Solving the 2-Disjoint Connected Subgraphs Problem Faster than 2 n

The 2-Disjoint Connected Subgraphs problem, given a graph along with two disjoint sets of terminals Z ₁,Z ₂, asks whether it is possible to find disjoint sets A ₁,A ₂, such that Z ₁?A ₁, Z ₂?A ₂ and A ₁,A ₂ induce connected subgraphs. While the naive algorithm runs in O(2 ⁿ n ^O(1)) time, solutions with complexity of form O((2?ε) ⁿ ) have been found only for special graph classes (van ’t Hof et al. in Theor. Comput. Sci. 410(47–49):4834–4843, 2009; Paulusma and van Rooij in Theor. Comput. Sci. 412(48):6761–6769, 2011). In this paper we present an O(1.933 ⁿ ) algorithm for 2-Disjoint Connected Subgraphs in general case, thus breaking the 2 ⁿ barrier. As a counterpoise of this result we show that if we parameterize the problem by the number of non-terminal vertices, it is hard both to speed up the brute-force approach and to find a polynomial kernel.     

The Good,the Bad,and the Commons: A Critical Review of Popular Discourse on Piracy and Power During Anti‐ACTA Protests

The article analyses popular discourse on piracy and power that emerged as a result of people's online anti‐ACTA (Anti‐Counterfeiting Trade Agreement) engagement in Poland. Drawing upon a social semiotic visual analysis of 921 ACTA‐related images shared online in 2012, the author analyzes a collective reconstruction of the concept of “piracy” and the popular narrative of the conflict in terms of its sides and subject. The study reveals how anti‐ACTA images form a medium of national popular culture adaptation of global pop‐ and countercultural modalities. The protesters appropriated them to oppose another attempt at global copyright enforcement. New media became not only the tool and environment for these activities but were also collectively depicted as “the commons,” endangered by the agreement.     

BDDC by a frontal solver and the stress computation in a hip joint replacement

A parallel implementation of the Balancing Domain Decomposition based on Constraints (BDDC) method using the frontal solver is employed to solve systems of linear equations from finite element analysis, and incorporated into a standard finite element system for engineering analysis by linear elasticity. Results of computation of stress in a hip replacement are presented. The part is made of titanium and loaded by the weight of human body. The performance of BDDC with added constraints by averages and with added corners is compared.     

Sensitivity analysis for frictional contact problems in the augmented Lagrangian formulation

Direct differentiation method of sensitivity analysis is developed for frictional contact problems. As a result of the augmented Lagrangian treatment of contact constraints, the direct problem is solved simultaneously for the displacements and Lagrange multipliers using the Newton method. The main purpose of the paper is to show that this formulation of the augmented Lagrangian method is particularly suitable for sensitivity analysis because the direct differentiation method leads to a non-iterative exact sensitivity problem to be solved at each time increment. The approach is applied to a general class of three-dimensional frictional contact problems, and numerical examples are provided involving large deformations, multibody contact interactions, and contact smoothing techniques.     

Ontology‐Based Representation and Modelling of Synthetic 3D Content: A State‐of‐the‐Art Review

An indispensable element of any practical 3D/VR/AR application is synthetic three‐dimensional (3D) content. Such content is characterized by a variety of features—geometry, structure, space, appearance, animation and behaviour—which makes the modelling of 3D content a much more complex, difficult and time‐consuming task than in the case of other types of content. One of the promising research directions aiming at simplification of modelling 3D content is the use of the semantic web approach. The formalism provided by semantic web techniques enables declarative knowledge‐based modelling of content based on ontologies. Such modelling can be conducted at different levels of abstraction, possibly domain‐specific, with inherent separation of concerns. The use of semantic web ontologies enables content representation independent of particular presentation platforms and facilitates indexing, searching and analysing content, thus contributing to increased content re‐usability. A range of approaches have been proposed to permit semantic representation and modelling of synthetic 3D content. These approaches differ in the methodologies and technologies used as well as their scope and application domains. This paper provides a review of the current state of the art in representation and modelling of 3D content based on semantic web ontologies, together with a classification, characterization and discussion of the particular approaches.     

Intelligent information processing for building university knowledge base

There are many ready-to-use software solutions for building institutional scientific information platforms, most of which have functionality well suited to repository needs. However, there have already been discussions about various problems with institutional digital libraries. As a remedy, an approach that is researcher-centric (rather than document-centric) has been proposed recently in some systems. This paper is devoted to research aimed at tools for building knowledge bases for university research. We focus on the AI methods that have been elaborated and applied practically within our platform for building such knowledge bases. In particular we present a novel approach to data acquisition and the semantic enrichment of the acquired data. In addition, we present the algorithms applied in the real life system for experts profiling and retrieval.     

Laminar fluid flow and heat transfer in an internally corrugated tube by means of the method of fundamental solutions and radial basis functions

The paper shows application of the method of fundamental solutions in combination with the radial basis functions for analysis of fluid flow and heat transfer in an internally corrugated tube. Cross-section of such a tube is mathematically described by a cosine function and it can potentially represent a natural duct with internal corrugations, e.g. inside arteries. The boundary value problem is described by two partial differential equations (one for fluid flow problem and one for heat transfer problem) and appropriate boundary conditions. During solving this boundary value problem the average fluid velocity and average fluid temperature are calculated numerically. In the paper the Nusselt number and the product of friction factor and Reynolds number are presented for some selected geometrical parameters (the number and amplitude of corrugations). It is shown that for a given number of corrugations a minimal value of the product of friction factor and Reynolds number can be found. As it was expected the Nusselt number increases with increasing amplitude and number of corrugations.     

Differences in lipid parameters among statins treated patients with coronary arteriosclerosis – a pilot study

LDL, total cholesterol (TC), high‐density lipoprotein (HDL) are poor predictors of the cardiovascular risk among patients undergoing hypolipidaemic therapy with statins. Thus, in this pilot study we have attempted to determine, on the basis of routinely used assessments of lipid profiles, sensitive and inexpensive parameter which would associate with the severity of coronary artery disease in patients undergoing hypolipidaemic treatment who achieved LDL goal. Apolipoprotein (apo) B100, apoA1, LDL, triglycerides, HDL, lipoprotein (a) and TC levels were assessed in 140 patients referred for coronary angiography. The various ratios based on lipid parameters were calculated and compared to patients taking statins. Coronary arteriosclerosis was determined by the degree of single stenosis and quantitatively by applying the Gensini score. Uing multivariate analysis we have found that in the group with hypolipidaemic therapy and/or with treatment LDL target (70–100 mg/dL) the TC/apoB100 ratio was associated with coronary artery stenosis. Additionally, univariate analysis showed that the TC/apoB100 ratio (among treated subjects) was significantly lower in patients with haemodynamically significant stenosis of coronary arteries than in matched patients without coronary artery lesions.