Subcritical turbulent condensate in rapidly rotating Rayleigh-B\'enard convection

The possibility of subcritical behaviour in the geostrophic turbulence regime of rapidly rotating thermally driven convection is explored. In this regime a non-local inverse energy transfer may compete with the more traditional and local direct cascade. We show that, even for control parameters for which no inverse cascade has previously been observed, a subcritical transition towards a large-scale vortex state can occur when the system is initialized with a vortex dipole of finite amplitude. This new example of bistability in a turbulent flow, which may not be specific to rotating convection, opens up new avenues for studying energy transfer in strongly anisotropic three-dimensional flows.Comment: 12 pages, 6 figure

Suppression of wall modes in rapidly rotating Rayleigh-B\'enard convection by narrow horizontal fins

The heat transport by rapidly-rotating Rayleigh-B\'enard convection is of fundamental importance to many geophysical flows. Laboratory measurements are impeded by robust wall modes which develop along vertical walls, significantly perturbing the heat flux. We show that narrow horizontal fins along the vertical walls efficiently suppress wall modes ensuring that their contribution to the global heat flux is negligible compared with bulk convection in the geostrophic regime, thereby paving the way for new experimental studies of geophysically relevant regimes of rotating convection.Comment: 6 pages, 6 figure

The Significance of Strategic Control on the Growth of Churches in Harare, Zimbabwe

The research aimed to assess the effect of strategic control on the growth of churches in Harare, Zimbabwe. The research looked at the influence of strategic control on the growth on both Mainline and Pentecostal churches. The study followed a positivism philosophy, where an explanatory research design was applied. A multi-stage stratified random sampling was used to select the study participants who were adult congregants and church leaders from two strata, one stratum being made up of mainline churches and the other one by Pentecostal churches. Multi-stage stratified random sampling was deemed appropriate for the research as it ensured that there was representativeness within and across the strata. Data was collected from systematically selected congregants and church leaders in selected churches through interviewer-administered questionnaires using Open Datakit, a mobile data collection platform. Data analysis revealed that there was evidence of implementation of strategic control (mean score of 4) as part of strategic management practices in both Mainline and Pentecostal churches. Additionally, the findings show that strategic control influences the growth of churches (p-value <0.001). These findings showed that churches like any other organizations can be affected by the change in the socio-economic environment and thus they should implement appropriate strategies to remain viable and relevant. Strategic control plays a crucial role in ensuring that those strategies are effectively implemented. An effective Strategic Management Framework should be formulated and guide how churches can continuously control the implementation of their strategies to remain viable and achieve their mandate. Keywords: strategic control, church, church growth, strategic management DOI: 10.7176/EJBM/12-32-06 Publication date: November 30th 202

The Utilisation Of Thermal Methods For The Screening Of Three Component Co-amorphous Systems

Indomethacin and piroxicam are known to become amorphous upon rapid cooling after melting. Multiple three-component co-amorphous mixtures have been produced via a melt quench method to evaluate the influence of the third component on stability and physical properties on the co-amorphous mixture of piroxicam and indomethacin. These have then been tested using thermal gravimetric analysis, differential scan calorimetry and hot stage microscopy. Results have confirmed the creation of a three-component co-amorphous system

Pressure-driven wrinkling of soft inner-lined tubes

Wrinkling of an inextensible elastic lining of an inner-lined tube under imposed pressure is considered. A simple equation modeling the elastic properties of the lining, the pressure, and the soft-substrate forces is derived. This equation aims to capture the wrinkling response of arterial endothelium to blood pressure changes. Numerical continuation is used to construct a bifurcation diagram as a function of the imposed pressure for in-plane deformations, in excellent agreement with weakly nonlinear theory, which we also develop. Our approach explains how the wavelength and amplitude of the wrinkles are selected as a function of the parameters in compressed wrinkling systems and shows how localized folds and mixed-mode states form in secondary bifurcations from wrinkled states.Comment: 5 pages, 5 figure

The Use Of XRPD And ATR-FTIR In The Screening Of Three Component Co-amorphous Systems Created Via A Melt-Quench Method.

Multiple three-component co-amorphous systems have been created via a melt- quench method. This has been confirmed by a single glass transition in the individual DSC traces and then reinforced by X-ray diffraction data, which show an absence of crystalline material. ATR-FTIR has also been used to show a change in bonding vibrations between the physical mixtures and co-amorphous samples. The change in bonding vibrations indicates different molecular interactions within the co-amorphous materials

Measuring agri-food supply chain performance: insights from the Peruvian kiwicha industry

Purpose: Agri-food firms face many challenges when assessing and managing their performance. The purpose of this research is to determine important factors for an integrated agri-food supply chain performance measurement system. Design/methodology/approach: This research uses the Peruvian kiwicha supply chain as a meaningful context to examine critical factors affecting agri-food supply chain performance. The research uses interpretative structural modelling (ISM) with fuzzy MICMAC methods to suggest a hierarchical performance measurement model. Findings: The resulting kiwicha supply chain performance management model provides insights for managers and academic theory regarding managing competing priorities within the agri-food supply chain. Originality/value: The model developed in this research has been validated by cooperative kiwicha associations based in Puno, Peru, and further refined by experts. Moreover, the results obtained through ISM and fuzzy MICMAC methods could help decision-makers from any agri-food supply chain focus on achieving high operational performance by integrating key performance measurement factors

Collisions of localized patterns in a nonvariational Swift-Hohenberg equation

The cubic-quintic Swift-Hohenberg equation (SH35) has been proposed as an order parameter description of several convective systems with reflection symmetry in the layer midplane, including binary fluid convection. We use numerical continuation, together with extensive direct numerical simulations, to study SH35 with an additional nonvariational quadratic term to model the effects of breaking the midplane reflection symmetry. The nonvariational structure of the model leads to the propagation of asymmetric spatially localized structures (LSs). An asymptotic prediction for the drift velocity of such structures is validated numerically. Next, we present an extensive study of possible collision scenarios between identical and nonidentical traveling structures, varying a temperature-like control parameter. The final state may be a simple bound state of the initial LSs or longer or shorter than the sum of the two initial states as a result of nonlinear interactions. The Maxwell point of the variational system is shown to have no bearing on which of these scenarios is realized. Instead, we argue that the stability properties of bound states are key. While individual LSs lie on a modified snakes-and-ladders structure in the nonvariational SH35, the multi-pulse bound states resulting from collisions lie on isolas in parameter space. In the gradient SH35, such isolas are always of figure-eight shape, but in the present non-gradient case they are generically more complex, some of which terminate in T-point bifurcations. A reduced model consisting of two coupled ordinary differential equations is proposed to describe the linear interactions between the tails of the LSs in which the model parameters are deduced using gradient descent optimization. For collisions leading to the formation of simple bound states, the reduced model reproduces the trajectories of LSs with high quantitative accuracy.Comment: 19 pages, 28 figure