Modeling airport capacity choice with real options

This study analyzes optimal choice of the airport capacity to invest immediately (the prior capacity) and the size of real option to acquire for possible future expansion. Facing demand uncertainty, an airport first chooses its prior capacity and real option, and then later chooses its final capacity and airport charge once demand is observed. Our analytical results show that if demand uncertainty is low and capacity and real option costs are relatively high, an airport will not acquire a real option. Otherwise, an airport can use a real option to improve its expected profit or social welfare. Both the magnitude of profit or welfare gain and the optimal size of the real option increase with demand uncertainty. A higher real option cost leads to a larger prior capacity and smaller real option, whereas a higher capital cost leads to lower prior capacity. A profit-maximizing airport would choose a smaller prior capacity and real option than a welfare-maximizing airport. Competition in the airline market promotes airport capacity investments and the adoption of real options by profit-maximizing airports, whereas airport commercial services increase prior capacity but not real option

p38α MAPK regulates proliferation and differentiation of osteoclast progenitors and bone remodeling in an aging-dependent manner.

Bone mass is determined by the balance between bone formation, carried out by mesenchymal stem cell-derived osteoblasts, and bone resorption, carried out by monocyte-derived osteoclasts. Here we investigated the potential roles of p38 MAPKs, which are activated by growth factors and cytokines including RANKL and BMPs, in osteoclastogenesis and bone resorption by ablating p38α MAPK in LysM+monocytes. p38α deficiency promoted monocyte proliferation but regulated monocyte osteoclastic differentiation in a cell-density dependent manner, with proliferating p38α-/- cultures showing increased differentiation. While young mutant mice showed minor increase in bone mass, 6-month-old mutant mice developed osteoporosis, associated with an increase in osteoclastogenesis and bone resorption and an increase in the pool of monocytes. Moreover, monocyte-specific p38α ablation resulted in a decrease in bone formation and the number of bone marrow mesenchymal stem/stromal cells, likely due to decreased expression of PDGF-AA and BMP2. The expression of PDGF-AA and BMP2 was positively regulated by the p38 MAPK-Creb axis in osteoclasts, with the promoters of PDGF-AA and BMP2 having Creb binding sites. These findings uncovered the molecular mechanisms by which p38α MAPK regulates osteoclastogenesis and coordinates osteoclastogenesis and osteoblastogenesis

Heavy Metal Emission Characteristics of Urban Road Runoff

Pavement runoff sampling points were set up on the main roads of Chengdu city. Six rainfall-runoff events from July to September in 2017 were sampled by synchronous observation of rainfall, runoff and pollution. The concentration changes of copper, lead, zinc, chromium and cadmium in the runoff process were monitored, and the pollution emission regularity and initial scouring effect were studied. The results show that the emission regularity of pavement runoff pollution is closely related to rainfall characteristics and pollutant occurrence, and the concentration of dissolved heavy metals reaches its peak at the initial stage of runoff. The peak time of particulate heavy metal concentration lagged slightly behind that of rainfall intensity. There is a big difference between the strength of initial scouring degree and dissolved heavy metals the stronger the initial scouring degree of total heavy metals, the weaker the dissolved heavy metals. Reducing pavement runoff in the early stage of rainfall is an effective means to control heavy metal pollution

A snoRNA modulates mRNA 3' end processing and regulates the expression of a subset of mRNAs.

mRNA 3' end processing is an essential step in gene expression. It is well established that canonical eukaryotic pre-mRNA 3' processing is carried out within a macromolecular machinery consisting of dozens of trans-acting proteins. However, it is unknown whether RNAs play any role in this process. Unexpectedly, we found that a subset of small nucleolar RNAs (snoRNAs) are associated with the mammalian mRNA 3' processing complex. These snoRNAs primarily interact with Fip1, a component of cleavage and polyadenylation specificity factor (CPSF). We have functionally characterized one of these snoRNAs and our results demonstrated that the U/A-rich SNORD50A inhibits mRNA 3' processing by blocking the Fip1-poly(A) site (PAS) interaction. Consistently, SNORD50A depletion altered the Fip1-RNA interaction landscape and changed the alternative polyadenylation (APA) profiles and/or transcript levels of a subset of genes. Taken together, our data revealed a novel function for snoRNAs and provided the first evidence that non-coding RNAs may play an important role in regulating mRNA 3' processing

Analysis of the effect of different withering methods on tea quality based on transcriptomics and metabolomics

Withering is very important to the quality of Wuyi rock tea. In this study, transcriptomics and metabolomics were used to analyze the effects of different withering methods on tea quality formation. The results showed that sunlight withering (SW) was most beneficial in increasing the gene expression of ubiquinone and other terpenoid-quinone biosynthesis (ko00130), pyruvate metabolism (ko00620), starch and sucrose metabolism (ko00500), and tryptophan metabolism (ko00380) pathways, and increasing the content of nucleotides and derivatives, terpenoids, organic acids and lipids, thus enhancing the mellowness, fresh and brisk taste and aroma of tea. Withering trough withering (WW) was most beneficial in increasing the gene expression of glutathione metabolism (ko00480), phenylpropanoid biosynthesis (ko00940) pathways, increasing the content of phenolic acids and flavonoids, thus enhancing tea bitterness. A comprehensive evaluation of the metabolite content and taste characteristics of tea leaves showed SW to be the best quality and charcoal fire withering (FW) to be the worst quality. This study provided an important basis for guiding the processing of Wuyi rock tea with different flavors

Effects of Thermal Boundary Resistance on Thermal Management of Gallium-Nitride-Based Semiconductor Devices: A Review

Wide-bandgap gallium nitride (GaN)-based semiconductors offer significant advantages over traditional Si-based semiconductors in terms of high-power and high-frequency operations. As it has superior properties, such as high operating temperatures, high-frequency operation, high breakdown electric field, and enhanced radiation resistance, GaN is applied in various fields, such as power electronic devices, renewable energy systems, light-emitting diodes, and radio frequency (RF) electronic devices. For example, GaN-based high-electron-mobility transistors (HEMTs) are used widely in various applications, such as 5G cellular networks, satellite communication, and radar systems. When a current flows through the transistor channels during operation, the self-heating effect (SHE) deriving from joule heat generation causes a significant increase in the temperature. Increases in the channel temperature reduce the carrier mobility and cause a shift in the threshold voltage, resulting in significant performance degradation. Moreover, temperature increases cause substantial lifetime reductions. Accordingly, GaN-based HEMTs are operated at a low power, although they have demonstrated high RF output power potential. The SHE is expected to be even more important in future advanced technology designs, such as gate-all-around field-effect transistor (GAAFET) and three-dimensional (3D) IC architectures. Materials with high thermal conductivities, such as silicon carbide (SiC) and diamond, are good candidates as substrates for heat dissipation in GaN-based semiconductors. However, the thermal boundary resistance (TBR) of the GaN/substrate interface is a bottleneck for heat dissipation. This bottleneck should be reduced optimally to enable full employment of the high thermal conductivity of the substrates. Here, we comprehensively review the experimental and simulation studies that report TBRs in GaN-on-SiC and GaN-on-diamond devices. The effects of the growth methods, growth conditions, integration methods, and interlayer structures on the TBR are summarized. This study provides guidelines for decreasing the TBR for thermal management in the design and implementation of GaN-based semiconductor devices