Modeling particle transport and discoloration risk in drinking water distribution networks

Discoloration of drinking water is a worldwide phenomenon caused by accumulation and subsequent remobilization of particulate matter in distribution systems (DWDSs). It contributes to a substantial fraction of customer complaints to water utilities. Accurate discoloration risk predictions could improve system operation by allowing for more effective programs on cleaning and prevention actions and field measurements, but are challenged by incomplete understanding on the origins and properties of particles and a complex and not fully understood interplay of processes in distribution networks. In this paper, we assess and describe relevant hydraulic processes that govern particle transport in turbulent pipe flow, including gravitational settling, bed-load transport, and particle entrainment into suspension. We assess which transport mechanisms are dominant for a range of bulk flow velocities, particle diameters, and particle mass densities, which includes common conditions for DWDS in The Netherlands, U.K., and Australia. Our analysis shows that the theoretically predicted particle settling velocity and threshold shear stresses for incipient particle motion are in the same range, but more variable than, previous estimates from lab experiments, field measurements, and modeling. The presented material will be used in the future development of a numerical modeling tool to determine and predict the spatial distribution of particulate material and discoloration risk in DWDSs. Our approach is aimed at understanding specific causalities and processes, which can complement data-driven approaches

Blending in, to transform the regime from within:Niche hybridisation strategies of Irish energy communities

This study aimed to get a better and more nuanced understanding of niche strategies in practice. Niche hybridisation strategies were conceptualised in relation to the three core dimensions of socio-technical systems (institutions, actors, and technology). This conceptualisation was applied to the case of Community Power (CP). CP is a community-owned supply company that combines elements of cooperative and commercial organisations, which are favoured by the community energy (niche) and commercial (regime) logics. CP was set up to enable energy communities to sell energy to their members and on electricity markets. As such, CP protected energy communities from market pressures, which allowed them to blend in and become more competitive within an unchanged selection environment. By stimulating wider diffusion of the community energy logic, CP passively stretched the regime. CP also actively stretched the regime by engaging in institutional entrepreneurship, to make it more favourable towards community energy.This study aimed to get a better and more nuanced understanding of niche strategies in practice. Niche hybridisation strategies were conceptualised in relation to the three core dimensions of socio-technical systems (institutions, actors, and technology). This conceptualisation was applied to the case of Community Power (CP). CP is a community-owned supply company that combines elements of cooperative and commercial organisations, favoured by the community energy (niche) and commercial (regime) logics. CP was set up to enable energy communities to sell energy to their members and on electricity markets. As such, CP protected energy communities from market pressures, which allowed them to blend in and become more competitive within an unchanged selection environment. By stimulating wider diffusion of the community energy logic, CP attempted to passively stretch the regime. CP also tried to actively stretch the regime by engaging in institutional entrepreneurship, to make it more favourable towards community energy

Biologically active Phytophthora mating hormone prepared by catalytic asymmetric total synthesis

A Phytophthora mating hormone with an array of 1,5-stereogenic centers has been synthesized by using our recently developed methodology of catalytic enantioselective conjugate addition of Grignard reagents. We applied this methodology in a diastereo- and enantioselective iterative route and obtained two of the 16 possible stereoisomers of Phytophthora hormone α1. These synthetic stereoisomers induced the formation of sexual spores (oospores) in A2 mating type strains of three heterothallic Phytophthora species, P. infestans, P. capsici, and P. nicotianae but not in A1 mating type strains. The response was concentration-dependent, and the oospores were viable. These results demonstrate that the biological activity of the synthetic hormone resembles that of the natural hormone α1. Mating hormones are essential components in the sexual life cycle of a variety of organisms. For plant pathogens like Phytophthora, sexual reproduction is important as a source of genetic variation. Moreover, the thick-walled oospores are the most durable propagules that can survive harsh environmental conditions. Sexual reproduction can thus greatly affect disease epidemics. The availability of synthetic compounds mimicking the activity of Phytophthora mating hormone will be instrumental for further unravelling sexual reproduction in this important group of plant pathogens.

