197 research outputs found

    Dominance-based rough set approach and analytic network process for assessing urban transformation scenarios

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    For half a century, the significant development of intensive farming has led to a massive use of products such as pesticides. The excessive use of these substances has contaminated surface water and groundwater. Drinking water extraction points have also had to be abandoned. Some thirty years ago, in the southwest of France, a group of farmers decided to improve their farming methods, as well as developing new Best Environmental Practices, such as grass strips along streams and riparian forests. By combining the use of ELECTRE TRI-C multi-criteria model with a GIS, we were able to characterise the contribution of each farming area to the risk of surface water contamination with pesticides. We also assessed the effectiveness of different environmental practices. We found that the use of Best Environmental Practices led to a reduction in the risk of pesticides transfer. This methodology re-enforces decision support tools for water resource managers and agricultural and environmental stakeholders

    A new parsimonious AHP methodology: assigning priorities to many objects by comparing pairwise few reference objects

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    We propose a development of the Analytic Hierarchy Process (AHP) permitting to use the methodology also for decision problems with a very large number of alternatives and several criteria. While the ap- plication of the original AHP method involves many pairwise comparisons between considered objects, that can be alternatives with respect to considered criteria or criteria between them, our parsimonious proposal is composed of five steps: (i) direct evaluation of the objects at hand; (ii) selection of some reference objects; (iii) application of the original AHP method to the reference objects; (iv) check of the consistency of the pairwise comparisons of AHP and the compatibility between the rating and the prior- itization with a subsequent discussion with the decision maker who can modify the rating or pairwise comparisons of reference objects; (v) revision of the direct evaluation on the basis of the prioritization supplied by AHP on reference objects. Our approach permits to avoid the distortion of comparing more relevant objects (reference points) with less relevant objects. Moreover, our AHP approach avoids rank reversal problems, that is, changes of the order in the prioritizations due to adding or removing one or more objects from the set of considered objects. The new proposal has been tested and experimentally validated

    Monitoring dynamics in bacterial competition by Imaging Mass Spectrometry

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    Microbial competition is a mechanism that occurs when two or more microbial species compete for ecological niches to support their survival and growth (Hibbing et al. 2010). Different factors can contribute to the outcome of microbial competition, such as molecules exchanged between the competing organisms for the regulation of cell densities and the initial spatial configuration of the microbe–microbe interaction. Specifically, production of compounds that kill or limit the growth of competing strains or species can promote niche monopolization (Gonzalez et al. 2011). The released compounds include secondary metabolite antibiotics, bacterial peptides or low-molecular-mass organic compounds. In that sense, it is very important to develop tools that could capture metabolic interactions between two or more bacterial populations. Imaging Mass Spectrometry (IMS) enables the visualization of both spatial and temporal production of a huge number of metabolites from a single bacterial species and can observe the effects of multiple microbial signals in an interspecies interaction without using tags or labels (Yang et al. 2009). This technique has the potential to be used for identification of novel metabolites and peptides that were previously undetected by other analytical methods. In this work, a combination of IMS and LC-MS/MS was used to study the competition between Listeria monocytogenes (LM) and Lactococcus lactis (LAC) to investigate the metabolic profile of each bacterium in the interacting microbial colonies. IMS analysis revealed several interesting compounds during interaction of microbial colonies. At least six compounds are uniquely expressed during the interaction between LM and LAC. These results could be useful to setup new molecular strategies in the control of bacterial species for a better food safety

    Food Safety: Secretome of Lactococcus lactis and Listeria monocytogenes in competition.

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    Listeria monocytogenes (LM) is a foodborne pathogen responsible of listeriosis. In the spreading of this pathology, milk and dairy products are key reservoir for this pathogen1. Food processing represents one of the major steps that could be linked to LM growth. Inhibition of LM growth through competition of Lactococcus lactis (LAC) could represent a solution to this problem. Exoproteome of LM and two different strains of Lactic Acid Bacteria in co-culture have been studied in order to highlight mechanisms of bacterial competition useful to improve food safety. Two different strains of LAC and one strain of LM were cultivated in appropriate medium cultures (BHI), also in competition. Filtrated cultures (SECRETOME) were lyophilized and resuspended for proteomics analysis. Shotgun analysis on each secretome was performed on nano UPLC-MS system. Obtained data reveal, during competition, the higher production by LM of moonlighting protein Enolase and Glucose 6 Phosphate isomerase, of Septation ring formation regulator EzrA, involved into cell replication and the lower secretion of Endopeptidase P60. In parallel, L. lactis produced higher amounts of Secreted 45 kDa protein and switched from lantibiotic Nisin A production to Nisin Z production. In competition with LM, LAC strain investigated produce higher amounts of Secreted 45 kDa protein with peptidoglycan lytic activity and the selective secretion of Nisin Z probably to improve lantibiotic solubility in less acidic environment. Next step will be validation of obtained results in dairy products. These results are of interesting to design new strategies of fighting LM as contaminant in food from animal origin.Work supported by Ministry of Health-CCM “Milano EXPO 2015 Project: Garantire la sicurezza alimentare- Valorizzare le produzioni
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