Algorithmic Techniques for Maintaining Shortest Routes in Dynamic Networks

In this paper, we survey algorithms for shortest paths in dynamic networks. Although research on this problem spans over more than three decades, in the last couple of years many novel algorithmic techniques have been proposed. In this survey, we will make a special effort to abstract some combinatorial and algebraic properties, and some common data-structural tools that are at the base of those techniques. This will help us try to present some of the newest results in a unifying framework so that they can be better understood and deployed also by non-specialists.     

Graph Spanners in the Streaming Model: An Experimental Study

This article reports the results of an extensive experimental analysis of efficient algorithms for computing graph spanners in the data streaming model, where an (α,β)-spanner of a graph G is a subgraph S⊆G such that for each pair of vertices the distance in S is at most α times the distance in G plus β. To the best of our knowledge, this is the first computational study of graph spanner algorithms in a streaming setting. We compare experimentally the randomized algorithms proposed by Baswana () and by Elkin (In: Proceedings of the 34th International Colloquium on Automata, Languages and Programming (ICALP 2007), Wroclaw, Poland, pp. 716–727, 9–13 July 2007) for general stretch factors with the deterministic algorithm presented by Ausiello et al. (In: Proceedings of the 15th Annual European Symposium on Algorithms (ESA 2007), Engineering and Applications Track, Eilat, Israel, 8–10 October 2007. LNCS, vol. 4698, pp. 605–617, 2007), designed for building small stretch spanners. All the algorithms we implemented work in a data streaming model where the input graph is given as a stream of edges in arbitrary order, and all of them need a single pass over the data. Differently from the algorithm in Ausiello et al., the algorithms in Baswana () and Elkin (In: Proceedings of the 34th International Colloquium on Automata, Languages and Programming (ICALP 2007), Wroclaw, Poland, pp. 716–727, 9–13 July 2007) need to know in advance the number of vertices in the graph. The results of our experimental investigation on several input families confirm that all these algorithms are very efficient in practice, finding spanners with stretch and size much smaller than the theoretical bounds and comparable to those obtainable by off-line algorithms. Moreover, our experimental findings confirm that small values of the stretch factor are the case of interest in practice, and that the algorithm by Ausiello et al. tends to produce spanners of better quality than the algorithms by Baswana and Elkin, while still using a comparable amount of time and space resources. Work partially supported by the Italian Ministry of University and Research under Project MAINSTREAM “Algorithms for Massive Information Structures and Data Streams”. A preliminary version of this paper was presented at the 15th Annual European Symposium on Algorithms (ESA 2007) 5.     

Illustration de la capacité discriminante du Questionnaire sur la ?esolution des conflits dans la mesure de la violence parentale.

Examined the discriminatory power of the Questionnaire sur la résolution des conflicts (QRC) to distinguish abusive parents or parents considered at risk of committing abuse toward their children from parents who were not. The QRC is the French-Canadian translation of the Conflict Tactics Scales. This instrument assesses different possible ways parents could deal with parent–child conflict. In this study, 3 scales of violence tactics were used: Verbal Aggression, Minor Physical Violence, and Severe Physical Violence. Frequency scores of parents who reported difficulties in their parent–child relationship were compared with those of parents who reported no such difficulties. Results supported the QRC's discriminatory power regarding these 2 parental groups based on the Verbal Aggression scale and the Minor Physical Violence scale. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Antimicrobial activity of the surface coatings on TiAlZr implant biomaterial

This study is devoted to antimicrobial activity of new surface coatings on TiAlZr. Ti alloys such as TiAlZr are used as implant biomaterials, but, despite the good behavior of such alloys in simulated conditions, bacterial infections appear after the introduction of an implant into the body. The infections are typically caused by the adherence and colonization of bacteria on the surfaces of the implants. The study presents preparation and surface morphology characterization of coatings obtained via anodizing, as well as biomimetic coatings with hydroxyapatite and silver ions with and without antibiotic. The percentage inhibition of Escherichia coli bacteria growth was evaluated for each of the studied coating, and a Trojan-horse model of silver nanoparticles (nAg) antibacterial activity at interface was proposed. Such coatings could be more important taking into account that antibacterial treatments with antibiotics are becoming less effective due to their intensive use.     

Characterisation and corrosion resistance of the electrodeposited hydroxyapatite and bovine serum albumin/hydroxyapatite films on Ti–6Al–4V–1Zr alloy surface

A new titanium base Ti–6Al–4V–1Zr alloy covered with hydroxyapatite or bovine serum albumin/hydroxyapatite was characterized in this paper in order to be used as implant material. Following techniques were used: linear polarization, electrochemical impedance spectroscopy, scanning electronic microscopy, Fourier transform infrared spectroscopy and atomic force microscopy. For HA or BSA/HA covered alloy, the electric equivalent circuit contains two time constants (for the passive film and for coatings). The resistance of the protective films increased in time and BSA/HA coating was slightly rougher than HA coating, this situation being favourably to the cell adhesion.     

Electrochemical stability and surface analysis of a new alkyd paint with low content of volatile organic compounds

This paper presents the results regarding the electrochemical stability and surface analysis of a new alkyd paint with low content of volatile organic compounds in comparison with a conventional alkyd paint. The alkyd films were realized on carbon steel substrate. Dry films thickness in 30–35 μm range was obtained. The experimental tests were carried out in 3% NaCl solution at the 25 °C temperature. The electrochemical techniques (electrochemical impedance spectroscopy (EIS), potentiodynamic and Tafel polarization) and surface analysis techniques (AFM, SEM, EDX) were used to evaluate protective properties of the tested paint films. The correlation of all experimental results established that the new alkyd paint with low content of volatile organic compounds presents better protective performances and lower permeability than conventional alkyd paint. AFM, SEM and EDX indicated a compact, homogenous, non-porous and adherent coating.     

Polypyrrole film architectures influence on platinum nanoparticles efficiency in ethanol electrooxidation

The electrodeposition of polypyrrole films from aqueous surfactant solution through a two‐dimensional polystyrene template onto indium‐tin oxide substrate has been investigated. The polymer grows in the interstitial spaces of the self‐assembled polystyrene spheres, which were subsequently removed by dissolution in toluene. The new obtained surface was characterized by scanning electron microscopy and atomic force microscopy. Platinum nanoparticles were deposited onto the nanostructured polypyrrole electrode and used as a catalyst for the oxidation of ethanol for direct ethanol fuel cells. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41375.     

Aspects relating to stability of modified passive stratum on TiO2 nanostructure

Two kinds of nanotube structures differing from the point of view of their dimensions were obtained using anodizing in two different fluoride electrolytes and these structures were investigated regarding stability. The nanotubes have diameters of around 100 and 65 nm, respectively, and the testing solutions were simulated body fluids (SBF) and NaCl 0.9%. As stability experiments, cyclic voltammetry was performed and ions release was measured. The quantity of released cations in time as a kinetic aspect of passive stratum behavior was followed with an inductively coupled plasma mass spectrometer (ICP-MS) and apatite forming in SBF was found with infrared spectra. This study led to a comparison between the modification and the behavior of passive stratum on nanotubes as a function of their diameters.