Issues of water supply and contemporary urban society: the case of Greater Amman, Jordan

Over the last two decades, Jordan has suffered a chronic water crisis, and is the tenth most water-scarce nation on Earth. Such water stress has been well illustrated in the case of Greater Amman, the capital, which has grown dramatically from a population of around 2000 in the 1920s, to 2.17 million today. One of the distinctive characteristics of the water supply regime of Greater Amman is that since 1987 it has been based on a system of rationing, with households receiving water once a week for various durations. Amman is highly polarized socio-economically, and by means of household surveys, both quantitative and qualitative, conducted in high- and low-income divisions of the city, a detailed empirical evaluation of the storage and use of water, the strategies used by households to manage water and overall satisfaction with water supply issues is provided in this paper, looking specifically at issues of social equity. The analysis demonstrates the social and economic costs of water rationing and consequent management to be high, as well as emphasizing that issues of water quality are of central importance to all consumers regardless of their socio-economic status within the city.

Rational conversion of substrate and product specificity in a Salvia monoterpene synthase: structural insights into the evolution of terpene synthase function

Terpene synthases are responsible for the biosynthesis of the complex chemical defense arsenal of plants and microorganisms. How do these enzymes, which all appear to share a common terpene synthase fold, specify the many different products made almost entirely from one of only three substrates? Elucidation of the structure of 1,8-cineole synthase from Salvia fruticosa (Sf-CinS1) combined with analysis of functional and phylogenetic relationships of enzymes within Salvia species identified active-site residues responsible for product specificity. Thus, Sf-CinS1 was successfully converted to a sabinene synthase with a minimum number of rationally predicted substitutions, while identification of the Asn side chain essential for water activation introduced 1,8-cineole and alpha-terpineol activity to Salvia pomifera sabinene synthase. A major contribution to product specificity in Sf-CinS1 appears to come from a local deformation within one of the helices forming the active site. This deformation is observed in all other mono- or sesquiterpene structures available, pointing to a conserved mechanism. Moreover, a single amino acid substitution enlarged the active-site cavity enough to accommodate the larger farnesyl pyrophosphate substrate and led to the efficient synthesis of sesquiterpenes, while alternate single substitutions of this critical amino acid yielded five additional terpene synthases.

Invertebrate food supply and breeding success of Mallards Anas platyrhynchos at flooded gravel quarries in southern Britain

Reproductive parameters of Mallard Anas platyrhynchos were investigated in relation to vegetative development, physical characteristics and invertebrate food abundance of a complex of flooded gravel quarries in southern Britain. Breeding pair density over the study area was particularly high with 2.2 pairs km(-1) of shoreline. Across all lakes breeding success was limited to an average of 0.9 ducklings fledged pair(-1), yet an associated study showed that very little of the mortality could be attributed to predation. The results of stepwise multiple regressions indicated that the availability of emerging insects was important in determining the breeding density and breeding success of Mallards rather than habitat structure. We suggest that the overall great availability of suitable nest-sites combined with the variable but unmeasured stocking densities of fish may explain the lack of the latter correlations.

Oxidation of biogenic and water-soluble compounds in aqueous and organic aerosol droplets by ozone: a kinetic and product analysis approach using laser Raman tweezers

