This paper presents the effects of a technology-based engagement platform, referred to as IMPRES (Interactive Mobile Platform for Retaining and Engaging Students). IMPRES is a mobile application, backed by a set of data analysis services, which seeks to engage and retain its users to enhance their professional development. The primary goal of the application is to enhance students’ engagement in their college and improve student retention. The method is influenced by and evaluated from the standpoints of four theoretical models previously used in research on the effect of a computer interface on user behavior. First, the self-determination theory perspective on digital games explains users’ motivation. Second, social identity theory explains users’ psychological connections to their college. Third, continuance theory explains continuity of users’ engagement. Finally, the persuasive system design perspective associates IMPRES’s features with users’ motivation. By integrating these theories, we develop and find much support for a model of IMPRES’s effects on students’ intent to continue their studies. This research makes a unique contribution to continuance theory by demonstrating how an application’s persuasive design features not only foster continued use of the application but also continued engagement with an organization.

This article introduces a complete storage and retrieval architecture for a database environment for XML documents. DocBase, a prototype system based on this architecture, uses a flexible storage and indexing technique to allow highly expressive queries without the necessity of mapping documents to other database formats. DocBase is an integration of several techniques that include (i) a formal model called Heterogeneous Nested Relations (HNR), (ii) a conceptual model XER (Extensible Entity Relationship), (ii) formal query languages (Document Algebra and Calculus), (iii) a practical query language (Document SQL or DSQL), (iv) a visual query formulation method with QBT (Query By Templates), and (v) the DocBase query processing architecture. This paper focuses on the overall architecture of DocBase including implementation details, describes the details of the query-processing framework, and presents results from various performance tests. The paper summarizes experimental and usability analyses to demonstrate its feasibility as a general architecture for native as well as embedded document manipulation methods.

This article presents DSQL, a conservative extension of SQL, as an ad-hoc query language for XML. The development of DSQL follows the theoretical foundations of first order logic, and uses common query semantics already accepted for SQL. DSQL represents a core subset of XQuery that lends well to optimization techniques, while at the same time allows easy integration into current databases and applications that useSQL. The intent of DSQL is not to replace XQuery, the current W3C recommended XML query language, but to serve as an ad-hoc querying frontend to XQuery. Further, the authors present proofs for important query language properties such as complexity and closure. An empirical study comparing DSQL and XQuery for the purpose of ad-hoc querying demonstrates that users perform better with DSQL for both flat and tree structures, in terms of both accuracy and efficiency.

This article introduces a measurement ontology for applications to Semantic Web applications, specifically for emerging domains such as microarray analysis. The Semantic Web is the next generation Web of structured data that are automatically shared by software agents, which apply definitions and constraints organized in ontologies to correctly process data from disparate sources. One facet needed to develop Semantic Web ontologies of emerging domains is creating ontologies of concepts that are common to these domains. These general “common-sense” ontologies can be used as building blocks to develop more domain-specific ontologies. However most measurement ontologies concentrate on representing units of measurement and quantities, and not on other measurement concepts such as sampling, mean values, and evaluations of quality based on measurements. In this article, we elaborate on a measurement ontology that represents all these concepts. We present the generality of the ontology, and describe how it is developed, used for analysis and validated.

We present ACXESS (Access Control for XML with Enhanced Security Specifications), a system for specifying and enforcing enhanced security constraints on XML via virtual "security views" and query rewrites. ACXESS is the first system that bears the capability to specify and enforce complicated security policies on both subtrees and structural relationships.

Being able to express and enforce role-based access control on XML data is a critical component of XML data management. However, given the semi-structured nature of XML, this is non-trivial, as access control can be applied on the values of nodes as well as on the structural relationship between nodes. In this context, we adopt and extend a graph editing language for specifying role-based access constraints in the form of security views. A Security Annotated Schema (SAS) is proposed as the internal representation for the security views and can be automatically constructed from the original schema and the security view specification. To enforce the access constraints on user queries, we propose Secure Query Rewrite (SQR) -- a set of rules that can be used to rewrite a user XPath query on the security view into an equivalent XQuery expression against the original data, with the guarantee that the users only see information in the view but not any data that was blocked. Experimental evaluation demonstrates the efficiency and the expressiveness of our approach.

We present a novel classifier based upon principles of logic-theoretic Boolean function minimization. The classifier, called Circle, recursively produces a set of implicants (or rules). The implicant set contains information not only about the presence of features, but also about their absence in determining class values. Thus, Circle's implicant set is initially non-monotonic with respect to inserting new tuples that have feature values that were not in the training set. One important benefit of this non-monotonicity, however, is that Circle is capable of being robust in the presence of novel feature values. We have created a full implementation of Circle using Java as a host language and Oracle database backend. Because we are interested in data mining in bioinformatics, particularly genomic data, the database was borne out of necessity to both manage and effectively query the information.

A method for augmenting an SGML document repository with database functionality is presented. SGML (ISO 8879, 1986) has been widely accepted as a standard language for writing text with added structural information that gives the text greater applicability. Recently there has been a trend to use this structural information as meta-data in databases. The complex structure of documents, however, makes it difficult to directly map the structural information in documents to database structures. In particular, the flat nature of relational databases makes it extremely difficult to model documents that are inherently hierarchical in nature. Consequently, documents are modeled in object-oriented databases (Abite-boul, Cluet, & Milo, 1993), and object-relational databases (Holst, 1995), in which SGML documents are mapped into the corresponding database models and are later reconstructed as necessary. However, this mapping strategy is not natural and can potentially cause loss of information in the original SGML documents. Moreover, interfaces for building queries for current document databases are mostly built on form-based query techniques and do not use the “look and feel” of the documents. This article introduces an implementation method for a complex-object modeling technique specifically for SGML documents and describes interface techniques tailored for text databases. Some of the concepts for a Structured Document Database Management System (SDDBMS) specifically designed for SGML documents are described. A small survey of some current products is also presented to demonstrate the need for such a system. © 1997 John Wiley & Sons, Inc.