Physiotherapy for Children with Functional Constipation:A Pragmatic Randomized Controlled Trial in Primary Care

Objective: To determine the effectiveness of physiotherapy plus conventional treatment compared with conventional treatment alone for the treatment of functional constipation in children age 4-17 years in primary care. Study design: Pragmatic randomized controlled trial with 8 months follow-up. Primary care physicians recruited children diagnosed with functional constipation (n = 234), and pediatricians recruited newly referred children with a diagnosis of functional constipation (n = 11). Conventional treatment comprised toilet training, nutritional advice, and laxative prescribing, whereas physiotherapy focused on resolving dyssynergic defecation. The primary outcome was treatment success over 8 months, defined as the absence of functional constipation (Rome III criteria) without laxative use. Secondary outcomes included the absence of functional constipation irrespective of continuation of laxative use and global perceived treatment effect. Results: Children were allocated to conventional treatment plus physiotherapy or conventional treatment alone (67 per group), mean (SD) age was 7.6 (3.5) years. Results of longitudinal analyses in the intention-to-treat population showed that the treatment success percentage was not statistically improved by adding physiotherapy to conventional treatment (adjusted relative risk [aRR] 0.80, 95% CI 0.44-1.30). At 4 months, fewer children receiving physiotherapy had treatment success (17%) than children receiving conventional treatment alone (28%), but this had equalized by 8 months (42% and 41%, respectively). The percentage of children without functional constipation, irrespective of continuation of laxative use, was not statistically different between groups over 8 months (aRR 1.12, 95% CI 0.82-1.34). Notably, parents reported significantly more global symptom improvement after physiotherapy than after conventional treatment (aRR 1.40; 95% CI 1.00-1.73). Conclusions: We find no evidence to recommend physiotherapy for all children with functional constipation in primary care. Trial registration: Netherlands Trial Registry: NTR4797

Possible Disintegrating Short-Period Super-Mercury Orbiting KIC 12557548

We report here on the discovery of stellar occultations, observed with Kepler, that recur periodically at 15.685 hour intervals, but which vary in depth from a maximum of 1.3% to a minimum that can be less than 0.2%. The star that is apparently being occulted is KIC 12557548, a K dwarf with T_eff = 4400 K and V = 16. Because the eclipse depths are highly variable, they cannot be due solely to transits of a single planet with a fixed size. We discuss but dismiss a scenario involving a binary giant planet whose mutual orbit plane precesses, bringing one of the planets into and out of a grazing transit. We also briefly consider an eclipsing binary, that either orbits KIC 12557548 in a hierarchical triple configuration or is nearby on the sky, but we find such a scenario inadequate to reproduce the observations. We come down in favor of an explanation that involves macroscopic particles escaping the atmosphere of a slowly disintegrating planet not much larger than Mercury. The particles could take the form of micron-sized pyroxene or aluminum oxide dust grains. The planetary surface is hot enough to sublimate and create a high-Z atmosphere; this atmosphere may be loaded with dust via cloud condensation or explosive volcanism. Atmospheric gas escapes the planet via a Parker-type thermal wind, dragging dust grains with it. We infer a mass loss rate from the observations of order 1 M_E/Gyr, with a dust-to-gas ratio possibly of order unity. For our fiducial 0.1 M_E planet, the evaporation timescale may be ~0.2 Gyr. Smaller mass planets are disfavored because they evaporate still more quickly, as are larger mass planets because they have surface gravities too strong to sustain outflows with the requisite mass-loss rates. The occultation profile evinces an ingress-egress asymmetry that could reflect a comet-like dust tail trailing the planet; we present simulations of such a tail.Comment: 14 pages, 7 figures; submitted to ApJ, January 10, 2012; accepted March 21, 201