The results of an experimental study into the oxidative degradation of proxies for atmospheric aerosol are presented. We demonstrate that the laser Raman tweezers method can be used successfully to obtain uptake coeffcients for gaseous oxidants on individual aqueous and organic droplets, whilst the size and composition of the droplets is simultaneously followed. A laser tweezers system was used to trap individual droplets containing an unsaturated organic compound in either an aqueous or organic ( alkane) solvent. The droplet was exposed to gas- phase ozone and the reaction kinetics and products followed using Raman spectroscopy. The reactions of three different organic compounds with ozone were studied: fumarate anions, benzoate anions and alpha pinene. The fumarate and benzoate anions in aqueous solution were used to represent components of humic- like substances, HULIS; a alpha- pinene in an alkane solvent was studied as a proxy for biogenic aerosol. The kinetic analysis shows that for these systems the diffusive transport and mass accommodation of ozone is relatively fast, and that liquid- phase di. ffusion and reaction are the rate determining steps. Uptake coe. ffcients, g, were found to be ( 1.1 +/- 0.7) x 10(-5), ( 1.5 +/- 0.7) x 10 (-5) and ( 3.0 - 7.5) x 10 (-3) for the reactions of ozone with the fumarate, benzoate and a- pinene containing droplets, respectively. Liquid- phase bimolecular rate coe. cients for reactions of dissolved ozone molecules with fumarate, benzoate and a- pinene were also obtained: k(fumarate) = ( 2.7 +/- 2) x 10 (5), k(benzoate) = ( 3.5 +/- 3) x 10 (5) and k(alpha-pinene) = ( 1-3) x 10(7) dm(3) mol (-1) s (- 1). The droplet size was found to remain stable over the course of the oxidation process for the HULIS- proxies and for the oxidation of a- pinene in pentadecane. The study of the alpha- pinene/ ozone system is the first using organic seed particles to show that the hygroscopicity of the particle does not increase dramatically over the course of the oxidation. No products were detected by Raman spectroscopy for the reaction of benzoate ions with ozone. One product peak, consistent with aqueous carbonate anions, was observed when following the oxidation of fumarate ions by ozone. Product peaks observed in the reaction of ozone with alpha- pinene suggest the formation of new species containing carbonyl groups.

Modelling sediment supply and transport in the River Lugg: strategies for controlling sediment loads

The River Lugg has particular problems with high sediment loads that have resulted in detrimental impacts on ecology and fisheries. A new dynamic, process-based model of hydrology and sediments (INCA- SED) has been developed and applied to the River Lugg system using an extensive data set from 1995–2008. The model simulates sediment sources and sinks throughout the catchment and gives a good representation of the sediment response at 22 reaches along the River Lugg. A key question considered in using the model is the management of sediment sources so that concentrations and bed loads can be reduced in the river system. Altogether, five sediment management scenarios were selected for testing on the River Lugg, including land use change, contour tillage, hedging and buffer strips. Running the model with parameters altered to simulate these five scenarios produced some interesting results. All scenarios achieved some reduction in sediment levels, with the 40% land use change achieving the best result with a 19% reduction. The other scenarios also achieved significant reductions of between 7% and 9%. Buffer strips produce the best result at close to 9%. The results suggest that if hedge introduction, contour tillage and buffer strips were all applied, sediment reductions would total 24%, considerably improving the current sediment situation. We present a novel cost-effectiveness analysis of our results where we use percentage of land removed from production as our cost function. Given the minimal loss of land associated with contour tillage, hedges and buffer strips, we suggest that these management practices are the most cost-effective combination to reduce sediment loads.

Housing supply and planning controls: the impact of development control processing times on housing supply in England

The National Housing and Planning Advice Unit commissioned Professor Michael Ball of Reading University to undertake empirical research into how long it was taking to obtain planning consent for major housing sites in England. The focus on sites as opposed to planning applications is important because it is sites that generate housing.

Housing supply and planning delay in the South of England

There is growing international interest in the impact of regulatory controls on the supply of housing The UK has a particularly restrictive planning regime and a detailed and uncertain process of development control linked to it. This paper presents the findings of empirical research on the time taken to gain planning permission for selected recent major housing projects from a sample of local authorities in southern England. The scale of delay found was far greater than is indicated by average official data measuring the extent to which local authorities meet planning delay targets. If these results are representative of the country as a whole, they indicate that planning delay could be a major cause of the slow responsiveness of British housing supply.

Housing supply and brownfield regeneration in a post-Barker world: is there enough brownfield land in England and Scotland?

