ALBERT

Description: Rice has the lowest grain protein content (GPC) among cereals. Efforts have been made to improve GPC through the modified bulk-pedigree method of selection. A total of 1780 F8 recombinant lines were derived in the year 2013 from five different cross combinations involving two high-GPC landraces, namely ARC10075 and ARC10063, three high-yielding parents, namely Swarna, Naveen and IR64, and one parent, namely Sharbati, known for superior grain quality with high micronutrient content. Near-infrared spectroscopy was used to facilitate high-throughput selection for GPC. Significant selection differential, response to selection and non-significant differences between the predicted and observed response to selection for GPC and protein yield indicated the effectiveness of this selection process. This resulted in lines with high GPC, protein yield and desirable levels of amylose content. Further, based on high mean and stability for GPC and protein yield over the environments in the wet seasons of 2013, 2014 and the dry season of 2014, 12 elite lines were identified. Higher accumulation of glutelin fraction and non-significant change in prolamin/glutelin ratio in the grain suggested safe guarding of the nutritional value of rice grain protein of most of these identified lines. Since rice is the staple food of millions, the output of breeding for high GPC could have a significant role in alleviating protein malnutrition, especially in the developing world.

Description: 〈div data-abstract-type="normal"〉〈p〉The shear-induced collective diffusivity down a concentration gradient in a viscous emulsion is computed using direct numerical simulation. A layer of randomly packed drops subjected to a shear flow, shows the layer width to increase with the 〈span〉〈span〉〈img data-mimesubtype="gif" data-type="simple" src="http://static.cambridge.org/resource/id/urn:cambridge.org:id:binary:20190402101259227-0380:S0022112019001228:S0022112019001228_inline1.gif"〉 〈span data-mathjax-type="texmath"〉 〈/span〉 〈/span〉〈/span〉 power of time, consistent with a semi-dilute theory that assumes a diffusivity linear with concentration. This characteristic scaling and the underlying theory are used to compute the collective diffusivity coefficient. This is the first ever computation of this quantity for a system of deformable particles using fully resolved numerical simulation. The results match very well with previous experimental observations. The coefficient of collective diffusivity varies non-monotonically with the capillary number, due to the competing effects of increasing deformation and drop orientation. A phenomenological correlation for the collective diffusivity coefficient as a function of capillary number is presented. We also apply an alternative approach to compute collective diffusivity, developed originally for a statistically homogeneous rigid sphere suspension – computing the dynamic structure factor from the simulated droplet positions and examining its time variation at small wavenumber. We show that the results from this alternative approach qualitatively agree with our computation of collective diffusivity including the prediction of the non-monotonic variation of diffusivity with the capillary number.〈/p〉〈/div〉

Description: The Caledonides of Britain and Ireland include terranes attributed to both Laurentian and Gondwanan sources, separated along the Solway line. Gondwanan elements to the south have been variably assigned to the domains Ganderia and East Avalonia. The Midland Platform forms the core of East Avalonia but its provenance is poorly known. Laser ablation split-stream analysis yields information about detrital zircon provenance by providing simultaneous U–Pb and Lu–Hf data from the same ablated volume. A sample of Red Callavia Sandstone from uppermost Cambrian Stage 3 of the Midland Platform yields a U–Pb age spectrum dominated by Neoproterozoic and Palaeoproterozoic sources, resembling those in the Welsh Basin, the Meguma Terrane of Nova Scotia and NW Africa. Initial εHf values suggest that the Neoproterozoic zircon component was derived mainly from crustal sources 〈 2 Ga, and imply that the more evolved Palaeoproterozoic grains were transported into the basin from an older source terrane, probably the Eburnean Orogen of West Africa. A sample from Cambrian Stage 4 in the Bray Group of the Leinster–Lakesman Terrane shows, in contrast, a distribution of both U–Pb ages and εHf values closely similar to those of the Gander Terrane in Newfoundland and other terranes attributed to Ganderia, interpreted to be derived from the margin of Amazonia. East Avalonia is clearly distinct from Ganderia, but shows evidence for older crustal components not present in West Avalonia of Newfoundland. These three components of the Appalachian–Caledonide Orogen came from distinct sources on the margin of Cambrian Gondwana.

Description: Summary Major advances in biology and ecology have sharpened our understanding of what the goals of biodiversity conservation might be, but less progress has been made on how to achieve conservation in the complex, multi-sectoral world of human affairs. The failure to deliver conservation outcomes is especially severe in the rapidly changing landscapes of tropical low-income countries. We describe five techniques we have used to complement and strengthen long-term attempts to achieve conservation outcomes in the landscapes and seascapes of such regions; these are complex social-ecological systems shaped by interactions between biological, ecological and physical features mediated by the actions of people. Conservation outcomes occur as a result of human decisions and the governance arrangements that guide change. However, much conservation science in these countries is not rooted in a deep understanding of how these social-ecological systems work and what really determines the behaviour of the people whose decisions shape the future of landscapes. We describe five scientific practices that we have found to be effective in building relationships with actors in landscapes and influencing their behaviour in ways that reconcile conservation and development. We have used open-ended inductive enquiry, theories of change, simulation models, network analysis and multi-criteria analysis. These techniques are all widely known and well tested, but seldom figure in externally funded conservation projects. We have used these techniques to complement and strengthen existing interventions of international conservation agencies. These five techniques have proven effective in achieving deeper understanding of context, engagement with all stakeholders, negotiation of shared goals and continuous learning and adaptation.

