Kinetic study of a hen-egg white lysozyme-based oenological preparation

The catalytic activity of a lysozyme-based oenological preparation toward the specific substrates i) glycol chitosan, as a non-cellular synthetic substrate, and ii) Oenococcus oeni, as a microbial substrate for muramidase activity, was investigated in wine-like acidic medium (tartaric buffer, pH 3.2). The good reproducibility and reliability of results revealed that both substrates are useful for lysozyme kinetics studies. Both the chitinolytic and muramidase activity of lysozyme were affected by uncompetitive substrate inhibition. However, the O. oeni effect occurred at very high concentration with respect to the typical wine bacterial content, even when microbial population reaches its maximum growth level during malolactic fermentation. The optimum pH and temperature for lysozyme activity were very far from the usual wine handling conditions, but residual enzyme activity was observed at pH 3.2 and 20°C, confirming that the oenological application of lysozyme is a useful practice.     

Credit risk in the pool—implications for private capital investments in Brazilian power generation

The new Brazilian Electric Sector Regulation of 2004 introduced two negotiation markets: the regulated pool and the free market. Competition in the pool is enforced via energy auctions, where the winning generator has to sign long-term power purchase agreements simultaneously with all distributors at the bidding-price.

To estimate the appropriate credit risk spread of the pool, we implement a clustering methodology to rank and rate the distributors. The results show an average spread between 5.75% and 8.5%, which corresponds to a credit rating of B− according to the spreads available in Reuters 2004. This estimation is at least 208 basis points higher than the credit rating Ba1/BB+ assigned to the distributors by the National Electric Energy Agency (ANEEL) in the periodic tariff revisions. Distributors with higher risk/spread are located in the South–Southeast, compared to the low risk/spread ones concentrated in the North–Northeast.

We estimate the opportunity cost of capital in real terms in the range of 13–16% to account for the credit risk of the pool. Essential to determine the bidding price at the auctions, this estimation is higher than the 11.26% opportunity cost estimated by ANEEL. The pool's credit risk has to be taken into consideration, especially for compensating new private capital investments in Brazilian power generation.     

An incentive mechanism for message relaying in unstructured peer-to-peer systems

Distributed message relaying is an important function of a peer-to-peer system to discover service providers. Existing search protocols in unstructured peer-to-peer systems create huge burden on communications, cause long response time, or result in unreliable performance. Moreover, with self-interested peers, these systems are vulnerable to the free-riding problem. In this paper we present an incentive mechanism that not only mitigates the free-riding problem, but also achieves good system efficiency in message relaying for peer discovery. In this mechanism promised rewards are passed along the message propagation process. A peer is rewarded if a service provider is found via a relaying path that includes this peer. The mechanism allows peers to rationally trade-off communication efficiency and reliability while maintaining information locality. We provide some analytic insights to the symmetric Nash equilibrium strategies of this game, and an approximate approach to calculate this equilibrium. Experiments show that this incentive mechanism brings a system utility generally higher than breadth-first search and random walks, based on both the estimated utility from our approximate equilibrium and the utility generated from learning in the incentive mechanism.     

A multi-agent legal recommender system

Infonorma is a multi-agent system that provides its users with recommendations of legal normative instruments they might be interested in. The Filter agent of Infonorma classifies normative instruments represented as Semantic Web documents into legal branches and performs content-based similarity analysis. This agent, as well as the entire Infonorma system, was modeled under the guidelines of MAAEM, a software development methodology for multi-agent application engineering. This article describes the Infonorma requirements specification, the architectural design solution for those requirements, the detailed design of the Filter agent and the implementation model of Infonorma, according to the guidelines of the MAAEM methodology.