A simple linear time certifying LBFS-based algorithm for recognizing trivially perfect graphs and their complements

We introduce a simple, linear time algorithm for recognizing trivially perfect (TP) graphs. It improves upon the algorithm of Yan et al. [J.-H. Yan, J.-J. Chen, G.J. Chang, Quasi-threshold graphs, Discrete Appl. Math. 69 (3) (1996) 247–255] in that it is certifying, producing a P₄ or a C₄ when the graph is not TP. In addition, our algorithm can be easily modified to recognize the complement of TP graphs (co-TP) in linear time as well. It is based on lexicographic BFS, and in particular the technique of partition refinement, which has been used in the recognition of many other graph classes [D.G. Corneil, Lexicographic breadth first search—a survey, in: WG 2004, in: Lecture Notes in Comput. Sci., vol. 3353, Springer, 2004, pp. 1–19].     

Acute kidney failure in hypothermia

Two cases with acute renal failure after prolonged hypothermia are presented. Both patients were found in come, became rapidly uremic and required hemodilaysis treatment. Although the laboratory findings were typical of severe muscle damage, e.g. elevated levels of serum creatinine phosphokinase, serum lactic dehydrogenase and serum aldolase activities, visible "crush-injuries" were not found. Acute renal failure was characterized by extreme catabolism and severe metabolic acidosis. After 4 and 10 hemodialyses respectively, the patients became polyuric and finally were discharges with normal renal and muscle function. Hypotension with diminished renal perfusion and nontraumatic rhabdomyolysis due to prolonged hypothermia are regarded as the dominant pathogenetic factors in the acute renal failure.     

Adoption of the Internet and WAP-enabled phones in Singapore

The Internet, and more recently mobile phones have seen tremendous growth over the past few years. This paper examines the adoption of the Internet and WAP-enabled mobile phones in Singapore. Specifically, we compare users of WAP-enabled mobile phones and non-WAP-enabled mobile phones in terms of profile of Internet users, Internet activities and issues relating to WAP-enabled mobile phones. The results indicate that short messaging system (SMS) and caller ID are popular functions for mobile phone users. Respondent also use the mobile phone for buying cinema/concert tickets and accessing personalised news. These results provide researchers and practitioners with some insights on the adoption of the Internet and WAP-enabled mobile phones. For researchers, such insights would be useful in understanding the adoption phenomenon, while for practitioners, such insights would provide some basis for adopting certain policies to promote adoption.     

A new perspective for the thermal degradation mechanism of blue BAM

A new thermal degradation mechanism for blue BAM (BaMgAl₁₀O₁₇:Eu²⁺) under thermal treatment in the presence of water is proposed. The water can be originated either from the thermal treatment steps, such as organic binder baking steps, or from the atmosphere under which blue BAM is being heated. Under such thermal treatment conditions, water molecules can be easily intercalated into the conduction layers of blue BAM, resulting in not only the depreciation of luminance but also in the emission color change toward green. The intercalated water molecules in the conduction layer, where Eu²⁺ ions are located along with Ba²⁺ ions, are strongly associated with Eu²⁺ ions, creating different coordination environments around Eu²⁺ ions. In this paper, the details of changes in emission behaviors along with water content in the water intercalated blue BAMs are discussed.     

Development of substrate-pumped nMOS protection for a 0.13 μm technology

A methodology is presented for improved process and circuit development of substrate-pumped nMOS protection. ESD process development is accelerated by applying factor analysis to completed non-ESD experiments. Factor analysis is complemented by a straightforward diagnosis of nMOS snapback. This approach enabled verification of two process solutions, including a novel method, in one fab cycle-time. HBM data that shows the substrate-pumped nMOS can provide dramatically higher protection than estimated from conventional I_t2 measurements. This motivates improved ESD circuit development. The nMOS clamp transistor is characterized as an actively biased LNPN, which is how it is used in a substrate-pumped protection circuit. A systematic approach to circuit development is described that is based upon empirical characterization of well-defined circuit components under conditions approximating ESD.     

Bandwidth and loss measurements of graded-index microstructured polymer optical fibre

The first bandwidth measurements of graded-index microstructured optical fibres are presented, demonstrating that this novel fibre geometry can provide high-bandwidth multimode polymer fibres without the need for complex doping techniques as with conventional polymer fibres.     

Synthesis and toxicity of some metabolites of the microbial degradation of synthetic naphthenic acids

Some ill-defined carboxylic acids, termed ‘naphthenic acids’ (NA), are best known as important constituents of the > 720 billion litres of process-affected water associated with the expanding oil sands industries. Other NA are components of some immature and biodegraded crude oils and these may enter the environment via produced water discharges from oil production platforms. Yet others are used as biocides and in the manufacture of steel radial tyres and these may also enter the environment through disposal and/or weathering. The environmental fate of NA, including the mechanisms of biodegradation, therefore needs to be better understood.In order to better elucidate such mechanisms, previously we studied the biodegradation in the laboratory of some alkylcyclohexylbutanoic synthetic NA. However, we could only tentatively identify the metabolites produced. In the present study we report the synthesis and characterisation of six alkylcyclohexylethanoic NA. Each was characterised by gas chromatography-mass spectrometry (GC-MS; trimethylsilyl esters) and we show by co-chromatography that these were indeed the metabolites. Also, a preferential degradation of the trans- isomers was revealed. Assessment of the toxicity of the synthetic NA (Microtox assay), revealed that the relative toxicity of the alkylcyclohexylbutanoic acids was reduced by biotransformation to the alkylcyclohexylethanoic acids, as observed recently for the corresponding aromatic acids.Very recent studies have shown that at least one commercial NA mixture contains cyclohexylbutanoic and alkylcyclohexylethanoic acids, suggesting that the biotransformation of the acids studied herein may be quite relevant to the environmental fate of such acids. A similar study of the acid extractables of one oil sands process-affected water sample suggests that the synthetic acids may be less good ‘models’ for oil sands NA. The consortia of microbes present in oil sands process-affected water may also be different to those used herein. However, the heterogeneity of oil sands process water is well-known and further detailed studies will need to be made in order to establish whether degradation of oil sands NA proceeds by beta oxidation as observed for the acids herein, or whether the oil sands acids are more resistant to bioremediation.     

Selective removal of impulse noise based on homogeneity level information

We propose a decision-based, signal-adaptive median filtering algorithm for removal of impulse noise. Our algorithm achieves accurate noise detection and high SNR measures without smearing the fine details and edges in the image. The notion of homogeneity level is defined for pixel values based on their global and local statistical properties. The cooccurrence matrix technique is used to represent the correlations between a pixel and its neighbors, and to derive the upper and lower bound of the homogeneity level. Noise detection is performed at two stages: noise candidates are first selected using the homogeneity level, and then a refining process follows to eliminate false detections. The noise detection scheme does not use a quantitative decision measure, but uses qualitative structural information, and it is not subject to burdensome computations for optimization of the threshold values. Empirical results indicate that our scheme performs significantly better than other median filters, in terms of noise suppression and detail preservation.