Rapid Thermal Annealing for Surface Optimisation of ZnO Substrates for MBE-Grown Oxide Two-Dimensional Electron Gases

Two-dimensional electron gases (2DEGs) at the ZnO/ZnMgO interface are promising for applications in spintronics and quantum computing due to the combination of low spin-orbit coupling and high electron mobility. Growing high mobility 2DEGs requires high quality substrates with low impurity densities. In this work we demonstrate a ZnO substrate sample treatment combining high temperature rapid thermal annealing and chemical etching to improve the surface quality for the subsequent growth of 2DEGs. This process enables the growth of a 2DEG with low-temperature mobility of $4.8\times10^4$~cm$^2$V$^{-1}$s$^{-1}$. An unannealed control sample shows a scattering rate at least three times greater than the annealed sample.Comment: 5 pages, 3 figure

Influence of Active Recovery on Cardiovascular Function During Ice Hockey

Background: Ice hockey is a popular sport comprised of high-intensity repeated bouts of activity. Light activity, as opposed to passive rest, has been shown to improve power output in repeated sprinting and could potentially help to offset venous pooling, poor perfusion, and the risk of an ischemic event. The objective of our study was, thus, to examine the efficacy of low-intensity lower body activity following a simulated hockey shift for altering hemodynamic function. Methods: In a cross-over design, 15 healthy hockey players (23 ± 1 years, 54 ± 3 mL/kg/min) performed two simulated hockey shifts. In both conditions, players skated up to 85 % of age-predicted heart rate maximum, followed by either passive recovery or active recovery while hemodynamic measures were tracked for up to 180 s of rest. Results: Light active recovery within the confines of an ice hockey bench, while wearing skates and protective gear, was effective for augmenting cardiac output (an average of 2.5 ± 0.2 L/min, p = 0.03) at 45, 50, and 120 s. These alterations were driven by a sustained elevation in heart rate (12 bpm, p = 0.05) combined with a physiological relevant but non-significant (11.6 mL, p = 0.06) increase in stroke volume. Conclusions: Standing and pacing between shifts offers a realistic in-game solution to help slow the precipitous drop in cardiac output (heart rate and stroke volume) that typically occurs with passive rest. Prolonging the duration of an elevated cardiac output further into recovery may be beneficial for promoting recovery of the working skeletal muscles and also avoiding venous pooling and reduced myocardial perfusion. Key Points: Evidence that light activity in the form of standing/pacing is effective for maintaining cardiac output, and thus venous return Increased cardiac output and venous return may help reduce the chances of poor perfusion (ischemia) and could also promote recovery for performance This is a simple, low-risk, intervention demonstrated for the first time to work within the confines of a player’s bench while wearing hockey gea

Listening to narrative speech after aphasic stroke: The role of the left anterior temporal lobe

The dorsal bank of the primate superior temporal sulcus (STS) is a polysensory area with rich connections to unimodal sensory association cortices. These include auditory projections that process complex acoustic information, including conspecific vocalizations. We investigated whether an extensive left posterior temporal (Wernicke’s area) lesion, which included destruction of early auditory cortex, may contribute to impaired spoken narrative comprehension as a consequence of reduced function in the anterior STS, a region not included within the boundary of infarction. Listening to narratives in normal subjects activated the posterior--anterior extent of the left STS, as far forward as the temporal pole. The presence of a Wernicke’s area lesion was associated with both impaired sentence comprehension and a reduced physiological response to heard narratives in the intact anterior left STS when compared to aphasic patients without temporal lobe damage and normal controls. Thus, in addition to the loss of language function in left posterior temporal cortex as the direct result of infarction, posterior ablation that includes primary and early association auditory cortex impairs language function in the intact anterior left temporal lobe. The implication is that clinical studies of language on stroke patients have underestimated the role of left anterior temporal cortex in comprehension of narrative speech

