How much does it cost? The LIFE Project - costing models for digital curation and preservation

Digital preservation is concerned with the long-term safekeeping of electronic resources. How can we be confident of their permanence, if we do not know the cost of preservation? The LIFE (Lifecycle Information for E-Literature) Project has made a major step forward in understanding the long-term costs in this complex area. The LIFE Project has developed a methodology to model the digital lifecycle and to calculate the costs of preserving digital information for the next 5, 10 or 100 years. National and higher education (HE) libraries can now apply this process and plan effectively for the preservation of their digital collections. Based on previous work undertaken on the lifecycles of paper-based materials, the LIFE Project created a lifecycle model and applied it to real-life digital collections across a diverse subject range. Three case studies examined the everyday operations, processes and costs involved in their respective activities. The results were then used to calculate the direct costs for each element of the digital lifecycle. The Project has made major advances in costing preservation activities, as well as making detailed costs of real digital preservation activities available. The second phase of LIFE (LIFE2), which recently started, aims to refine the lifecycle methodology and to add a greater range and breadth to the project with additional exemplar case studies

The LIFE Model v1.1

Extract: This document draws together feedback, discussion and review of the LIFE Model from a number of sources: 1. The LIFE and LIFE2 Project Teams, and the staff of their institutions 2. Feedback from review by independent economics expert 3. The LIFE Project Conference 4. Early adopters of the Life Model (particularly the Royal Danish Library, State Archives and the State and University Library, Denmark) The result is a revision of the LIFE Model which was first published in 2006 by the LIFE Project . In line with the objectives of the LIFE2 Project, this revision aims to: 1. fix outstanding anomalies or omissions in the Model 2. scope and define the Model and its components more precisely 3. facilitate useful and repeatable mapping and costing of digital lifecycles

How effective is harassment on infalling late-type dwarfs?

A new harassment model is presented that models the complex, and dynamical tidal field of a Virgo like galaxy cluster. The model is applied to small, late-type dwarf disc galaxies (of substantially lower mass than in previous harassment simulations) as they infall into the cluster from the outskirts. These dwarf galaxies are only mildly affected by high speed tidal encounters with little or no observable consequences; typical stellar losses are $<10\%$, producing very low surface brightness streams ($\mu_B > 31$ mag arcsec$^{-2}$), and a factor of two drop in dynamical mass-to-light ratio. Final stellar discs remain disc-like, and dominated by rotation although often with tidally induced spiral structure. By means of Monte-Carlo simulations, the statistically likely influences of harassment on infalling dwarf galaxies are determined. The effects of harassment are found to be highly dependent on the orbit of the galaxy within the cluster, such that newly accreted dwarf galaxies typically suffer only mild harassment. Strong tidal encounters, that can morphologically transform discs into spheroidals, are rare occurring in $<15 \%$ of dwarf galaxy infalls for typical orbits of sub-structure within $\Lambda$CDM cluster mass halos. For orbits with small apocentric distances ($<$250 kpc), harassment is significantly stronger resulting in complete disruption or heavy mass loss ($>90 \%$ dark matter and $> 50 \%$ stellar), however, such orbits are expected to be highly improbable for newly infalling galaxies due to the deep potential well of the cluster.Comment: 15 pages, 11 figures, 4 table

Lifecycle information for E-literature: an introduction to the second phase of the LIFE project

Introduction: The first phase of LIFE (Lifecycle Information For E-Literature) made a major contribution to understanding the long-term costs of digital preservation; an essential step in helping institutions plan for the future. The LIFE work models the digital lifecycle and calculates the costs of preserving digital information for future years. Organisations can apply this process in order to understand costs and plan effectively for the preservation of their digital collections The second phase of the LIFE Project, LIFE2, has refined the LIFE Model adding three new exemplar Case Studies to further build upon LIFE1. LIFE2 is an 18-month JISC-funded project between UCL (University College London) and The British Library (BL), supported by the LIBER Access and Preservation Divisions. LIFE1 was completed in April 2006. LIFE2 started in March 2007, and was completed in August 2008. This summary aims to give an overview of the LIFE Project, summarising some of the key outputs. There are four main areas discussed: 1 From LIFE1 to LIFE2 outlines some of the key findings from the first phase of the project as well as summarising the motivation behind this second phase. 2 The LIFE Model describes the current version of the model (version 2) which has been thoroughly updated from the first phase. 3 LIFE2 Case Studies describes the three new Case Studies for LIFE2. It does not include the results from the Case Studies (these are available in the overall LIFE2 Report), but offers some background on each of the studies as well as discussion of why they were chosen. 4 Findings and Conclusions outlines all of the findings and outputs from the entire project

