Banana root and soil health project - Australia

The banana plant forms an adventitious root system that is dependent on soil physical, chemical and biological properties to function efficiently. A pot experiment demonstrated that increasing soil compaction was able to significantly reduce the weight of banana roots and shoots. However, in the presence of Radopholus similis the effects of soil compaction were obscured, due to the significant reduction in root weight caused by the nematode. The use of a basic set of soil quality indicators that can be readily used by farmers, was linked to soil nematode indicators to determine relationships between soil properties. In a survey of banana fields in North Queensland, different diameter root classes were affected differently by changing soil properties. Banana roots greater than 5 mm diameter were positively correlated with aggregate stability and negatively correlated with soil bulk density. Banana roots less than 1 mm were positively correlated with electrical conductivity. Specific interactions between soil properties become apparent as crop production systems become more uniform. This allows farmers to prioritise management options to improve the most deficient soil health indicators. The addition of organic amendments is one possible method of correcting degrading soils. The use of amendments with high carbon contents, such as grass hay, banana trash and lucerne hay, were able to significantly suppress R. similis in the roots of banana plants relative to untreated soil. Due to banana production being located near environmentally sensitive areas there is an increasing need to monitor and modify soil management practices. However, this needs to be linked with a framework that allows the integration of all soil components with a system to allow continual improvement in soil management to allow banana production to have minimal impact on the surrounding environment

Banana root and soil health project - Australia

The banana plant forms an adventitious root system that is dependent on soil physical, chemical and biological properties to function efficiently. A pot experiment demonstrated that increasing soil compaction was able to significantly reduce the weight of banana roots and shoots. However, in the presence of Radopholus similis the effects of soil compaction were obscured, due to the significant reduction in root weight caused by the nematode. The use of a basic set of soil quality indicators that can be readily used by farmers, was linked to soil nematode indicators to determine relationships between soil properties. In a survey of banana fields in North Queensland, different diameter root classes were affected differently by changing soil properties. Banana roots greater than 5 mm diameter were positively correlated with aggregate stability and negatively correlated with soil bulk density. Banana roots less than 1 mm were positively correlated with electrical conductivity. Specific interactions between soil properties become apparent as crop production systems become more uniform. This allows farmers to prioritise management options to improve the most deficient soil health indicators. The addition of organic amendments is one possible method of correcting degrading soils. The use of amendments with high carbon contents, such as grass hay, banana trash and lucerne hay, were able to significantly suppress R. similis in the roots of banana plants relative to untreated soil. Due to banana production being located near environmentally sensitive areas there is an increasing need to monitor and modify soil management practices. However, this needs to be linked with a framework that allows the integration of all soil components with a system to allow continual improvement in soil management to allow banana production to have minimal impact on the surrounding environment

NUMERICAL SIMULATION OF FILM COOLING IN HYPERSONIC FLOWS

Abstract In this paper, a numerical study of film cooling in both laminar and turbulent hypersonic flows has been performed. The aim of this computational work was to investigate the mechanism and effectiveness of film cooling in hypersonic flows. The coolant fluid was found to affect the primary boundary layer in two ways: 1) a separate boundary layer established by the coolant fluid itself, 2) a mixing layer between the primary and coolant flow streams. According to the analysis of the film cooling effectiveness, it has been revealed that under the same primary flow conditions the flow field of film cooling could be recognized as two separate regions. These two regions are divided by the point of the cooling length x A . For laminar flow, film cooling effectiveness was observed to obey a second-order curve in the log-log coordinates against log 10 η = f (log 10 x hṁ ) 2 . For turbulent flow, a linear relation was found suitable to describe the relation between log 10 η and log 10 x hṁ

Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

We report the direct generation of linearly polarized single photons with a deterministic polarization axis in self-assembled quantum dots (QDs), achieved by the use of non-polar InGaN without complex device geometry engineering. Here, we present a comprehensive investigation of the polarization properties of these QDs and their origin with statistically significant experimental data and rigorous k·p modeling. The experimental study of 180 individual QDs allows us to compute an average polarization degree of 0.90, with a standard deviation of only 0.08. When coupled with theoretical insights, we show that these QDs are highly insensitive to size differences, shape anisotropies, and material content variations. Furthermore, 91% of the studied QDs exhibit a polarization axis along the crystal [1–100] axis, with the other 9% polarized orthogonal to this direction. These features give non-polar InGaN QDs unique advantages in polarization control over other materials, such as conventional polar nitride, InAs, or CdSe QDs. Hence, the ability to generate single photons with polarization control makes non-polar InGaN QDs highly attractive for quantum cryptography protocols

Study of Blade/Vortex interaction using Computational Fluid Dynamics and Computational Aeroacoustics

Abstract A parametric study of the aerodynamics and the acoustics of parallel BVI has been carried out for different aerofoil shapes and vortex properties. Computing BVI using Computational Fluid Dynamics is challenging since the solution scheme tends to alter the characteristics of the vortex which must be preserved until the interaction. The present work uses the Compressible Vorticity Confinement Method (CVCM) for capturing the vortex characteristics, which is easier to implement and has minimal overhead in the performance of existing CFD solvers either in terms of CPU time or robustness during convergence. Apart from applying the CVCM method with an upwind solver, something not encountered in the literature, the present work couples CFD with Computational Aeroacoustics (CAA) and uses the strengths of both techniques in order to predict the nearfield and farfield noise. Results illustrate the importance of the aerofoil shape at transonic flow and show that the magnitude of the BVI noise depends strongly on the vortex strength and the miss-distance. The effect of the vortex core radius was also found to be important

Training school teachers to promote mental and social well-being in low and middle income countries : lessons to facilitate scale-up from a participatory action research trial of youth first in India

Mental and social wellbeing (MSWB) promotion programs could improve mental health and other outcomes for youth in Low and Middle Income Countries (LMICs). Unfortunately, few such programs have progressed to scale-up and few studies have detailed processes and considerations that could facilitate doing so. This study begins to fill these gaps, describing key findings from training and supporting government middle school teachers to deliver the Youth First Resilience Curriculum, a MSWB promotion program, in Bihar, India. We conducted a Participatory Action Research trial of the resilience curriculum among 792 middle school youth and 55 teachers at 15 government schools. Participant-observations, exit interviews, and group discussions were conducted and analyzed via multiple rounds of coding to generate thematic findings. A number of schools showed relatively high levels of interest, session reliability and fidelity, student interaction and teacher facilitative abilities, but there was great variation within the sample. Three leverage points emerged to facilitate future scale-up: factors for successful site assessment and program initiation, supporting teacher success via interest and motivation, and responding to varied teacher skill levels. These points represent critical focus areas for practitioners and policy-makers as more MSWB promotion programs begin to scale in LMICs.peer-reviewe

Separate banks of information channels encode size and aspect ratio

Size and aspect ratio are ecologically important visual attributes. Relative size confers depth, and aspect ratio is a size-invariant cue to object identity. The mechanisms of their analyses by the visual system are uncertain. In a series of three psychophysical experiments we show that adaptation causes perceptual repulsion in these properties. Experiment 1 shows that adaptation to a square causes a subsequently viewed smaller (larger) test square to appear smaller (larger) still. Experiment 2 reveals that a test rectangle with an aspect ratio (height/width) of two appears more slender after adaptation to rectangles with aspect ratios less than two, while the same test stimulus appears more squat after adaptation to a rectangle with an aspect ratio greater than two. Significantly, aftereffect magnitudes peak and then decline as the sizes or aspect ratios of adaptor and test diverge. Experiment 3 uses the results of Experiments 1 and 2 to show that the changes in perceived aspect ratio are due to adaptation to aspect ratio rather than adaptation to the height and width of the stimuli. The results are consistent with the operation of distinct banks of information channels tuned for different values of each property. The necessary channels have log-Gaussian sensitivity profiles, have equal widths when expressed as ratios, are labeled with their preferred magnitudes, and are distributed at exponentially increasing intervals. If an adapting stimulus reduces each channel's sensitivity in proportion to its activation then the displacement of the centroid of activity due to a subsequently experienced test stimulus predicts the measured size or aspect ratio aftereffect