Algorithms for the maximum satisfiability problem

Old and new algorithms for the Maximum Satisfiability problem are studied. We first summarize the different heuristics previously proposed, i.e., the approximation algorithms of Johnson and of Lieberherr for the general Maximum Satisfiability problem, and the heuristics of Lieberherr and Specker, Poljak and Turzik for the Maximum 2-Satisfiability problem. We then consider two recent local search algorithmic schemes, the Simulated Annealing method of Kirkpatrick, Gelatt and Vecchi and the Steepest Ascent Mildest Descent method, and adapt them to the Maximum Satisfiability problem. The resulting algorithms, which avoid being blocked as soon as a local optimum has been found, are shown empirically to be more efficient than the heuristics previously proposed in the literature.     

Initiation of cationic polymerization by tetramethylene zwitterions from tetracyanocyclobutanes

The initiating ability of tetramethylene zwitterions formed from cyclobutane adducts of donor olefins with TCNE was investigated. Polar solvents increased the ability of vinyl ether-TCNE cyclobutane adducts to initiate the cationic polymerization of N-vinylcarbazole. The concept of charge separation in the tetramethylene zwitterions was also investigated.     

Reduced percolation concentration in polypropylene/expanded graphite composites: Effect of viscosity and polypyrrole

With the goal to obtain material combining electrical and thermal conductivity at low filler loadings, composites based on polypropylenes (PP) and expanded graphite (EG) have been prepared. The effects of matrix viscosity and of coating the EG particles with polypyrrole (PPy, EG/PPy = 37.5/62.5 by weight) on the EG dispersibility and formation of percolation structures have been analyzed. When increasing the EG amount from 6 to 8 wt %, the electrical conductivity of PP/EG composites increased by 7–9 orders of magnitude, independent of matrix viscosity. When EG‐PPy is added, percolation was observed between 8 and 12 wt % EG‐PPy (3 and 4.5 wt % EG) in case of PP with higher viscosity and 6 wt % EG (2.25 wt % EG) in case of PP with lower viscosity, exhibiting a strong synergistic effect of EG and PPy in the latter case. In contrast, PPy does not contribute to reduction of thermal percolation concentration. Thermal percolation is observed at 8 wt % EG in PP/EG composites, but no percolation was found in PP/EG‐PPy composites with EG‐PPy contents of up to 20 wt %, corresponding to 7.5 wt % EG. Analyzing the melt rheology it becomes clear that the contribution of PPy to the formation of a filler network is strongly dependent on the matrix viscosity. The comparison of thermal, electrical and rheological percolation reveals that PPy participates in electron transport reducing the electrical percolation but not to heat transport. Overall, we found a good correlation between electrical, thermal, and melt rheological percolation concentrations. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41994.     

The Tyrosine Gate of the Bacterial Lectin FimH: A Conformational Analysis by NMR Spectroscopy and X‐ray Crystallography

Urinary tract infections caused by uropathogenic E. coli are among the most prevalent infectious diseases. The mannose‐specific lectin FimH mediates the adhesion of the bacteria to the urothelium, thus enabling host cell invasion and recurrent infections. An attractive alternative to antibiotic treatment is the development of FimH antagonists that mimic the physiological ligand. A large variety of candidate drugs have been developed and characterized by means of in vitro studies and animal models. Here we present the X‐ray co‐crystal structures of FimH with members of four antagonist classes. In three of these cases no structural data had previously been available. We used NMR spectroscopy to characterize FimH–antagonist interactions further by chemical shift perturbation. The analysis allowed a clear determination of the conformation of the tyrosine gate motif that is crucial for the interaction with aglycone moieties and was not obvious from X‐ray structural data alone. Finally, ITC experiments provided insight into the thermodynamics of antagonist binding. In conjunction with the structural information from X‐ray and NMR experiments the results provide a mechanism for the often‐observed enthalpy–entropy compensation of FimH antagonists that plays a role in fine‐tuning of the interaction.     

