Los modelos de negocio de las revistas científicas en España

This chapter analyses the business models of Spanish scientific journals. This analysis is based on an integrated approach to the business model, which incorporates operational and strategic aspects of publishing, in addition to economic and financial factors. The data are taken from a survey that was distributed between 2012 and 2013 among 1,280 publishers of Spanish scientific journals included in the DULCINEA database and achieved a response rate of 44% (n=561). In addition to providing a statistical overview of the findings, the chapter also describes the basic business model profiles used for Spanish scientific journals. A descriptive analysis of the business model components reveals that Spanish scientific journals are dependent on institutional aid, whether in the form of subsidies, aid from the owner or income in kind and, to a lesser extent, sponsorships and donations. With respect to strategy, although the experience of publishers with open access is mostly positive, the areas for improvement most cited by respondents were financial limitations and a weak organizational structure. Regarding operations, the strong dependence of scientific journals on voluntary work to sustain their organizational structure (present among 70% of the publishers that responded), as well as the limited time of the staff in charge of the journals (fewer than nine percent of all respondents had full-time in-house staff). Furthermore, the joint role of scientific editor and administrator that is frequently taken on by publishers is hindering professionalization in the scientific publishing industry

Improving Integrity Constraints Checking In Distributed Databases by Exploiting Local Checking

Integrity constraints are important tools and useful for specifying consistent states of a database. Checking integrity constraints has proven to be extremely difficult to implement, particularly in distributed database. The main issue concerning checking the integrity constraints in distributed database system is how to derive a set of integrity tests (simplified forms) that will reduce the amount of data transferred, the amount of data accessed, and the number of sites involved during the constraint checking process. Most of the previous approaches derive integrity tests (simplified forms) from the initial integrity constraints with the sufficiency property, since the sufficient test is known to be cheaper to execute than the complete test as it involved less data to be transferred across the network and always can be evaluated at the target site, i.e. only one site is involved during the checking process thus, achieving local checking. The previous approaches assume that an update operation will be executed at a site where the relation specified in the update operation is located (target site), which is not always true. If the update operation is submitted at a different site, the sufficient test is no longer local as it will definitely access data from the remote sites. Therefore, an approach is needed so that local checking can be performed regardless the location of the submitted update operation. In this thesis we proposed an approach for checking integrity constraints in a distributed database system by utilizing as much as possible the information stored at the target site. The proposed constraints simplification approach produces support tests and this is integrated with complete and sufficient tests which are proposed by previous researchers. It uses the initial integrity constraint, the update template, and the other integrity constraints to generate the support tests. The proposed constraints simplification approach adopted the substitution technique and the absorption rules to derive the tests. Since the constraint simplification approach derives several different types of integrity tests for a given update operation and integrity constraint, therefore a strategy to select the most suitable test is needed. We proposed a model to rank and select the suitable test to be checked based on the properties of the tests, the amount of data transferred across the network, the number of sites participated, and the amount of data accessed. Three analyses have been performed to evaluate the proposed checking integrity constraints approach. The first analysis shows that applying different types of integrity tests gives different impacts to the performance of the constraint checking, with respect to the amount of data transferred across the network which is considered as the most critical factor that influences the performance of the checking mechanism. Integrating these various types of integrity tests during constraint checking has enhanced the performance of the constraint mechanisms. The second analysis shows that the cost of checking integrity constraints is reduced when various combinations of integrity tests are selected. The third analysis shows that in most cases localizing integrity checking can be achieved regardless of the location where the update operation is executed when various types of integrity tests are considered

A Taxonomy of Data Grids for Distributed Data Sharing, Management and Processing

Data Grids have been adopted as the platform for scientific communities that need to share, access, transport, process and manage large data collections distributed worldwide. They combine high-end computing technologies with high-performance networking and wide-area storage management techniques. In this paper, we discuss the key concepts behind Data Grids and compare them with other data sharing and distribution paradigms such as content delivery networks, peer-to-peer networks and distributed databases. We then provide comprehensive taxonomies that cover various aspects of architecture, data transportation, data replication and resource allocation and scheduling. Finally, we map the proposed taxonomy to various Data Grid systems not only to validate the taxonomy but also to identify areas for future exploration. Through this taxonomy, we aim to categorise existing systems to better understand their goals and their methodology. This would help evaluate their applicability for solving similar problems. This taxonomy also provides a "gap analysis" of this area through which researchers can potentially identify new issues for investigation. Finally, we hope that the proposed taxonomy and mapping also helps to provide an easy way for new practitioners to understand this complex area of research.Comment: 46 pages, 16 figures, Technical Repor

Query processing of geometric objects with free form boundarie sin spatial databases

The increasing demand for the use of database systems as an integrating factor in CAD/CAM applications has necessitated the development of database systems with appropriate modelling and retrieval capabilities. One essential problem is the treatment of geometric data which has led to the development of spatial databases. Unfortunately, most proposals only deal with simple geometric objects like multidimensional points and rectangles. On the other hand, there has been a rapid development in the field of representing geometric objects with free form curves or surfaces, initiated by engineering applications such as mechanical engineering, aviation or astronautics. Therefore, we propose a concept for the realization of spatial retrieval operations on geometric objects with free form boundaries, such as B-spline or Bezier curves, which can easily be integrated in a database management system. The key concept is the encapsulation of geometric operations in a so-called query processor. First, this enables the definition of an interface allowing the integration into the data model and the definition of the query language of a database system for complex objects. Second, the approach allows the use of an arbitrary representation of the geometric objects. After a short description of the query processor, we propose some representations for free form objects determined by B-spline or Bezier curves. The goal of efficient query processing in a database environment is achieved using a combination of decomposition techniques and spatial access methods. Finally, we present some experimental results indicating that the performance of decomposition techniques is clearly superior to traditional query processing strategies for geometric objects with free form boundaries