A systematic study of the effects of cell geometry on the dynamics of large-scale flows in turbulent thermal convection is carried out in horizontal cylindrical cells of different lengths filled with water. Four different flow modes are identified with increasing aspect ratio Γ . For small aspect ratios (Γ 6 0.16), the flow is highly confined in a thin disc-like cell with a quasi-two-dimensiona...

Phase 1, with electrical conductivity σ1, occupies the “bowtie” region of angle ±α, while phase 2, with conductivity σ2 σ1, occupies the remaining region. Deduce the approximate form of lines of current density J when a background electric field is applied along the symmetry axis of phase 1. What is the effective conductivity σ of the system, defined by the relation I = σΔφ between the total cu...

It is well established that there are collective economic gains that can be realised from local industrial agglomerations. These gains arise from labour market pooling, knowledge and information flows, collective learning and shared business services. Realising the potential gains requires collective action, often facilitated by government and other public institutions. Recent economic policy i...

We prove explicit coercivity estimates for the linearized Boltzmann and Landau operators, for a general class of interactions including any inversepower law interactions, and hard spheres. The functional spaces of these coecivity estimates depend on the collision kernel of these operators. For Maxwell molecules they coincide with the spectral gap estimates. For hard potentials they are stronger...

Transient development of perturbations in inviscid stratified shear flow is investigated. Use is made of closed form analytic solutions that allow concise identification of optimally growing plane-wave solutions for the case ofan unbounded flow with constant shear and stratification. For the case of channel flow, variational techniques are employed to determine the optimally growing disturbance...

We present a PDE model for dilute suspensions of swimming bacteria in a three-dimensional Stokesian fluid. This model is used to calculate the statistically-stationary bulk deviatoric stress and effective viscosity of the suspension from the microscopic details of the interaction of an elongated body with the background flow. A bacterium is modeled as an impenetrable prolate spheroid with self-...

Problems often arise when partners in regional integration agreements (RIA) have divergent exchange rate policies, as has happened in recent years with the Southern Cone Common Market (Mercosur). The January 1999 devaluation of the Brazilian real strained the relationship between Argentina and Brazil, setting off a series of events that included protectionist measures in Argentina, Argentine bu...

it was thought previously that cardiac muscle gap junctions provide low-resistance connections between cells and permit the local-circuit current to flow. some evidences show that myocardial cells may not require low-resistance connections for successful propagation of the action potential (ap). it seems that some other types of mechanisms must be involved in ap propagation. in this article, we...