Converting rain into drinking water: Quality issues and technological advances

With growing pressures on water supplies worldwide, rainwater harvesting is increasingly seen as a viable option to provide drinking water to an ever expanding population, particularly in developing countries. However, rooftop runoff is not without quality issues. Microbiological and chemical contamination have been detected in several studies, well above local and international guidelines, posing a health risk for consumers. Our research explores the use of silver ions, combined with conventional filtration and settling mechanisms, as a safe and affordable model for purification that can be applied on a small scale. The complete systems were installed and tested in rural communities in a Mexican semi-arid region. Efficiencies up to 99.9% were achieved in the removal of indicator microorganisms, with a marked exception where cross-contamination from external seepage occurs. Sites without overhanging branches or with relatively clean surfaces show an absence of total coliforms in the untreated runoff, compared with others where values as high as 1,650 CFU/100 ml were recorded. Thus, given adequate maintenance, the system can successfully deliver high quality drinking water, even when storage is required for long periods of time. © IWA Publishing 2011

Evaluation of a silver-ion based purification system for rainwater harvesting at a small-scale community level

Silver has been known for centuries to be a powerful disinfectant, with no known harmful effects to humans if applied in adequate doses. Although its use was partially discontinued with the advent of chlorination and modern antibiotics, the discovery of bacterial resistance and disinfection by-products has enabled its re-emergence as a viable water purification option. On the other hand, implementation in small-scale rainwater harvesting (RWH) systems has received little attention, possibly due to a general perception that it is a complex and/or expensive technology. This can be overcome by efficient designs that dose silver ions into the water at a minimal cost. The authors evaluated a dozen RWH systems equipped with silver releasing devices, which have been providing drinking water to schools and clinics in a rural area of Mexico. This paper represents a follow-up to a previously published study on an evaluation performed in the same region. A number of water quality parameters have been analysed, examining the long-term efficiency of the projects. Our observations show that the silver ion devices act as an effective disinfection mechanism, as long as adequate maintenance is provided. The combination with conventional settling tanks and filtration units seems to greatly enhance the overall performance of the system

Challenges in Bridging Social Semantics and Formal Semantics on the Web

This paper describes several results of Wimmics, a research lab which names stands for: web-instrumented man-machine interactions, communities, and semantics. The approaches introduced here rely on graph-oriented knowledge representation, reasoning and operationalization to model and support actors, actions and interactions in web-based epistemic communities. The re-search results are applied to support and foster interactions in online communities and manage their resources

An Experimental Study of Effects of Step Roughness in Skimming Flows on Stepped Chutes

On a spillway chute, a stepped design increases the rate of energy dissipation on the chute itself and reduces the size of a downstream energy dissipator. Up to date, the effects of step roughness on the flow properties remain unknown despite the practical relevance to damaged concrete steps, rock chutes and gabions weirs. New measurements were conducted in a large-size laboratory facility with two step conditions (smooth and rough) and three types of step roughness. Detailed air-water flow properties were measured systematically for several flow rates. The results showed faster flow motion on rough step chutes. Although the finding is counter-intuitive, it is linked with the location of the inception point of free-surface aeration being located further downstream than for a smooth stepped chute for an identical flow rate. In the aerated flow region, the velocities on rough-step chutes were larger than those of smooth chute flows for a given flow rate and dimensionless location from the inception point of free-surface aeration both at step edges and between step edges. The results suggest that design guidelines for smooth (concrete) stepped spillway may not be suitable to rough stepped chutes including gabion stepped weirs, and older stepped chutes with damaged steps

Increased osteoclastic activity in acute Charcot’s osteoarthopathy: the role of receptor activator of nuclear factor-kappaB ligand