The LIFE2 final project report

Executive summary: The first phase of LIFE (Lifecycle Information For E-Literature) made a major contribution to understanding the long-term costs of digital preservation; an essential step in helping institutions plan for the future. The LIFE work models the digital lifecycle and calculates the costs of preserving digital information for future years. Organisations can apply this process in order to understand costs and plan effectively for the preservation of their digital collections The second phase of the LIFE Project, LIFE2, has refined the LIFE Model adding three new exemplar Case Studies to further build upon LIFE1. LIFE2 is an 18-month JISC-funded project between UCL (University College London) and The British Library (BL), supported by the LIBER Access and Preservation Divisions. LIFE2 began in March 2007, and completed in August 2008. The LIFE approach has been validated by a full independent economic review and has successfully produced an updated lifecycle costing model (LIFE Model v2) and digital preservation costing model (GPM v1.1). The LIFE Model has been tested with three further Case Studies including institutional repositories (SHERPA-LEAP), digital preservation services (SHERPA DP) and a comparison of analogue and digital collections (British Library Newspapers). These Case Studies were useful for scenario building and have fed back into both the LIFE Model and the LIFE Methodology. The experiences of implementing the Case Studies indicated that enhancements made to the LIFE Methodology, Model and associated tools have simplified the costing process. Mapping a specific lifecycle to the LIFE Model isn’t always a straightforward process. The revised and more detailed Model has reduced ambiguity. The costing templates, which were refined throughout the process of developing the Case Studies, ensure clear articulation of both working and cost figures, and facilitate comparative analysis between different lifecycles. The LIFE work has been successfully disseminated throughout the digital preservation and HE communities. Early adopters of the work include the Royal Danish Library, State Archives and the State and University Library, Denmark as well as the LIFE2 Project partners. Furthermore, interest in the LIFE work has not been limited to these sectors, with interest in LIFE expressed by local government, records offices, and private industry. LIFE has also provided input into the LC-JISC Blue Ribbon Task Force on the Economic Sustainability of Digital Preservation. Moving forward our ability to cost the digital preservation lifecycle will require further investment in costing tools and models. Developments in estimative models will be needed to support planning activities, both at a collection management level and at a later preservation planning level once a collection has been acquired. In order to support these developments a greater volume of raw cost data will be required to inform and test new cost models. This volume of data cannot be supported via the Case Study approach, and the LIFE team would suggest that a software tool would provide the volume of costing data necessary to provide a truly accurate predictive model

New Cosmological Structures on Medium Angular Scales Detected with the Tenerife Experiments

We present observations at 10 and 15 GHz taken with the Tenerife experiments in a band of the sky at Dec.=+35 degrees. These experiments are sensitive to multipoles in the range l=10-30. The sensitivity per beam is 56 and 20 microK for the 10 and the 15 GHz data, respectively. After subtraction of the prediction of known radio-sources, the analysis of the data at 15 GHz at high Galactic latitude shows the presence of a signal with amplitude Delta Trms ~ 32 microK. In the case of a Harrison-Zeldovich spectrum for the primordial fluctuations, a likelihood analysis shows that this signal corresponds to a quadrupole amplitude Q_rms-ps=20.1+7.1-5.4 microK, in agreement with our previous results at Dec.+=40 degrees and with the results of the COBE DMR. There is clear evidence for the presence of individual features in the RA range 190 degrees to 250 degrees with a peak to peak amplitude of ~110 microK. A preliminary comparison between our results and COBE DMR predictions for the Tenerife experiments clearly indicates the presence of individual features common to both. The constancy in amplitude over such a large range in frequency (10-90 GHz) is strongly indicative of an intrinsic cosmological origin for these structures.Comment: ApJ Letters accepted, 13 pages Latex (uses AASTEX) and 4 encapsulated postscript figures

Commensurability oscillations due to pinned and drifting orbits in a two-dimensional lateral surface superlattice

We have simulated conduction in a two-dimensional electron gas subject to a weak two-dimensional periodic potential, $V_x \cos(2\pi x/a) + V_y \cos(2\pi y/a)$. The usual commensurability oscillations in $\rho_{xx}(B)$ are seen with $V_x$ alone. An increase of $V_y$ suppresses these oscillations, rather than introducing the additional oscillations in $\rho_{yy}(B)$ expected from previous perturbation theories. We show that this behavior arises from drift of the guiding center of cyclotron motion along contours of an effective potential. Periodic modulation in the magnetic field can be treated in the same way.Comment: 3 pages text, 4 eps figures, revte

Stellar and Molecular Gas Kinematics of NGC1097: Inflow Driven by a Nuclear Spiral

We present spatially resolved distributions and kinematics of the stars and molecular gas in the central 320pc of NGC1097. The stellar continuum confirms the previously reported 3-arm spiral pattern extending into the central 100pc. The stellar kinematics and the gas distribution imply this is a shadowing effect due to extinction by gas and dust in the molecular spiral arms. The molecular gas kinematics show a strong residual (i.e. non-circular) velocity, which is manifested as a 2-arm kinematic spiral. Linear models indicate that this is the line-of-sight velocity pattern expected for a density wave in gas that generates a 3-arm spiral morphology. We estimate the inflow rate along the arms. Using hydrodynamical models of nuclear spirals, we show that when deriving the accretion rate into the central region, outflow in the disk plane between the arms has to be taken into account. For NGC1097, despite the inflow rate along the arms being ~1.2Msun/yr, the net gas accretion rate to the central few tens of parsecs is much smaller. The numerical models indicate that the inflow rate could be as little as ~0.06Msun/yr. This is sufficient to generate recurring starbursts, similar in scale to that observed, every 20-150Myr. The nuclear spiral represents a mechanism that can feed gas into the central parsecs of the galaxy, with the gas flow sustainable for timescales of a Gigayear.Comment: accepted by Ap