Wodel-Test: a model-based framework for language-independent mutation testing

Software and Systems Modeling - Mutation testing (MT) targets the assessment of test cases by measuring their efficiency to detect faults. This technique involves modifying the program under test...     

The Freeze-Tag Problem: How to Wake Up a Swarm of Robots

An optimization problem that naturally arises in the study of swarm robotics is the Freeze-Tag Problem (FTP) of how to awaken a set of "asleep" robots, by having an awakened robot move to their locations. Once a robot is awake, it can assist in awakening other slumbering robots. The objective is to have all robots awake as early as possible. While the FTP bears some resemblance to problems from areas in combinatorial optimization such as routing, broadcasting, scheduling, and covering, its algorithmic characteristics are surprisingly different. We consider both scenarios on graphs and in geometric environments. In graphs, robots sleep at vertices and there is a length function on the edges. Awake robots travel along edges, with time depending on edge length. For most scenarios, we consider the offline version of the problem, in which each awake robot knows the position of all other robots. We prove that the problem is NP-hard, even for the special case of star graphs. We also establish hardness of approximation, showing that it is NP-hard to obtain an approximation factor better than 5/3, even for graphs of bounded degree. These lower bounds are complemented with several positive algorithmic results, including: · We show that the natural greedy strategy on star graphs has a tight worst-case performance of 7/3 and give a polynomial-time approximation scheme (PTAS) for star graphs. · We give a simple O(log δ)-competitive online algorithm for graphs with maximum degree δ and locally bounded edge weights. · We give a PTAS, running in nearly linear time, for geometrically embedded instances.     

Club convergence in innovation activity across European regions

The goal of this paper is to analyse the innovation activity convergence process across European regions from 2002 to 2012. A novel methodology that allows either detection of overall convergence or endogenous identification of groups of regions was applied. The results support the club convergence hypothesis for explaining the convergence process of Europe's regions during the period analysed and seven innovation convergence clubs were identified. In addition, the research results indicate that initial regional R&D expenditure is the most relevant factor driving the formation of the convergence clubs after controlling for the effects of regional structural characteristics.     

Evaluation Model for Assessing the Suitability of Public-Private Partnership Projects

This paper presents an evaluation model useful for assessing the suitability of public-private partnership (PPP) projects by studying their attractive and negative factors. A survey of industrial practitioners in Hong Kong was conducted. Respondents were asked to rank the importance of 15 attractive and 13 negative factors for adopting PPP. From the rankings, relative weights of each factor were derived. The weights of these factors formed the basis for the evaluation model presented in this paper. The Hong Kong Zhuhai Macau Bridge was used to demonstrate how this evaluation model could be applied. From the list of attractive and negative factors the writers selected those that were foreseeable in this project. Calculating the total weights of each group of factors showed that negative factors outweighed attractive factors by 27%. The result indicated that PPP would not be a suitable method for delivering this project. The evaluation model presented in this paper can help both the public and private sectors to assess whether potential public projects are suited for PPP.     

INDITEP: The first pre-commercial DSG solar power plant

This paper presents the conceptual design of the first solar power plant using Direct Steam Generation (DSG) in a parabolic-trough solar field. Experience and know-how in the DSG process acquired during the DISS project were applied in designing the solar field of this plant. The 5-MWe plant is composed of a DSG parabolic-trough solar field connected to a superheated steam Rankine power cycle. The solar field produces 410 °C/70-bar superheated steam. Detail engineering of this plant is currently underway within the framework of the INDITEP project, which is promoted by a German-Spanish consortium with the financial support of the European Commission (Contract No. ENK5-CT-2001-00540). The main design objective is to assure high operational flexibility and reliability. This is the reason why a robust superheated steam turbine has been selected, though the efficiency of its power block is modest.     

Analysis of the colorimetric properties of goniochromatic colors using the MacAdam limits under different light sources

Technological innovation in all areas has led to the appearance in recent years of new metallic and pearlescent materials, yet no exhaustive studies have been conducted to assess their colorimetric capabilities. The chromatic variability of these special-effect pigments may largely be due to the three-dimensional effect of their curved shapes and orientations when they are directionally or diffusely illuminated. Our study examines goniochromatic colors using the optimal colors (MacAdam limits) associated with normal colors (photometric scale of relative spectral reflectance from 0 to 1) under certain conventional illuminants and other light sources. From a database of 91 metallic and interference samples and using a multi-gonio-spectrophotometer, we analyzed samples with lightness values of more than 100 and others with lightness values of less than 100, but with higher chromaticities than optimal colors, which places them beyond the MacAdam limits. Our study thus demonstrates the existence of chromatic perceptions beyond the normal solid color associated with these materials and independent of the light source. The challenge for future research, therefore, is to replicate and render these color appearances in current and future color reproduction technologies for computer graphics.     