The findings of the Barker review, which examined the reasons for the undersupply of UK housing, have important implications for the devolved constituents of the UK, including Scotland. This paper traces the emergence of the brownfi eld regeneration policy agenda across the UK and examines how the Barker review connects with this brownfi eld policy focus. The paper compares housing and brownfi eld policies and practices in England and Scotland, places them in an international context and elicits wider lessons for devolved governance in relation to housing policy, in terms of ‘centrist–local’ tensions. Estimates based on published data suggest that Barker’s emphasis on increased housing supply cannot easily be reconciled with the current emphasis on brownfi eld development and is likely to require a return to greenfield development in both countries.

Competition and product survival in the UK car market

The paper examines the extent to which inter- and intra-firm competition influenced the survival of cars in the UK market between 1971 and 1998. It is shown that, while competition influenced product survival in all market segments within the UK car market, the nature of that competition differed between them. In the small family and large family car segments, intra-firm competition dominated inter-firm competition. In contrast, in the luxury/sports car segment only inter-firm competition conditions resulted in product survival. Evidence was also found that the luxury/sports car segment has grown more competitive over time and that firms marketing products in the family car segments have become considerably more successful at avoiding the effects of intra-firm competition.

Demand, supply and willingness-to-pay for extension services in an emerging-market setting

Although it may be wholly inappropriate to generalize, the most important resource available to a subsistence household is the total amount of time that its members have available to spend in productive enterprises. In this context, services that minimize the time that it takes to perform productive activities are valuable to the household. Consequently the household is willing to relinquish quantities of other resources in exchange for quantities of the time-saving service. These simple observations motivate a search for the values that subsistence households place on time-saving services. This search is especially important when it is realized that extension services promote productivity, enhance the surplus-generating potential of the household and can, as a consequence, promote immersion into markets that are currently constrained by thinness and instability. In this capacity, extension visitation has the potential to overcome one of the principal impediments to economic development, namely lack of density of market participation. In this article, we consider this issue in the context of a rich data set on milk-market participation by small-holder dairy producers in the Ethiopian highlands.

The supply and movement of Denarii in Roman Britain

Hoards of denarii are common in Britain and the number which have been recorded in detail means that it is now possible to suggest reasonably accurately what a ‘normal’ hoard of a particular date should look like. That being the case, we can then look for variation around that norm and both investigate and speculate what that variation means. A methodology is developed which suggests periods of faster and less rapid coin circulation which has implications for consideration of monetisation. The model also enables us to view where denarii entered circulation; unsurprisingly the army looms large in this picture. The methodology is directly transferable to other provinces and other periods where there are longlived, relatively stable monetary systems.

British working-class household composition, labour supply, and commercial leisure participation during the 1930s

The early twentieth century constituted the heyday of the ‘breadwinner–homemaker’ household, characterized by a high degree of intra-household functional specialization between paid and domestic work according to age, gender, and marital status. This article examines the links between formal workforce participation and access to resources for individualized discretionary spending in British working-class households during the late 1930s, via an analysis of household leisure expenditures. Leisure spending is particularly salient to intra-household resource allocation, as it constitutes one of the most highly prioritized areas of individualized expenditure, especially for young, single people. Using a database compiled from surviving returns to the Ministry of Labour's national 1937/8 working-class expenditure survey, we examine leisure participation rates for over 600 households, using a detailed set of commercial leisure activities together with other relevant variables. We find that the employment status of family members other than the male breadwinner was a key factor influencing their access to commercial leisure. Our analysis thus supports the view that the breadwinner–homemaker household was characterized by strong power imbalances that concentrated resources—especially for individualized expenditures—in the hands of those family members who engaged in paid labour.

Collusion in a Bertrand duopoly model with decreasing returns and product differentiation

We study cartel stability in a differentiated price-setting duopoly with returns to scale. We show that a cartel may be equally stable in the presence of lower differentiation, provided that the decreasing returns parameter is high. In addition we demonstrate that for a given factor of discount, there are technologies that can have decreasing returns to scale where the cartel always is stable independent of the differentiation degree.