Chlorine disinfection of Pseudomonas aeruginosa, total coliforms, Escherichia coli and Enterococcus faecalis: revisiting reclaimed water regulations

Pathogenic organisms can be transmitted orally through drinking water or through skin and mucosae by both direct and indirect contact, and their presence in water thus has a negative impact on public health. In wastewater treatment plants (WWTP), water is disinfected to inactivate pathogens. The quantification of several microbial indicators in aquatic systems is required to estimate the biological quality of such systems. So far, coliform bacteria have been used as traditional indicators world-wide. This study has assessed the resistance of total coliforms, Escherichia coli, Pseudomonas aeruginosa and Enterococcus faecalis to three dosages of sodium hypochlorite (NaClO) at two exposure times. The bacteria were isolated from secondary effluents of a WWTP located in Hidalgo, Mexico. The results show that the number of colony-forming units of all studied bacterial types decreased when both the NaClO concentration and exposure times increased. However, they were not eliminated. The inclusion of the species Pseudomonas aeruginosa in regulations for treated wastewater quality as a new indicator is highly recommended due to its importance as an opportunistic pathogen. The detection of this species along with the traditional organisms could be particulary significant for reclaimed water to be used with direct human contact.     

Development and validation of a FISH-based method for the detection and quantification of E. coli and coliform bacteria in water samples

Monitoring of microbiological contaminants in water supplies requires fast and sensitive methods for the specific detection of indicator organisms or pathogens. We developed a protocol for the simultaneous detection of E. coli and coliform bacteria based on the Fluorescence in situ Hybridization (FISH) technology. This protocol consists of two approaches. The first allows the direct detection of single E. coli and coliform bacterial cells on the filter membranes. The second approach includes incubation of the filter membranes on a nutrient agar plate and subsequent detection of the grown micro-colonies. Both approaches were validated using drinking water samples spiked with pure cultures and naturally contaminated water samples. The effects of heat, chlorine and UV disinfection were also investigated. The micro-colony approach yielded very good results for all samples and conditions tested, and thus can be thoroughly recommended for usage as an alternative method to detect E. coli and coliform bacteria in water samples. However, during this study, some limitations became visible for the single cell approach. The method cannot be applied for water samples which have been disinfected by UV irradiation. In addition, our results indicated that green fluorescent dyes are not suitable to be used with chlorine disinfected samples.     

Landscape integration of North Patagonian mountain lakes: a first approach using characterization of dissolved organic matter

North‐western Patagonia contains a variety of glacially formed mountain lakes located at different positions from the treeline in the Andean Patagonian forest region. Water chemistry of six North Patagonian lakes located in an altitudinal gradient, above, at and below the treeline (~41°S) were analysed in this study. The relative importance of allochtonous to autochthonous carbon inputs along a marked catchment vegetation gradient encompassing altoandino vegetation and Nothofagus forests was addressed. The dissolved organic carbon (DOC) concentration varied among the study lakes, with the lakes located higher in the landscape exhibiting lower DOC concentrations (<1 mg L^?1) than lakes located at or below the treeline (>2 mg L^?1). Analysis of coloured and fluorescent dissolved organic matter (CDOM and FDOM, respectively) followed the DOC pattern, despite the contrasting catchments of the study lakes. The results indicated the CDOM in all the lakes had low molecular weight and low aromaticity. The excitation–emission matrices (EEMs) highlighted three distinctive fluorophores in the FDOM, including two humic‐like (peak A and peak C) revealing the presence of humic terrestrial material, and a protein‐like fluorophore (peak T) generally associated with autochthonous DOM. The increased intensities of the humic fluorophores in the lakes located below the treeline suggest higher allochtonous carbon inputs from their catchments. This evidence collectively suggests that mountain lakes exhibit some heterogeneity in terms of DOM, likely attributable to their position in relation to the treeline, which determines the contribution of the catchment. As remote lakes are extremely sensitive to changes in their catchments, these North Patagonian mountain lakes may accurately track the impact of climate and anthropogenic changes on the landscape.     

