Water and health. [Chapter 6 of 'Sustainable water: chemical science priorities summary report']

Water transports contaminants, including inorganic, organic and biological materials, from various sources both natural and man-made. Such contaminants can enter the human body via water by ingestion, inhalation of water droplets and contact, particularly with broken skin. Water borne diseases have historically had the greatest impact upon human health and continue to contribute to millions of deaths globally per year. Water use and sanitation in the form of hygiene practices act as an important barrier to disease transmission. Disease incidences in countries without basic water and sanitation services are estimated to be eleven times higher for than those in areas with clean water, hygiene practices, and the safe disposal of human wastes. Naturally occurring arsenic compounds (in particular toxic organic species) contaminate substantial groundwater sources. The most seriously affected areas in Sustainable Water: Chemical Science Priorities Royal Society of Chemistry report the world are in India and Bangladesh. Here, 60–100 million people are currently at risk of poisoning as a result of drinking contaminated groundwater where the arsenic arises from the natural bedrock geology. There is a need for portable field-testing kits that are quick, accurate, cheap and reliable that can support remediation efforts. Additionally there is a need for arsenic mitigation technologies that are effective and appropriate for use by local populations. There is also a growing problem with uranium contamination of groundwater, particularly in Eastern Europe. Society is reliant upon man-made chemicals, particularly for food and health, and inevitably such chemicals end up in water systems. Typically these chemical contaminants are either neurotoxins, pharmaceutically active or endocrine disruptors. Additionally there is growing concern over multiple chemical sensitivity1, although scientific evidence is insufficient to prove or disprove this theory at this time. There are two specific problems with man-made chemicals in wastewater: firstly, treatment plants are not designed to remove these chemical products; secondly, chemicals entrained in sediments can be mobilised by chemical and biological processes. Traditionally, pollution by man-made chemicals is reduced by either dilution or through end of pipe remediation technologies. This can be minimised by adopting good practice and integrated pollution prevention and control. This would include measures such as minimising the quantity of materials used and recovering unused materials. Additionally, industrial waste streams should be concentrated as far as possible and mixtures of materials should be avoided, as this will require additional treatment steps and effort

Cluster randomised trials in the medical literature: two bibliometric surveys

Background: Several reviews of published cluster randomised trials have reported that about half did not take clustering into account in the analysis, which was thus incorrect and potentially misleading. In this paper I ask whether cluster randomised trials are increasing in both number and quality of reporting. Methods: Computer search for papers on cluster randomised trials since 1980, hand search of trial reports published in selected volumes of the British Medical Journal over 20 years. Results: There has been a large increase in the numbers of methodological papers and of trial reports using the term 'cluster random' in recent years, with about equal numbers of each type of paper. The British Medical Journal contained more such reports than any other journal. In this journal there was a corresponding increase over time in the number of trials where subjects were randomised in clusters. In 2003 all reports showed awareness of the need to allow for clustering in the analysis. In 1993 and before clustering was ignored in most such trials. Conclusion: Cluster trials are becoming more frequent and reporting is of higher quality. Perhaps statistician pressure works

Geometric and dynamic perspectives on phase-coherent and noncoherent chaos

Statistically distinguishing between phase-coherent and noncoherent chaotic dynamics from time series is a contemporary problem in nonlinear sciences. In this work, we propose different measures based on recurrence properties of recorded trajectories, which characterize the underlying systems from both geometric and dynamic viewpoints. The potentials of the individual measures for discriminating phase-coherent and noncoherent chaotic oscillations are discussed. A detailed numerical analysis is performed for the chaotic R\"ossler system, which displays both types of chaos as one control parameter is varied, and the Mackey-Glass system as an example of a time-delay system with noncoherent chaos. Our results demonstrate that especially geometric measures from recurrence network analysis are well suited for tracing transitions between spiral- and screw-type chaos, a common route from phase-coherent to noncoherent chaos also found in other nonlinear oscillators. A detailed explanation of the observed behavior in terms of attractor geometry is given.Comment: 12 pages, 13 figure

Inadequate reporting of research ethics review and informed consent in cluster randomized trials : review of random sample of published trials

Peer reviewedPublisher PD

The Potential-Density Phase Shift Method for Determining the Corotation Radii in Spiral and Barred Galaxies

We have developed a new method for determining the corotation radii of density waves in disk galaxies, which makes use of the radial distribution of an azimuthal phase shift between the potential and density wave patterns. The approach originated from improved theoretical understandings of the relation between the morphology and kinematics of galaxies, and on the dynamical interaction between density waves and the basic-state disk stars which results in the secular evolution of disk galaxies. In this paper, we present the rationales behind the method, and the first application of it to several representative barred and grand-design spiral galaxies, using near-infrared images to trace the mass distributions, as well as to calculate the potential distributions used in the phase shift calculations. We compare our results with those from other existing methods for locating the corotations, and show that the new method both confirms the previously-established trends of bar-length dependence on galaxy morphological types, as well as provides new insights into the possible extent of bars in disk galaxies. Application of the method to a larger sample and the preliminary analysis of which show that the phase shift method is likely to be a generally-applicable, accurate, and essentially model-independent method for determining the pattern speeds and corotation radii of single or nested density wave patterns in galaxies. Other implications of this work are: most of the nearby bright disk galaxies appear to possess quasi-stationary spiral modes; that these density wave modes and the associated basic state of the galactic disk slowly transform over time; and that self-consistent N-particle systems contain physics not revealed by the passive orbit analysis approaches.Comment: 48 pages, 16 figures. Accepted for publication in the Astronomical Journa

