Consistent Model and Moment Selection Criteria for GMM Estimation with Applications to Dynamic Panel Data Models

This paper develops consistent model and moment selection criteria for GMM estimation. The criteria select the correct model specification and all correct moment conditions asymptotically. The selection criteria resemble the widely used likelihood-based selection criteria BIC, HQIC, and AIC. (The latter is not consistent.) The GMM selection criteria are based on the J statistic for testing over-identifying restrictions. Bonus terms reward the use of fewer parameters for a given number of moment conditions and the use of more moment conditions for a given number of parameters. The paper applies the model and moment selection criteria to dynamic panel data models with unobserved individual effects. The paper shows how to apply the selection criteria to select the lag length for lagged dependent variables, to detect the number and locations of structural breaks, to determine the exogeneity of regressors, and/or to determine the existence of correlation between some regressors and the individual effect. To illustrate the finite sample performance of the selection criteria and their impact on parameter estimation, the paper reports the results of a Monte Carlo experiment on a dynamic panel data model.Akaike information criterion, Bayesian information criterion, consistent selection procedure, generalized method of moments estimator, instrumental variables estimator, model selection, moment selection, panel data model, test of over-identifying restrictions

The Effect of Interfacial Chemical Bonding in TiO2-SiO2 Composites on their Photocatalytic NOx Abatement Performance

The authors gratefully acknowledge funding from the UK Engineering and Physical Sciences Research Council (Grant Ref: EP/M003299/1) and the Natural Science Foundation of China (No. 51461135005) International Joint Research Project (EPSRC-NSFC).Peer reviewedPublisher PD

Photocatalyst efficiencies in concrete technology : the effect of photocatalyst placement

The authors gratefully acknowledge funding from the UK Engineering and Physical Sciences Research Council (Grant Ref: EP/M003299/1) and the Natural Science Foundation of China (No. 51461135005, No. 51478370) International Joint Research Project (EPSRC-NSFC).Peer reviewedPublisher PD

The Effect of Sibship Size on Educational Attainment in China: Period Variations

In industrialized nations, sibship size generally depresses educational attainment: the larger the number of siblings, the lower the educational attainment. This association is much less consistent in developing nations, however. This article examines the effect that the number of siblings has on educational attainment in China, a nation that has experienced sharp vacillations between policies designed to promote equality (between urban and rural residents and between men and women) and policies designed to promote economic development. The implementation of these policies in the educational arena has alternately reduced and increased competition for educational resources and, as we show, has correspondingly reduced and increased the effect of sibship size on educational attainment

An investigation into eukaryotic pseudouridine synthases

A common post-transcriptional modification of RNA is the conversion of uridine to its isomer pseudouridine. We investigated the biological significance of eukaryotic pseudouridine synthases using the yeast Saccharomyces cerevisiae. We conducted a comprehensive statistical analysis on growth data from automated perturbation (gene deletion) experiments, and used bi-logistic curve analysis to characterise the yeast phenotypes. The deletant strains displayed different alteration in growth properties, including in some cases enhanced growth and/or biphasic growth curves not seen in wild-type strains under matched conditions. These results demonstrate that disrupting pseudouridine synthases can have a significant qualitative effect on growth. We further investigated the significance of post-transcriptional pseudouridine modification through investigation of the scientific literature. We found that (1) In Toxoplasma gondii, a pseudouridine synthase gene is critical in cellular differentiation between the two asexual forms: Tachyzoites and bradyzoites; (2) Mutation of pseudouridine synthase genes has also been implicated in human diseases (mitochondrial myopathy and sideroblastic anemia (MLASA); dyskeratosis congenita). Taken together, these results are consistent with pseudouridine synthases having a Gene Ontology function of "biological regulation". </jats:p

Migration, Remittances, and Educational Stratification among Blacks in Apartheid and Post-Apartheid South Africa

This paper extends previous work on family structure and children’s education by conceptualizing migration as a distinct form of family disruption that reduces parental input but brings substantial economic benefits through remittances. It examines the multiple and countervailing effects of migration on schooling in the context of substantial migration and limited educational opportunities for blacks in South Africa. The receipt of remittances substantially increases black children’s school attendance, but has no such effect for whites. The effect for blacks is in part attributable to improved household economic conditions that increase household educational spending and reduce the demand for child labor. We also find a negative effect of parental absence due to migration, but it is largely cushioned by inflows of remittances. Sensitivity analyses using propensity score methods and contextual fixed-effect modeling suggest that the beneficial effect of remittances is relatively robust. We find further that remittances help ameliorate inter-familial socioeconomic inequality in schooling. Finally, we evaluate possible temporal changes and show that the positive and equalizing effects of remittances persisted during and after the apartheid regime. We conclude that labor migration and remittances, as institutionalized family strategies adopted by many blacks, help reconfigure structural opportunities in the educational stratification process in South Africa

Connecting proline metabolism and signaling pathways in plant senescence

The amino acid proline has a unique biological role in stress adaptation. Proline metabolism is manipulated under stress by multiple and complex regulatory pathways and can profoundly influence cell death and survival in microorganisms, plants, and animals. Though the effects of proline are mediated by diverse signaling pathways, a common theme appears to be the generation of reactive oxygen species (ROS) due to proline oxidation being coupled to the respiratory electron transport chain. Considerable research has been devoted to understand how plants exploit proline metabolism in response to abiotic and biotic stress. Here, we review potential mechanisms by which proline metabolism influences plant senescence, namely in the petal and leaf. Recent studies of petal senescence suggest proline content is manipulated to meet energy demands of senescing cells. In the flower and leaf, proline metabolism may influence ROS signaling pathways that delay senescence progression. Future studies focusing on the mechanisms by which proline metabolic shifts occur during senescence may lead to novel methods to rescue crops under stress and to preserve post-harvest agricultural products