Gradual Generalization of Nautical Chart Contours with a Cube B-Spline Snake Model

—B-spline snake methods have been used in cartographic generalization in the past decade, particularly in the generalization of navigational charts where this method yields good results with respect to the shoal-bias rules for generalization of chart contours. However, previous studies only show generalization results at particular generalization (or scale) levels, and the user can only see two conditions: before the generalization and after generalization, but nothing in between. This paper presents an improved method of using B-spline snakes for generalization in the context of nautical charts, where the generalization process is done gradually, and the user can see the complete process of the generalization

Optical Counterparts of Two Fermi Millisecond Pulsars: PSR J1301+0833 and PSR J1628-3205

Using the 1.3m and 2.4m telescopes of the MDM Observatory, we identified the close companions of two eclipsing millisecond radio pulsars discovered by the Green Bank Telescope in searches of Fermi Gamma-ray Space Telescope sources, and measured their light curves. PSR J1301+0833 is a black widow pulsar in a 6.5 hr orbit whose companion star is strongly heated on the side facing the pulsar. It varies from R = 21.8 to R > 24 around the orbit. PSR J1628-3205 is a "redback," a nearly Roche-lobe filling system in a 5.0 hr orbit whose optical modulation in the range 19.0 < R < 19.4 is dominated by strong ellipsoidal variations, indicating a large orbital inclination angle. PSR J1628-3205 also shows evidence for a long-term variation of about 0.2 mag, and an asymmetric temperature distribution possibly due to either off-center heating by the pulsar wind, or large starspots. Modelling of its light curve restricts the inclination angle to i > 55 degrees, the mass of the companion to 0.16 < M_c < 0.30 M_sun, and the effective temperature to 3560 < T_eff < 4670 K. As is the case for several redbacks, the companion of PSR J1628-3205 is less dense and hotter than a main-sequence star of the same mass.Comment: 9 pages, 5 figures, accepted for publication in Ap

Deducing Cosmological Observables from the S-matrix

We study one loop quantum gravitational corrections to the long range force induced by the exchange of a massless scalar between two massive scalars. The various diagrams contributing to the flat space S-matrix are evaluated in a general covariant gauge and we show that dependence on the gauge parameters cancels at a point considerably {\it before} forming the full S-matrix, which is unobservable in cosmology. It is possible to interpret our computation as a solution to the effective field equations --- which could be done even in cosmology --- but taking account of quantum gravitational corrections from the source and from the observer.Comment: 28 pages, 5 figures, uses LaTeX2

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

Design, fabrication, and structural testing of a lightweight shadow shield for deep-space application

Two full-scale, lightweight, double-sheeted shadow shields were developed as the primary element of a deep-space thermal protection system for liquid-hydrogen propellant tankage. The thermal and mechanical considerations used in s, the method of fabrication, and the environmental testing results on a prototype shield are discussed. Testing consisted of a transient cooldown period, a prolonged cold soak, and a transient warmup. The mechanical and thermal analyses used in the shield design are sufficient to produce a lightweight rugged shadow shield assembly that is structurally adequate for its intended application

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

On a Localized Riemannian Penrose Inequality

Consider a compact, orientable, three dimensional Riemannian manifold with boundary with nonnegative scalar curvature. Suppose its boundary is the disjoint union of two pieces: the horizon boundary and the outer boundary, where the horizon boundary consists of the unique closed minimal surfaces in the manifold and the outer boundary is metrically a round sphere. We obtain an inequality relating the area of the horizon boundary to the area and the total mean curvature of the outer boundary. Such a manifold may be thought as a region, surrounding the outermost apparent horizons of black holes, in a time-symmetric slice of a space-time in the context of general relativity. The inequality we establish has close ties with the Riemannian Penrose Inequality, proved by Huisken and Ilmanen, and by Bray.Comment: 16 page