Preservation in the age of large-scale digitization

The digitization of millions of books under programs such as Google Book Search and Microsoft Live Search Books is dramatically expanding our ability to search and find information. The aim of these large-scale projects?to make content accessible?is interwoven with the question of how one keeps that content, whether digital or print, fit for use over time. This report by Oya Y. Rieger examines large-scale digital initiatives (LSDIs) to identify issues that will influence the availability and usability, over time, of the digital books these projects create. Ms. Rieger is interim assistant university librarian for digital library and information technologies at the Cornell University Library. The paper describes four large-scale projects?Google Book Search, Microsoft Live Search Books, Open Content Alliance, and the Million Book Project?and their digitization strategies. It then discusses a range of issues affecting the stewardship of the digital collections they create: selection, quality in content creation, technical infrastructure, and organizational infrastructure. The paper also attempts to foresee the likely impacts of large-scale digitization on book collections

Legacy Missions in Times of Change: Defining and Shaping Collections in the 21st Century

Despite the rapidly changing information and technology landscape, collections remain at the heart of academic libraries, signifying their enduring importance in providing access to our cultural heritage. Given broader trends in research and the current information ecology of an increasingly networked, distributed, and licensed environment, building collections and developing collection polices is increasingly ambiguous. These trends impact librarians in form of ever-expanding portfolios, diffusion of effort, weakened sense of focus, and a rising sense of persistent yet unmet needs for developing new skills. This paper outlines current research on collection trends and summarizes the interactive exchanges from the 2019 Charleston Conference Lively Session (https://sched.co/UZR5). Through live polling, session participants identified key trends in libraries and collections: Key trends included business models, budget constraints, consortium deals, continued importance of subscribed content, access vs. ownership, digitization of unique local collections, digital humanities, digital scholarship, library publishing projects, growing library investments in Open Access (OA), and collection diversification efforts with a view to equity and social justice. Among emerging library services, data services and digitization ranked highest in importance. The most-cited wish-list items included transformative deals, stronger campus partnerships, more OA projects, reduced copyright barriers in sharing homegrown digitized video content, as well as skill development in Counter 5 and data analysis. Existing physical and digital preservation programs received only lower-middle strength ratings. Among long-established library characteristics, collection policies, subscribed content, interlibrary loan, and consortial borrowing and lending retained enduring value and high rankings in importance. Tensions continue between ownership, borrowing, and access

Successful Digital Repositories: Selecting an Institutional Repository Model

Contributing institution: Cornell UniversityOya Rieger offers strategies to select and implement repository system features and functionality and illustrates a broad range of case studies

Enduring Access to Digitized Books: Organizational and Technical Framework

The digitization of millions of books under corporate and non-profit programs is dramatically expanding our ability to search, discover, and retrieve published materials. Accompanying this progress are cultural heritage institutions’ concerns about the long-term management challenges associated with providing enduring access to a hlarge corpus of digitized materials, especially within the confinements of copyright laws. The goal of this presentation is to describe Cornell University Library’s program to illustrate a range of organizational and technical issues involved in planning and implementing a preservation infrastructure for digitized books

Leading by Diversifying Collections : A Guide for Academic Library Leadership

Ithaka S+R fournit des recherches et des conseils stratégiques pour aider le monde universitaire. Ithaka S+R fait partie d’ITHAKA, un organisme sans but lucratif dont la mission est d’améliorer l’accès à l’éducation pour les populations du monde entier. Nous croyons que l’éducation est la clé du bien-être des individus et de la société, et nous nous efforçons de le rendre plus efficace et abordable

Characterizing the gamma-ray long-term variability of PKS 2155-304 with H.E.S.S. and Fermi-LAT