Design of survivable WDM networks using pre-configured protection structures with unrestricted shapes

We propose a novel protection approach for the design of link-protection schemes in survivable Wavelength Division Multiplexing mesh networks by merging the well-known p-cycle- and p-tree-protection structures. So doing, we aim at gathering the advantages of p-cycles in terms of protection capabilities, and of p-trees in terms of protection flexibilities (local re-routing, scalability) in a single protection scheme. As opposed to existing protection schemes based on protection structures with a pre-defined shape, the building blocks of the new scheme are protection structures with unrestricted shapes. Thus, they allow more flexibility in provisioning spare capacity, and provide higher capacity efficiency when compared to the shaped-protection schemes that have been proposed so far. In order to cope with the size of the solution space which includes all the possible protection structures, we propose an efficient and scalable optimization technique in large-scale systems named column generation (CG). In our CG-based optimization approach, the shape of a candidate protection structure is dynamically decided during the optimization process according to a link spare capacity budget. Experimental results on different network instances show that the protection plan resulting from the merging of p-cycle and p-tree structures is, on average, ~15% less capacity redundant and ~15% more reliable than the pure p-cycle one. It also requires, on average, ~30% less protection structures. In addition, those structures provide backup paths ~30% smaller than those of the p-cycle-based scheme.     

Use of volatile compound metabolic signatures in poultry liver to back-trace dietary exposure to rapidly metabolized xenobiotics

The study investigated the feasibility of using volatile compound signatures of liver tissues in poultry to detect previous dietary exposure to different types of xenobiotic. Six groups of broiler chickens were fed a similar diet either noncontaminated or contaminated with polychlorinated dibenzo-p-dioxins/-furans (PCDD/Fs; 3.14 pg WHO-TEQ/g feed, 12% moisture), polychlorinated biphenyls (PCBs; 0.08 pg WHO-TEQ/g feed, 12% moisture), polybrominated diphenyl ethers (PBDEs; 1.63 ng/g feed, 12% moisture), polycyclic aromatic hydrocarbons (PAHs; 0.72 μg/g fresh matter), or coccidiostats (0.5 mg/g feed, fresh matter). Each chicken liver was analyzed by solid-phase microextraction - mass spectrometry (SPME-MS) for volatile compound metabolic signature and by gas chromatography - high resolution mass spectrometry (GC-HRMS), gas chromatography - tandem mass spectrometry (GC-MS/MS), and liquid chromatography - tandem mass spectrometry (LC-MS/MS) to quantify xenobiotic residues. Volatile compound signature evidenced a liver metabolic response to PAH although these rapidly metabolized xenobiotics are undetectable in this organ by the reference methods. Similarly, the volatile compound metabolic signature enabled to differentiate the noncontaminated chickens from those contaminated with PBDEs or coccidiostats. In contrast, no clear signature was pointed out for slowly metabolized compounds such as PCDD/Fs and PCBs although their residues were found in liver at 50.93 (±6.71) and 0.67 (±0.1) pg WHO-TEQ/g fat, respectively.     

Fuzzy inference systems: An integrated modeling environment for collaboration between expert knowledge and data using FisPro

The present paper aims to demonstrate the interest of fuzzy inference systems in system modeling when human interaction is important. It discusses the originality of FIS and their capability to integrate expertise and rule learning from data into a single framework, analyzing their place relatively to concurrent approaches. An open source software implementation is presented, with a focus on the useful features for modeling. Two real world case studies are presented to illustrate the approach and the software utility.     

Effects of caffeine on lipoprotein lipase gene expression during the adipocyte differentiation process

In this study, the effects of caffeine on lipoprotein lipase (LPL) gene expression were investigated in the 3T3-F442A preadipocyte cell line during the adipocyte differentiation process by determining LPL enzymatic activity and its messenger RNA (mRNA) level. The results demonstrate that caffeine acts on the gene expression of LPL, an early marker of adipocyte differentiation. It has a biphasic action: it increases gene expression in terms of mRNA when it is added to preadipocytes during the early stage of differentiation, but this is accompanied by a reduction of enzymatic activity. On the other hand, when caffeine is added for long periods during differentiation and/or when it is added to mature adipocytes, it induces marked inhibition of mRNA levels, correlated with a marked reduction of secreted enzymatic activity. The inhibitory effect of caffeine on LPL mRNA level can be reproduced by theophylline, a phosphodiesterase inhibitor, and by dibutyryl cyclic AMP, a non-metabolizable analog of cyclic AMP. However, the effect of caffeine and theophylline lasts longer than that of cyclic AMP, suggesting that a mechanism other than inhibition of cyclic AMP hydrolysis may be involved in the action of caffeine.