Effect of fermentation temperature and culture media on the yeast lipid composition and wine volatile compounds

The temperature of a wine fermentation strongly affects lipid metabolism and thus, aromatic profiles. Most of the metabolic studies are done in well-controlled laboratory conditions, yet wine is produced in less-reproducible industrial conditions. The aim of this study is to analyse the effect of fermentation temperature (13 degrees C and 25 degrees C) and culture media (synthetic media and grape must) on yeast lipid composition and volatile compounds in wine. Our results show that yeast viability was better at 13 degrees C than at 25 degrees C whichever growth medium is used, but that the complexity of the grape must enabled cells to reach higher viable population size. Viability was also related to the incorporation of linoleic acid and beta-sitosterol, which were present in the grape must. A lower temperature modified the cellular lipid composition of yeast, increasing the degree of unsaturation at the beginning of fermentation and decreasing the chain length as fermentation progressed. We also found that medium-chain fatty acids, mainly dodecanoic acid, were present in the cell phospholipids. Wines produced from grape must were more aromatic and had a lower volatile acidity content than those derived from a synthetic medium. Fermentations that were performed at the lower temperature also emphasized this feature.     

Metabolism and toxicology of heterocyclic aromatic amines when consumed in diet: Influence of the genetic susceptibility to develop human cancer. A review

There is not sufficient scientific evidence to support the hypothesis that human cancer risk is specifically due to the intake of heterocyclic aromatic amines (HAAs) in diet. Epidemiological evidence appears to imply two main factors in the HAAs carcinogenicity. These factors are the very high frequency of consumption of red meats, and very darkly browned meats from cooking, which are HAAs-containing foods. The present review focuses on the fact that the cancer risk is notably enhanced when certain genotypes related to HAAs metabolism are present. Thus, genetic predisposition seems to be the main factor in cancer development related to HAAs, and possibly the co-presence of other mutagenic compounds in diet.     

Off-line synthesis of evolutionarily stable normative systems

Within the area of multi-agent systems, normative systems are a widely used framework for the coordination of interdependent activities. A crucial problem associated with normative systems is that of synthesising norms that will effectively accomplish a coordination task and that the agents will comply with. Many works in the literature focus on the on-line synthesis of a single, evolutionarily stable norm (convention) whose compliance forms a rational choice for the agents and that effectively coordinates them in one particular coordination situation that needs to be identified and modelled as a game in advance. In this work, we introduce a framework for the automatic off-line synthesis of evolutionarily stable normative systems that coordinate the agents in multiple interdependent coordination situations that cannot be easily identified in advance nor resolved separately. Our framework roots in evolutionary game theory. It considers multi-agent systems in which the potential conflict situations can be automatically enumerated by employing MAS simulations along with basic domain information. Our framework simulates an evolutionary process whereby successful norms prosper and spread within the agent population, while unsuccessful norms are discarded. The outputs of such a natural selection process are sets of codependent norms that, together, effectively coordinate the agents in multiple interdependent situations and are evolutionarily stable. We empirically show the effectiveness of our approach through empirical evaluation in a simulated traffic domain.     

Execution infrastructure for normative virtual environments

Virtual Institutions (VIs) have proven to be adequate to engineer applications where participants can be humans and software agents. VIs combine Electronic Institutions (EIs) and 3D Virtual Worlds (VWs). In this context, Electronic Institutions are used to establish the regulations that structure interactions and support software agent participation while Virtual Worlds facilitate human participation. In this paper we propose Virtual Institution eXEcution Environment (VIXEE) as an innovative communication infrastructure for VIs. Using VIXEE to connect Virtual Worlds and EI opens EI to humans, providing a fully operational and comprehensive environment. The main features of the infrastructure are (i) the causal connection between Virtual Worlds and Electronic Institutions, (ii) the automatic generation and update of the VIs' 3D visualization and (iii) the simultaneous participation of users from different virtual world platforms. We illustrate the execution of VIXEE system in a simple eAuction house example and use this example to evaluate the performance of our solution.     

On climate reconstruction using bivalves: three methods to interpret the chemical signature of a shell

To improve our understanding of the climate process and to assess the human impact on current global warming, past climate reconstruction is essential. The chemical composition of a bivalve shell is strongly coupled to environmental variations and therefore ancient shells are potential climate archives. The nonlinear nature of the relation between environmental condition (e.g. the seawater temperature) and proxy composition makes it hard to predict the former from the latter, however. In this paper we compare the ability of three nonlinear system identification methods to reconstruct the ambient temperature from the chemical composition of a shell. The comparison shows that nonlinear multi-proxy approaches are potentially useful tools for climate reconstructions and that manifold based methods result in smoother and more precise temperature reconstruction.     

