Role of edaphic factors on VAM fungal colonization and Spore populations in certain tropical wild legumes

Four nodulating annual tropical wild legumes, viz., Alysicarpus monilifer, Desmodium triflorum, Indigofera linnaei and Tephrosia purpurea from three different regions in the Western Ghats ecosystem were investigated to assess their mycorrhizal status. The response ofvesicular-arbuscular mycorrhizal (VAM) root colonization and spore number to edaphicfactors such as soil moisture, pH and available Nand P was analysed. Though the spore number varied significantly both within and between sites, a uniformly high degree ofroot colonization was observed for all the plants in the present study. The spore number recorded was high, rangingfrom 15 to 165 spores gl soil. Spores of sixteen VAM fungal species belonging to Acaulospora, Glomus and Scutellospora were isolated from the rhizosphere soils. Soil moisture generally had a positive influence on VAM colonization and sporulation except in I. linnaei. The pH correlated negatively with root infection in I. linnaei and T. purpurea, but had no influence in the other two species. The effect of 2-pH on sporulation varied with host species and sites. No general correlation existed between available soil nutrients, root colonization and spore number but the influence ofNand P was counteractive on VAM infection. The present study indicates that the response of root colonization and spore number to edaphic factors is a localised rather than a generalised phenomenon

Polymers pushing Polymers: Polymer Mixtures in Thermodynamic Equilibrium with a Pore

We investigate polymer partitioning from polymer mixtures into nanometer size cavities by formulating an equation of state for a binary polymer mixture assuming that only one (smaller) of the two polymer components can penetrate the cavity. Deriving the partitioning equilibrium equations and solving them numerically allows us to introduce the concept of "polymers-pushing-polymers" for the action of non-penetrating polymers on the partitioning of the penetrating polymers. Polymer partitioning into a pore even within a very simple model of a binary polymer mixture is shown to depend in a complicated way on the composition of the polymer mixture and/or the pore-penetration penalty. This can lead to enhanced as well as diminished partitioning, due to two separate energy scales that we analyse in detail.Comment: 10 pages, 6 figure

GIS BASED MORPHOMETRIC CHARACTERISTICS OF KADAVANAR RIVER BASIN IN TAMIL NADU, INDIA

The Remote Sensing and GIS technique is an effective tool for analyzing the morphological characteristics of a river basin. The geographical location of Kadavanar river basin between latitudes 10° 52' 34.70"N and 10° 10' 57.59"N, and longitudes 77° 37' 48.14"E and 78° 13' 27.69"E, and one of the contributors to Cauvery river. The study focused on the river basin linear, areal, and relief aspects of morphometric characteristics. The study concentrated on the morphometric parameters and evolution of the stream order (U), stream length (Lu), bifurcation ratio (Rb), drainage density (Dd), stream frequency (Fs), drainage texture (Rt), elongation ratio (Re), circularity ratio (Rc), form factor (Rf), basin relief (Bh), relief ratio (Rh) and ruggedness number (Rn). The Kadavanar basin has a six-order of the drainage system, with a total of 841 stream networks, of which are 653 in the first-order, 143 in the second-order, 34 in the third-order, 8 in the fourth-order, 2 in the fifth-order stream, and 1 in the sixth-order stream according to morphometric study. The first order of the stream has a longer overall length, which decreases as the stream order increases. The average bifurcation ratio is 3.80, signifying that there were more structural disruptions due to geological influence. There has observed a low drainage density of the value of 0.91 km/km2. It indicates that the river basin has a dense vegetation cover and is highly permeable. The basin morphometric study revealed that it has a slight risk of soil erosion and flood of the basin, indicating that surface runoff of the upland region of the river basin is significantly infiltration gently downstream of the basin, contributing to the groundwater potentiality of the region. Further study of Remote Sensing and GIS techniques is more effective in developing an appropriate natural resource for the groundwater management system of the region

Active and Paleo floodplain mapping of Palam Cauvery using Geospatial Technology

This paper presents precise active floodplain and paleo floodplain mapping of the Palam Cauvery in its deltaic region implementing various Geospatial Techniques, as well as a comparative analysis to comprehend the changes that have occurred to the river course in the past. False Colour Composite (FCC), Normalized Difference Water Index (NDWI), Principal Component Analysis (PCA), Synthetic Aperture Radar (SAR) ALOS PALSAR L- Band and Digital Elevation Model of ALOS PALSAR has been used to carried out the detailed mapping. The active floodplain and paleo flood plains are mapped using the method proposed above and ten separate cross-sectional profiles were obtained along the river course, revealing that the paleo flood plain has an aerial extent that is 86% broader than the present flood plain. This clearly shows that the principal river was formerly running along the Palam Cauvery in this course and has progressively shifted or migrated

Prediction of Algal Bloom Using Genetic Programming

In this study, an attempt was made to mathematically model and predict algal blooms in Tolo Harbor (Hong Kong) using genetic programming (GP). Chlorophyll plays a vital role in blooms and was used in this model as a measure of algal bloom biomass, and eight other variables were used as input for its prediction. It has been observed that GP evolves multiple models with almost the same values of errors-of-measure. Previous studies on GP modeling have primarily focused on comparing GP results with actual values. In contrast, in this study, the main aim was to propose a systematic procedure for identifying the most appropriate GP model from a list of feasible models (with similar error-of-measure) using a physical understanding of the process aided by data interpretation. Evaluation of the GP-evolved equations shows that they correctly identify the ecologically significant variables. Analysis of the final GP-evolved mathematical model indicates that, of the eight variables assumed to affect algal blooms, the most significant effects are due to chlorophyll, total inorganic nitrogen and dissolved oxygen for a 1-week prediction. For longer lead predictions (biweekly), secchi-disc depth and temperature appear to be significant variables, in addition to chlorophyll

Anomalous Dynamics of Forced Translocation

We consider the passage of long polymers of length N through a hole in a membrane. If the process is slow, it is in principle possible to focus on the dynamics of the number of monomers s on one side of the membrane, assuming that the two segments are in equilibrium. The dynamics of s(t) in such a limit would be diffusive, with a mean translocation time scaling as N^2 in the absence of a force, and proportional to N when a force is applied. We demonstrate that the assumption of equilibrium must break down for sufficiently long polymers (more easily when forced), and provide lower bounds for the translocation time by comparison to unimpeded motion of the polymer. These lower bounds exceed the time scales calculated on the basis of equilibrium, and point to anomalous (sub-diffusive) character of translocation dynamics. This is explicitly verified by numerical simulations of the unforced translocation of a self-avoiding polymer. Forced translocation times are shown to strongly depend on the method by which the force is applied. In particular, pulling the polymer by the end leads to much longer times than when a chemical potential difference is applied across the membrane. The bounds in these cases grow as N^2 and N^{1+\nu}, respectively, where \nu is the exponent that relates the scaling of the radius of gyration to N. Our simulations demonstrate that the actual translocation times scale in the same manner as the bounds, although influenced by strong finite size effects which persist even for the longest polymers that we considered (N=512).Comment: 13 pages, RevTeX4, 16 eps figure