295 research outputs found
Schema Correspondences between Objects
No full textIn a multi-database system, schematic conflicts between two objects are usually of interest only when the objects have some semantic similarity. In this paper we try to reconcile the schematic and semantic perspectives. We introduce a uniform formalism called schema correspondences to represent structural similarities between the objects. We represent the semantic similarities between the objects using the concept of semantic proximity. We show how the reconciliation is achieved by illustrating the association of the schema correspondence(s) with and as component(s) of the semantic proximity. We also provide a data model independent semantic taxonomy on the basis of the semantic proximity defined. We then enumerate and classify the schematic and data conflicts. The association between the schema correspondences and semantic proximity helps represent the possible semantic similarities between two objects having these conflicts. One representation of uncertain information using semantic proximity as the basis is explored. Issues of inconsistent information are also discussed in the framework of semantic proximity.Technical report DCS-TR-30
Semantics-based Information Brokering: A step towards realizing the Infocosm
No full textThe rapid advances in computer and communication technologies, and their merger, is leading to a global information market place. It will consist of federations of very large number of information systems that will cooperate to varying extents to support the users' information needs. We propose an architecture which may facilitate meeting these needs. It consists of three main components: information providers, information brokers and information consumers. We also propose an approach to information brokering. We discuss two of it's tasks: information resource discovery, which identities relevant information sources for a given query, and query processing, which involves the generation of appropriate mapping from relevant but structurally heterogeneous objects. Query processing consists of information focusing and information correlation.
While the access-based search, and syntactic and hierarchical information organization has been adequate in the past, information brokering in presence of huge digital libraries or millions of information sources will likely require semantics and information-content based search and structuring of information. Our approach is based on: semantic proximity, which represents semantic similarities based on the context of comparison, and schema correspondences which are used to represent structural mappings and are associated with the context. The context of comparison of the two objects is the primary vehicle to represent the semantics for determining semantic proximity. Specifically, we use a context to capture the semantics in terms of the meaning and/or the use of an object. Using a partial context representation, we capture the assumptions in the intended use of the objects and the intended meaning of the user query. Information focusing is supported by subsequent context comparison. The same mechanism can be used to support information resource discovery. Context comparison leads to changes in schema correspondences that are used to support information correlation.Technical report DCS-TR-30
UM modelo de mapeamento de estruturas e dados relacionais para documentos XML
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência da Computação, Florianópolis, 2001.As trocas de informações entre os vários tipos de sistemas de banco de dados se dão atualmente de diversas maneiras, onde até então não se havia um padrão. Usam-se muito drivers específicos de comunicação e protocolos proprietários e diversos outros meios com o objetivo de integrar e trocar informações entre diferentes sistemas de bancos de dados. Com a crescente necessidade de compartilhamento de informações entre sistemas, pessoas e organizações, a tendência é usar protocolos abertos e altamente compatíveis com a internet para intercâmbio dessas informações (principalmente para comércio eletrônico), e por esse motivo pode-se dizer que o XML é o mais indicado, dado sua capacidade de processar (estruturar, organizar, armazenar e recuperar) conjuntos complexos de informações, como arquivos multimídia, estruturas hierárquicas de dados e imagens digitais, entre diversos outros tipos de documentos, assim como dados em estruturas relacionais ou baseadas em objetos, tudo isso com velocidade, confiabilidade e escalabilidade sem igual. Dado essas premissas, essa dissertação propõe um modelo de conversão de estruturas de dados relacionais, que é o modelo mais comum atualmente, para documentos XML e vice-versa
Preemptive and upfront plerixafor: Safe and effective strategy for patients undergoing autologous stem cell transplant and at high risk for mobilization failure
No full textIntroduction: Approximately 10%–30% of patients are unable to collect the minimum number of stem cells to support high-dose chemotherapy and autologous stem cell transplant (hematopoietic stem cell transplantation). Plerixafor alone or in combination with granulocyte colony-stimulating factor (G-CSF) has been shown to significantly increase the CD34 cell collection, especially in patients who failed their initial harvest strategy. This is a retrospective study of 17 preselected patients (relapsed lymphoma and myeloma), who were considered to have high risk of mobilization failure and who had undergone upfront and preemptive plerixafor mobilization. Patients and Methods: The mobilization protocol consisted of G-CSF (10–15 μg/kg) subcutaneously daily for 4 days before the initiation of plerixafor on evening of day 4. The patients then underwent apheresis on day 5. Results: Among 17 patients who underwent apheresis, 16 (93%) yielded the minimum required cell collection of ≥2 × 106 CD34+ cells/kg in a single apheresis session (2 days). Out of these 16 patients, 8 (53%) patients achieved the minimum target dose in a single day. Eight (50%) of all patients achieved the optimum target cell collection in a single apheresis session. Out of these eight patients, five (62%) patients collected optimum yield in a single day. Conclusion: Plerixafor is safe and effective if used upfront and preemptively for patients in whom mobilization of stem cells is considered to be a problem
Semantics-based Information Brokering: A step towards realizing the Infocosm
No full textThe rapid advances in computer and communication technologies, and their merger, is leading to a global information market place. It will consist of federations of very large number of information systems that will cooperate to varying extents to support the users' information needs. We propose an architecture which may facilitate meeting these needs. It consists of three main components: information providers, information brokers and information consumers. We also propose an approach to information brokering. We discuss two of it's tasks: information resource discovery, which identifies relevant information sources for a given query, and query processing, which involves the generation of appropriate mapping from relevant but structurally heterogeneous objects. Query processing consists of information focusing and information correlation. While the access-based search, and syntactic and hierarchical information organization has been adequate in the past, information brokering in pre..
