A method for improving classification reliability of multilayerperceptrons

Criteria for evaluating the classification reliability of a neural classifier and for accordingly making a reject option are proposed. Such an option, implemented by means of two rules which can be applied independently of topology, size, and training algorithms of the neural classifier, allows one to improve the classification reliability. It is assumed that a performance function P is defined which, taking into account the requirements of the particular application, evaluates the quality of the classification in terms of recognition, misclassification, and reject rates. Under this assumption the optimal reject threshold value, determining the best trade-off between reject rate and misclassification rate, is the one for which the function P reaches its absolute maximum. No constraints are imposed on the form of P, but the ones necessary in order that P actually measures the quality of the classification process. The reject threshold is evaluated on the basis of some statistical distributions characterizing the behavior of the classifier when operating without reject option; these distributions are computed once the training phase of the net has been completed. The method has been tested with a neural classifier devised for handprinted and multifont printed characters, by using a database of about 300000 samples. Experimental results are discussed.     

Information systems in the public sector: The e-Government enactment framework

Despite the burgeoning number of studies of public sector information systems, very few scholars have focussed on the relationship between e-Government policies and information systems choice and design. Drawing on Fountain’s (2001) technology enactment framework, this paper endeavours to conduct an in-depth investigation of the intricacies characterising the choice and design of new technologies in the context of e-Government reforms. By claiming that technologies are carriers of e-Government reform aims, this study investigates the logics embedded in the design of new technology and extant political interests and values inscribed in e-Government policies. The e-Government enactment framework is proposed as a theoretical and analytical approach to understand and study the complexity of these relationships which shape e-Government policies.     

Government policy,public value and IT outsourcing: The strategic case of ASPIRE

The paper examines government IT outsourcing polices. The paper critiques the concept of ‘the Contract State’, and suggests how more disciplined uses of outsourcing can assist the creation of public value, more broadly conceived. Within the context of international developments, we study the United Kingdom Inland Revenue (IR), Customs and Excise (HMRC) and Department of Social Security (DSS) and their IT outsourcing contracts. The evidence suggests that outsourcing and marketization initiatives have adverse public value impacts, and may need to be rethought. Major IT operations and innovations, for example e-government, National Health Service (NHS) and identity card IT policies in the UK, are managed and generate legacies that do not always make efficient and effective use of the market. Moreover, their objectives, implementation and management over time may truncate their value to the public at large. Applying a revised Public Value policy approach offers a richer perspective to guide central government decisions worldwide about future IT outsourcing.     

The increase in oxidative stability of sunflower oil enriched with Nigella sativa L. Seed extracts

Nigella sativa L. seeds are rich sources of phenolic compounds. The aim of this study was to evaluate the efficiency of Nigella seed extract as natural antioxidant compared with butylated hydroxytoluene (BHT) during accelerated oxidation of edible vegetable oils at 120 °C. The modifications during heating were monitored by 3D-front-face fluorescence spectroscopy. The fluorescence spectra were obtained with excitations from 280 to 500 nm and emission wavelengths from 300 to 550 nm and analysed using independent components analysis. Decomposition products formed during heating were also evaluated by means of ¹H-NMR spectroscopy and classic chemical methods such as anisidine value and viscosity. The results of the study clearly indicate that the natural seed extract at a level of 800 ppm exhibited antioxidant effects similar to those of the synthetic antioxidant BHT at a level of 200 ppm and thus contributes to an increase in the oxidative stability of the oil.     

Geometric properties of the union of maximal neighborhoods

The problem of computing area and perimeter of a digital figure presented by its discrete medial axis transform (MAT) is addressed. The figure is seen as the union of the square-shaped maximal neighborhoods centered on the local maxima of the MAT. The contribution given by each maximal neighborhood to figure area and perimeter is computed while tracing the MAT. Multiple overlaps among the maximal neighborhoods are possible. However, due to the properties of the local maxima and their associated maximal neighborhoods a single tracing of the MAT is provided to be sufficient to obtain the desired result. Thus, the procedure requires O(N) time, where N is the number of MAT pixels     

EvoGeneSys,a new evolutionary approach to graph generation

Graphs are widely used to represent complex and structured information of interest in various fields of science and engineering. When using graph representations, problems of special interest often imply searching. For example, searching for the prototypes representing a dataset of graphs or for the graph that optimizes a set of parameters. In any case, it is necessary that the problem solution be expressed in terms of graphs. Therefore, defining effective methods for automatically generating single graphs, or sets of graphs, representing problem solutions, is a key issue. A new evolutionary computation-based approach specifically devised for generating graphs is presented. The method is based on a special data structure, called multilist, which allows the encoding of any type of graph, directed or undirected, with or without attributes. Graph encoding by multilists makes it possible to define effective crossover and mutation operators, overcoming the problems normally encountered when implementing genetic operators on graphs. Further advantages of the proposed approach are that it does not require any problem specific knowledge and it is able to search for graphs whose number of nodes is not known a priori. Three sets of experiments were performed to test the proposed approach and the solutions found were compared with those obtained by other approaches proposed in the literature.