How Does Land Rental Affect Agricultural Labor Productivity? An Empirical Study in Rural China

Due to the striking gap in agricultural labor productivity (ALP) between China and developed countries, improving agricultural labor productivity is critically important. This study investigates the effect of land rental on agricultural labor productivity from two levels including household agricultural labor productivity and aggregated village-level agricultural labor productivity by employing propensity matching methods and instrumental variables method. Mediation analysis is also applied to explore the influencing mechanism and underlying paths for household agricultural labor productivity improvement. The results analyses based on the nation-wide data sets in 2017 reveal that renting-in land has a significant positive impact on promoting household agricultural labor productivity and renting-out land has significant opposite effects. The mediation analysis indicates that renting-in land affects household ALP indirectly through the land-labor ratio, intermediate inputs, and agricultural assets investment. Moreover, from the village perspective, we further found that the development of the land rental market positively affects the improvement of aggregated agricultural labor productivity of the village. Land rental is an effective channel to stimulate land transferred from lower agricultural labor productivity to higher ones and then promote the resource allocation within the village

Complete mitochondrial genome sequence of Abraximorpha davidii (Lepidoptera: Hesperiidae: Tagiadinae)

Taxonomic status and phylogenetic position of some skippers within Hesperiidae remains a controversial issue, here, we sequenced and analyzed the complete mitochondrial genome (mitogenome) of Abraximorpha davidii, one of species in Hesperiidae. This mitogenome is 15,469 bp long and encodes 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and two ribosomal RNA unit genes (rRNAs). The overall base composition of the mitogenome is A 40.2%, T 41.4%, C 11.2%, and G 7.2%, with a high A + T content of 81.6%. Except for cox1 starting with CGA, all other PCGs start with the standard ATN codons (seven ATG and five ATT). Most of the PCGs terminate with the stop codon TAA, whereas cox1, cox2, nad5, and nad4 end with the incomplete codon T−. Phylogenetic analysis showed that A. davidii is closely related to Daimio tethys and Tagiades vajuna, then this clade clusters Ctenoptilum vasava and Celaenorrhinus maculosa

Phylogenetic relationship and characterization of the complete mitochondrial genome of Colias fieldii (Lepidoptera: Papilionoidea: Pieridae)

Colias fieldii is a common seen diurnal butterflies in the fields and widely distributed in many provinces of China. In this study, we sequenced and analyzed the complete mitochondrial genome (mitogenome) of C. fieldii. This mitogenome was 15,150 bp long and encoded 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and two ribosomal RNA unit genes (rRNAs). The overall base composition of the mitogenome was estimated to be A 39.8%, T 41.2%, C 11.4% and G 7.6%, with a high A + T content of 81.0%. Except for cox1 started with CGA, all other PCGs started with the standard ATN codons (seven ATG, four ATT and one ATC). Most of the PCGs terminated with the stop codon TAA or TAG, whereas cox1, cox2, nad5 and nad4 end with the incomplete codon T––. Phylogenetic analysis showed that C. fieldii is indeed the sister species of Colias erate with a high support value. All seven Coliadinae species formed one clade and was sister to Pierinae butterflies. Within Coliadinae, the relationships (Eurema + (Gonepteryx + (Catopsilia + Colias))) were highly supported

Exclusive Production of Gentamicin C1a from Micromonospora purpurea by Metabolic Engineering

Gentamicin C1a is an important precursor to the synthesis of etimicin, a potent antibiotic. Wild type Micromonospora purpurea Gb1008 produces gentamicin C1a, besides four other gentamicin C components: C1, C2, C2a, and C2b. While the previously reported engineered strain M. purpurea GK1101 can produce relatively high titers of C1a by blocking the genK pathway, a small amount of undesirable C2b is still being synthesized in cells. Gene genL (orf6255) is reported to be responsible for converting C1a to C2b and C2 to C1 in Micromonospora echinospora ATCC15835. In this work, we identify the genL that is also responsible for the same methylation in Micromonospora purpurea. Based on M. purpurea GK1101, we construct a new strain with genL inactivated and show that no C2b is produced in this strain. Therefore, we successfully engineer a strain of M. purpurea that solely produces gentamicin C1a. This strain can potentially be used in the industrial production of C1a for the synthesis of etimicin

Numerical Study on Transient State of Inductive Fault Current Limiter Based on Field-Circuit Coupling Method

As the capacity of the power grid continues to expand, high-level fault currents might be caused during a contingency, and the problem of short-circuit current over-limitation is imminent. The high-temperature superconducting (HTS) fault current limiter (FCL) is an effective method to solve this problem. In this paper, a transient numerical model for the process of limiting current in the inductive FCL is proposed. The model is based on the coupling of multiphysics finite element simulation and a circuit model. The voltage source is used as input, which can simulate the macroscopic characteristics in the process of limiting current, such as the voltage and current waveforms, and can also simulate microscopic characteristics, such as temperature, magnetic field, and electrodynamic force distribution. The short-circuit experimental data of an air core inductive superconducting fault current limiter (SFCL) prototype was compared with the simulation results to verify the reliability of the simulation