Between Regulation and Targeted Expropriation: Rural-to-urban Groundwater Reallocation in Jordan

In response to rising urban water demand, some regions have reallocated water from irrigation to more valuable uses. Groundwater over-exploitation, however, continues to degrade aquifer quality, and states rarely succeed at stopping overuse. This study asks whether growing urban requirements enable the reallocation of groundwater from irrigation to higher value added uses in domestic and industrial consumption. The paper is based on a series of interviews with policy makers and academics in Jordan, combined with data from remote sensing analysis. The results find that regulatory measures such as tariffs and well licensing have a limited impact on agricultural water use when opposed by a broad coalition of interest groups; instead, a targeted expropriation n a single small area, combined with an expansion of supply, did succeed in reallocating 35 million cubic metres of groundwater. The results suggest that urban water needs do increase state interest in reallocation. That reallocation was successful in only one of the attempted basins suggests that donor-region resistance is a major factor in reallocation outcomes. We discuss the strategy of, for future reallocators, targeting only aquifers with low political and enforcement costs

Addressing the path-length-dependency confound in white matter tract segmentation

We derive the Iterative Confidence Enhancement of Tractography (ICE-T) framework to address the problem of path-length dependency (PLD), the streamline dispersivity confound inherent to probabilistic tractography methods. We show that PLD can arise as a non-linear effect, compounded by tissue complexity, and therefore cannot be handled using linear correction methods. ICE-T is an easy-to-implement framework that acts as a wrapper around most probabilistic streamline tractography methods, iteratively growing the tractography seed regions. Tract networks segmented with ICE-T can subsequently be delineated with a global threshold, even from a single-voxel seed. We investigated ICE-T performance using ex vivo pig-brain datasets where true positives were known via in vivo tracers, and applied the derived ICE-T parameters to a human in vivo dataset. We examined the parameter space of ICE-T: the number of streamlines emitted per voxel, and a threshold applied at each iteration. As few as 20 streamlines per seed-voxel, and a robust range of ICE-T thresholds, were shown to sufficiently segment the desired tract network. Outside this range, the tract network either approximated the complete white-matter compartment (too low threshold) or failed to propagate through complex regions (too high threshold). The parameters were shown to be generalizable across seed regions. With ICE-T, the degree of both near-seed flare due to false positives, and of distal false negatives, are decreased when compared with thresholded probabilistic tractography without ICE-T. Since ICE-T only addresses PLD, the degree of remaining false-positives and false-negatives will consequently be mainly attributable to the particular tractography method employed. Given the benefits offered by ICE-T, we would suggest that future studies consider this or a similar approach when using tractography to provide tract segmentations for tract based analysis, or for brain network analysis

Intuiting, Socializing and Playing Around: Women’s Stories of Informal Learning in the Information Technology Field

This report is based on a study of the informal and alternative approaches to learning of women who are working in the rapidly expanding and changing IT field. Using their intuition, borrowing and sharing expertise, and through trial and error, study participants describe essential forms of learning often unacknowledged by both workers and employer

Community metabolism and phosphorus dynamics in a seasonally closed South African estuary

