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Hollow fiber liquid-phase microextraction (HF-LPME) technique was used as a clean-up procedure for the determination of organophosphorus pesticides (OPPs) in fish tissue. In this study, eight OPPs were first extracted with acetone from fish sample, the organic extract after rotatory evaporation was then redissolved with water-methanol (95:5, v/v) solution,(More)
The system GMM estimator developed by Blundell and Bond (1998) for dynamic panel data models has been widely used in empirical work; however, it does not perform well with weak instruments. This paper proposes a variation on the system GMM estimator, based on a simple transformation of the dependent variable. Simulation results indicate that, in finite(More)
A new customizable user interface for smart devices based on hyperlink associability is presented. Although mobile devices should be easy to use, many current devices have complex and widely varying interfaces. The proposed framework, Hyrax, attempts to improve the menu structure and accessibility of functions while considering user preferences. In Hyrax,(More)
The two-step GMM estimators of Arellano and Bond (1991) and Blundell and Bond (1998) for dynamic panel data models have been widely used in empirical work; however, neither of them performs well in small samples with weak instruments. The continuous-updating GMM estimator proposed by Hansen, Heaton, and Yaron (1996) is in principle able to reduce the(More)
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