Adaptive case-based reasoning using retention and forgetting strategies

Case-based reasoning systems need to maintain their case base in order to avoid performance degradation. Degradation mainly results from memory swamping or exposure to harmful experiences and so, it becomes vital to keep a compact, competent case base. This paper proposes an adaptive case-based reasoning model that develops the case base during the reasoning cycle by adding and removing cases. The rationale behind this approach is that a case base should develop over time in the same way that a human being evolves her overall knowledge: by incorporating new useful experiences and forgetting invaluable ones. Accordingly, our adaptive case-based reasoning model evolves the case base by using a measure of “case goodness” in different retention and forgetting strategies. This paper presents empirical studies of how the combination of this new goodness measure and our adaptive model improves three different performance measures: classification accuracy, efficiency and case base size.     

The effect of free nitrous acid on the anabolic and catabolic processes of glycogen accumulating organisms

Nitrite/Free Nitrous Acid (FNA) has previously been shown to inhibit aerobic and anoxic phosphate uptake by polyphosphate accumulating organisms (PAOs). The inhibitory effect of FNA on the aerobic metabolism of Glycogen Accumulating Organisms (GAOs) is investigated. A culture highly enriched (92 ± 3%) in Candidatus Competibacter phosphatis (hereafter called Competibacter) was used. The experimental data strongly suggest that FNA likely directly inhibits the growth of Competibacter, with 50% inhibition occurring at 1.5 × 10⁻³ mgN-HNO₂/L (equivalent to approximately 6.3 mgN-NO₂⁻/L at pH 7.0). The inhibition is well described by an exponential function. The organisms ceased to grow at an FNA concentration of 7.1 × 10⁻³ mgN-HNO₂/L. At this FNA level, glycogen production, another anabolic process performed by GAOs in parallel to growth, decreased by 40%, while the consumption of polyhydroxyalkanoates (PHAs), the intracellular carbon and energy sources for GAOs, decreased by approximately 50%. FNA likely inhibited either or both of the PHA oxidation and glycogen production processes, but to a much less extent in comparison to the inhibition on growth. The comparison of these results with those previously reported on PAOs suggest that FNA has much stronger inhibitory effects on the aerobic metabolism of PAOs than on GAOs, and may thus provide a competitive advantage to GAOs over PAOs in enhanced biological phosphorus removal (EBPR) systems.     

Antimicrobial activity of whey protein isolate edible films with essential oils against food spoilers and foodborne pathogens

The use of antimicrobial edible film is proposed as a means of improving food safety and extending the shelf-life of food systems by controlling the release of antimicrobials on food surfaces. In this work we first selected and studied 8 different essential oils (EOs) from plants, namely, oregano, clove, tea tree, coriander, mastic thyme, laurel, rosemary, and sage as natural antimicrobials against 2 gram-positive bacteria (Listeria innocua and Staphylococcus aureus) and 2 gram-negative bacteria (Salmonella enteritidis and Pseudomona fragi) by using the agar disk diffusion method. EOs from oregano, clove, and tea tree produced the largest surfaces of inhibition against the growth of the 4 bacterial strains tested. Second and following the assessment of compatibility, stable antimicrobial edible films based on whey protein isolate (WPI) with increasing concentrations (0.5% to 9%) of the 8 EOs were developed and tested for antimicrobial activity against the same gram-positive and gram-negative bacteria. WPI-edible films incorporating oregano or clove EO were found to have the most intense inhibitory effect of microbial growth. The bacterial strain gram-negative P. fragi presented the less susceptibility to the effect of those films. Moreover, only the edible films based on these 2 EOs were active against all 4 studied microorganisms. On the other hand, the edible films incorporating tea tree, coriander, mastic thyme, laurel, rosemary, or sage EOs even at high concentrations (7% to 9%) did not cause any antimicrobial effect against the pathogens S. aureus or S. enteritidis. PRACTICAL APPLICATION: Potential applications of this technology can introduce direct benefits to the food industry by improving safety and microbial product quality. The results of this research have direct application in the food industry with potential applications in various foodstuffs, including meat and poultry products where the control of spoilage bacteria such as P. fragi throughout their chilled storage or the improvement of food safety by controlling pathogens such as S. enteritidis are topics of particular interest for the industry.     

Scientific output and impact of postdoctoral scientists: a gender perspective

This paper analyses the scientific output and impact of 731 Ph.D. holders who were awarded their doctorate at Spanish universities between 1990 and 2002. The aim was to identify any differences in the amount of scientific output and the impact of publications, in terms of citations, according to gender. The analysis revealed no significant differences in the amount of scientific output between males and females. However, the proportion of female Ph.D. holders with no postdoctoral output was significantly higher than that of their male counterparts, and the median number of papers published after Ph.D. completion was also lower among women. As regards pre- and postdoctoral research, the data showed that early scientific output may be a good predictor of subsequent productivity in both gender groups. The results also indicated that articles by female Ph.D. holders were cited significantly more often, even when self-citations were excluded.