Such a differentiation theory leads to many interesting applications some of which we address in an upcoming article.Comment: 10 pages, 9/9 papers from my 2000-2006 collection. I proved these results and more earlier in 2004. I generalize this theory in upcoming articles. I also apply this theory in upcoming article

The Medical and the Anti-Modern: Horse-and-Buggy Mennonite Migrants and Medicine in Latin America

How did migrants from “old” societies negotiate their “new worlds”? How did they make the move from simple to complex societies, from village culture to urban society, from folk medicine to modern, state-sanctioned medicine? In this essay, I explore the question of medicine and social boundaries in an instance in which this trajectory of the primitive-to-the-modern has been complicated. It considers the medical history within a recent set of migrations that aimed to distance a people from modernity rather than integrate them into it. It argues that although the lure of modern medicine to any immigrant is relentless, the relationship of this medicine and the immigrant is also always a contested exchange.Comment des migrants originaires des « vieilles » sociétés se sont-ils insérés dans leurs « nouveaux mondes » ? Comment sont-ils passés d’une société simple à une société complexe, de la culture villageoise à la société urbaine, de la médecine traditionnelle à la médecine moderne, approuvée par l’État ? Dans cet essai, l’auteur explore la question de la médecine et des frontières sociales dans un cas où la trajectoire menant du primitif au moderne a été compliquée. Il envisage les rapports à la médecine à l’intérieur d’une série de migrations récentes qui visaient à éloigner une population de la modernité plutôt qu’à l’y intégrer. Selon lui, si la médecine moderne exerce continuellement de l’attirance sur tout immigrant, le recours à celle-ci est également toujours un échange contesté

U.S. Climate Change Policy Under President Clinton: A Look Back

This article describes the evolution of the Clinton Administration\u27s policy on climate change and point to factors that influenced its deliberations. It focuses on the U.S. positions in international negotiations, international reaction to these positions, and domestic policies and politics that influenced these positions. More detailed analyses of certain issues - such as full descriptions of all the climate change-related activities undertaken by the federal government, both abroad and at home - are beyond the scope of this article

Competing Cosmologies: Reading Migration and Identity in an Ethno-religious Newspaper

Between 1977 and 2000, the Mennonitische Post, a Canadian-based newspaper, published thousands of letters by members of a unique diaspora. The extended community of Mennonites whose grandparents had emigrated from Canada in the 1920s to resist the imposition of English-language public schools now rediscovered old ties within the pages of this newspaper. It was, however, a divided community: many of the children and grandchildren of the emigrants had “returned” to middle-class Canada; others had built “horse and buggy” communities in Central and South America. Yet the two groups shared the literary space of the Post, and in doing so they engaged in an intricate task of setting boundaries, both external and internal. This essay thus considers how immigrants speak to one another through letters published in ethnic newspapers in transnational contexts. When they do so, they enter a complex, multilayered discussion, articulating not only a common social boundary between the diasporic community and the host society, but significantly, self-validating sub-lines built on competing cosmologies within the diaspora.Entre 1977 et 2000, le Mennonitische Post, un journal qui a son siège au Canada, publia des milliers de lettres provenant de membres d’une incomparable diaspora. La communauté étendue des mennonites dont les grands-parents avaient émigré du Canada dans les années 1920 afin de résister à l’imposition d’écoles publiques de langue anglaise redécouvrit alors des liens anciens dans les pages de ce journal. Il s’agissait cependant d’une communauté divisée : bon nombre d’enfants et de petits-enfants des émigrants étaient « rentrés » au Canada où ils faisaient partie de la classe moyenne; d’autres, par contre, avaient formé en Amérique centrale ou en Amérique du Sud des communautés utilisant encore le cheval de trait. Les deux groupes partagèrent pourtant les pages du Post consacrées au courrier des lecteurs, assumant de la sorte une tâche complexe : celle consistant à fixer des frontières, à la fois intérieures et extérieures. Nous examinons ici la façon dont des immigrants se sont parlé par le truchement de lettres publiées dans des journaux ethnoculturels en contexte transnational. Ce faisant, ces gens ont amorcé un débat complexe, multidimensionnel, qui, en plus de donner expression à une frontière sociale commune entre la communauté diasporique et la société d’accueil, a validé par lui-même des sous-entendus reposant sur des cosmologies concurrentes à l’intérieur de la diaspora

Review of: \u3cem\u3eA Geography of the Hutterites of North America\u3c/em\u3e—Simon M. Evans

Imagine a complex academic book without a subtitle: straightforward, lucid, accessible. These qualities describe Simon Evans’ final word on Hutterites of the western plains of Canada and the United States. It’s an historical geography, distinctive from the more numerous social scientific studies of the Hutterites. It methodically traces the dispersion of an 1870s Dakota settlement into Manitoba and Alberta during World War I, and then into Montana and Saskatchewan after World War II, with small representations in Washington State and British Columbia. Along the way, Evans deepens his analysis and interlaces theological consideration, demographic change, ecological intrusion, marketplace engagement, political interaction, gender relations, and internecine differences with the geographer’s craft, spatial arrangement. Indeed, these various intersections make for a richly textured historical geography that no subtitle could capture. And they rely on Evans’ own expansive on-colony ethnography, rich map collections, and broad engagement with a multi-disciplinary secondary literature. In the process Evans gives us a fresh look at the Hutterites and produces a historical geography that does much more than document the Hutterite diaspora in the North American grassland. [First paragraph.

You Make Yourself Human

A safari in Africa becomes a journey of painful self-discovery

Review of \u3ci\u3eDutch Farmer in the Missouri Valley: The Life and Letters of Ulbe Eringa, 1866-1950\u3c/i\u3e By Brian W. Beltman

How large should an immigrant community be to shed light effectively on the wider immigrant experience? This is a subject of frequent debate. Here is an excellent study of immigration to the American Midwest based on a single person, a Dutch farmer, Ulbe Eringa. And for the better part of the book, Eringa himself speaks through memoir and letter, translated from the Dutch by a daughter. The narration and reproduced texts recreate Eringa\u27s life story. It begins with his birth in 1866 to a dairy farming family in western Friesland and continues through his early formative years in Calvinist schools and his pitiful teenaged years as an orphaned servant. In 1892, at twenty-six, he migrated to the United States, joining the Dutch farm community of Sioux County, Iowa. Within a year he moved on to better fortune in Bon Homme County, Dakota. Here in 1899 he and his wife, Maaike Rypstra, a fellow lower-class Frisian, became land owners. They also became central players in the community, assisting Frisian chain migrants and supporting the local Dutch Reformed church. Over the next thirty years the Eringas raised six children, increased their land holdings to 640 acres, secured a college education for several of their daughters, and passed the farm on to their only son, Pier. In 1926 the Eringas returned to Iowa to settle in a town, and here in 1949 Ulbe wrote his last known letter. He died a year later

Computing heading in the presence of moving objects: a model that uses motion-opponent operators

AbstractPsychophysical experiments have shown that human heading judgments can be biased by the presence of moving objects. Here we present a theoretical argument that motion differences can account for the direction of bias seen in humans. We further examine the responses of a computer simulation of a model for computing heading that uses motion-opponent operators similar to cells in the primate middle temporal visual area. When moving objects are present, this model shows similar biases to those seen with humans, suggesting that such a model may underlie human heading computations