Fast and Perfect Sampling of Subgraphs and Polymer Systems

We give an efficient perfect sampling algorithm for weighted, connected induced subgraphs (or graphlets) of rooted, bounded degree graphs. Our algorithm utilizes a vertex-percolation process with a carefully chosen rejection filter and works under a percolation subcriticality condition. We show that this condition is optimal in the sense that the task of (approximately) sampling weighted rooted graphlets becomes impossible in finite expected time for infinite graphs and intractable for finite graphs when the condition does not hold. We apply our sampling algorithm as a subroutine to give near linear-time perfect sampling algorithms for polymer models and weighted non-rooted graphlets in finite graphs, two widely studied yet very different problems. This new perfect sampling algorithm for polymer models gives improved sampling algorithms for spin systems at low temperatures on expander graphs and unbalanced bipartite graphs, among other applications

Urban real estate technologies: genealogies, frontiers, & critiques

The production, perception, and representation of urban space and urban property relations have been urgent “technological” questions since before the birth of urban geography as a discipline. The growth and differentiation of cities worldwide has been shaped by a long-evolving technical frontier, one often turned toward the accumulation imperatives and exclusions of private real estate development. Today, real estate in global cities is experiencing a fresh technological boom, featuring novel techniques for real estate mapping, valuation, financialization, and other key functions. This special issue explores and theorizes these technological developments in real estate, past and present. Collected papers articulate urban geographical scholarship with insights from critical political economy and technology studies, including digital geographies. The collection argues that the relational politics of property manifest in crucial ways through the development and application of urban real estate technologies, and that geography and urban planning are well positioned to offer insights into such technological and political economic mediations, both historical and unfolding

Collective Digital Innovation: Integrating The Expertise Of Multiple Specialist Stakeholders Including Young Homeless People In The Creation Of Mobile Apps For Social Change

This paper reports on a collaborative action research project which sought to combine the knowledge and expertise of multiple specialist organisations with the understanding and insight of young homeless people in order to find digital ways of supporting them before they became homeless. We discovered that adopting a collective approach to the demands of digital innovation enabled us to develop precise hypotheses and resulted in mobile apps for young people targeted at specific moments of emotional and practical need. The action research project is reflexively analysed in seeking to understand this process of collective digital innovation

Brainstorming und Mind-Mapping im Multi-Device-Kontext. Konzeption und prototypische Implementierung für Multi-Touch-Tabletop und Smartphone

Die vorliegende Arbeit beschreibt die Konzeption und prototypische Implemen­tierung einer Anwendung zur elektronischen Unterstützung von Brainstorming- und Mind-Mapping-Sitzungen an einem multitouchfähigen Tabletop mit Smart­phones. Während der Tabletop durch seine große, horizontal ausgerichtete Oberfläche die kollaborative Erstellung und Strukturierung von Ideen in Gruppen unterstützt, werden Smartphones einen zusätzlichen Eingabekanal zur Verfügung stellen sowie Individualarbeit fördern. Somit wird zunächst einerseits die Motivation für die Verwirklichung einer Anwendung zum Brainstorming und Mind- Mapping am Tabletop und andererseits das Potential einer Ergänzung eines sol­chen Systems durch zusätzliche private Geräte im Sinne der Multi-Device-Inter­aktion erläutert werden. Um eine geeignete theoretische Basis zu schaffen, wird darüber hinaus ein detaillierter Überblick über die Entwicklung der Tabletop­technologie in den letzten Jahren und den dabei zentralen Forschungs- und Pro­blemfeldern im Kontext der Entwicklung von Benutzerschnittstellen für Tabletopsysteme gegeben. Zudem werden schließlich auch im Rahmen der Arbeit relevante Aspekte der Multi-Device-Interaktion skizziert. Diesem theoretisch ausgerichteten Teil der Arbeit folgt schließlich eine Beschreibung der Entwicklung des Anwendungskonzepts und der dabei formulierten Anforderungen und Designzielen, welche in Form eines ersten, papierbasierten Prototypen visualisiert werden. Aufbauend auf diesen konzeptuellen Überlegungen wird schließlich die konkrete technische Umsetzung der Anwendung Multi/Touch/Device Mind­ Mapper in Form eines High-Level-Prototypen auf Basis des MT4j-Frameworks (Tabletop) und des Android-Betriebssystems (Smartphone) beleuchtet. Eine Dis­kussion dieses finalen Prototypen und erster praktischer Erfahrungen sowie ein Ausblick auf Erweiterungsmöglichkeiten des Systems und über den Rahmen der Arbeit hinaus gehende Fragestellungen schließen die Arbeit ab. Schlussendlich kann gezeigt werden, dass die im Rahmen des Anwendungskonzept definierten Anforderungen mit Hilfe der verwendeten Frameworks bis auf wenige Ausnahmen erfolgreich umgesetzt werden konnten. Darüber hinaus kann der Anwendung durch die aus dem Testbetrieb gewonnenen Erkenntnisse eine grundsätzli­ che Praktikabilität attestiert, ebenso konnten einige Ansatzpunkte für weitere Verbesserungen und Tests aufgedeckt werden

Decision-Making by and for Academic Libraries during Covid-19

Academic libraries are fundamental in promoting equitable access to education but are often overlooked and underfunded. The COVID-19 pandemic amplified these inequities. This study investigates how 39 library deans and directors perceived decision-making by university administration during COVID-19’s onset. Open-ended survey questions were sent to deans and directors asking them to describe their experiences working with university administration to adjust library services during the crisis. Some library leaders reported that working closely with other departments strengthened their campus connections. Others commented that disagreement between library personnel and university administration caused discord. Some deans and directors were forced to cut staff funding or felt pressured to reopen, while others were trusted to choose their budget and service priorities. The authors recommend that library leaders be more consistently relied upon for their expertise during university decision-making

A spatially explicit degree-day model of Rift Valley fever transmission risk in the continental United States

A spatially explicit degree-day model was used to evaluate the risk of Rift Valley fever virus (RVFV) transmission by mosquitoes to humans and livestock within five target states in the continental United States: California, Minnesota, Nebraska, New York, and Texas. A geographic information system was used to model potential virus transmission based on a 12-day moving window assessment of the extrinsic incubation period theorized for RVFV in the United States. Risk of potential virus transmission in each state was spatially evaluated on a 10-km grid using average historical daily temperature data from 1994 to 2003. The highest levels of transmission risk occur in California and Texas, with parts of these states at risk of RVFV transmission for up to 8 months per year. Northern Minnesota, central New York, and most of coastal and high-elevation California are at low to null risk. Risk of impact to the livestock industry is greatest in California, Texas, and Nebraska. A standard global climate model was used to evaluate future risk in the year 2030 in Nebraska, and showed an increase of transmission risk days from approximately 3 to 4 months per year

Task Force on the StaffWeb: Final Report

On 30 March 1999, a StaffWeb Committee was created to make recommendations about the future development, content, and maintenance of the StaffWeb. This is a final report

Engine of Innovation: Building the High-Performance Catalog

Numerous studies have indicated that sophisticated web-­based search engines have eclipsed the primary importance of the library catalog as the premier tool for researchers in higher education. We submit that the catalog remains central to the research process. Through a series of strategic enhancements, the University of North Carolina at Chapel Hill, in partnership with the other members of the Triangle Research Libraries Network (TRLN), has made the catalog a carrier of services in addition to bibliographic data, facilitating not simply discovery, but also delivery of the information researchers seek