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

Quasiparticles as composite objects in the RVB superconductor

We study the nature of the superconducting state, the origin of d-wave pairing, and elementary excitations of a resonating valence bond (RVB) superconductor. We show that the phase string formulation of the t-J model leads to confinement of bare spinon and holon excitations in the superconducting state, though the vacuum is described by the RVB state. Nodal quasiparticles are obtained as composite excitations of spinon and holon excitations. The d-wave pairing symmetry is shown to arise from short range antiferromagnetic correlations

Efficient Set Sharing Using ZBDDs

Set sharing is an abstract domain in which each concrete object is represented by the set of local variables from which it might be reachable. It is a useful abstraction to detect parallelism opportunities, since it contains definite information about which variables do not share in memory, i.e., about when the memory regions reachable from those variables are disjoint. Set sharing is a more precise alternative to pair sharing, in which each domain element is a set of all pairs of local variables from which a common object may be reachable. However, the exponential complexity of some set sharing operations has limited its wider application. This work introduces an efficient implementation of the set sharing domain using Zero-suppressed Binary Decision Diagrams (ZBDDs). Because ZBDDs were designed to represent sets of combinations (i.e., sets of sets), they naturally represent elements of the set sharing domain. We show how to synthesize the operations needed in the set sharing transfer functions from basic ZBDD operations. For some of the operations, we devise custom ZBDD algorithms that perform better in practice. We also compare our implementation of the abstract domain with an efficient, compact, bit set-based alternative, and show that the ZBDD version scales better in terms of both memory usage and running time

Spontaneous breaking of the Fermi surface symmetry in the t-J model: a numerical study

We present a variational Monte Carlo (VMC) study of spontaneous Fermi surface symmetry breaking in the t-J model. We find that the variational energy of a Gutzwiller projected Fermi sea is lowered by allowing for a finite asymmetry between the x- and the y-directions. However, the best variational state remains a pure superconducting state with d-wave symmetry, as long as the underlying lattice is isotropic. Our VMC results are in good overall agreement with slave boson mean field theory (SBMFT) and renormalized mean field theory (RMFT), although apparent discrepancies do show up in the half-filled limit, revealing some limitations of mean field theories. VMC and complementary RMFT calculations also confirm the SBMFT predictions that many-body interactions can enhance any anisotropy in the underlying crystal lattice. Thus, our results may be of consequence for the description of strongly correlated superconductors with an anisotropic lattice structure.Comment: 6 pages, 7 figures; final versio

Response of Siratro (Macroptilium atropurpureum Urb. Rabaceae) to Vesicular-arbuscular Mycorrhizal Fungi and Rhizobium sp. in Sterilized Soil

The effect of inoculation of six species of vesicular-arbuscular mycorrhizal fungi viz., Gigaspora margarita, Glomus mosseae, G. monosporum, G. versiformis, G. fasciculatum, G. deserticola and Rhizobium sp. on growth and NPK content in siratro (Macroptilium atropurpureum) was studied. The mycorrhizal species were isolated from the rhizosphere forest soils of the Western Ghats and multiplied in pot culture with Sorghum bicolor as the host plant. Rhizobium sp. isolated from fresh nodules of siratro was cultured and maintained in yeast extract mannitol broth. The influence of VAM fungi and Rhizobium sp. either singly or in combination on growth and nutrient contents of siratro showed statistically significant increase after only 60 days of plant growth. Dual inoculation with VAM fungi and Rhizobium increased plant nodule number and tissue NPK content. Highest growth and nutrient content were exhibited by plants inoculated with Rhizobium together with multiple VAM fungi

Mycorrhizae in sedges as related to root character and its ecological significance

Twenty four sedges were examined to assess the role of root characters on mycorrhizal status. Vesicular-arbuscular mycorrhizal (VAM) injection was positively related to root thickness and negatively to root hair number and length. Dried mycorrhizal roots of Bulbostylis barbata, Cyperus cyperinus. C. kyllingia and Fimbristylis ovata served as inocula oj VAMJungi in pot culture study indicating that mycorrhizal sedge roots could act as inocula in initiating and reviving mycorrhizae in natural soils

Novel Nonreciprocal Acoustic Effects in Antiferromagnets

The possible occurrence of nonreciprocal acoustic effects in antiferromagnets in the absence of an external magnetic field is investigated using both (i) a microscopic formulation of the magnetoelastic interaction between spins and phonons and (ii) symmetry arguments. We predict for certain antiferromagnets the existence of two new nonreciprocal (non-time invariant) effects: A boundary-condition induced nonreciprocal effect and the occurrence of transversal phonon modes propagating in opposite directions having different velocities. Estimates are given and possible materials for these effects to be observed are suggested.Comment: Euro. Phys. Lett. (in press

Theory of Non-Reciprocal Optical Effects in Antiferromagnets: The Case Cr_2O_3

A microscopic model of non-reciprocal optical effects in antiferromagnets is developed by considering the case of Cr_2O_3 where such effects have been observed. These effects are due to a direct coupling between light and the antiferromagnetic order parameter. This coupling is mediated by the spin-orbit interaction and involves an interplay between the breaking of inversion symmetry due to the antiferromagnetic order parameter and the trigonal field contribution to the ligand field at the magnetic ion. We evaluate the matrix elements relevant for the non-reciprocal second harmonic generation and gyrotropic birefringence.Comment: accepted for publication in Phys. Rev.

Single Stranded DNA Translocation Through A Nanopore: A Master Equation Approach

We study voltage driven translocation of a single stranded (ss) DNA through a membrane channel. Our model, based on a master equation (ME) approach, investigates the probability density function (pdf) of the translocation times, and shows that it can be either double or mono-peaked, depending on the system parameters. We show that the most probable translocation time is proportional to the polymer length, and inversely proportional to the first or second power of the voltage, depending on the initial conditions. The model recovers experimental observations on hetro-polymers when using their properties inside the pore, such as stiffness and polymer-pore interaction.Comment: 7 pages submitted to PR