The 7DL.7Ag translocation from Lophopyrum elongatum that carries Lr19, a leaf rust resistance gene, was found to be associated with a significant increase in grain yield under irrigated, disease-free conditions, but a generally lower yield under moisture stress conditions. These studies, however, involved a limited number of genetic recipients and environments, and the effect of the translocation on physiological traits was not considered. We examined the translocation effect in six different recipient genotypes and under five environmental conditions, including drought and heat stress. The increase in grain yield under irrigated conditions was associated with a higher rate of biomass production in the 7DL.7Ag lines and may be attributed to higher sink strength. Effect of the translocation on physiological traits was noted only under heat stress and was not associated with difference in yield. Under moisture stress conditions, 7DL.7Ag lines yielded less than their corresponding recipients, possibly because of a longer growing cycle. It is concluded that the effect of the 7DL.7Ag translocation may very much depend on the phenological adaptation of the recipient genotype and the translocation may be useful for enhancing yield, mainly under favourable conditions.

Strict pollutant emission regulations are pushing gas turbine manufacturers to develop devices that operate in lean conditions, with the downside that combustion instabilities are more likely to occur. Methods to predict and control unstable modes inside combustion chambers have been developed in the last decades but, in some cases, they are computationally expensive. Sensitivity analysis aided by adjoint methods provides valuable sensitivity information at a low computational cost. This paper introduces adjoint methods and their application in wave-based low order network models, which are used as industrial tools, to predict and control thermoacoustic oscillations. Two thermoacoustic models of interest are analysed. First, in the zero Mach number limit, a nonlinear eigenvalue problem is derived, and continuous and discrete adjoint methods are used to obtain the sensitivities of the system to small modifications. Sensitivities to base-state modification and feedback devices are presented. Second, a more general case with non-zero Mach number, a moving flame front and choked outlet, is presented. The influence of the entropy waves on the computed sensitivities is shown.

In gas turbines, thermoacoustic oscillations grow if moments of high fluctuating heat release rate coincide with moments of high acoustic pressure. The phase between the heat release rate and the acoustic pressure depends strongly on the flame behaviour (specifically the time delay) and on the acoustic period. This makes the growth rate of thermoacoustic oscillations exceedingly sensitive to small changes in the acoustic boundary conditions, geometry changes, and the flame time delay. In this paper, adjoint-based sensitivity analysis is applied to a thermoacoustic network model of an annular combustor. This reveals how each eigenvalue is affected by every parameter of the system. This information is combined with an optimization algorithm in order to stabilize all thermoacoustic modes of the combustor by making only small changes to the geometry. The final configuration has a larger plenum area, a smaller premix duct area and a larger combustion chamber volume. All changes are less than 6% of the original values. The technique is readily scalable to more complex models and geometries and the inclusion of further constraints, such that the combustion chamber itself should not change. This demonstrates why adjoint-based sensitivity analysis and optimization could become an indispensible tool for the design of thermoacoustically-stable combustors.

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ResumenEl trabajo analiza el comportamiento de las microempresas bajo un marco de competencia imperfecta donde dichas unidades económicas son capaces de fijar un precio por encima de su costo marginal, el cual les permite subsistir e incluso ser rentables a pesar de las condiciones en las que suelen operar. Para probarlo, se estima un modelo econométrico que considera al índice de Lerner como variable dependiente de un conjunto de variables cualitativas previamente clasificadas por área de influencia. Se concluye que las microempresas son capaces de ser rentables y operar con poder de mercado gracias a la publicidad y estrategia de ventas utilizada, así como a la flexibilidad del proceso productivo. En cualquier caso, su capacidad de fijar precios está altamente influenciada por las condiciones socioeconómicas del mercado en el que operan.Palabras clave: Microempresas, poder de mercado, marginación, índice de Lerner. jel: D4, D41, D21 AbstRActThe paper analyzes the behavior of microenterprises in a context of imperfect competition in which they have the ability to profitably raise the market price of goods over their marginal cost. This allows them to survive and even be profitable despite the conditions under which they typically operate. We use an econometric model to conduct the analysis, in which we explain the Lerner index as a function of several qualitative variables previously classified by area of influence. We conclude that microenterprises are capable of being profitable and operating with market power through advertising and sales strategies due to the flexibility of the production process. In any case, the capacity to set prices is strongly influenced by the socioeconomic conditions of the market in which they operate.