Refactoring by Transformation

In this paper we present how refactoring of object-oriented programs can be accomplished by using refinement. Our approach is based on algebraic laws of an object-oriented language for refinement similar to Java. We follow a strategy involving data and algorithmic refinement of classes.     

Extending the shelf-life and proximate composition stability of ready to eat foods in vacuum or modified atmosphere packaging

The stability of the proximate composition (moisture, proteins, lipids and ash) and the microbiological state of cooked ‘ready to eat’ foods in vacuum or modified atmosphere packaging were examined and compared with conventionally packaged (in air) foods. The study was carried out for 7 and 29 days, during which time the food products were stored at 3°C. Vacuum or modified atmosphere packaging were effective for prolonging the shelf-life of the studied products up to 29 days with minimal changes in the proximate composition. Aerobic mesophilic, psychrotrophic microrganisms, and yeasts and moulds increased with time regardless of packaging type but more rapidly under conventional packaging.     

A Distributed Approach for Coordination of Traffic Signal Agents

Innovative control strategies are needed to cope with the increasing urban traffic chaos. In most cases, the currently used strategies are based on a central traffic-responsive control system which can be demanding to implement and maintain. Therefore, a functional and spatial decentralization is desired. For this purpose, distributed artificial intelligence and multi-agent systems have come out with a series of techniques which allow coordination and cooperation. However, in many cases these are reached by means of communication and centrally controlled coordination processes, giving little room for decentralized management. Consequently, there is a lack of decision-support tools at managerial level (traffic control centers) capable of dealing with decentralized policies of control and actually profiting from them. In the present work a coordination concept is used, which overcomes some disadvantages of the existing methods. This concept makes use of techniques of evolutionary game theory: intersections in an arterial are modeled as individually-motivated agents or players taking part in a dynamic process in which not only their own local goals but also a global one has to be taken into account. The role of the traffic manager is facilitated since s/he has to deal only with tactical ones, leaving the operational issues to the agents. Thus the system ultimately provides support for the traffic manager to decide on traffic control policies. Some application in traffic scenarios are discussed in order to evaluate the feasibility of transferring the responsibility of traffic signal coordination to agents. The results show different performances of the decentralized coordination process in different scenarios (e.g. the flow of vehicles is nearly equal in both opposing directions, one direction has a clearly higher flow, etc.). Therefore, the task of the manager is facilitate once s/he recognizes the scenario and acts accordingly.     

A hierarchy of probabilistic system types

We arrange various types of probabilistic transition systems studied in the literature in an expressiveness hierarchy. The expressiveness criterion is the existence of an embedding of systems of the one class into those of the other. An embedding here is a system transformation which preserves and reflects bisimilarity. To facilitate the task, we define the classes of systems and the corresponding notion of bisimilarity coalgebraically and use the new technical result that an embedding arises from a natural transformation with injective components between the two coalgebra functors under consideration. Moreover, we argue that coalgebraic bisimilarity, on which we base our results, coincides with the concrete notions proposed in the literature for the different system classes, exemplified by a detailed proof for the case of general Segala-type systems.     

On-line diagnosis and uncertainty management using evidence theory––experimental illustration to anaerobic digestion processes

The on-line diagnosis is a key requirement in biological processes. This is particularly true in the case of wastewater treatment processes due to the composition of media, the requirements of operating conditions and the wide variety of possible disturbances that necessitate careful and constant monitoring of the processes. Moreover, because only partial information is available in an on-line context and because of the technical and biological complexities of the involved processes, specific characteristics are required for diagnosis purposes. Several approaches like quantitative model based, qualitative model based and process history based methods were applied over the years. This paper present a methodological framework based on evidence theory to manage the fault signals generated by conventional approaches (i.e., residuals from hardware and software redundancies, fuzzy logic based modules for process state assessment) and to account for uncertainty. The advantages of using evidence theory like modularity, detection of conflict and doubt in the information sources are illustrated with experimental results from a 1 m³ fixed bed anaerobic digestion process used for the treatment of industrial distillery wastewater.     

