Echocardiographic prediction of outcome after cardiac resynchronization therapy: conventional methods and recent developments

Echocardiography plays an important role in patient assessment before cardiac resynchronization therapy (CRT) and can monitor many of its mechanical effects in heart failure patients. Encouraged by the highly variable individual response observed in the major CRT trials, echocardiography-based measurements of mechanical dyssynchrony have been extensively investigated with the aim of improving response prediction and CRT delivery. Despite recent setbacks, these techniques have continued to develop in order to overcome some of their initial flaws and limitations. This review discusses the concepts and rationale of the available echocardiographic techniques, highlighting newer quantification methods and discussing some of the unsolved issues that need to be addressed

Low potato yields in Kenya: do conventional input innovations account for the yields disparity?

Background: Potato yields in Kenya are less than half the amount obtained by some developed countries. Despite more acreage being dedicated to the crop, annual production has not improved. Kenya’s low yields have been blamed on a failure to use clean seeds, fertilizers, fungicides and irrigation. The article examines the impact of adopting these innovations on enhancements of yields. Results: The regression coefficients indicate that clean seeds have the greatest impact followed by irrigation, fungicides and fertilizers. However, clean seeds have the lowest adoption rate, with only 4.5% of the respondent sample using such seeds. Irrigation adoption was also low at 23% but there is widespread usage of fungicides and fertilizers at 92% and 96% respectively. Adoption of the four innovations more than doubled the yields but the absolute amount remained less than 50% of the 40 tons per hectare obtained by the leading world producers. The less than optimal gains can be attributed to the nonlinear relationships of the variables, which indicate the importance of more precise, proper application of inputs in order to obtain higher yields. Linear regression could only explain 10% of the variation but nonlinear regression improved R squared to 80%. The unexplained variables accounting for 20% appear to be essential for a further enhancement of yields, given the big difference between those currently achieved in Kenya and those in developed countries. Conclusions: Whereas adoption of the inputs is important, there is a need to use precise, recommended application regimes in order to obtain better potato yields. Training, in the form of visits by innovation propagation agents, are shown to improve adoption rates although only about half (55%) of farmers reported receiving such visits in the preceding three years. This points to a need for the Ministry of Agriculture to lead in increasing the coverage of such visits. Taken together, the four innovations account for only a fraction of the yield variances highlighting the need for further research to identify other determinants of Kenya’s low potato production