Wall's finiteness obstruction

The purpose of this note is to give a self contained description of Walls finiteness obstruction

Ecology of Thioploca spp.: Nitrate and sulfur storage in relation to chemical microgradients and influence of Thioploca spp. on the sedimentary nitrogen cycle

Microsensors, including a recently developed NO3 − biosensor, were applied to measure O2 and NO3 − profiles in marine sediments from the upwelling area off central Chile and to investigate the influence of Thioploca spp. on the sedimentary nitrogen metabolism. The studies were performed in undisturbed sediment cores incubated in a small laboratory flume to simulate the environmental conditions of low O2, high NO3 −, and bottom water current. On addition of NO3 −and NO2 −, Thioploca spp. exhibited positive chemotaxis and stretched out of the sediment into the flume water. In a core densely populated with Thioploca, the penetration depth of NO3 − was only 0.5 mm and a sharp maximum of NO3 − uptake was observed 0.5 mm above the sediment surface. In sediments with only fewThioploca spp., NO3 − was detectable down to a depth of 2 mm and the maximum consumption rates were observed within the sediment. No chemotaxis toward nitrous oxide (N2O) was observed, which is consistent with the observation that Thioploca does not denitrify but reduces intracellular NO3 − to NH4 +. Measurements of the intracellular NO3 − and S0 pools inThioploca filaments from various depths in the sediment gave insights into possible differences in the migration behavior between the different species. Living filaments containing significant amounts of intracellular NO3 − were found to a depth of at least 13 cm, providing final proof for the vertical shuttling of Thioploca spp. and nitrate transport into the sediment

Amaranth farming: Rural sustainable livelihood of the future?

Though amaranth has been studied intensively for its exceptional nutritional properties, little has been reported about its capacity for fighting poverty, securing food supplies, turning migrations, or its impact on the environment and the prospect for improvement of living conditions of those farmers cultivating amaranth. This paper addresses possibilities and limitations that Mexican small-scale farmers are facing to enhance sustainable livelihoods in the amaranth value chain. The study reveals that amaranth, as an alternative crop and livelihood, is perhaps one of the most complete endogenous natural resources that small-scale farmers have to combat the above-mentioned problems. The study identified several local and regional barriers for increasing the level of farming, production, processing and consumption. A striking and paradoxical limitation is the monopolization practices developed by some of the associations in relation to knowledge and technology transfer, seeds distribution and contact to potential national and foreign buyers

Analysis of ridge formation

A mathematical model is discussed, which analyses the elastic and plastic deformation of a tube under a specified local load applied axisymmetrically to the inner tube surface. The model accounts for anisotropic plastic properties of the materials. Creep behaviour during irradiation is described by Nichols' model. Numerical results have been obtained by means of a digital computer. A discussion of these results is given