Use of thermal infrared and colour infrared imagery to detect crop moisture stress

The author has identified the following significant results. In the presence of variable plant cover (primarily percent cover) and variable available water content, the remotely sensed apparent temperatures correlate closely with plant cover and poorly with soil water. To the extent that plant cover is not systematically related to available soil water, available water in the root zone values may not be reliably predicted from the thermal infrared data. On the other hand, if plant cover is uniform and the soil surface is shown in a minor way, the thermal data indicate plant stress and consequently available water in the soil profile

The role of cosmic rays and Alfven waves in the structure of the galactic halo

The effect that cosmic rays and the Alfven waves they generate have on the structure of the plasma distribution perpendicular to the galactic disk is examined. It is shown that the plasma distribution exhibits two length scales and the predicted values of gas density far from the galactic plane indicate that models involving hydrostatic equilibrium should be replaced by those allowing for a galactic wind

Spin Fluctuations and the Pseudogap in Organic Superconductors

We show that there are strong similarities in the spin lattice relaxation of non-magnetic organic charge transfer salts, and that these similarities can be understood in terms of spin fluctuations. Further, we show that, in all of the kappa-phase organic superconductors for which there is nuclear magnetic resonance data, the energy scale for the spin fluctuations coincides with the energy scale for the pseudogap. This suggests that the pseudogap is caused by short-range spin correlations. In the weakly frustrated metals k-(BEDT-TTF)_2Cu[N(CN)_2]Br, k-(BEDT-TTF)_2Cu(NCS)_2, and k-(BEDT-TTF)_2Cu[N(CN)_2]Cl (under pressure) the pseudogap opens at the same temperature as coherence emerges in the (intralayer) transport. We argue that this is because the spin correlations are cut off by the loss of intralayer coherence at high temperatures. We discuss what might happen to these two energy scales at high pressures, where the electronic correlations are weaker. In these weakly frustrated materials the data is well described by the chemical pressure hypothesis (that anion substitution is equivalent to hydrostatic pressure). However, we find important differences in the metallic state of k-(BEDT-TTF)_2Cu_2(CN)_3, which is highly frustrated and displays a spin liquid insulating phase. We also show that the characteristic temperature scale of the spin fluctuations in (TMTSF)_2ClO_4 is the same as superconducting critical temperature, which may be evidence that spin fluctuations mediate the superconductivity in the Bechgaard salts.Comment: 7 pages, 4 figures; to appear in PR

Spin Bose-Metal phase in a spin-1/2 model with ring exchange on a two-leg triangular strip

Recent experiments on triangular lattice organic Mott insulators have found evidence for a 2D spin liquid in proximity to the metal-insulator transition. A Gutzwiller wavefunction study of the triangular lattice Heisenberg model with appropriate four-spin ring exchanges has found that the projected spinon Fermi sea state has a low variational energy. This wavefunction, together with a slave particle gauge theory, suggests that such spin liquid possesses spin correlations that are singular along surfaces in momentum space ("Bose surfaces"). Signatures of this state, which we refer to as a "Spin Bose-Metal" (SBM), are expected to be manifest in quasi-1D ladder systems: The discrete transverse momenta cut through the 2D Bose surface leading to a distinct pattern of 1D gapless modes. Here we search for a quasi-1D descendant of the triangular lattice SBM state by exploring the Heisenberg plus ring model on a two-leg strip (zigzag chain). Using DMRG, variational wavefunctions, and a Bosonization analysis, we map out the full phase diagram. Without ring exchange the model is equivalent to the J_1 - J_2 Heisenberg chain, and we find the expected Bethe-chain and dimerized phases. Remarkably, moderate ring exchange reveals a new gapless phase over a large swath of the phase diagram. Spin and dimer correlations possess particular singular wavevectors and allow us to identify this phase as the hoped for quasi-1D descendant SBM state. We derive a low energy theory and find three gapless modes and one Luttinger parameter controlling all power laws. Potential instabilities out of the zigzag SBM give rise to other interesting phases such as a period-3 VBS or a period-4 Chirality order, which we discover in the DMRG; we also find an interesting SBM state with partial ferromagnetism.Comment: 30 pages, 23 figure

Spin Bose-Metal and Valence Bond Solid phases in a spin-1/2 model with ring exchanges on a four-leg triangular ladder

We study a spin-1/2 system with Heisenberg plus ring exchanges on a four-leg triangular ladder using the density matrix renormalization group and Gutzwiller variational wave functions. Near an isotropic lattice regime, for moderate to large ring exchanges we find a spin Bose-metal phase with a spinon Fermi sea consisting of three partially filled bands. Going away from the triangular towards the square lattice regime, we find a staggered dimer phase with dimers in the transverse direction, while for small ring exchanges the system is in a featureless rung phase. We also discuss parent states and a possible phase diagram in two dimensions.Comment: 4 pages, 5 figures, v3 is the print versio

H-bond competition experiments in solution and the solid state

The H-bonding outcomes in crystal structures of simple molecules, where two potential H-bonds can be formed, have been used to calculate relative H-bond probabilities for 59 combinations of Hbond donors and H-bond acceptors. H-bond probabilities are shown to correlate well with the difference in solution phase free energy between the two competing H-bonds.We acknowledge the financial support from the EPSRC through a CASE award scheme in collaboration with the Cambridge Crystallographic Data Centre.This is the author accepted manuscript. The final version is available from RSC via http://dx.doi.org/10.1039/C5CE02223

An evolving approach to developing academics understanding of transition for first year students. A Practice Report

The purpose of this paper is to describe the strategies used in the First Year Experience (FYE) Project at the University of Technology, Sydney (UTS) to engage and support academics to address student transition and diversity. The UTS FYE framework has provided a mechanism for third generation transition pedagogy which has been realised through a range of strategies including the establishment of a UTS FYE Coordinator overseeing the design and implementation of FYE Forums, the FYE small grant scheme, and supporting the First Year Transition Experience (FYTE) coordinators in faculties. These strategies have resulted in an evolving learning community in which staff have a sense of belonging and identity and their learning is situated and negotiated. The impact of this project on academics is demonstrated through the increasing participation in forums, increasing sophistication of grant applications and the leadership of the FYTE coordinators

Achieving academic engagement: Supporting academics to embed first year transition pedagogies in the curriculum

This paper describes a small grants scheme aimed at supporting academics to embed first year (FY) transition pedagogies in the curriculum, as part of a university-wide FYE strategy. The scheme enables first year subject coordinators to apply for funding to address one or more of the six transition pedagogy principles in ways appropriate for their disciplines and students. Over three years, fifty grants have been awarded to coordinators from all faculties for projects that range from resource creation to tutor development to changes in assessment and feedback practices. The paper describes the operation of the scheme and provides an initial analysis of the successes and challenges of its first two years from the perspectives of the grant holders and the UTS FYE Coordinator. Two examples of FYE grants are used to illustrate some features of successful projects