The effect of paraoxon on spermatogenesis in <Emphasis Type="Italic">Dugesia gonocephala</Emphasis> from the Chilean Altiplano: proliferation and apoptosis

Introduction and aims  

The Chilean Altiplano ecosystem is conserved free from contaminants and pollutants because of the absence of major local human activities such as agriculture or other industries. We studied the effects of paraoxon on proliferation and apoptosis of testicular cells during active spermatogenesis in Dugesia gonocephala collected from a pristine river (Guacollo) in the Altiplano region nearby Visviri town, Chile.     

Inactivation of pathogenic micro-organisms in hospital waste using a microwave

The aim of this study was to investigate the efficiency of dry sterilization by microwave in the inactivation of pathogenic bacteria in blood wastes. Eight bacteria strains were selected for this purpose and these are S. aureus, Salmonella sp., E. faecalis, K. pneumonia, P. aeruginosa, E. coli, Streptococcus Group B and Bacillus sp. Sterilization by microwave was carried out at 385, 450 and 700 watts for 1, 5 and 10 min, respectively. Isolation and enumeration of pathogenic bacteria before and after treatments were carried out using direct plate technique and inactivation was determined in terms of log reduction. Increasing the running time and power to 10 min and 700 watts did not increase log reduction of most of pathogenic bacteria especially of gram negative bacteria. Revival of pathogenic bacteria during the storage period might be aided by the presence of a low moisture content which helps bacterial cells to revive but not to reproduce or over-grow. It can be concluded that dry sterilization of blood wastes by microwave reduces the number and limited re-growth of these pathogenic bacteria during storage time, due to the lower moisture content in the blood wastes.     

Decision making under uncertainty using PEES–fuzzy AHP–fuzzy TOPSIS methodology for landfill location selection

The location selection for landfill municipal solid waste is an important issue in waste management. Selection of the optimal location requires consideration of multiple alternative solutions and evaluation factors because of system complexity. Further, ranking of the alternative locations and selection of the most optimal and efficient locations for landfill waste are an important multi-criteria decision-making problem. In this study, the candidate locations for landfill are determined based on Political, Economical, Environmental and Social factors are assessed through decision-makers’ opinion and by the methodology that incorporates fuzzy analytic hierarchy process (fuzzy AHP) and fuzzy technique for order preference by similarity to ideal solution (fuzzy TOPSIS). Specifically, the fuzzy AHP technique is applied to determine the weights of selected criteria impacting the location selection process, and the fuzzy AHP is adapted to model the linguistic vagueness and ambiguity, which can also be expressed as triangular fuzzy numbers. Furthermore, fuzzy TOPSIS technique is employed to rank the alternative locations. The applicability of this methodology is demonstrated by a case study of landfill waste location selection in the region of Casablanca, Morocco, and the results are compared with other techniques. Finally, to complete the treatment, a sensitivity analysis is performed to examine the impact of the preferences given by decision-makers to choose the best location.     

Future agriculture with minimized phosphorus losses to waters: Research needs and direction

The series of papers in this issue of AMBIO represent technical presentations made at the 7th International Phosphorus Workshop (IPW7), held in September, 2013 in Uppsala, Sweden. At that meeting, the 150 delegates were involved in round table discussions on major, predetermined themes facing the management of agricultural phosphorus (P) for optimum production goals with minimal water quality impairment. The six themes were (1) P management in a changing world; (2) transport pathways of P from soil to water; (3) monitoring, modeling, and communication; (4) importance of manure and agricultural production systems for P management; (5) identification of appropriate mitigation measures for reduction of P loss; and (6) implementation of mitigation strategies to reduce P loss. This paper details the major challenges and research needs that were identified for each theme and identifies a future roadmap for catchment management that cost-effectively minimizes P loss from agricultural activities.     

