Fish protection in medium and large open water intakes

A new layout of a fish-protecting facility is proposed. __________ Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 12, December 2006, pp. 24–26.     

Some 'real' problems of 'virtual' organisation

This paper presents an ethnographic study of organisational change in a retail bank considering issues surrounding the supposed emergence of the 'virtual organisation'. It outlines emerging problems in organisational work as a consequence of the shift toward 'virtuality' and questions the explanatory value of such theoretical stances.     

Optimal Lending Contracts and Firm Dynamics

We develop a general model of lending in the presence of endogenous borrowing constraints. Borrowing constraints arise because borrowers face limited liability and debt repayment cannot be perfectly enforced. In the model, the dynamics of debt are closely linked with the dynamics of borrowing constraints. In fact, borrowing constraints must satisfy a dynamic consistency requirement: the value of outstanding debt restricts current access to short-term capital, but is itself determined by future access to credit. This dynamic consistency is not guaranteed in models of exogenous borrowing constraints, where the ability to raise short-term capital is limited by some prespecified function of debt. We characterize the optimal default-free contract—which minimizes borrowing constraints at all histories—and derive implications for firm growth, survival, leverage and debt maturity. The model is qualitatively consistent with stylized facts on the growth and survival of firms. Comparative statics with respect to technology and default constraints are derived.     

Phosphorus Inputs to Lake Simcoe from 1990 to 2003: Declines in Tributary Loads and Observations on Lake Water Quality

Total phosphorus (TP) inputs to Lake Simcoe have led to hypolimnetic dissolved oxygen (DO) depletion and loss of cold water fish habitat. Since 1990, efforts have been made to reduce the total TP input to the lake below a defined target of 75 t/year, which was predicted to lead to reductions in spring TP concentration and improvements in end-of-summer hypolimnetic DO concentrations. The total TP load to the lake during the most recent period of record (1998/99-2003/04) ranged from 53 to 76 t/yr and averaged 67 t/yr, compared to an average of 114 t/yr estimated between 1990/91 and 1997/98 (range 85-157 t/yr). Reductions in TP loads from the catchment via tributary discharge (∼26 t) accounted for the majority of the decrease in total load between the two time periods. Total P concentrations decreased significantly in four out of six long-term monitored tributaries; however, concentrations in all six tributaries remain above the level recommended to avoid nuisance plant growth (30 μg/L). Although TP loads to the lake are currently below the target 75 t/yr, excessive growths of filamentous algae and macrophytes continue to be a problem in the nearshore zone. End-of-summer minimum hypolimnetic DO concentrations (average 4.3 mg/L, 1998/99-2003/04) remain substantially below the level (7 mg/L) that is considered protective of lake trout. Efforts to reduce TP loads to the lake therefore need to continue.     

A Proposed Arbitration Mechanism to Ensure Free Trade in Livestock Products

Trade negotiations between Canada and the United States are to begin in the near future. For there to be an ongoing free movement of commodities the question of nontariff barriers must be addressed in the negotiations. Livestock commodities are particularly prone to nontariff barriers due to the public health aspects of domestic regulations and the perishability of the products. Potential nontariff barriers in livestock and meat products are identified and the problems of normal negotiation procedures outlined. A proposal for an arbitration mechanism for the settlement of disputes is developed. It's essential elements are pre-approval of changes to regulations, extremely short arbitration periods and decentralized adjudication.
Les négociations de commerce entre le Canada et les États-Unis commenceront bientôt. Pour avoir un mouvement continuel des denrées, la question des barrières nontarifaires doit être adressée dans les négotiations. Les denrées bestiaux sont particulièrement portées aux barrières nontarifaires à cause des aspects de la santé publique dans les régulations domestiques et la nature périssable des produits. On identifie les barrières nontarifaires potentielles en des produits bestiaux et de viande. On indique aussi les problèmes avec les processus de négotiation normale. Une proposition pour un mécanisme d'arbitrage pour la résolution des disputes est developpée. Les elements essentiels de cette proposition sont l'approbation en avance des changements aux régulations, les périodes d'arbitration très courtes et les prononcements de jugements décentralisés.     

Modeling of anaerobic treatment of wastewater in ponds.

A mathematical model to simulate the performance of anaerobic ponds was developed incorporating both settling of particulate components and the biological anaerobic digestion process. The biological activity includes solubilization of particulate organic matter; methanogenesis and the sulphate reduction process. The model considers that an anaerobic pond comprises a series of equal size columns. Each column has three compartments viz. liquid layer, active sediment layer and inert sediment layer. The existence of organic matter and sulphate removal mechanisms both in the bulk as well as sediment layer of the ponds and the exchange of the soluble components between the layers has been included in the model. The model was transferred to a computer program using VisSim Basic software. The model was verified by comparing simulated results with full-scale as well as with laboratory-scale anaerobic pond performance data. A good agreement between the simulated and the observed pond performance was achieved.     

Maturation ponds, rock filters and reedbeds in the UK: statistical analysis of winter performance.

Wastewater treatment technologies suitable for serving large populations are generally reliable and reasonably cost-effective, yet they are almost always financially inappropriate for small communities (< 2,000 p.e.). Comparative cost data suggests that waste stabilization ponds should be an attractive option for small communities, yet perceptions relating to land costs, climate and effluent quality have limited their application in the UK. This paper details typical UK land costs, climate and winter performance data for a pilot-scale waste stabilization pond with various upgrading technologies: system A, two tertiary maturation ponds in series; B, two tertiary maturation ponds in series followed by a reed bed channel; C, a control rock filter; D, an aerated rock filter; and E, a constructed wetland. System D was found to perform best, closely followed by system B.     

Influences of land use/cover on water quality in the upper and middle reaches of River Njoro, Kenya

Data from 10 sampling sites along the River Njoro are used to examine the contribution of nutrients from upstream land uses draining each of the sampling sites. The data also are used to assess whether both the proportion of land uses and the size of the subwatersheds account for the variability in water quality in the River Njoro watershed. Geographical Information System analysis was used to determine the spatial distribution of land‐cover types and subwatersheds contributing run‐off to the sampling sites in the River Njoro. Standard Digital Elevation Model‐based routines were used to establish the watershed area contributing run‐off to each sampling site. Water and sediment samples were collected for chemical analysis, and the nutrient levels were related to the upstream land‐use types and the size of the subwatersheds. The mid‐stream portion of the River Njoro (near Egerton University) accounts for the highest nutrient contributions. The percentage contribution is magnified by additions from industrial, human settlements and agricultural land uses around the University. There is a significant decrease in nutrient levels downstream, however, indicating natural purification as the river flows through an area of large‐scale farming with intense, well‐preserved riparian and in‐stream vegetation. Steep slopes of the land upstream of Egerton University enhance erosion and nutrient losses from those subwatersheds. Mixed small‐scale agricultural and bare lands contribute over 55% of the phosphorus load to the upper and mid‐reaches of the River Njoro. The size of the subwatershed accounts for about 53% of the variability in the soluble phosphorus in the river. The land‐use subwatershed proportions are important for characterizing and modelling water quality in the River Njoro watershed. Upland land uses are as important as near‐stream land uses. We suggest that conservation of intact riparian corridor along the river and its tributaries contributes significantly to natural purification processes and recovery of the ecological integrity of the River Njoro ecosystem.