A map-based place-browser for a PDA

This article describes PlaceBrowser, a PDA based application that allows the user of the application to navigate around an area of geographical interest, such as a city, using a zoomable, panable hierarchy of aerial images, in a fashion similar to Google Maps. The novel aspect to the work is that an area of precise interest within the map can be pin-pointed by the user by directly dragging out a rectangular area on the map. This forms the source to a spatial search that returns landmarks that are then used to trigger a Web based query. The results of this query are displayed to the user. The net effect is that, in response to dragging out a rectangular area, web pages that are relevant to this area but have not been explicitly geo-spatially tagged with metadata (longitude,latitude) are shown to the user

Horocycle dynamics: new invariants and eigenform loci in the stratum H(1,1)

We study dynamics of the horocycle flow on strata of translation surfaces, introduce new invariants for ergodic measures, and analyze the interaction of the horocycle flow and real Rel surgeries. We use this analysis to complete and extend results of Calta and Wortman classifying horocycle-invariant measures in the eigenform loci. We classify the orbit-closures and prove that every orbit is equidistributed in its orbit-closure. We also prove equidistribution statements regarding limits of sequences of measures, some of which have applications to counting problems.Comment: 100 page

Digital libraries on an iPod: Beyond the client-server model

This paper describes an experimental system that enhanced an iPod with digital library capabilities. Using the open source digital library software Greenstone as a base, this paper more specifically maps out the technical steps necessary to achieve this, along with an account of our subsequent experimentation. This included command-line usage of Greenstone's basic runtime system on the device, augmenting the iPod’s main interactive menu-driven application to include searching and hierarchical browsing of digital library collections stored locally, and a selection of "launcher" applications for target documents such as text files, images and audio. Media rich applications for digital stories and collaging were also developed. We also configured the iPod to run as a web server to provide digital library content to others over a network, effectively turning the traditional mobile client-server upsidedown

Digital libraries for creative communities

Digital library technologies have a great deal to offer to creative, design communities. They can enable large collections of text, images, music, video and other information objects to be organised and accessed in interesting and diverse ways. Ordinary people—people not traditionally viewed as 'creators' or 'designers'—can now conceive, assemble, build, and disseminate new information collections. This paper explores the development rationale behind the Greenstone digital library technology. We also examine three examples of creative new techniques for accessing and presenting information in digital libraries and stress the importance of tailoring information access to support the requirements of the users and application area

Strata of k-differentials

A k-differential on a Riemann surface is a section of the kth power of the canonical line bundle. Loci of k-differentials with prescribed number and multiplicities of zeros and poles form a natural stratification of the moduli space of k-differentials. In this paper, we give a complete description for the compactification of the strata of k-differentials in terms of pointed stable k-differentials, for all k. The upshot is a global k-residue condition that can also be reformulated in terms of admissible covers of stable curves. Moreover, we study properties of k-differentials regarding their deformations, residues, and at geometric structure