A Goal-based Framework for Contextual Requirements Modeling and Analysis

Requirements Engineering (RE) research often ignores, or presumes a uniform nature of the context in which the system operates. This assumption is no longer valid in emerging computing paradigms, such as ambient, pervasive and ubiquitous computing, where it is essential to monitor and adapt to an inherently varying context. Besides influencing the software, context may influence stakeholders' goals and their choices to meet them. In this paper, we propose a goal-oriented RE modeling and reasoning framework for systems operating in varying contexts. We introduce contextual goal models to relate goals and contexts; context analysis to refine contexts and identify ways to verify them; reasoning techniques to derive requirements reflecting the context and users priorities at runtime; and finally, design time reasoning techniques to derive requirements for a system to be developed at minimum cost and valid in all considered contexts. We illustrate and evaluate our approach through a case study about a museum-guide mobile information system

ATP-binding cassette (ABC) transporters in normal and pathological lung

ATP-binding cassette (ABC) transporters are a family of transmembrane proteins that can transport a wide variety of substrates across biological membranes in an energy-dependent manner. Many ABC transporters such as P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1) and breast cancer resistance protein (BCRP) are highly expressed in bronchial epithelium. This review aims to give new insights in the possible functions of ABC molecules in the lung in view of their expression in different cell types. Furthermore, their role in protection against noxious compounds, e.g. air pollutants and cigarette smoke components, will be discussed as well as the (mal)function in normal and pathological lung. Several pulmonary drugs are substrates for ABC transporters and therefore, the delivery of these drugs to the site of action may be highly dependent on the presence and activity of many ABC transporters in several cell types. Three ABC transporters are known to play an important role in lung functioning. Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene can cause cystic fibrosis, and mutations in ABCA1 and ABCA3 are responsible for respectively Tangier disease and fatal surfactant deficiency. The role of altered function of ABC transporters in highly prevalent pulmonary diseases such as asthma or chronic obstructive pulmonary disease (COPD) have hardly been investigated so far. We especially focused on polymorphisms, knock-out mice models and in vitro results of pulmonary research. Insight in the function of ABC transporters in the lung may open new ways to facilitate treatment of lung diseases

Keratan sulphate in the tumour environment

Keratan sulphate (KS) is a bioactive glycosaminoglycan (GAG) of some complexity composed of the repeat disaccharide D-galactose β1→4 glycosidically linked to N-acetyl glucosamine. During the biosynthesis of KS, a family of glycosyltransferase and sulphotransferase enzymes act sequentially and in a coordinated fashion to add D-galactose (D-Gal) then N-acetyl glucosamine (GlcNAc) to a GlcNAc acceptor residue at the reducing terminus of a nascent KS chain to effect chain elongation. D-Gal and GlcNAc can both undergo sulphation at C6 but this occurs more frequently on GlcNAc than D-Gal. Sulphation along the developing KS chain is not uniform and contains regions of variable length where no sulphation occurs, regions which are monosulphated mainly on GlcNAc and further regions of high sulphation where both of the repeat disaccharides are sulphated. Each of these respective regions in the KS chain can be of variable length leading to KS complexity in terms of chain length and charge localization along the KS chain. Like other GAGs, it is these variably sulphated regions in KS which define its interactive properties with ligands such as growth factors, morphogens and cytokines and which determine the functional properties of tissues containing KS. Further adding to KS complexity is the identification of three different linkage structures in KS to asparagine (N-linked) or to threonine or serine residues (O-linked) in proteoglycan core proteins which has allowed the categorization of KS into three types, namely KS-I (corneal KS, N-linked), KS-II (skeletal KS, O-linked) or KS-III (brain KS, O-linked). KS-I to -III are also subject to variable addition of L-fucose and sialic acid groups. Furthermore, the GlcNAc residues of some members of the mucin-like glycoprotein family can also act as acceptor molecules for the addition of D-Gal and GlcNAc residues which can also be sulphated leading to small low sulphation glycoforms of KS. These differ from the more heavily sulphated KS chains found on proteoglycans. Like other GAGs, KS has evolved molecular recognition and information transfer properties over hundreds of millions of years of vertebrate and invertebrate evolution which equips them with cell mediatory properties in normal cellular processes and in aberrant pathological situations such as in tumourogenesis. Two KS-proteoglycans in particular, podocalyxin and lumican, are cell membrane, intracellular or stromal tissue–associated components with roles in the promotion or regulation of tumour development, mucin-like KS glycoproteins may also contribute to tumourogenesis. A greater understanding of the biology of KS may allow better methodology to be developed to more effectively combat tumourogenic processes

JOINT COGNITIVE SYSTEMS, COOPERATIVE SYSTEMS AND DECISION SUPPORT SYSTEMS: A COOPERATION IN CONTEXT

We present the lessons drawn from a review of the main concepts put forward by the designers of decision support systems, joint cognitive systems and cooperative systems. A striking observation is that these systems stumble on user-system cooperation. The main idea of this paper is that interactive system must behave more as an intelligent assistant than as an expert. Key elements of an effective cooperation between a user and a system are making explicit cooperation context and extending consequently the notions of explanations, knowledge acquisition and machine learning

Int. J. Expert Systems with Applications,, 8(4): 445-462 (1995) Cooperative problem solving and explanation

Recent studies have pointed out several limitations of expert systems regarding user needs, and have introduced the concepts of cooperation and joint cognitive systems in the focus of AI. While research on explanation generation by expert systems has been widely developed, there has been little consideration of explanation in relation to cooperative systems. Our aim is to elaborate a conceptual framework for studying explanation in cooperation. This work relies heavily on the study of human-human cooperative dialogues. We present our results according to two dimensions, namely, the relation between explanation and problem solving, and the explanation process. Finally, we discuss the implications of these results for the design of cooperative systems

Multidisciplinary Optimization of a Generic 2D High-Lift Configuration Regarding Kinematics, Aerodynamics and Flight Mechanics

This work deals with the multidisciplinary optimization of a generic two dimensional three element high-lift configuration. The objective of this work is to conduct a proof-of concept optimization and to find an optimized high-lift system with a feasible flap mechanism and enhanced aerodynamic performance which is reflected in a decreased take-off and landing distance. During the multidisciplinary optimization following disciplines are analyzed: Kinematics, Aerodynamics and Flight Mechanics. The proof-of-concept optimization is performed successfully and reveals a configuration with improved aerodynamic performance, reduced take-off and landing distance while the kinematic and aerodynamic constraints are satisfied. The overall take-off distance is reduced due to the augmentation of the maximum lift coefficient for the take-off configuration which leads to a significant shorter ground roll distance. At landing the moderate reduction in the overall landing distance is related to the enhanced maximum lift coefficient, which lowers the approach and touch-down speed. According to the data sets of the optimization it seems that the take-off and landing distance that form the objective function are not in conflict in this scenario. The optimization results indicate that the aerodynamic performance is more sensitive to parameters that define the slat setting and the magnitude of the flap deployment than to parameters that define the geometry of the flap mechanism

A Context-aware Security Framework for Next Generation Mobile Networks

The openness and heterogeneity of next generation communication networks are now highlighting more security issues than those of traditional communication environments. Moreover users’ security requirements can often change in mobile communication environments, depending on the situation in which the user is immersed. Our objective is to define a context-aware security framework for addressing the problems of end-to-end security on behalf of end-users. Based on context data acquisition and aggregation features, the framework uses contextual graphs to define security policies encompassing actions at different layers of communication systems’ architecture, while adapting to changing circumstances