Optical second harmonic generation in encapsulated single-layer InSe

We report the observation of optical second harmonic generation (SHG) in single-layer indium selenide (InSe). We measure a second harmonic signal of $>10^3$ $\textrm{cts/s}$ under nonresonant excitation using a home-built confocal microscope and a standard pulsed pico-second laser. We demonstrate that polarization-resolved SHG serves as a fast, non-invasive tool to determine the crystal axes in single-layer InSe and to relate the sharp edges of the flake to the armchair and zigzag edges of the crystal structure. Our experiment determines these angles to an accuracy better than $\pm$ $0.2^{\circ}$. Treating the two-dimensional material as a nonlinear polarizable sheet, we determine a second-order nonlinear sheet polarizability $| \chi_{\textrm{sheet}}^{(2)}|=(17.9 \pm 11.0)\times 10^{-20}$ $\textrm{m}^2 \textrm{V}^{-1}$ for single-layer InSe, corresponding to an effective nonlinear susceptibility value of $| \chi_\textrm{eff}^{(2)}| \approx (223 \pm 138) \times 10^{-12}$ $\textrm{m} \textrm{V}^{-1}$ accounting for the sheet thickness ($\textrm{d} \approx 0.8$ $\textrm{nm}$). We demonstrate that the SHG technique can also be applied to encapsulated samples to probe their crystal orientations. The method is therefore suitable for creating high quality van der Waals heterostructures with control over the crystal directions

Critical assessment and validation of a time-integrating fluvial suspended sediment sampler

Delivery of fine sediment to fluvial systems is of considerable concern given the physical and ecological impacts of elevated levels in drainage networks. Although it is possible to measure the transfer of fine sediment at high frequency by using a range of surrogate and automated technologies, the demands for assessing sediment flux and sediment properties at multiple spatially distributed locations across catchments can often not be met using established sampling techniques. The time-integrated mass-flux sampler (TIMS) has the potential to bridge this gap and further our understanding of fine sediment delivery in fluvial systems. However, these devices have undergone limited testing in the field. The aim of this paper was to provide a critical validation of TIMS as a technique for assessing fluvial fine sediment transfer. Fine sediment flux and sediment properties were assessed over 2 years with individual sampling periods of approximately 30 days. Underestimation of sediment flux ranged between 66% and 99% demonstrating that TIMS is unsuitable for assessing absolute sediment loads. However, assessment of relative efficiency showed that six of seven samplers produced statistically strong relationships with the reference sediment load (P < 0.05). Aggregated data from all sites produced a highly significant relationship between reference and TIMS loads (R2 = 0.80; P < 0.001) demonstrating TIMS may be suitable for characterizing patterns of suspended sediment transfer. Testing also illustrated a consistency in sediment properties between multiple samplers in the same channel cross section. TIMS offers a useful means of assessing spatial and temporal patterns of fine sediment transfer across catchments where expensive monitoring frameworks cannot be commissioned

Variability in carbapenemase activity of intrinsic OxaAb (OXA-51-like) β-lactamase enzymes in Acinetobacter baumannii

Objectives: To measure the variability in carbapenem susceptibility conferred by different OxaAb variants, characterize the molecular evolution of oxaAb and elucidate the contribution of OxaAb and other possible carbapenem resistance factors in the clinical isolates using WGS and LC–MS/MS. Methods: Antimicrobial susceptibility tests were performed on 10 clinical Acinetobacter baumannii isolates. Carbapenem MICs were evaluated for all oxaAb variants cloned into A. baumannii CIP70.10 and BM4547, with and without their natural promoters. Molecular evolution analysis of the oxaAb variants was performed using FastTree and SplitsTree4. Resistance determinants were studied in the clinical isolates using WGS and LC–MS/MS. Results: Only the OxaAb variants with I129L and L167V substitutions, OxaAb(82), OxaAb(83), OxaAb(107) and OxaAb(110) increased carbapenem MICs when expressed in susceptible A. baumannii backgrounds without an upstream IS element. Carbapenem resistance was conferred with the addition of their natural upstream ISAba1 promoter. LC–MS/MS analysis on the original clinical isolates confirmed overexpression of the four I129L and L167V variants. No other differences in expression levels of proteins commonly associated with carbapenem resistance were detected. Conclusions: Elevated carbapenem MICs were observed by expression of OxaAb variants carrying clinically prevalent substitutions I129L and L167V. To drive carbapenem resistance, these variants required overexpression by their upstream ISAba1 promoter. This study clearly demonstrates that a combination of IS-driven overexpression of oxaAb and the presence of particular amino acid substitutions in the active site to improve carbapenem capture is key in conferring carbapenem resistance in A. baumannii and other mechanisms are not required

