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Discussion of: Foundation design for gravity retaining walls under earthquake by M. J. Pender
No full textThe discussers read the paper by Pender (2018) with great
interest. The author addresses the important issue of computing the pseudostatic critical acceleration of gravity/cantilever
retaining walls, corresponding to which a plastic mechanism is
activated within the soil–structure system and the wall starts
to move under the applied earthquake. In fact, the critical
acceleration is the key ingredient for the seismic design of
these structures, controlling both the maximum internal
forces and the final displacement (Conti and Caputo, 2018;
Conti et al., 2013)
Pender Bay (Australia), Indigenous Australians at Pender Bay Station
No full textNatives at Pender Bay Station, Western Australia. (1924)Clapp Nitrate Negatives, Box 16Grayscal
Community natural resource management: the case of woodlots in northern Ethiopia
No full textThis paper examines the nature of community management of woodlots and investigates the determinants of collective action and its effectiveness in managing woodlots, based on a survey of 100 villages in Tigray, northern Ethiopia. We find that collective management of woodlots generally functions well in Tigray. Despite limited current benefits received by community members, the woodlots contribute substantially to community wealth, increasing members' willingness to provide collective effort to manage the woodlots. We find that benefits are greater and problems less on woodlots managed at the village level than those managed at a higher municipality level, and that the average intensity of management is greater on village-managed woodlots. Nevertheless, we find little evidence of differences in collective management of woodlots or its effectiveness on village vs. municipality-managed woodlots, after controlling for other factors. The factors that do significantly affect collective action include population density (higher collective labor input and lower planting density at intermediate than at low or high density), market access (less labor input, planting density and tree survival where market access is better), and presence of external organizations promoting the woodlot (reduces local effort to protect the woodlot and tree survival). The negative effect of market access suggests that higher opportunity costs of labor and/or increased “exit options” undermine collective resource management. The findings suggest collective action may be more beneficial and more effective when managed at a more local level, when the role of external organizations is more demand-driven, and when promoted in intermediate population density communities more remote from markets. In higher population density settings and areas closer to markets, private-oriented approaches are likely to be more effective.resource management, Forest management, Population density, Collective behavior, Ethiopia,
Environmental indicators for the urban environment : a literature review
No full textA vast body of literature exists on the genesis and evolution of environmental indicators of all varieties. This document attempts to track the somewhat complicated progress of urban environmental indicators, where they are in usage and to what avail. It also emphasises the search to narrow down the range of 'ideal' indicators. The literature suggests that as experience and practice with indicators grows both in Ireland and world-wide the key set of urban environmental indicators can help policy makers and the public track sustainability issues more effectively. Indicators thus have a valuable role to play in the future of sustainable planning for urban areas.European Regional Development Fund through the Operational Programme for Environmental Services 1994-199
Land lease markets and agricultural efficiency: theory and evidence from Ethiopia
No full textThis paper develops a theoretical model of land leasing that includes transaction costs of enforcing labor effort, risk pooling motives and non-tradable productive inputs. We test the implications of this model compared to those of the “Marshallian” (unenforceable labor effort) and “New School” (costlessly enforceable effort) perspectives using data collected from four villages in Ethiopia. We find that land lease markets operate relatively efficiently in the villages studied, supporting the New School perspective relative to the other two models. Land contract choice is found to depend upon the social relationships between landlords and tenants, but differences in contracts are not associated with significant differences in input use or output value per hectare. We find that other household and village characteristics do affect input use and output value, suggesting imperfections in other factor markets. These results imply that interventions to improve the functioning of land lease markets are likely to be of little benefit for agricultural efficiency in the villages studied, whereas improvements in other factor markets may be more beneficial.Land use Ethiopia., Agriculture Economic aspects Egypt.,
The role of trees for sustainable management of less-favored lands: the case of eucalyptus in Ethiopia
No full textIn recent years the planting of eucalyptus trees in Ethiopia has expanded from State owned plantations to community woodlots and household compounds. In an environment suffering from severe woody biomass shortages water scarcity, erosion and land degradation, fast growing and resilient eucalyptus species perform better than most indigenous woodland and forest tree species (as well as most crops). In addition to increasing biomass and providing ground cover, the sale of eucalyptus poles and products has substantial potential to raise farm incomes, reduce poverty, increase food security and diversify smallholder-farming systems in less-favored areas of northern Ethiopia. Despite the potential for eucalyptus to improve rural livelihoods in northern Ethiopia in 1997, the regional government of Tigray imposed a ban on eucalyptus tree planting on farmlands. The regional government promotes planting of eucalyptus and other species in community woodlots, and has recently begun to allow private planting of eucalyptus on community wasteland and steep hillsides. In this paper, we review the debate about the ecological impacts of eucalyptus trees, as well as the economic factors that influence whether smallholders invest in these trees. Ex ante benefit-cost analysis based on community level survey data from Tigray illustrates that under most conditions planting eucalyptus trees yields high rates of return, well above 20% under most circumstances. The effect of variable harvest rates, the costs of decreased crop production when eucalyptus trees are planted on farmlands, and differences between administrative zones are considered relative to our base case in our rate of return estimates. The importance of fast growing tree species that can accommodate the high discount rates associated with smallholders in this region is emphasized.Tree planting., Ecology., Ethiopia., Land degradation.,
