Nonparametric identification of a binary random factor in cross section data

Suppose V and U are two independent mean zero random variables, where V has an asymmetric distribution with two mass points and U has a symmetric distribution. We show that the distributions of V and U are nonparametrically identified just from observing the sum V +U, and provide a rate root n estimator. We apply these results to the world income distribution to measure the extent of convergence over time, where the values V can take on correspond to country types, i.e., wealthy versus poor countries. We also extend our results to include covariates X, showing that we can nonparametrically identify and estimate cross section regression models of the form Y = g(X;D*)+U, where D* is an unobserved binary regressor.

Redescription of Plagiopholis styani (Serpentes, Pseudoxenodontidae), with description of two new species from China

During a long period, the genus Plagiopholis included four species and was extremely scarce. One of the members, Plagiopholis styani Boulenger, 1893, was treated as a single species widely distributed in the Dongyang domain of China. However, after new samplings of this species and examination of historical collection specimens, combined with molecular phylogenetic results based on two mitochondrial gene fragments (CO1 and Cyt b) and morphological comparisons of different populations, we found distinct divergences among them. Based on these results, we made the following taxonomic decisions and described the taxa in detail: (1) the populations from the type locality and adjacent areas such as Zhejiang, Anhui, and northeastern Jiangxi were considered Plagiopholis styani sensu stricto; (2) the population from Hunan Province is herein described as a new species, Plagiopholis acuta sp. nov.; (3) the populations from Sichuan and Guizhou provinces are also described herein as a new species, Plagiopholis pluvialis sp. nov. This study brings the total number of Plagiopholis to six and highlights the importance of documenting the cryptic diversity of small-bodied snakes in East Asia’s fragmented montane ecosystems

Stable RuIr Nanoalloy Catalyst for Levulinic Acid Hydrogenation Reaction

Hydrogenation of levulinic acid (LA) represents a significant approach for producing the high-value biomass-based platform compound γ-valerolactone (GVL). In this study, an efficient RuIr alloy bimetallic catalyst supported on SiC was synthesized and applied for the aqueous hydrogenation of LA into GVL under mild conditions. The RuIr/SiC catalyst exhibited high LA conversion and GVL selectivity (both > 99%) in water at 0.2 MPa H2 pressure and 25 °C. The excellent performance is attributed to the synergistic interaction between Ru and Ir nanoparticles on the semiconducting SiC support. Furthermore, the catalytic activity of the RuIr/SiC alloy remained basically unchanged after five cycles, confirming the high stability of the bimetallic alloy catalyst