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Native and invasive inoculation sources modify fungal community assembly and biomass production of a chaparral shrub
Feedbacks between plants and surrounding soil microbes can contribute to the establishment and persistence of invasive annual grasses as well as limit the success of restoration efforts. In this study, we aim to understand how three sources of soil inocula – native, invasive (from under Bromus diandrus) and sterile – affect the growth response and fungal community composition in the roots of a chaparral shrub, Adenostoma fasciculatum. We grew A. fasciculatum from seed in a greenhouse with each inoculum source and harvested at six months. We measured above- and below-ground biomass, arbuscular mycorrhizal fungal (AMF) colonization and conducted targeted-amplicon sequencing of the 18S and ITS2 loci to characterize AMF and general fungal community composition, respectively. Native inoculum resulted in roots with richer communities of some groups of AMF and non-AMF symbionts, when compared to roots grown with invasive or sterile inoculum. Seedlings grown with invasive and native inoculum did not have different growth responses, but both produced more biomass than a sterile control. These findings suggest that inoculation with soil from native species can increase the diversity of multiple groups of fungal symbionts and inoculation with live soil (invasive or native) can increase seedling biomass. Moreover, future work would benefit from assessing if a more diverse community of fungal symbionts increases seedling survival when planted in field restoration sites
A Variational Principle for the Asymptotic Speed of Fronts of the Density Dependent Diffusion--Reaction Equation
We show that the minimal speed for the existence of monotonic fronts of the
equation with , and in
derives from a variational principle. The variational principle allows
to calculate, in principle, the exact speed for arbitrary . The case
when is included as an extension of the results.Comment: Latex, postcript figure availabl
The ILR School at Fifty: Voices of the Faculty, Alumni & Friends (Full Text)
A collection of reflections on the first fifty years of the School of Industrial and Labor Relations at Cornell University. Compiled by Robert B. McKersie, J. Gormly Miller, Robert L. Aronson, and Robert R. Julian. Edited by Elaine Gruenfeld Goldberg. It was the hope of the compilers that the reflections contained in this book would both kindle memories of the school and stimulate interest on the part of future generations of ILRies who have not yet shared in its special history.
Dedicated to the Memory of J. Gormly Miller, 1914-1995.
Copyright 1996 by Cornell University. All rights reserved
Erosion waves: transverse instabilities and fingering
Two laboratory scale experiments of dry and under-water avalanches of
non-cohesive granular materials are investigated. We trigger solitary waves and
study the conditions under which the front is transversally stable. We show the
existence of a linear instability followed by a coarsening dynamics and finally
the onset of a fingering pattern. Due to the different operating conditions,
both experiments strongly differ by the spatial and time scales involved.
Nevertheless, the quantitative agreement between the stability diagram, the
wavelengths selected and the avalanche morphology reveals a common scenario for
an erosion/deposition process.Comment: 4 pages, 6 figures, submitted to PR
Development of a theory of the spectral reflectance of minerals, part 2
Theory of diffuse reflectance of particulate media including garnet, glass, corundum powders, and mixture
Test of Special Relativity and Equivalence principle from K Physics
A violation of Local Lorentz Invariance (VLI) and hence the special theory of
relativity or a violation of equivalence principle (VEP) in the Kaon system
can, in principle, induce oscillations between and . We
construct a general formulation in which simultaneous pairwise diagonalization
of mass, momemtum, weak or gravitational eigenstates is not assumed. %and the
maximum attainable %velocities of the velocity eigenstates are different. We
discuss this problem in a general way and point out that, as expected, the VEP
and VLI contributions are indistinguishable. We then insist on the fact that
VEP or VLI can occur even when CPT is conserved. A possible CP violation of the
superweak type induced by VEP or VLI is introduced and discussed. We show that
the general VEP mechanism (or the VLI mechanism, but not both simultaneously),
with or without conserved CPT, could be clearly tested experimentally through
the energy dependence of the mass difference and of ,
, . Constraints imposed by present experiments are
calculated.Comment: Latex, 15 pages, 1 figure, version to appear in Phys. Rev.
Shift in the velocity of a front due to a cut-off
We consider the effect of a small cut-off epsilon on the velocity of a
traveling wave in one dimension. Simulations done over more than ten orders of
magnitude as well as a simple theoretical argument indicate that the effect of
the cut-off epsilon is to select a single velocity which converges when epsilon
tends to 0 to the one predicted by the marginal stability argument. For small
epsilon, the shift in velocity has the form K(log epsilon)^(-2) and our
prediction for the constant K agrees very well with the results of our
simulations. A very similar logarithmic shift appears in more complicated
situations, in particular in finite size effects of some microscopic stochastic
systems. Our theoretical approach can also be extended to give a simple way of
deriving the shift in position due to initial conditions in the
Fisher-Kolmogorov or similar equations.Comment: 12 pages, 3 figure
Neutron, electron and X-ray scattering investigation of Cr1-xVx near Quantum Criticality
The weakness of electron-electron correlations in the itinerant
antiferromagnet Cr doped with V has long been considered the reason that
neither new collective electronic states or even non Fermi liquid behaviour are
observed when antiferromagnetism in CrV is suppressed to zero
temperature. We present the results of neutron and electron diffraction
measurements of several lightly doped single crystals of CrV in
which the archtypal spin density wave instability is progressively suppressed
as the V content increases, freeing the nesting-prone Fermi surface for a new
striped charge instability that occurs at x=0.037. This novel nesting
driven instability relieves the entropy accumulation associated with the
suppression of the spin density wave and avoids the formation of a quantum
critical point by stabilising a new type of charge order at temperatures in
excess of 400 K. Restructuring of the Fermi surface near quantum critical
points is a feature found in materials as diverse as heavy fermions, high
temperature copper oxide superconductors and now even elemental metals such as
Cr.Comment: 6 pages, 6 figures. Accepted to Physical Review
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