Studying the temporal variability of BL Lac objects at the highest energies provides unique insights into the extreme physical processes occurring in relativistic jets and in the vicinity of super-massive black holes. To this end, the long-term variability of the BL Lac object PKS 2155-304 is analyzed in the high (HE, 100 MeV 200 GeV) gamma-ray domain. Over the course of ~9 yr of H.E.S.S observations the VHE light curve in the quiescent state is consistent with a log-normal behavior. The VHE variability in this state is well described by flicker noise (power-spectral-density index {\ss}_VHE = 1.10 +0.10 -0.13) on time scales larger than one day. An analysis of 5.5 yr of HE Fermi LAT data gives consistent results ({\ss}_HE = 1.20 +0.21 -0.23, on time scales larger than 10 days) compatible with the VHE findings. The HE and VHE power spectral densities show a scale invariance across the probed time ranges. A direct linear correlation between the VHE and HE fluxes could neither be excluded nor firmly established. These long-term-variability properties are discussed and compared to the red noise behavior ({\ss} ~ 2) seen on shorter time scales during VHE-flaring states. The difference in power spectral noise behavior at VHE energies during quiescent and flaring states provides evidence that these states are influenced by different physical processes, while the compatibility of the HE and VHE long-term results is suggestive of a common physical link as it might be introduced by an underlying jet-disk connection.Comment: 11 pages, 16 figure

Detailed spectral and morphological analysis of the shell type SNR RCW 86

Aims: We aim for an understanding of the morphological and spectral properties of the supernova remnant RCW~86 and for insights into the production mechanism leading to the RCW~86 very high-energy gamma-ray emission. Methods: We analyzed High Energy Spectroscopic System data that had increased sensitivity compared to the observations presented in the RCW~86 H.E.S.S. discovery publication. Studies of the morphological correlation between the 0.5-1~keV X-ray band, the 2-5~keV X-ray band, radio, and gamma-ray emissions have been performed as well as broadband modeling of the spectral energy distribution with two different emission models. Results:We present the first conclusive evidence that the TeV gamma-ray emission region is shell-like based on our morphological studies. The comparison with 2-5~keV X-ray data reveals a correlation with the 0.4-50~TeV gamma-ray emission.The spectrum of RCW~86 is best described by a power law with an exponential cutoff at $E_{cut}=(3.5\pm 1.2_{stat})$ TeV and a spectral index of $\Gamma$~$1.6\pm 0.2$. A static leptonic one-zone model adequately describes the measured spectral energy distribution of RCW~86, with the resultant total kinetic energy of the electrons above 1 GeV being equivalent to $\sim$0.1\% of the initial kinetic energy of a Type I a supernova explosion. When using a hadronic model, a magnetic field of $B$~100$\mu$G is needed to represent the measured data. Although this is comparable to formerly published estimates, a standard E$^{-2}$ spectrum for the proton distribution cannot describe the gamma-ray data. Instead, a spectral index of $\Gamma_p$~1.7 would be required, which implies that ~$7\times 10^{49}/n_{cm^{-3}}$erg has been transferred into high-energy protons with the effective density $n_{cm^{-3}}=n/ 1$ cm^-3. This is about 10\% of the kinetic energy of a typical Type Ia supernova under the assumption of a density of 1~cm^-3.Comment: accepted for publication by A&

Detection of variable VHE gamma-ray emission from the extra-galactic gamma-ray binary LMC P3

Context. Recently, the high-energy (HE, 0.1-100 GeV) $\gamma$-ray emission from the object LMC P3 in the Large Magellanic Cloud (LMC) has been discovered to be modulated with a 10.3-day period, making it the first extra-galactic $\gamma$-ray binary. Aims. This work aims at the detection of very-high-energy (VHE, >100 GeV) $\gamma$-ray emission and the search for modulation of the VHE signal with the orbital period of the binary system. Methods. LMC P3 has been observed with the High Energy Stereoscopic System (H.E.S.S.); the acceptance-corrected exposure time is 100 h. The data set has been folded with the known orbital period of the system in order to test for variability of the emission. Energy spectra are obtained for the orbit-averaged data set, and for the orbital phase bin around the VHE maximum. Results. VHE $\gamma$-ray emission is detected with a statistical significance of 6.4 $\sigma$. The data clearly show variability which is phase-locked to the orbital period of the system. Periodicity cannot be deduced from the H.E.S.S. data set alone. The orbit-averaged luminosity in the $1-10$ TeV energy range is $(1.4 \pm 0.2) \times 10^{35}$ erg/s. A luminosity of $(5 \pm 1) \times 10^{35}$ erg/s is reached during 20% of the orbit. HE and VHE $\gamma$-ray emissions are anti-correlated. LMC P3 is the most luminous $\gamma$-ray binary known so far.Comment: 5 pages, 3 figures, 1 table, accepted for publication in A&