Enforcing Efficient Equilibria in Network Design Games via Subsidies

The efficient design of networks has been an important engineering task that involves challenging combinatorial optimization problems. Typically, a network designer has to select among several alternatives which links to establish so that the resulting network satisfies a given set of connectivity requirements and the cost of establishing the network links is as low as possible. The Minimum Spanning Tree problem, which is well-understood, is a nice example.In this paper, we consider the natural scenario in which the connectivity requirements are posed by selfish users who have agreed to share the cost of the network to be established according to a well-defined rule. The design proposed by the network designer should now be consistent not only with the connectivity requirements but also with the selfishness of the users. Essentially, the users are players in a so-called network design game and the network designer has to propose a design that is an equilibrium for this game. As it is usually the case when selfishness comes into play, such equilibria may be suboptimal. In this paper, we consider the following question: can the network designer enforce particular designs as equilibria or guarantee that efficient designs are consistent with users’ selfishness by appropriately subsidizing some of the network links? In an attempt to understand this question, we formulate corresponding optimization problems and present positive and negative results.     

Use of lambda DNA as a marker to assess DNA stability in olive oil during storage

Filtered olive oil samples spiked with three different concentrations of λDNA were stored at 25 °C under a 12 h photoperiod for up to a year. These samples were used for DNA extraction and PCR amplification of λDNA amplicons of 107, 415 and 691 bp length. The amplification signal was gradually decreased with longer storage periods, while the strength of the signal was related to the initial concentration of spiking λDNA particularly during longer storage periods. The 107 bp amplicon was the only one successfully amplified from all the samples, regardless of both concentration of spiking λDNA and storage period. The amplification of 415 and 691 bp amplicons was not successful for samples stored longer than a threshold period of 20 and 10 days, respectively. These results suggest that detection of polymorphic markers requiring DNA templates shorter than 100 bp might have a wider range of applications in DNA fingerprinting of olive oil. In addition, the DNA extracts were tested for the presence of inhibitors in PCR amplification reactions of yeast DNA amplicons. The inhibitory effect of olive DNA extracts was partial and gradually increased with the storage period of the olive oil samples used for the DNA extraction.     

Composting of energetic materials

Abstract

Composting has been used for centuries for stabilization of organic residues and production of a humus-like end product traditionally used as a soil conditioner. The process may be successfully adopted for the treatment of solid organic matrices contaminated with various hazardous wastes including energetic materials. Composting methods and their application for treatment of energetic materials are reviewed along with design methodologies. The design and operation of composting facilities for treatment of energetic materials must be based on thermodynamic, kinetic, public health and aesthetic principles. A generalized design methodology is presented. Composting treatability studies are necessary for derivation of thermodynamic and kinetic data. Concerns related to production and fate of metabolites require a careful study and should be always addressed. Ultimate disposal of composted energetic materials must be studied extensively.     

A SNP-based PCR–RFLP capillary electrophoresis analysis for the identification of the varietal origin of olive oils

Authenticity and traceability of high quality monovarietal extra virgin olive oils is a major concern for markets and consumers. Although analytical chemistry techniques are widely used to satisfy these needs recently developed DNA-based methods can serve as complementary approaches. A SNP database comprising 10 Greek olive varieties was constructed and five SNPs, residing in restriction sites, were selected for the development of a PCR–RFLP capillary electrophoresis method to discriminate these varieties using leaf DNA as template. An identification key was constructed indicating that five SNPs were adequate to discriminate nine out of the 10 varieties. As a proof of principle the assay was applied on DNA extracted from five of their corresponding monovarietal olive oils. Three SNPs were able to identify the varietal origin of these olive oils confirming the validity of this approach.     

Olive oil authentication,traceability and adulteration detection using DNA‐based approaches

Olive oil is the fresh juice produced by pressing olive fruits. It serves as the main component of the Mediterranean diet and one of the most valuable products of the agro‐food industry, not only for its taste, but also for its high nutritional value. As it is considered the lipid constituent of the olive fruits, it is composed mainly of triglycerides and phenolics. Authentication and traceability of extra virgin olive oil is a challenging research task due to the complexity of fraudulent practices. Various chemical and biochemical techniques have been developed for determining the authenticity of olive oil. Olive oil DNA‐based analyses have gained attention in recent years, due to high specificity, sensitivity and reliability. DNA analyses have very high discriminating power because ultimately the unique identity of a variety or species is to a great extent genetically dependent. Polymorphisms are genetic variations which refer to the variation in populations or species. Molecular markers provide information on genetic variations and are valuable tools to determine olive oil authenticity. Molecular markers such as SNPs, microsatellites, SCARs and AFLPs have been used for the identification of the varietal origin of olive oils. This feature provides an overview of the current trends and critical issues on DNA‐targeted approaches used for traceability and authenticity of olive oil.     

Three different polygalacturonases are expressed in tomato leaf and flower abscission, each with a different temporal expression pattern

Abscission, or organ separation, is accompanied by a marked increase in hydrolases, which are responsible for the degradation of the middle lamella and the loosening of the primary cell wall surrounding cells in the separation layer. We recently reported on the cloning of a tomato (Lycopersicon esculentum) polygalacturonase (PG) cDNA, TAPG1, expressed during leaf and flower abscission. In addition to TAPG1, we have cloned two more PG cDNAs (TAPG2 and TAPG4) that are also expressed during leaf and flower abscission. The peptide sequences for the three abscission PGs are relatively similar (76-93% identity) yet different from the those of tomato fruit PG (38-41% identity). None of the three abscission PG mRNAs are expressed in fruit, stems, petioles, or anthers of fully open flowers. An RNase protection assay revealed that all three PGs are expressed in leaf and flower abscission zones and in pistils of fully open flowers. TAPG4 mRNA is detected much earlier than TAPG1 and TAPG2 mRNA during both leaf and flower abscission.