Kink stability, propagation, and length-scale competition in the periodically modulated sine-gordon equation

We have examined the dynamical behavior of the kink solutions of the one-dimensional sine-Gordon equation in the presence of a spatially periodic parametric perturbation. Our study clarifies and extends the currently available knowledge on this and related nonlinear problems in four directions. First, we present the results of a numerical simulation program that are not compatible with the existence of a radiative threshold predicted by earlier calculations. Second, we carry out a perturbative calculation that helps interpret those previous predictions, enabling us to understand in depth our numerical results. Third, we apply the collective coordinate formalism to this system and demonstrate numerically that it reproduces accurately the observed kink dynamics. Fourth, we report on the occurrence of length-scale competition in this system and show how it can be understood by means of linear stability analysis. Finally, we conclude by summarizing the general physical framework that arises from our study.

Our Lady of Guadalupe : contemporary explorations of personal and cultural identity

Since it first appeared, the image of Our Lady of Guadalupe has remained relatively unchanged. In the last thirty-five years, however, this has been changing. Artists are creating new variations of the icon to represent and express their reinterpretations. In some of these more contemporary images, the figure of Guadalupe has changed dramatically, but still retains enough traditional elements to be easily recognizable. Some of these images have been received with mixed results and have even sparked major controversy. These new, and sometimes controversial depictions of Guadalupe, specifically those created by Ester Hernández, Yolanda M. López and Alma López, will be explored here. Although each artist has her own individual motivations and intentions, all of the images presented here explore personal and cultural identity, as well as seek in some way to honor ordinary, human women through the sacred iconography of Our Lady of Guadalupe.

Note from William Croswell to President Kirkland and the Corporation of Harvard College, 1817-1821

This folder contains six documents: three drafts of a brief March 10, 1817, note to Harvard President John Kirkland, with two of the drafts followed by an October 25, 1819, note to the Harvard College Corporation concerning Croswell's work on Harvard's Library Catalogue.

Letters from William Croswell to Redford Webster, 1821 January

This folder contains drafts of two one-page letters, dated January 5, 1821, and January 9, 1821, regarding financial assistance.

Letter from William Croswell to Judge Davis, 1821 January 16-18

Four drafts of a letter to Judge Davis requesting his aid in obtaining payment from Harvard.

Letters from William Croswell to Sarah Bumstead, 1821

This folder contains three letters from Croswell to his sister dated January 19, 1821; February 22, 1821; and March 18, 1821, that mention money and Croswell's activities.

Letter from William Croswell to Charles Stimpson, 1821 March 5

Draft of a one-page letter regarding Croswell's maps of the stars.

Letter from William Croswell to Judge Davis, 1821 March 8

Draft of a letter regarding Croswell's compensation from Harvard.

Letter from William Croswell to Thaddeus Harris, 1821 May 16

Draft of a letter regarding the Harvard Library Catalogue.

Letter from William Croswell to Abraham Biglow, 1821 September 11

Draft of a letter regarding the Harvard Library Catalogue.

Memorials to the Harvard Corporation, 1819 October-1821 June

Six documents containing drafts and copies of eleven letters.

Memorial to the Harvard Corporation, 1821 November

Three drafts of a letter.

Financial bills and receipts, 1820-1821

This folder contains six bills and receipts.

Printed proposal for the works of Horace, 1821

This folder contains two copies of a proposal for publishing the works of Horace.