Semantic Heterogeneity in Global Information Systems: The Role of Metadata, Context and Ontologies
No full textSemantic heterogeneity has been identified as one of the most important and toughest problems when dealing with interoperability and cooperation among multiple databases. It was earlier studied in the context of exchanging, sharing and integrating data, especially during the schema/view analysis phase of schema or view integration, or when writing a view or query using a multidatabase language. With the advent of global interconnectivity, we now need to deal with more heterogeneous information resources consisting of a variety of digital data, and the scale of the problem has changed from a few databases to millions of information resources, thus making it more important than ever to address this problem. It is also recognized that the problem has only become harder and that simplistic solutions involving only representational or structural components of data will not work beyond a very restricted set of cases.
In this chapter, we explore approached to tackle the semantic heterogeneity problem in the context of Global Information Systems (GIS) which are systems geared to handle information requests on the Global information Infrastructure (GII). These approached are based on the capture and representation of metadata, contexts and ontologies. In order to handle information overload, it would be advantageous to abstract out the representational details of the underlying data and capture the information content by using domain specific metadata. The next important step is that of understanding the context of the query, using metadata to construct the context and identifying the relevant data in the context. Another critical issue that arises here is that of different vocabularies used to characterize similar information. We present an approach to deal with this problem at the metadata/context level by using terms from domain specific ontologies to construct metadata/context. We deal with semantic heterogeneity at this level and propose an approach using terminological relationships to achieve semantic interoperability
So Far (Schematically) yet So Near (Semantically)
No full textIn a multidatabase system, schematic conflicts between two objects are usually of interest only when the objects have some semantic affinity. In this paper we try to reconcile the two perspectives. We first define the concept of semantic proximity and provide a semantic taxonomy. We then enumerate and classify the schematic and data conflicts. We discuss possible semantic similarities between two objects that have various types of schematic and data conflicts. Issues of uncertain information and inconsistent information are also addressed. 1 Introduction Many organizations face the challenge of interoperating among multiple independently developed database systems to perform critical functions. With high interconnectivity and access to many information sources, the primary issue in the future will not be how to efficiently process the data that is known to be relevant, but which data is relevant. Three of the best known approaches to deal with multiple databases are tightlycoupled f..
Semantics-based Information Brokering
No full textThe rapid advances in computer and communication technologies, and their merger, is leading to a global information market place. It will consist of federations of very large number of information systems that will cooperate to varying extents to support the users' information needs. We discuss an approach to information brokering in the above environment. We discuss two of it's tasks: information resource discovery, which identifies relevant information sources for a given query, and query processing, which involves the generation of appropriate mapping from relevant but structurally heterogeneous objects. Query processing consists of information focusing and information correlation. Our approach is based on: semantic proximity, which represents semantic similarities based on the context of comparison, and schema correspondences which are used to represent structural mappings and are associated with the context. The context of comparison of the two objects is the primary vehicle to ..
Semantic and Schematic Similarities between Database Objects: A Context-based approach
No full textIn a multidatabase system, schematic conflicts between two objects are usually of interest only when the objects have some semantic similarity. We use the concept of semantic proximity, which is essentially an abstraction/mapping between the domains of the two objects associated with the context of comparison. An explicit though partial context representation is proposed and the specificity relationship between contexts is defined. The contexts are organized as a meet semi-lattice and associated operations like the greatest lower bound (glb) are defined. The context of comparison and the type of abstractions used to relate the two objects form the basis of a semantic taxonomy. At the semantic level, the intensional description of database objects provided by the context is expressed in a description logic language. Schema correspondences are used to store mappings from the semantic level to the data level and are associated with the respective contexts. Inferences about database conten..
- …
