28,343 research outputs found
Important Lessons Derived from X.500 Case Studies
X.500 is a new and complex electronic directory technology, whose basic specification was first published as an international standard in 1988, with an enhanced revision in 1993. The technology is still unproven in many organisations. This paper presents case studies of 15 pioneering pilot and operational X.500 based directory services. The paper provides valuable insights into how organisations are coming to understand this new technology, are using X.500 for both traditional and novel directory based services, and consequently are deriving benefits from it. Important lessons that have been learnt by these X.500 pioneers are presented here, so that future organisations can benefit from their experiences. Factors critical to the success of implementing X.500 in an organisation are derived from the studies
Hierarchical progressive surveys. Multi-resolution HEALPix data structures for astronomical images, catalogues, and 3-dimensional data cubes
Scientific exploitation of the ever increasing volumes of astronomical data
requires efficient and practical methods for data access, visualisation, and
analysis. Hierarchical sky tessellation techniques enable a multi-resolution
approach to organising data on angular scales from the full sky down to the
individual image pixels. Aims. We aim to show that the Hierarchical progressive
survey (HiPS) scheme for describing astronomical images, source catalogues, and
three-dimensional data cubes is a practical solution to managing large volumes
of heterogeneous data and that it enables a new level of scientific
interoperability across large collections of data of these different data
types. Methods. HiPS uses the HEALPix tessellation of the sphere to define a
hierarchical tile and pixel structure to describe and organise astronomical
data. HiPS is designed to conserve the scientific properties of the data
alongside both visualisation considerations and emphasis on the ease of
implementation. We describe the development of HiPS to manage a large number of
diverse image surveys, as well as the extension of hierarchical image systems
to cube and catalogue data. We demonstrate the interoperability of HiPS and
Multi-Order Coverage (MOC) maps and highlight the HiPS mechanism to provide
links to the original data. Results. Hierarchical progressive surveys have been
generated by various data centres and groups for ~200 data collections
including many wide area sky surveys, and archives of pointed observations.
These can be accessed and visualised in Aladin, Aladin Lite, and other
applications. HiPS provides a basis for further innovations in the use of
hierarchical data structures to facilitate the description and statistical
analysis of large astronomical data sets.Comment: 21 pages, 6 figures. Accepted for publication in Astronomy &
Astrophysic
Retailing under resale price maintenance: economies of scale and scope, and firm strategic response, in the inter-war British retail pharmacy sector
The article examines the impact of resale price maintenance (RPM) on market structure, productivity, and competitive advantage in British retail pharmacy. In contrast to influential studies, but consistent with contemporary and recent work, it is shown that the major multiples were able to ameliorate the negative growth impacts of RPM. Higher profit margins â principally from larger manufacturer discounts and backward integration â were used to fund initiatives aimed at boosting aggregate sales and economies of scale and scope. These relationships are explored using a recently discovered national establishment-level survey of retail pharmacistsâ costs and margins, together with internal data for Boots Ltd
Routing Protocols for Lossy Wireless Networks
Tato prĂĄce zkoumĂĄ vhodnost a poĆŸadavky nĂĄvrhu simulacĂ pro simulĂĄtor NS-3 pro pĆĂpad bezdrĂĄtovĂœch sĂtĂ pouĆŸĂvanĂœch v mÄĆĂcĂ infrastruktuĆe spoleÄnosti Kamstrup. V prĂĄci je popsĂĄn simulĂĄtor NS-3 a je vytvoĆena zĂĄkladnĂ implementace dvou protokolĆŻ. Wireless M-Bus jako pĆĂklad jednosmÄrnĂ©ho protokolu pro zaĆĂzenĂ napĂĄjenĂ© z bateriĂ. Simulace Wireless M-Bus je porovnĂĄna s daty namÄĆenĂœmi v reĂĄlnĂ©m systĂ©mu. NS-3 poskytuje flexibilnĂ prostĆedĂ pro vĂœvoj simulacĂ rĆŻznĂœch sĂĆ„ovĂœch protokolĆŻ, vÄetnÄ tÄch urÄenĂœch pro sĂtÄ inteligentnĂch mÄĆidel.This thesis investigates suitability and design constraints of the NS-3 Simulator for simulations of wireless protocols used by Kamstrup metering infrastructure. An overview of NS-3 Simulator is given and preliminary implementations of two protocols are created. Wireless M-Bus as an example of a one-way protocol for battery-powered devices. The simulation of Wireless M-Bus is compared with measurements obtained in a real deployment. NS-3 proves to be a flexible framework for developing simulations of various network protocols, including the ones used for smart metering.
The Digital Anatomist Information System and Its Use in the Generation and Delivery of Web-Based Anatomy Atlases
Advances in network and imaging technology, coupled with the availability of 3-D datasets
such as the Visible Human, provide a unique opportunity for developing information systems
in anatomy that can deliver relevant knowledge directly to the clinician, researcher or educator. A software framework is described for developing such a system within a distributed architecture that includes spatial and symbolic anatomy information resources, Web and custom servers, and authoring and end-user client programs. The authoring tools have been used to create 3-D atlases of the brain, knee and thorax that are used both locally and throughout the world. For the one and a half year period from June 1995âJanuary 1997, the on-line atlases were accessed by over 33,000 sites from 94 countries, with an average of over 4000 ââhitsââ per day, and 25,000 hits per day during peak exam periods. The atlases have been linked to by over 500 sites, and have received at least six unsolicited awards by outside rating institutions. The flexibility of the software framework has allowed the information system to evolve with advances in technology and representation methods. Possible new features include knowledge-based image retrieval and tutoring, dynamic generation of 3-D scenes, and eventually, real-time virtual reality navigation through the body. Such features, when coupled with other on-line biomedical information resources, should lead to interesting new ways for
managing and accessing structural information in medicine
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