Recent developments in the immunology of inflammatory bowel disease
No full textCrohn's disease and ulcerative colitis are caused by excessive immune reactivity in the gut wall. Analysis of the type of immune responses ongoing in diseased gut has revealed important features which suggest that these conditions are different. In Crohn's disease tissue there is considerable evidence for an ongoing T helper cell type 1 response, with excess interleukin-12, interferon-gamma and TNF-alpha. There is circumstantial evidence in patients that this response is directed against the normal bacterial flora and definitive evidence in mouse models that T cell responses to the flora cause gut disease. In ulcerative colitis, the role of tissue damaging T cell responses in the gut mucosa is much less clear and there is more evidence that the lesion is owing to antibody-mediated hypersensitivity. Although different types of immune reactions initiate tissue injury in both Crohn's disease and ulcerative colitis, the downstream events which actually damage the tissue are the same in each condition. Elevated cytokine concentrations in the mucosa lead to the production of excess matrix degrading enzymes by gut fibroblasts, loss of mucosal integrity and ulceration. The same process also leads to an increased production of epithelial growth factors such as KGF Keratinocyte Growth Factor by gut fibroblasts and produces the crypt cell hyperplasia characteristic of all gut inflammatory conditions
Shallow water hydrodynamic models for hyperconcentrated sediment-laden floods over erodible bed
No full textThe majority of the huge annual sediment load of the Yellow River in China is transported by a few hyperconcentrated sediment-laden floods. Being hyperconcentrated, these floods are still so "starved" as to entrain enormous volumes of sediment from the bed, triggering quick and extensive bed-tearing scour. In the recession period of the floods, river blockage might occur as characterized by an abrupt halt of the flow. The physics of these fluvial processes has remained unclear for several decades. Previous hydrodynamic models were built upon simplified conservation laws and are applicable only for processes with weak sediment transport. A complete shallow water hydrodynamic model is deployed here to reveal new insights into the phenomena. A self-amplifying mechanism of the interaction between the flow and bed scour is identified, which explains how bed-tearing scour occurs. River blockage is ascribable to the longitudinally positive pressure gradient due to a non-uniform distribution of sediment concentration. The spatial and temporal development of the system of flow, sediment transport and morphology is far more complicated than represented by previous models that have evolved from fixed-bed, single-phase hydrodynamics or involved a capacity description of sediment transport. The present approach may facilitate a better understanding of active sediment transport by flash floods in ephemeral desert rivers and by subaqueous turbidity currents.Sediment transport; Sediment-laden flow; Erosion and sedimentation; Floods; Unsteady flow; Hyperconcentrated flow; Alluvial rivers;The Yellow River; Fluvial morphology; Shallow water hydrodynamic
Organizational development and natural resource management: evidence from central Honduras
No full textThe determinants of local organizational density and the impacts of local and external organizations on collective and private natural resource management decisions are investigated based on a survey of 48 villages in central Honduras. Factors positively associated with local organizational development include the presence of external organizations, population level, moderate population growth, lower population density, the presence of immigrants, distance from the urban market, literacy and coffee production. Local organizations are found to contribute to collective action to conserve resources, while government organizations appear to displace it, though not in all cases. The findings suggest that external organizations can play a catalytic role in fostering development of local organizations and emphasize the importance of improved understanding of the roles of local organizations, in order to enhance complementarity and minimize competition between these different agents in promoting sustainable development.Honduras., Natural resources Management., Collective behaviour., Government.,
FIGURE 23 in Reappraisal of the parrots (Aves: Psittacidae) from the Mascarene Islands, with comments on their ecology, morphology, and affinities
No full textFIGURE 23. Comparison of humeri of Mascarene parrots with species of Psittacula, caudal aspect; A–C, right side, D– G, left side. A, UMZC596 Lophopsittacus mauritianus; B, UMZC596 Psittacula bensoni, new comb.; C, UMZC600 Psittacula echo; D, UMZCA1455 Necropsittacus rodericanus; E, UMZCA1463 Psittacula exsul; F, BMNHS/1999.11.5 Psittacula eupatria ♂; G, BMNHS/1975.103.62 Psittacula krameri borealis ♂. Scale bar = 10mm.Published as part of HUME, JULIAN PENDER, 2007, Reappraisal of the parrots (Aves: Psittacidae) from the Mascarene Islands, with comments on their ecology, morphology, and affinities, pp. 1-76 in Zootaxa 1513 (1) on page 58, DOI: 10.11646/zootaxa.1513.1.1, http://zenodo.org/record/508818
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