Save angels perhaps: A critical examination of unconscious thought theory and the deliberation-without-attention effect.

Based on Unconscious Thought Theory (UTT) and a series of experimental and correlational studies, Dijksterhuis and his colleagues conclude that when making complex choices/decisions, conscious thought--deliberation while attention is directed at the problem--leads to poorer choices/decisions than unconscious thought--deliberation in the absence of conscious attention directed at the problem. UTT comprises six principles said to apply to decision making, impression formation, attitude formation and change, problem solving, and creativity. Because the implications of UTT for psychological research and theory are considerable, the authors critically examined these six principles (and the studies used to support them) in light of the extant scholarship on unconscious processes, memory, attention, and social cognition. Our examination reveals that UTT is a theory of the unconscious that fails to take into account important work in cognitive psychology, particularly in the judgment and decision making area. Moreover, established literatures in social psychology that contradict fundamental tenets of UTT and its empirical basis are ignored. The authors conclude that theoretical and experimental deficiencies undermine the claims of the superiority of unconscious thinking as portrayed by UTT. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Doping of lanthanum cobaltite by Mn: thermal,magnetic, and catalytic effect

Great differences in crystallographic phases, magnetic properties, and catalytic activity were detected in lanthanum cobaltite and cobaltite modified with the insertion of 10 wt.% of Mn. Atomic absorption spectroscopy, BET area measurements, XRD analysis, TPR, and FT-IR suggest that the total insertion of manganese in the LaCoO₃ structure is successful. Thermal stability is reached for LaCo_0.90Mn_0.10O₃ up to 973 K without loss of the perovskite structure. The magnetic properties of the as-grown compounds are maintained after a first reduction process up to 723–773 K, while presence of segregated phases is observed after reduction at 973 K. The catalytic activity evaluated in the total combustion of acetyl acetate shows a decrease in the ignition temperature, i.e. an increase in the catalytic activity for the LaCo_0.90Mn_0.10O₃ perovskite. A significant enhancement in the catalytic activity expressed as intrinsic activity, mol m⁻² h⁻¹, with the manganese substitution was found.     

NetNeg: A connectionist-agent integrated system for representing musical knowledge

The system presented here shows the feasibility of modeling the knowledge involved in a complex musical activity by integrating sub-symbolic and symbolic processes. This research focuses on the question of whether there is any advantage in integrating a neural network together with a distributed artificial intelligence approach within the music domain. The primary purpose of our work is to design a model that describes the different aspects a user might be interested in considering when involved in a musical activity. The approach we suggest in this work enables the musician to encode his knowledge, intuitions, and aesthetic taste into different modules. The system captures these aspects by computing and applying three distinct functions: rules, fuzzy concepts, and learning. As a case study, we began experimenting with first species two-part counterpoint melodies. We have developed a hybrid system composed of a connectionist module and an agent-based module to combine the sub-symbolic and symbolic levels to achieve this task. The technique presented here to represent musical knowledge constitutes a new approach for composing polyphonic music. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of probability mode on preference reversal.

Estimated verbally and numerically the chances that specific events will occur using 6 analysts. 60 decision makers used each type of estimate to make binary-choice decisions and to bid for lotteries based on the events. The usual reversal of preference between choice and bidding procedures was found in the numerical condition, but the frequency of preference reversals was significantly reduced in the verbal condition. This reduction occurred because risk aversion was reduced in choice when verbal estimates were given, whereas bidding was unaffected by presentation mode. The pattern of results was predicted by and supports the hypothesis that the relative importance given to the dimensions of a prospect depends on the form in which the information is displayed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

IMPROVING THE COMPUTATIONAL EFFICIENCY OF THE BAYESIAN DECOMPOSITION OF A TIME SERIES: A COMMENT

Abstract. This note describes an improvement of Ishiguro's algorithm for the Bayesian decomposition of a time series based on the use of a specialized band Cholesky factorization.