Structural precursor to the metal-insulator transition in V_2O_3

The temperature dependence of the local structure of V_2O_3 in the vicinity of the metal to insulator transition (MIT) has been investigated using hard X-ray absorption spectroscopy. It is shown that the vanadium pair distance along the hexagonal c-axis changes abruptly at the MIT as expected. However, a continuous increase of the tilt of these pairs sets in already at higher temperatures and reaches its maximum value at the onset of the electronic and magnetic transition. These findings confirm recent theoretical results which claim that electron-lattice coupling is important for the MIT in V_2O_3. Our results suggest that interactions in the basal plane play a decisive role for the MIT and orbital degrees of freedom drive the MIT via changes in hybridization.Comment: 6 pages, 5 figures, 2 table

Financing agricultural research and development in rich countries: what's happening and why

Governments around the globe are trimming their support for agricultural R&D, giving greater scrutiny to the support that they do provide, and reforming the public agencies that fund, oversee, and carry out the research. These contemporary developments represent a break from previous patterns, which, since WWII, had seen a significant and steady expansion in the public funds provided for agricultural R&D. The growth rate of private-sector spending on agricultural research has slowed along with the growth of public spending in recent years, but the balance continues to shift toward the private sector. This paper presents a quantitative review of these funding trends and the considerable institutional changes that have accompanied them. We present and discuss new data for 22 OECD countries, provide additional data and institutional details for five of these countries, namely Australia, Netherlands, New Zealand, United Kingdom, and the United States, and conclude the paper with an assessment of these policy developments.Agricultural research., Government spending policy., OECD countries., Australia., Netherlands., New Zealand., United Kingdom., United States., Assessment,

Financing agricultural R&D in rich countries: what's happening and why

Governments everywhere are trimming their support for agricultural R&D, giving greater scrutiny to the support that they do provide, and reforming the public agencies that fund, oversee, and carry out the research. This represents a break from previous patterns, which had consisted of expansion in the public funds for agricultural R&D. Private‐sector spending on agricultural research has slowed along with the growth of public spending in recent years, but the balance continues to shift towards the private sector. This article presents a quantitative review of these funding trends and the considerable institutional changes that have accompanied them. We discuss new data for 22 OECD countries, providing institutional details for five of these countries, and conclude with an assessment of policy developments.Research and Development/Tech Change/Emerging Technologies,

Polymer Maximum Drag Reduction: A Unique Transitional State

The upper bound of polymer drag reduction is identified as a unique transitional state between laminar and turbulent flow corresponding to the onset of the nonlinear breakdown of flow instabilities

Spin-Dependent Hubbard Model and a Quantum Phase Transition in Cold Atoms

We describe an experimental protocol for introducing spin-dependent lattice structure in a cold atomic fermi gas using lasers. It can be used to realize Hubbard models whose hopping parameters depend on spin and whose interaction strength can be controlled with an external magnetic field. We suggest that exotic superfluidities will arise in this framework. An especially interesting possibility is a class of states that support coexisting superfluid and normal components, even at zero temperature. The quantity of normal component varies with external parameters. We discuss some aspects of the quantum phase transition that arises at the point where it vanishes.Comment: 9 pages, 7 figures; added/corrected references in [11] and [44

A comprehensive study of electric, thermoelectric and thermal conductivities of Graphene with short range unitary and charged impurities

Motivated by the experimental measurement of electrical and hall conductivity, thermopower and Nernst effect, we calculate the longitudinal and transverse electrical and heat transport in graphene in the presence of unitary scatterers as well as charged impurities. The temperature and carrier density dependence in this system display a number of anomalous features that arise due to the relativistic nature of the low energy fermionic degrees of freedom. We derive the properties in detail including the effect of unitary and charged impurities self-consistently, and present tables giving the analytic expressions for all the transport properties in the limit of small and large temperature compared to the chemical potential and the scattering rates. We compare our results with the available experimental data. While the qualitative variations with temperature and density of carriers or chemical potential of all transport properties can be reproduced, we find that a given set of parameters of the impurities fits the Hall conductivity, Thermopower and the Nernst effect quantitatively but cannot fit the conductivity quantitatively. On the other hand a single set of parameters for scattering from Coulomb impurities fits conductivity, hall resistance and thermopower but not Nernst