Atomic Hydrogen and Star Formation in the Bridge/Ring Interacting Galaxy Pair NGC 7714/7715 (Arp 284)

We present high spatial resolution 21 cm HI maps of the interacting galaxy pair NGC 7714/7715. We detect a massive (2 x 10**9 M(sun)) HI bridge connecting the galaxies that is parallel to but offset from the stellar bridge. A chain of HII regions traces the gaseous bridge, with H-alpha peaks near but not on the HI maxima. An HI tidal tail is also detected to the east of the smaller galaxy NGC 7715, similarly offset from a stellar tail. The strong partial stellar ring on the eastern side of NGC 7714 has no HI counterpart, but on the opposite side of NGC 7714 there is a 10**9 M(sun) HI loop 11 kpc in radius. Within the NGC 7714 disk, clumpy HI gas is observed associated with star formation regions. Redshifted HI absorption is detected towards the starburst nucleus. We compare the observed morphology and gas kinematics with gas dynamical models in which a low-mass companion has an off-center prograde collision with the outer disk of a larger galaxy. These simulations suggest that the bridge in NGC 7714/7715 is a hybrid between bridges seen in systems like M51 and the purely gaseous `splash' bridges found in ring galaxies like the Cartwheel. The offset between the stars and gas in the bridge may be due to dissipative cloud-cloud collisions occuring during the impact of the two gaseous disks.Comment: 31 pages, Latex, 11 figures, to be published in the July 10, 1997 issue of the Astrophysical Journa

Investigating the topology of interacting networks - Theory and application to coupled climate subnetworks

Network theory provides various tools for investigating the structural or functional topology of many complex systems found in nature, technology and society. Nevertheless, it has recently been realised that a considerable number of systems of interest should be treated, more appropriately, as interacting networks or networks of networks. Here we introduce a novel graph-theoretical framework for studying the interaction structure between subnetworks embedded within a complex network of networks. This framework allows us to quantify the structural role of single vertices or whole subnetworks with respect to the interaction of a pair of subnetworks on local, mesoscopic and global topological scales. Climate networks have recently been shown to be a powerful tool for the analysis of climatological data. Applying the general framework for studying interacting networks, we introduce coupled climate subnetworks to represent and investigate the topology of statistical relationships between the fields of distinct climatological variables. Using coupled climate subnetworks to investigate the terrestrial atmosphere's three-dimensional geopotential height field uncovers known as well as interesting novel features of the atmosphere's vertical stratification and general circulation. Specifically, the new measure "cross-betweenness" identifies regions which are particularly important for mediating vertical wind field interactions. The promising results obtained by following the coupled climate subnetwork approach present a first step towards an improved understanding of the Earth system and its complex interacting components from a network perspective

Intracluster correlation coefficients in cluster randomized trials: empirical insights into how should they be reported

BACKGROUND: Increasingly, researchers are recognizing that there are many situations where the use of a cluster randomized trial may be more appropriate than an individually randomized trial. Similarly, the need for appropriate standards of reporting of cluster trials is more widely acknowledged. METHODS: In this paper, we describe the results of a survey to inform the appropriate reporting of the intracluster correlation coefficient (ICC) – the statistical measure of the clustering effect associated with a cluster randomized trial. RESULTS: We identified three dimensions that should be considered when reporting an ICC – a description of the dataset (including characteristics of the outcome and the intervention), information on how the ICC was calculated, and information on the precision of the ICC. CONCLUSIONS: This paper demonstrates the development of a framework for the reporting of ICCs. If adopted into routine practice, it has the potential to facilitate the interpretation of the cluster trial being reported and should help the development of new trials in the area

Citescore of publications indexed in Scopus: an implementation of panel data

This article is intended to establish the variables that explain the behavior of the CiteScore metrics from 2014 to 2016, for journals indexed in Scopus in 2017. With this purpose, journals with a CiteScore value greater than 11 were selected in any of the periods, that is to say, 133 journals. For the data analysis, a model of standard corrected errors for panel was used, from which a coefficient of determination of 77% was obtained. From the results, it was possible to state that journals of arts and humanities; business; administration and accounting; economics, econometrics, and finance; immunology and microbiology; medicine and social sciences, have the greatest impact.Corporación Universitaria Minuto de Dios, Fundación Universitaria Konrad Lorenz, Universidad de La Habana, Universidad de la Costa