Effect of soaking,cooking and crude α-galactosidase treatment on the oligosaccharide content of cowpea flours

Abstract : The effects of soaking, cooking and crude α-galactosidase treatment on the level of stachyose and raffinose present in cowpea flours were investigated. Soaking for 16 h resulted in an average reduction of 26·2% for stachyose and 28·0% for raffinose, while cooking for 50 min resulted in a reduction of 28·6% for stachyose and 44·0% for raffinose. On the other hand, treatment of cowpea flours for 2 h at 50°C with crude fungal preparations having an α-galactosidase activity equivalent to 64 units μg^?1 protein, brought about a mean decrease of 82·3% for stachyose and 93·3% for raffinose. These results show that the enzyme treatment was more effective in removing the raffinose-family oligosaccharides and hence could be a useful technique for control of the flatulence-inducing activity of cowpea flours.     

Repurposing the Chemical Scaffold of the Anti‐Arthritic Drug Lobenzarit to Target Tryptophan Biosynthesis in Mycobacterium tuberculosis

The emergence of extensively drug‐resistant strains of Mycobacterium tuberculosis (Mtb) highlights the need for new therapeutics to treat tuberculosis. We are attempting to fast‐track a targeted approach to drug design by generating analogues of a validated hit from molecular library screening that shares its chemical scaffold with a current therapeutic, the anti‐arthritic drug Lobenzarit (LBZ). Our target, anthranilate phosphoribosyltransferase (AnPRT), is an enzyme from the tryptophan biosynthetic pathway in Mtb. A bifurcated hydrogen bond was found to be a key feature of the LBZ‐like chemical scaffold and critical for enzyme inhibition. We have determined crystal structures of compounds in complex with the enzyme that indicate that the bifurcated hydrogen bond assists in orientating compounds in the correct conformation to interact with key residues in the substrate‐binding tunnel of Mtb‐AnPRT. Characterising the inhibitory potency of the hit and its analogues in different ways proved useful, due to the multiple substrates and substrate binding sites of this enzyme. Binding in a site other than the catalytic site was found to be associated with partial inhibition. An analogue, 2‐(2‐5‐methylcarboxyphenylamino)‐3‐methylbenzoic acid, that bound at the catalytic site and caused complete, rather than partial, inhibition of enzyme activity was found. Therefore, we designed and synthesised an extended version of the scaffold on the basis of this observation. The resultant compound, 2,6‐bis‐(2‐carboxyphenylamino)benzoate, is a 40‐fold more potent inhibitor of the enzyme than the original hit and provides direction for further structure‐based drug design.     

Detection of DNA hybridization using the near-infrared band-gap fluorescence of single-walled carbon nanotubes

We demonstrate the optical detection of DNA hybridization on the surface of solution suspended single-walled carbon nanotubes (SWNTs) through a SWNT band gap fluorescence modulation. Hybridization of a 24-mer oligonucleotide sequence with its complement produces a hypsochromic shift of 2 meV, with a detection sensitivity of 6 nM. The energy shift is modeled by correlating the surface coverage of DNA on SWNT to the exciton binding energy, yielding an estimated initial fractional coverage of 0.25 and a final coverage of 0.5. Hybridization on the nanotube surface is confirmed using Forster resonance energy transfer of fluorophore-labeled DNA oligonucleotides. This detection is enabled through a new technique to suspend SWNTs using adsorption of single-stranded DNA and subsequent removal of free DNA from solution. While the kinetics of free DNA hybridization are relatively fast (<10 min), the kinetics of the process on SWNTs are slower under comparable conditions, reaching steady state after 13 h at 25 degrees C. A second-order kinetic model yields a rate constant of k = 4.33 x 10(5) (M h)(-1). This optical, selective detection of specific DNA sequences may have applications in the life sciences and medicine as in vitro or in vivo detectors of oligonucleotides.