Algorithms for flows over time with scheduling costs

Flows over time have received substantial attention from both an optimization and (more recently) a game-theoretic perspective. In this model, each arc has an associated delay for traversing the arc, and a bound on the rate of flow entering the arc; flows are time-varying. We consider a setting which is very standard within the transportation economic literature, but has received little attention from an algorithmic perspective. The flow consists of users who are able to choose their route but also their departure time, and who desire to arrive at their destination at a particular time, incurring a scheduling cost if they arrive earlier or later. The total cost of a user is then a combination of the time they spend commuting, and the scheduling cost they incur. We present a combinatorial algorithm for the natural optimization problem, that of minimizing the average total cost of all users (i.e., maximizing the social welfare). Based on this, we also show how to set tolls so that this optimal flow is induced as an equilibrium of the underlying game

Assignment of PolyProline II Conformation and Analysis of Sequence – Structure Relationship

International audienceBACKGROUND: Secondary structures are elements of great importance in structural biology, biochemistry and bioinformatics. They are broadly composed of two repetitive structures namely α-helices and β-sheets, apart from turns, and the rest is associated to coil. These repetitive secondary structures have specific and conserved biophysical and geometric properties. PolyProline II (PPII) helix is yet another interesting repetitive structure which is less frequent and not usually associated with stabilizing interactions. Recent studies have shown that PPII frequency is higher than expected, and they could have an important role in protein - protein interactions. METHODOLOGY/PRINCIPAL FINDINGS: A major factor that limits the study of PPII is that its assignment cannot be carried out with the most commonly used secondary structure assignment methods (SSAMs). The purpose of this work is to propose a PPII assignment methodology that can be defined in the frame of DSSP secondary structure assignment. Considering the ambiguity in PPII assignments by different methods, a consensus assignment strategy was utilized. To define the most consensual rule of PPII assignment, three SSAMs that can assign PPII, were compared and analyzed. The assignment rule was defined to have a maximum coverage of all assignments made by these SSAMs. Not many constraints were added to the assignment and only PPII helices of at least 2 residues length are defined. CONCLUSIONS/SIGNIFICANCE: The simple rules designed in this study for characterizing PPII conformation, lead to the assignment of 5% of all amino as PPII. Sequence - structure relationships associated with PPII, defined by the different SSAMs, underline few striking differences. A specific study of amino acid preferences in their N and C-cap regions was carried out as their solvent accessibility and contact patterns. Thus the assignment of PPII can be coupled with DSSP and thus opens a simple way for further analysis in this field

Narrative discourse in multiple sclerosis: An investigation of conceptual structure

The aim of the present study was to determine whether multiple sclerosis (MS) affects a person's ability to formulate message content in narrative discourse. Discourse samples were elicited from 47 persons with MS and 47 matched controls in response to computer-generated, animated sequences. Within the conceptual level of discourse processing, data were analysed for story schema and informative content. The two groups, MS and control, could not be distinguished by measures of the quantity of information conveyed. However, results revealed a difference in the nature of the information produced by the two groups. The persons with MS produced less essential story information than control subjects, while a tendency for the persons with MS to produce more incorrect and ambiguous information than controls was also noted. A number of factors were considered in an attempt to explain the underlying source of these differences. It was postulated that both pragmatic and cognitive skills impact on performance in the narrative genre; hence, deficits in these areas may have contributed to the observed performance deficits. The nature of the deficits was considered consistent with subcortical plaque damage affecting fibre tracts between and within cerebral hemispheres. The findings of the present study suggest that further research into narrative production in MS is warranted

Algorithms for Flows over Time with Scheduling Costs

Flows over time have received substantial attention from both an optimization and (more recently) a game-theoretic perspective. In this model, each arc has an associated delay for traversing the arc, and a bound on the rate of flow entering the arc; flows are time-varying. We consider a setting which is very standard within the transportation economic literature, but has received little attention from an algorithmic perspective. The flow consists of users who are able to choose their route but also their departure time, and who desire to arrive at their destination at a particular time, incurring a scheduling cost if they arrive earlier or later. The total cost of a user is then a combination of the time they spend commuting, and the scheduling cost they incur. We present a combinatorial algorithm for the natural optimization problem, that of minimizing the average total cost of all users (i.e., maximizing the social welfare). Based on this, we also show how to set tolls so that this optimal flow is induced as an equilibrium of the underlying game

A critical analysis of decision support systems research revisited: The rise of design science

© Association for Information Technology Trust 2016.Decision support systems (DSS) is the area of the information systems (IS) discipline that is focused on supporting and improving managerial decision making. In 2005 the Journal of Information Technology (JIT) published our paper that critically analyzed DSS research from 1990 to 2003 (Arnott and Pervan, 2005). That paper used bibliometric content analysis as its method and analyzed 1020 articles in 14 journals. The analysis illuminated a vibrant and important part of IS research. Personal DSS and group support systems (GSS) dominated DSS research and two-thirds of DSS research was empirical, a higher proportion than general IS research. Interpretive DSS research was growing from a low base while design-science research (DSR) and laboratory experiments were major research categories. Unfortunately, it was found that DSS research to 2003 was relatively poorly founded on judgment and decision-making theory and faced what was described as ‘a crisis of relevance’