PurposeThe improvement in the efficiency of public management leads to an increase in the quality of services, boosting confidence in institutions and thus generating a multiplier effect. This paper aims to update the literature on the data envelopment analysis (DEA), which uses a frontier methodology, for measuring the efficiency applied to the defence sector.Design/methodology/approachTwo main research areas are related through this study: Defence Economics and Efficiency and Productivity Analysis. The frontier methods for measuring technical efficiency are grouped into parametric, non-parametric and semi-parametric. The DEA literature review in the selected sector allows to identify three main fields of work that are discussed in detail.FindingsExisting empirical research has hardly applied bootstrapping methods to remove bias from the estimates. No empirical work has applied an analysis of efficiency determinants by the inclusion of exogenous variables.Originality/valueThe managerial implications of efficiency are numerous. A line of research is proposed to examine the extent to which efficiency improvements have an impact on reputation and, therefore, on the image of and confidence in institutions. The link between Defence Economics and Corruption Economics is also considered.

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This work presents a novel procedure for the removal of Cu2+ from water, an essential element in human nutrition considered toxic in high concentrations, based on a microextraction technique involving the formation of a micellar phase. To achieve the total elimination of copper from aqueous samples, a Cu2+-complexing reagent based on silver nanoparticles functionalized with sodium mercaptoethane sulfonate (AgNPs@MESNa) was used. The complex formed by Cu2+ and the reagent was extracted into a micellar microphase formed by Triton X-114, a harmless surfactant. Volumes of 200 µL of the 10−4 mol L−1 suspension of AgNPs@MESNa and 100 µL of a solution of Triton X-114 at 30% m/m were employed to successfully remove 10 mg L−1 of Cu from 20 mL of water samples. The time and temperature needed to achieve 100% microextraction efficiency were 10 min and 40 °C, respectively. The procedure is considered environmentally friendly due to the low volume of the extracting phase and the simple experimental conditions that achieve total removal of Cu2+ from water samples.

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Previous works have highlighted the suitability of the concept of fractal structure, which derives from asymmetric topology, to propound generalized de nitions of fractal dimension. The aim of the present article is to collect some results and approaches allowing to connect the self-similarity index and the fractal dimension of a broad spectrum of random processes. To tackle with, we shall use the concept of induced fractal structure on the image set of a sample curve. The main result in this paper states that given a sample function of a random process endowed with the induced fractal structure on its image, it holds that the self-similarity index of that function equals the inverse of its fractal dimension.