Sheep Updates 2003 - Posters

This session covers eleven papers from different authors:1 Sheep production on annual stubbles/pastures vs lucerne Maxine Brown Gaye Krebs Muresk Institute, Curtin University Diana Fedorenko Kathryn Egerton-Warburton Centre for Cropping Systems, Department of Agriculture Western Australia 2. The value chain of the Lake Grace livestock industry Evan Burt Nazrul Islam Department of Agriculture Western Australia 3. Native pastures, Dorper sheep and the 2002 drought Roy Butler Department of Agriculture Western Australia 4. Commercial sheep breeders can improve their sheep breeding program using wether trials L.G. Butler, S.R. Brown, M.F. D’Antuono, J.C. Greeff Department of Agriculture 5. Western Australia Linked ewe trials to benchmark wool traits and reproductive performance of Western Australian sheep flocks Ken Hart Department of Agriculture Western Australia 6. Damara sheep - what is their potential? A case study from the North-eastern wheatbelt Tanya Kilminster Evan Burt Department of Agriculture Western Australia 7, Australian Sheep Industry CRC - nutrition sub-program Rachel Kirby Sheep CRC Research Fellow 8. Dust penetration is not genetically and phenotypically the same trait as dust content M.E. Ladyman J.C. Greeff Department of Agriculture Western Australia A.C. Schlink CSIRO Livestock Industries, Private Bag 5, Wembley WA I.H. Williams P.E. Vercoe University of Western Australia, Crawley WA 9.Developing sustainable fodder crop systems with new annual pasture legumes Anyou Lui Department of Agriculture Western Australia 10. Seasonal pricing and seasonality of supply of prime lambs in the western wheatbelt Karen Smith Martin Bent Muresk Institute, Curtin University 11. The role of alternative and exotic sheep breeds in the Western Australian sheep industry Matthew Young Department of Agriculture Western Australi

The Genomic Signature of Crop-Wild Introgression in Maize

The evolutionary significance of hybridization and subsequent introgression has long been appreciated, but evaluation of the genome-wide effects of these phenomena has only recently become possible. Crop-wild study systems represent ideal opportunities to examine evolution through hybridization. For example, maize and the conspecific wild teosinte Zea mays ssp. mexicana, (hereafter, mexicana) are known to hybridize in the fields of highland Mexico. Despite widespread evidence of gene flow, maize and mexicana maintain distinct morphologies and have done so in sympatry for thousands of years. Neither the genomic extent nor the evolutionary importance of introgression between these taxa is understood. In this study we assessed patterns of genome-wide introgression based on 39,029 single nucleotide polymorphisms genotyped in 189 individuals from nine sympatric maize-mexicana populations and reference allopatric populations. While portions of the maize and mexicana genomes were particularly resistant to introgression (notably near known cross-incompatibility and domestication loci), we detected widespread evidence for introgression in both directions of gene flow. Through further characterization of these regions and preliminary growth chamber experiments, we found evidence suggestive of the incorporation of adaptive mexicana alleles into maize during its expansion to the highlands of central Mexico. In contrast, very little evidence was found for adaptive introgression from maize to mexicana. The methods we have applied here can be replicated widely, and such analyses have the potential to greatly informing our understanding of evolution through introgressive hybridization. Crop species, due to their exceptional genomic resources and frequent histories of spread into sympatry with relatives, should be particularly influential in these studies