The effects of seawater inflows and macrophyte beds on community metabolism and phosphorus dynamics in the seasonally-closed Swartvlei estuary were investigated. Metabolic rates were determined by diurnal oxygen curve analysis. Gross primary production ranged from 0,7 to 14,9 g 0₂ m⁻² day⁻¹, and respiration from 0,9 to 25,2 g 0₂ m⁻² day⁻¹. The highest production rates were recorded inside the dense beds of Zostera capens is Setchell (x- = 7,8 g 0₂ m⁻² day⁻¹ ). Metabolism was positively correlated to submersed macrophyte cover, and decreased upstream of the mouth region. No seasonal variation in gross production could be detected, and mouth closure had no detectable effect on metabolic rates. Growth of the green alga Enteromorpha sp. in winter, and the effect of decay of this alga on dissolved oxygen, total inorganic carbon and total dissolved phosphorus in the water column is discussed. High day-time respiration values, measured in a darkened polythene enclosure, indicate that photorespiration occurs in Zostera. Apparently the annual amount of oxygen respired throughout the estuary exceeded that produced by 2 7100 tonnes, i.e. the estuary was heterotrophic. This is discussed in relation to the effectiveness of the diurnal curve method as a way of measuring metabolic rates, and to the possibility of organic matter input via river inflows. There is a net gain of up to 17,4 kg of particulate phosphorus over mean tides. Diurnal phosphorus studies indicate that Zostera releases phosphate into the water column in the light. Enteromorpha takes up phosphate in the morning, which it appears to release over the rest of the day. The cycling of phosphorus between seawater, sediments, macrophytes and the water column is discussed

Recent Advances in Organic and Organic–Inorganic Hybrid Materials for Piezoelectric Mechanical Energy Harvesting

This article provides a comprehensive overview of piezo- and ferro-electric materials based on organic molecules and organic–inorganic hybrids for mechanical energy harvesting. Molecular (organic and organic–inorganic hybrid) piezo- and ferroelectric materials exhibit significant advantages over traditional materials due to their simple solution-phase synthesis, light-weight nature, thermal stability, mechanical flexibility, high Curie temperature, and attractive piezo- and ferroelectric properties. However, the design and understanding of piezo- and ferroelectricity in organic and organic–inorganic hybrid materials for piezoelectric energy harvesting applications is less well developed. This review describes the fundamental characterization of piezo- and ferroelectricity for a range of recently reported organic and organic–inorganic hybrid materials. The limits of traditional piezoelectric harvesting materials are outlined, followed by an overview of the piezo- and ferroelectric properties of organic and organic–inorganic hybrid materials, and their composites, for mechanical energy harvesting. An extensive description of peptide-based and other biomolecular piezo- and ferroelectric materials as a biofriendly alternative to current materials is also provided. Finally, current limitations and future perspectives in this emerging area of research are highlighted. This perspective aims to guide chemists, materials scientists, and engineers in the design of practically useful organic and organic–inorganic hybrid piezo- and ferroelectric materials and composites for mechanical energy harvesting.</p

Structural and mechanistic insights into s-block bimetallic catalysis : sodium magnesiate-catalyzed guanylation of amines

To advance the catalytic applications of s-block mixed-metal complexes, sodium magnesiate [NaMg(CH2SiMe3)3] (1) is reported as an efficient precatalyst for the guanylation of a variety of anilines and secondary amines with carbodiimides. First examples of hydrophosphination of carbodiimides by using a Mg catalyst are also described. The catalytic ability of the mixed-metal system is much greater than that of its homometallic components [NaCH2SiMe3 ] and [Mg(CH2SiMe3)2]. Stoichiometric studies suggest that magnesiate amido and guanidinate complexes are intermediates in these catalytic routes. Reactivity and kinetic studies imply that these guanylation reactions occur via (tris)amide intermediates that react with carbodiiimides in insertion steps. The rate law for the guanylation of N,N'-diisopropylcarbodiimide with 4-tert-butylaniline catalyzed by 1 is first order with respect to [amine], [carbodiimide], and [catalyst], and the reaction shows a large kinetic isotopic effect, which is consistent with an amine-assisted rate-determining carbodiimide insertion transition state. Studies to assess the effect of sodium in these transformations denote a secondary role with little involvement in the catalytic cycle

Tributyltin (TBT) and the decline of the Norfolk Broads: Hickling Broad and Barton Broad

This study furthers the work of Sayer et al (2001), in which a model was presented regarding the collapse of the plant-dominated state in the aquatic ecosystem of the Norfolk Broads, E. England. The boat antifouling biocide tributyltin (TBT) was implicated as a toxic switching mechanism from evidence gathered in a palaeolimnological study of Wroxham Broad