Aims/hypothesis Our aims were to compare osteoclastic activity between patients with acute Charcot’s osteoarthropathy and diabetic and healthy controls, and to determine the effect of the receptor activator of nuclear factor-kappaB ligand (RANKL) and its decoy receptor osteoprotegerin (OPG). Methods Peripheral blood monocytes isolated from nine diabetic Charcot patients, eight diabetic control and eight healthy control participants were cultured in the presence of macrophage-colony stimulating factor (M-CSF) alone, M-CSF and RANKL, and also M-CSF and RANKL with excess concentrations of OPG. Osteoclast formation was assessed by expression of tartrate-resistant acid phosphatase on glass coverslips and resorption on dentine slices. Results In cultures with M-CSF, there was a significant increase in osteoclast formation in Charcot patients compared with healthy and diabetic control participants (p = 0.008). A significant increase in bone resorption was also seen in the former, compared with healthy and diabetic control participants (p < 0.0001). The addition of RANKL to the cultures with M-CSF led to marked increase in osteoclastic resorption in Charcot (from 0.264 ± 0.06% to 41.6 ± 8.1%, p < 0.0001) and diabetic control (0.000 ± 0.00% to 14.2 ± 16.5%, p < 0.0001) patients, and also in healthy control participants (0.004 ± 0.01% to 10.5 ± 1.9%, p < 0.0001). Although the addition of OPG to cultures with M-CSF and RANKL led to a marked reduction of resorption in Charcot patients (41.6 ± 8.1% to 5.9 ± 2.4%, p = 0.001), this suppression was not as complete as in diabetic control patients (14.2 ± 16.5% to 0.45 ± 0.31%, p = 0.001) and in healthy control participants (from 10.5 ± 1.9% to 0.00 ± 0.00%, p < 0.0001). Conclusions/interpretation These results indicate that RANKL-mediated osteoclastic resorption occurs in acute Charcot’s osteoarthropathy. However, the incomplete inhibition of RANKL after addition of OPG also suggests the existence of a RANKL-independent pathway

Prospecting environmental mycobacteria: combined molecular approaches reveal unprecedented diversity

Background: Environmental mycobacteria (EM) include species commonly found in various terrestrial and aquatic environments, encompassing animal and human pathogens in addition to saprophytes. Approximately 150 EM species can be separated into fast and slow growers based on sequence and copy number differences of their 16S rRNA genes. Cultivation methods are not appropriate for diversity studies; few studies have investigated EM diversity in soil despite their importance as potential reservoirs of pathogens and their hypothesized role in masking or blocking M. bovis BCG vaccine. Methods: We report here the development, optimization and validation of molecular assays targeting the 16S rRNA gene to assess diversity and prevalence of fast and slow growing EM in representative soils from semi tropical and temperate areas. New primer sets were designed also to target uniquely slow growing mycobacteria and used with PCR-DGGE, tag-encoded Titanium amplicon pyrosequencing and quantitative PCR. Results: PCR-DGGE and pyrosequencing provided a consensus of EM diversity; for example, a high abundance of pyrosequencing reads and DGGE bands corresponded to M. moriokaense, M. colombiense and M. riyadhense. As expected pyrosequencing provided more comprehensive information; additional prevalent species included M. chlorophenolicum, M. neglectum, M. gordonae, M. aemonae. Prevalence of the total Mycobacterium genus in the soil samples ranged from 2.3×107 to 2.7×108 gene targets g−1; slow growers prevalence from 2.9×105 to 1.2×107 cells g−1. Conclusions: This combined molecular approach enabled an unprecedented qualitative and quantitative assessment of EM across soil samples. Good concordance was found between methods and the bioinformatics analysis was validated by random resampling. Sequences from most pathogenic groups associated with slow growth were identified in extenso in all soils tested with a specific assay, allowing to unmask them from the Mycobacterium whole genus, in which, as minority members, they would have remained undetected

A 30-Min Nucleic Acid Amplification Point-of-Care Test for Genital Chlamydia trachomatis Infection in Women: A Prospective, Multi-center Study of Diagnostic Accuracy.