Maize processing waste water arabinoxylans: Gelling capability and cross-linking content

Water-soluble feruloylated arabinoxylans were extracted from maize processing waste water (nejayote) generated from tortilla-making industries. Nejayote arabinoxylans (NAX) presented a ferulic acid content of 0.23 μg/mg, an arabinose to xylose ratio (A/X) of 0.65, an intrinsic viscosity, [η], of 183 ml/g and a molecular weight (Mw) of 60 kDa. Laccase-induced gels were obtained from 4% (w/v) NAX solution while, at lower concentrations, no gelation was observed. Laccase covalent cross-linking of NAX led to the formation of diferulic (di-FA) and triferulic (tri-FA) acid structures. 4% (w/v) NAX gel presented di-FA and tri-FA contents of 0.02 and 0.01 μg/mg NAX, respectively, and a G′ value of 2 Pa. Recuperation of this gum from a low-value maize by-product could represent a commercial advantage over other gums commonly used in the food industry.     

Volatile compounds in Spanish dry-fermented sausage ‘salchichón’ subjected to high pressure processing. Effect of the packaging material

The effect of high pressure treatment (400 MPa, 10 min at 12 °C) on the volatile profile of Spanish dry-fermented sausage ‘salchichón’, packaged with or without aluminium foil in a multilayer polymeric bag, was investigated. The analysis of the volatile fraction was carried out by dynamic headspace extraction coupled to gas chromatography–mass spectrometry. Pressure-treated samples showed significantly higher levels of alcohols, aldehydes and alkanes and lower levels of two methylketones as compared with control samples. An intense migration was observed of compounds from the plastic material into the product, mainly linear and branched-chain alkanes, alkenes and benzene compounds. Most of these migrating compounds were significantly more abundant in pressurized samples than in untreated samples.     

Identification of Aspergillus tubingensis strains responsible for OTA contamination in grapes and wine based on the acyl transferase domain of a polyketide synthase gene

Restriction digestion analysis of the acyl transferase (AT) domain sequences of a polyketide synthase (PKS) gene was tested as a rapid method to identify isolates of Aspergillus tubingensis from grapes. Restriction endonuclease digestion of PKS products using the endonucleases Bcc I, Hae III, Hpa II, Mbo I and Taq I distinguished five types of restriction fragment length polymorphism (RFLP). Ochratoxigenic isolates were only identified within RFLP-types I and III. The RFLP assay is proposed as a rapid and easy method to identify A. tubingensis isolates from grapes. Amino acid sequences of AT domains from representative A. tubingensis isolates of the RFLP types obtained were aligned and analysed using phylogenetic methods. A comparison was also made with reference strains of Aspergillus section Nigri . Most of the A. tubingensis strains clustered into two distinct groups Gr1 and Gr2 with the exception of two isolates that remained unclustered. These results support the intraspeficific variability within A. tubingensis species reported using other techniques.     

Determination of fruit origin by using 26S rDNA fingerprinting of yeast communities by PCR–DGGE: preliminary application to Physalis fruits from Egypt

The determination of geographical origin is a demand of the traceability system of import–export food products. One hypothesis for tracing the source of a product is by global analysis of the microbial communities of the food and statistical linkage of this analysis to the geographical origin of the food. For this purpose, a molecular technique employing 26S rDNA profiles generated by PCR–DGGE was used to detect the variation in yeast community structures of three species of Physalis fruit (Physalis ixocarpa Brat, Physalis pubescens L, Physalis pruinosa L) from four Egyptian regions (Qalyoubia, Minufiya, Beheira and Alexandria Governments). When the 26S rDNA profiles were analysed by multivariate analysis, distinct microbial communities were detected. The band profiles of Physalis yeasts from different Governments were specific for each location and could be used as a bar code to discriminate the origin of the fruits. This method is a new traceability tool which provides fruit products with a unique biological bar code and makes it possible to trace back the fruits to their original location. Copyright © 2009 John Wiley & Sons, Ltd.