How Much of the Web Is Archived?

Although the Internet Archive's Wayback Machine is the largest and most well-known web archive, there have been a number of public web archives that have emerged in the last several years. With varying resources, audiences and collection development policies, these archives have varying levels of overlap with each other. While individual archives can be measured in terms of number of URIs, number of copies per URI, and intersection with other archives, to date there has been no answer to the question "How much of the Web is archived?" We study the question by approximating the Web using sample URIs from DMOZ, Delicious, Bitly, and search engine indexes; and, counting the number of copies of the sample URIs exist in various public web archives. Each sample set provides its own bias. The results from our sample sets indicate that range from 35%-90% of the Web has at least one archived copy, 17%-49% has between 2-5 copies, 1%-8% has 6-10 copies, and 8%-63% has more than 10 copies in public web archives. The number of URI copies varies as a function of time, but no more than 31.3% of URIs are archived more than once per month.Comment: This is the long version of the short paper by the same title published at JCDL'11. 10 pages, 5 figures, 7 tables. Version 2 includes minor typographical correction

Evaluating the Temporal Coherence of Archived Pages

PDF of a powerpoint presentation from the International Internet Preservation Consortium (IIPC) 2015 Conference at Stanford University, April 28, 2015. Also available on Slideshare.https://digitalcommons.odu.edu/computerscience_presentations/1004/thumbnail.jp

Marine heatwave hotspots in coral reef environments: physical drivers, ecophysiological outcomes and impact upon structural complexity

A changing climate is driving increasingly common and prolonged marine heatwaves (MHWs) and these extreme events have now been widely documented to severely impact marine ecosystems globally. However MHWs have rarely recently been considered when examining temperature-induced degradation of coral reef ecosystems. Here we consider extreme, localised thermal anomalies, nested within broader increases in sea surface temperature, which fulfil the definitive criteria for MHWs. These acute and intense events, referred to here as MHW hotspots, are not always well represented in the current framework used to describe coral bleaching, but do have distinct ecological outcomes, including widespread bleaching and rapid mass mortality of putatively thermally tolerant coral species. The physical drivers of these localised hotspots are discussed here, and in doing so we present a comprehensive theoretical framework that links the biological responses of the coral photo-endosymbiotic organism to extreme thermal stress and ecological changes on reefs associated after MHW hotspots. We describe how the rapid onset of high temperatures drives immediate heat-stress induced cellular damage, overwhelming mechanisms that would otherwise mitigate the impact of gradually accumulated thermal stress. The warm environment, and increased light penetration of the coral skeleton due to the loss of coral tissues, coupled with coral tissue decay support rapid microbial growth in the skeletal microenvironment, resulting in the widely unrecognised consequence of rapid decay and degeneration of the coral skeletons. This accelerated degeneration of the coral skeletonson a reef scale hinder the recovery of coral populations and increase the likelihood of phase shifts towards algal dominance. We suggest that MHW hotspots, through driving rapid heat-induced mortality, compromise reefs' structural frameworks to the detriment of long term recovery. We propose that MHW hotspots be considered as a distinct class of thermal stress events in coral reefs, and that the current framework used to describe coral bleaching and mass mortality be expanded to include these. We urge further research into how coral mortality affects bioerosion by coral endoliths

Implementing Time Travel for the Web

This article discusses the challenges and solutions discovered for implementing the Memento protocol in a variety of browser environments. It describes the design and deployment of the client technologies which have been developed: a web application that functioned as a browser, an add-on for FireFox called MementoFox, a plugin for Internet Explorer and an Android-based client application. The design and technical solutions identified during the development will be of interest to those considering implementation of a Memento based platform, especially on the client side, however the interactions are also important for building conformant server-side systems

Memento: Time Travel for the Web

PDF of a powerpoint presentation from the Web UNC Scholarly Communications Working Group Meeting, Chapel Hill, North Carolina, November 10, 2010. Also available on Slideshare.https://digitalcommons.odu.edu/computerscience_presentations/1020/thumbnail.jp

Towards an Efficient Finite Element Method for the Integral Fractional Laplacian on Polygonal Domains

We explore the connection between fractional order partial differential equations in two or more spatial dimensions with boundary integral operators to develop techniques that enable one to efficiently tackle the integral fractional Laplacian. In particular, we develop techniques for the treatment of the dense stiffness matrix including the computation of the entries, the efficient assembly and storage of a sparse approximation and the efficient solution of the resulting equations. The main idea consists of generalising proven techniques for the treatment of boundary integral equations to general fractional orders. Importantly, the approximation does not make any strong assumptions on the shape of the underlying domain and does not rely on any special structure of the matrix that could be exploited by fast transforms. We demonstrate the flexibility and performance of this approach in a couple of two-dimensional numerical examples

Assessing the Quality of Web Archives

PDF of a powerpoint presentation from the 2014 Digital Preservation Meeting, Washington D. C., July 22-23, 2014. Also available from Slideshare.https://digitalcommons.odu.edu/computerscience_presentations/1010/thumbnail.jp

2024 Wheelchair Compendium of Physical Activities: An Update of Activity Codes and Energy Expenditure Values

Purpose: This paper presents an update of the 2011 Wheelchair Compendium of Physical Activities designed for wheelchair users and is referred to as the 2024 Wheelchair Compendium. The Wheelchair Compendium aims to curate existing knowledge of the energy expenditure for wheelchair physical activities (PAs). Methods: A systematic review of the published energy expenditure of PA for wheelchair users was completed between 2011 and May 2023. We added these data to the 2011 Wheelchair Compendium data that was compiled previously in a systematic review through 2011. Results: A total of 47 studies were included, and 124 different wheelchair PA reported energy expenditure values ranging from 0.8 metabolic equivalents for wheelchair users (filing papers, light effort) to 11.8 metabolic equivalents for wheelchair users (Nordic sit skiing). Conclusion: In introducing the updated 2024 Wheelchair Compendium, we hope to bridge the resource gap and challenge the prevailing narratives that inadvertently exclude wheelchair users from physical fitness and health PAs