Geometry - Research from Rensselaer Polytechnic Institute Broadens Understanding of Geometry
2012 APR 12 - (VerticalNews.com) -- "Macroscopic measurements and observations in two-dimensional soil-thin sections indicate that fungal hyphae invade preferentially the larger, air-filled pores in soils. This suggests that the architecture of soils and the microscale distribution of water are likely to influence significantly the dynamics of fungal growth," scientists writing in the journal Soil Science report.
"Unfortunately, techniques are lacking at present to verify this hypothesis experimentally, and as a result, factors that control fungal growth in soils remain poorly understood. Nevertheless, to design appropriate experiments later on, it is useful to indirectly obtain estimates of the effects involved. Such estimates can be obtained via simulation, based on detailed micron-scale X-ray computed tomography information about the soil pore geometry. In this context, this article reports on a series of simulations resulting from the combination of an individual-based fungal growth model, describing in detail the physiological processes involved in fungal growth, and of a Lattice Boltzmann model used to predict the distribution of air-liquid interfaces in soils. Three soil samples with contrasting properties were used as test cases. Several quantitative parameters, including Minkowski functionals, were used to characterize the geometry of pores, air-water interfaces, and fungal hyphae. Simulation results show that the water distribution in the soils is affected more by the pore size distribution than by the porosity of the soils. The presence of water decreased the colonization efficiency of the fungi, as evinced by a decline in the magnitude of all fungal biomass functional measures, in all three samples. The architecture of the soils and water distribution had an effect on the general morphology of the hyphal network, with a 'looped'' configuration in one soil, due to growing around water droplets," wrote R.E. Falconer and colleagues, Rensselaer Polytechnic Institute ...read more
Geometry - Data on Geometry Discussed by G.C. Setua and Colleagues
2012 MAR 8 - (VerticalNews.com) -- "A field experiment was conducted under irrigated condition to study the effect of planting geometry and intercropping on growth characters, leaf yield and quality in newly evolved, triploid, high yielding, recommended and popular S 1635 mulberry (Morus alba L.) along with intercrop yield and additional net profit. The plants were established through saplings in seven different spacing with variable number of plants / ha and were maintained through recommended package of practices for irrigated garden," researchers in Bengal, India report ...read more
Geometry - Research from University of Arkansas Provides New Data on Geometry
2011 OCT 27 - (VerticalNews.com) -- According to the authors of a study from Fayetteville, Arkansas, "Headwater stream morphology is a direct reflection of watershed characteristics and therefore can inform our understanding of anthropogenic influence on channel geometry and sediment dynamics. Little knowledge of the geomorphology of headwater streams in the Ozark Plateaus region of northwest Arkansas exists."
"The Illinois River watershed, in northwest Arkansas, is of critical interest within the region because of land use changes in the headwaters due to rapid population growth. A mixture of forest and agricultural (open pasture and poultry houses) land use dominates the watershed, but urban areas are rapidly expanding. These land use types: forest, agriculture and urban are an effective proxy for increasing anthropogenic disturbance. Analysis of longitudinal profile, cross-section and sediment distribution in streams from each land use type shows a strong trend of increasing slope and channel cross-sectional area with a greater degree of anthropogenic disturbance. Additionally, urban streams are characterized by the presence of exposed bedrock in the stream bed, while agricultural and forested streams are gravel mantled," wrote S.L. Shepherd and colleagues, University of Arkansas ...read more
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