BACKGROUND: Rapid Point-Of-Care Tests for Chlamydia trachomatis (CT) may reduce onward transmission and reproductive sexual health (RSH) sequelae by reducing turnaround times between diagnosis and treatment. The io® single module system (Atlas Genetics Ltd.) runs clinical samples through a nucleic acid amplification test (NAAT)-based CT cartridge, delivering results in 30min. METHODS: Prospective diagnostic accuracy study of the io® CT-assay in four UK Genito-Urinary Medicine (GUM)/RSH clinics on additional-to-routine self-collected vulvovaginal swabs. Samples were tested "fresh" within 10days of collection, or "frozen" at -80°C for later testing. Participant characteristics were collected to assess risk factors associated with CT infection. RESULTS: CT prevalence was 7.2% (51/709) overall. Sensitivity, specificity, positive and negative predictive values of the io® CT assay were, respectively, 96.1% (95% Confidence Interval (CI): 86.5-99.5), 97.7% (95%CI: 96.3-98.7), 76.6% (95%CI: 64.3-86.2) and 99.7% (95%CI: 98.9-100). The only risk factor associated with CT infection was being a sexual contact of an individual with CT. CONCLUSIONS: The io® CT-assay is a 30-min, fully automated, high-performing NAAT currently CE-marked for CT diagnosis in women, making it a highly promising diagnostic to enable specific treatment, initiation of partner notification and appropriately intensive health promotion at the point of care

Time-resolved measurements of fast electron recirculation for relativistically intense femtosecond scale laser-plasma interactions

A key issue in realising the development of a number of applications of high-intensity lasers is the dynamics of the fast electrons produced and how to diagnose them. We report on measurements of fast electron transport in aluminium targets in the ultra-intense, short-pulse (<50 fs) regime using a high resolution temporally and spatially resolved optical probe. The measurements show a rapidly (≈0.5c) expanding region of Ohmic heating at the rear of the target, driven by lateral transport of the fast electron population inside the target. Simulations demonstrate that a broad angular distribution of fast electrons on the order of 60° is required, in conjunction with extensive recirculation of the electron population, in order to drive such lateral transport. These results provide fundamental new insight into fast electron dynamics driven by ultra-short laser pulses, which is an important regime for the development of laser-based radiation and particle sources

Characterization of complex networks: A survey of measurements

Each complex network (or class of networks) presents specific topological features which characterize its connectivity and highly influence the dynamics of processes executed on the network. The analysis, discrimination, and synthesis of complex networks therefore rely on the use of measurements capable of expressing the most relevant topological features. This article presents a survey of such measurements. It includes general considerations about complex network characterization, a brief review of the principal models, and the presentation of the main existing measurements. Important related issues covered in this work comprise the representation of the evolution of complex networks in terms of trajectories in several measurement spaces, the analysis of the correlations between some of the most traditional measurements, perturbation analysis, as well as the use of multivariate statistics for feature selection and network classification. Depending on the network and the analysis task one has in mind, a specific set of features may be chosen. It is hoped that the present survey will help the proper application and interpretation of measurements.Comment: A working manuscript with 78 pages, 32 figures. Suggestions of measurements for inclusion are welcomed by the author

Using co-authorship networks to map and analyse global Neglected Tropical Disease research with an affiliation to Germany

Neglected tropical disease research has changed considerably in recent decades, and the German government is committed to addressing its past neglect of NTD research. Our aim was to use an innovative social network analysis of bibliometric data to map neglected tropical disease research networks that are inside of and affiliated with Germany, thereby enabling data-driven health policy decision-making. We created and analysed co-author networks from publications in the SCOPUS database, with a focus on five diseases. We found that Germany's share of global publication output for NTDs is approximately half that of other medical research fields. Furthermore, we identified institutions with prominent NTD research within Germany and strong research collaborations between German institutions and partners abroad, mostly in other high-income countries. This allowed an assessment of strong collaborations for further development, e.g., for research capacity strengthening in low-income-countries, but also for identifying missed opportunities for collaboration within the network. Through co-authorship network analysis of individual researcher networks, we identified strong performers by using classic bibliometric parameters, and we identified academic talent by social network analysis parameters on an individual level