Estimation of TFP growth:a semiparametric smooth coefficient approach

This article uses a semiparametric smooth coefficient model (SPSCM) to estimate TFP growth and its components (scale and technical change). The SPSCM is derived from a nonparametric specification of the production technology represented by an input distance function (IDF), using a growth formulation. The functional coefficients of the SPSCM come naturally from the model and are fully flexible in the sense that no functional form of the underlying production technology is used to derive them. Another advantage of the SPSCM is that it can estimate bias (input and scale) in technical change in a fully flexible manner. We also used a translog IDF framework to estimate TFP growth components. A panel of U.S. electricity generating plants for the period 1986–1998 is used for this purpose. Comparing estimated TFP growth results from both parametric and semiparametric models against the Divisia TFP growth, we conclude that the SPSCM performs the best in tracking the temporal behavior of TFP growth

On the le-semigroups whose semigroup of bi-ideal elements is a normal band

It is well known that the semigroup B(S) of all bi-ideal elements of an le-semigroup S is a band if and only if S is both regular and intra-regular. Here we show that B(S) is a band if and only if it is a normal band and give a complete characterization of the le-semigroups S for which the associated semigroup B(S) is in each of the seven nontrivial subvarieties of normal bands. We also show that the set Bm(S) of all minimal bi-ideal elements of S forms a rectangular band and that Bm(S) is a bi-ideal of the semigroup B(S)

Assessing the efficiency of maintenance operators: a case study of turning railway wheelsets on an under-floor wheel lathe

The present paper assesses the technical efficiency of different operators turning railway wheelsets on a under-floor wheel lathe. This type of lathe is a Computer Numerical Control (CNC) machine used to turn wheelsets in-situ on the train. As railway wheels are turned, a certain amount of the wheel diameter is lost to restore the tread profile and full flange thickness of the wheel. The technical efficiencies of the different wheel lathe operators are assessed using a Stochastic Frontier Analysis (SFA), whilst controlling for other explaining variables such as the flange thickness and the occurrence of rolling contact fatigue (RCF) defects, wheel flats and cavities. Different model specifications for the SFA are compared with Linear Mixed Model (LMM) specifications, showing that the SFA model exhibits a better Akaike Information Criterion (AIC)

Are you slacking? Where do you and your country stand in the happiness pursuit?

This paper contributes to the literature on subjective well-being of individuals by estimating a “happiness frontier” under the premise that individuals seek to maximize happiness. The happiness frontier is defined as the pinnacle of happiness, given the resources and personal characteristics of individuals. However, individuals may not only strive to maximize their happiness but also to achieve higher levels of income, ceteris paribus. Thus, there is a trade-off between these two objectives, and the happiness�income frontier is attained when one can neither increase her happiness nor income, given her resources and personal characteristics. If one fails to attain the happiness-income frontier, there is a shortfall. The shortfall measures the rate at which both happiness and income for an individual, who has failed to attain the happiness frontier, could be increased given everything else. We also explore the determinants of this shortfall and conduct an empirical analysis using micro-level data gathered from the World Values Survey (WVS) for 74 countries. Our results suggest that age as well as certain personal circumstances, such as being unemployed or having a partner, have a strong influence on the levels the estimated well-being and income attainment measures. Likewise, we also find that the quality of the government of the country of residence also greatly affects individuals’ capacity to convert their resources into higher levels of happiness and income

Purification and Activity Testing of the Full-Length YycFGHI Proteins of Staphylococcus aureus

Background: The YycFG two-component regulatory system (TCS) of Staphylococcus aureus represents the only essential TCS that is almost ubiquitously distributed in Gram-positive bacteria with a low G+C-content. YycG (WalK/VicK) is a sensor histidine-kinase and YycF (WalR/VicR) is the cognate response regulator. Both proteins play an important role in the biosynthesis of the cell envelope and mutations in these proteins have been involved in development of vancomycin and daptomycin resistance. Methodology/Principal Findings: Here we present high yield expression and purification of the full-length YycG and YycF proteins as well as of the auxiliary proteins YycH and YycI of Staphylococcus aureus. Activity tests of the YycG kinase and a mutated version, that harbours an Y306N exchange in its cytoplasmic PAS domain, in a detergent-micelle-model and a phosholipid-liposome-model showed kinase activity (autophosphorylation and phosphoryl group transfer to YycF) only in the presence of elevated concentrations of alkali salts. A direct comparison of the activity of the kinases in the liposomemodel indicated a higher activity of the mutated YycG kinase. Further experiments indicated that YycG responds to fluidity changes in its microenvironment. Conclusions/Significance: The combination of high yield expression, purification and activity testing of membrane and membrane-associated proteins provides an excellent experimental basis for further protein-protein interaction studies an