“A home-like atmosphere”: The advent of children’s rooms at St. Louis Public Library, 1906–1912

Most public libraries in the United States did not include collections, rooms, or librarians dedicated to work with children until the early twentieth century. The establishment of children’s rooms as a customary feature of U.S. public libraries coincided with bequests to public libraries by the Carnegie Corporation. One such library, St. Louis (Missouri) Public Library, provides an example of how large, urban library systems expanded to included neighborhood branches as well as a central branch building, all of which contained a purpose-built space for work with children. As branch buildings with children’s rooms emerged, so did the need for trained children’s librarians. Paradoxically, as soon as there were rooms dedicated to children, librarians extended their reach to municipal playgrounds, schools, and other venues outside of the library. Children’s librarians found themselves traversing a variety of spaces, serving a diverse population in multiple sites.published or submitted for publicationOpe

Three-body Casimir-Polder interactions

As part of our program to develop the description of three-body effects in quantum vacuum phenomena, we study the three-body interaction of two anisotropically polarizable atoms with a perfect electrically conducting plate, a generalization of earlier work. Three- and four-scattering effects are important, and lead to nonmonotonic behavior.Comment: 10 pages, 5 figures, for the proceedings of the conference Mathematical Structures in Quantum Systems, Benasque, Spain, July 2012, to be published in Nuovo Ciment

Electromagnetic Non-contact Gears: Prelude

We calculate the lateral Lifshitz force between corrugated dielectric slabs of finite thickness. Taking the thickness of the plates to infinity leads us to the lateral Lifshitz force between corrugated dielectric surfaces of infinite extent. Taking the dielectric constant to infinity leads us to the conductor limit which has been evaluated earlier in the literature.Comment: 7 pages, 2 figures, Contribution to Proceedings of 9th Conference on Quantum Field Theory Under the Influence of External Conditions (QFEXT09), Norman, OK, September 21-25, 200

Positioning adolescents in literacy teaching and learning

Secondary literacy instruction often happens to adolescents rather than with them. To disrupt this trend, we collaborated with 12th-grade “literacy mentors” to reimagine literacy teaching and learning with 10th-grade mentees in a public high school classroom. We used positioning theory as an analytic tool to (a) understand how mentors positioned themselves and how we positioned them and (b) examine the literacy practices that enabled and constrained the mentor position. We found that our positioning of mentors as collaborators was taken up in different and sometimes unexpected ways as a result of the multiple positions available to them and institutional-level factors that shaped what literacy practices were and were not negotiable. We argue that future collaborations with youth must account for the rights and duties of all members of a classroom community, including how those rights and duties intersect, merge, or come into conflict within and across practices.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was supported by a Faculty Research Award from the School of Education at Boston University. (Faculty Research Award from the School of Education at Boston University)Accepted manuscrip

PT-Symmetric Quantum Electrodynamics and Unitarity

More than 15 years ago, a new approach to quantum mechanics was suggested, in which Hermiticity of the Hamiltonian was to be replaced by invariance under a discrete symmetry, the product of parity and time-reversal symmetry, $\mathcal{PT}$. It was shown that if $\mathcal{PT}$ is unbroken, energies were, in fact, positive, and unitarity was satisifed. Since quantum mechanics is quantum field theory in 1 dimension, time, it was natural to extend this idea to higher-dimensional field theory, and in fact an apparently viable version of $\mathcal{PT}$-invariant quantum electrodynamics was proposed. However, it has proved difficult to establish that the unitarity of the scattering matrix, for example, the K\"all\'en spectral representation for the photon propagator, can be maintained in this theory. This has led to questions of whether, in fact, even quantum mechanical systems are consistent with probability conservation when Green's functions are examined, since the latter have to possess physical requirements of analyticity. The status of $\mathcal{PT}$QED will be reviewed in this report, as well as the general issue of unitarity.Comment: 13 pages, 2 figures. Revised version includes new evidence for the violation of unitarit