Description: Direct numerical simulation of turbulent homogeneous shear flow is performed in order to clarify compressibility effects on the turbulence growth in the flow. The two Mach numbers relevant to homogeneous shear flow are the turbulent Mach number Mt and the gradient Mach number Mg. Two series of simulations are performed where the initial values of Mg and Mt are increased separately. The growth rate of turbulent kinetic energy is observed to decrease in both series of simulations. This ‘stabilizing’ effect of compressibility on the turbulent energy growth rate is observed to be substantially larger in the DNS series where the initial value of Mg is changed. A systematic comparison of the different DNS cases shows that the compressibility effect of reduced turbulent energy growth rate is primarily due to the reduced level of turbulence production and not due to explicit dilatational effects. The reduced turbulence production is not a mean density effect since the mean density remains constant in compressible homogeneous shear flow. The stabilizing effect of compressibility on the turbulence growth is observed to increase with the gradient Mach number Mg in the homogeneous shear flow DNS. Estimates of Mg for the mixing layer and the boundary layer are obtained. These estimates show that the parameter Mg becomes much larger in the high-speed mixing layer relative to the high-speed boundary layer even though the mean flow Mach numbers are the same in the two flows. Therefore, the inhibition of turbulent energy production and consequent 6 stabilizing ’ effect of compressibility on the turbulence (over and above that due to any mean density variation) is expected to be larger in the mixing layer relative to the boundary layer, in agreement with experimental observations. © 1995, Cambridge University Press. All rights reserved.

Description: Turbulent plane jets are prototypical free shear flows of practical interest in propulsion, combustion and environmental flows. While considerable experimental research has been performed on planar jets, very few computational studies exist. To the authors' knowledge, this is the first computational study of spatially evolving three-dimensional planar turbulent jets utilizing direct numerical simulation. Jet growth rates as well as the mean velocity, mean scalar and Reynolds stress profiles compare well with experimental data. Coherency spectra, vorticity visualization and autospectra are obtained to identify inferred structures. The development of the initial shear layer instability, as well as the evolution into the jet column mode downstream is captured well.The large- and small-scale anisotropies in the jet are discussed in detail. It is shown that, while the large scales in the flow field adjust slowly to variations in the local mean velocity gradients, the small scales adjust rapidly. Near the centreline of the jet, the small scales of turbulence are more isotropic. The mixing process is studied through analysis of the probability density functions of a passive scalar. Immediately after the rollup of vortical structures in the shear layers, the mixing process is dominated by large-scale engulfing of fluid. However, small-scale mixing dominates further downstream in the turbulent core of the self-similar region of the jet and a change from non-marching to marching PDFs is observed. Near the jet edges, the effects of large-scale engulfing of coflow fluid continue to influence the PDFs and non-marching type behaviour is observed.

Description: The unsteady separated flow produced by a finite-core vortex on a plane shear layer is studied here as a vortex-induced instability. The mechanism of such an interaction, where the distance between the wall and the vortex is many times the local boundary layer thickness, is shown here by flow visualization and the solution of the unsteady Navier-Stokes equation. A new theory is proposed here, which is generic to the Navier-Stokes equation without any assumptions, that is based on growth of disturbance energy in time. A dynamical systems approach based on the proper orthogonal decomposition technique is used to provide a quantitative measure.

Description: Boundary-forced stratified turbulence is studied in the prototypical case of turbulent channel flow subject to stable stratification. The large-eddy simulation approach is used with a mixed subgrid model that involves a dynamic eddy viscosity component and a scale-similarity component. After an initial transient, the flow reaches a new balanced state corresponding to active wall-bounded turbulence with reduced vertical transport which, for the cases in our study with moderate-to-large levels of stratification, coexists with internal wave activity in the core of the channel. A systematic reduction of turbulence levels, density fluctuations and associated vertical transport with increasing stratification is observed. Countergradient buoyancy flux is observed in the outer region for sufficiently high stratification. Mixing of the density field in stratified channel flow results from turbulent events generated near the boundaries that couple with the outer, more stable flow. The vertical density structure is thus of interest for analogous boundary-forced mixing situations in geophysical flows. It is found that, with increasing stratification, the mean density profile becomes sharper in the central region between the two turbulent layers at the upper and lower walls, similar to observations in field measurements as well as laboratory experiments with analogous density-mixing situations. Channel flow is strongly inhomogeneous with alternative choices for the Richardson number. In spite of these complications, the gradient Richardson number, Rig, appears to be important local determinant of buoyancy effects. All simulated cases show that correlation coefficients associated with vertical transport collapse from their nominal unstratified values over a narrow range, 0.15 〈 Rig 〈 0.25. The vertical turbulent Froude number, Frw, has an O(1) value across most of the channel. It is remarkable that stratified channel flow, with such a large variation of overall density difference (factor of 26) between cases, shows a relatively universal behaviour of correlation coefficients and vertical Froude number when plotted as a function of Rig. The visualizations show wavy motion in the core region where the gradient Richardson number, Rig, is large and low-speed streaks in the near-wall region, typical of unstratified channel flow, where Rig is small. It appears from the visualizations that, with increasing stratification, the region with wavy motion progressively encroaches into the zone with active turbulence; the location of Rig ≃ 0.2 roughly corresponds to the boundary between the two zones.