Distributed,high-resolution modelling of critical source areas for erosion and phosphorus losses

Phosphorus losses from arable land need to be reduced to prevent eutrophication of surrounding waters. Owing to the high spatial variability of P losses, cost-effective countermeasures need to target parts of the catchment that are most susceptible to P losses. Field surveys identified critical source areas for overland flow and erosion amounting to only 0.4–2.6 % of total arable land in four different catchments in southern Sweden. Distributed modelling using high-resolution digital elevation data identified 72–96 % of these observed erosion and overland flow features. The modelling results were also successfully used to predict occurrence of overland flow and rill and gully erosion in a catchment in central Sweden. Such exact high-resolution modelling allows for accurate placement of planned countermeasures. However, current legislative and environmental subsidy programmes need to change their approach from income-loss compensation to rewarding high cost effectiveness of implemented countermeasures.     

Heavy metal enrichment in surface sediments from the SW Gulf of Mexico

The south west coastal zone in the Gulf of Mexico is an area with great industrial and agricultural development, which experiences intensive prospecting and extraction of hydrocarbons. After running through industrial, agricultural, and urban areas, waters from both the Jamapa River and La Antigua River arrive here. The rivers’ discharge areas of influence were estimated considering the textural and chemical composition of the supplied sediments. The main factors that determine sediment distribution were mineralogy, heavy minerals, carbonates, and anthropic contributions. The presence of metals in excess was evaluated using various pollution indicators, such as the enrichment factor, contamination factor, modified contamination factor, and geo-accumulation indexes. Data from different used contamination indexes show metal enrichments in As, Cu, Zn, Co, Cr, and V in La Antigua; As, Cu, and Cr in Jamapa; and As, Zn, and Pb in the Continental slope area. The adverse effects of metals on aquatic organisms were assessed using sediment quality guidelines that show Ni, As, Cu, and Cr may produce adverse effects on coastal areas. There was no evidence of contamination associated to the oil industry.     

Fabrication Mechanical Properties of Unidirectional Jute/PP Composites Using Jute Yarns by Film Stacking Method

This paper mainly focuses on the fabrication process of long fibre reinforced unidirectional thermoplastic composites made using both natural (untreated) treated jute yarns. Jute yarns were wound in layers onto a metallic frame. Polypropylene films were inserted between these layers and compression moulded to fabricate unidirectional jute/PP composite specimens. Static mechanical properties were evaluated from tensile three point bending tests. Pre- post-failure examination were carried out on the test specimens using optical scanning electron microscopy to analyse the test results and investigate the correlations between their impregnation state, processing conditions, mechanical performances and fracture morphologies. For the unidirectional jute/PP film-stacked composites, the results indicated that the processing condition at the moulding temperature of 160°C and moulding pressure of 2.0 MPa for 15 min was ideally suited to obtain optimized properties. Improved wettability of resin melts due to complete matrix fusion at this processing condition facilitated thorough impregnation with minimum microstructural imperfections (microvoids) being generated. Jute/PP composites that contained treated jute yarns have shown superiority in tensile bending properties. Jute yarns polished or coated with PVA/PP (polyvinyl alcohol/polypropylene) must have contributed positively to fibre/matrix interfacial interactions leading to matrix to fibre effective stress transfer, thereby improving their reinforcing effects. Tensile strength and modulus of PP resin increased by approximately 285% and 388%, respectively, due to 50 wt% reinforcement by natural jute yarns. Further improvements in strength and modulus were achieved by approximately 14% and 10%, respectively, when treated yarns were used . The maximum bending stress modulus of jute/PP composites containing untreated yarns were approximately 190% and 460% higher than those of the virgin PP materials, and bending properties were improved by further 11% and 23%, respectively, due to coating treatments on the yarn surface.     

Capturing the dynamics of leader–follower interactions: Stalemates and future theoretical progress

Despite being based on the premise of a dynamic interpersonal process, studies on leader–member exchange theory often fail to acknowledge its dyadic and dynamic nature. We discuss how the interpersonal affect dynamics literature—and particularly its focus on the emergence of relationship patterns—may advance research on leader–follower interactions.