Measurement report: The promotion of low-level jet and thermal-effect on development of deep convective boundary layer at the southern edge of the Taklimakan Desert

A vigorous development process of the deep convective boundary layer (CBL) was observed at the southern edge of the Taklimakan Desert on 6 June, 2022. Based on coherent Doppler wind lidar and ERA5 data, the formation mechanism of the deep CBL exceeding 5 km was well analyzed, which was mainly promoted by the low-level jet (LLJ) and thermal-effect. The LLJ has made sufficient momentum, energy and material preparations for the development of the deep CBL. Firstly, the cold downhill airflow of the Tibet Plateau leading to LLJ weakens the height and intensity of the temperature inversion layer, which reduces the energy demand for the broken of the IL. Secondly, the LLJ not only supplements the material and energy in the residual layer, but also suppresses the exchange with the lower atmosphere. In addition, the LLJ provides a driving force for the development of the deep CBL. In terms of thermal factors, the Tibet Plateau sensible heat driven air-pump and cold front transit provide additional impetus for the development of the deep CBL. Finally, the formation of deep CBL was catalyzed by the extreme thermal effects of the underlying surface, such as the furnace effect and the atmospheric superadiabatic expansion process. The study of the development of the deep CBL is important for revealing the land-air exchange process of momentum, energy, and material between the Taklimakan Desert and the Tibetan Plateau

Software for doing computations in graded Lie algebras

We introduce the Macaulay2 package GradedLieAlgebras for doing computations in graded Lie algebras presented by generators and relations.Comment: 5 page

Hiding behind Writing: Communication in Offering Process and MBS Performance

Abstract Securities Offering Reform (SOR) in 2005 formalized free writing prospectus (FWP) as permittable written communication in the offering process by securities issuers. Using non-agency mortgage deals securitized following SOR, we find the surprising result that MBS deals with more usage of FWPs sufferred up to 20% higher cumulative net loss. Using textual analysis as an identification strategy, we attribute our finding to the more aggressive sales tactic associated with more FWP usage being employed for deals with more adverse information withholding. Consequently, the cumulative net loss on these deals are worse than their reported characteristics. Lending support to this explanation, we find that the FWP effect persists even after controlling for deal initial yield spreads and credit enhancements, and higher usage of FWPs are associated with increased content ambiguity in the final prospectus. The latter is a tactic often used to hedge litigation risk on undisclosed information. Keywords: Written Communication, Free Writing Prospectus, Information withholding, Uncertain Text, MBS Performance * We thank Zhonglan Dai, Jun Li, Tim Loughran, and Han Xia for helpful comments. All three authors are from Naveen Jindal School of Management, University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas, 75080, email: [email protected], [email protected], [email protected] "In many ways, mortgage products such as RMBS were ground zero in the financial crisis. Misrepresentations in connection with the creation and sale of mortgage securities contributed greatly to the tremendous losses suffered by investors once the U.S. housing market collapsed.&quot

Proximity effect induced intriguing superconductivity in van der Waals heterostructure of magnetic topological insulator and conventional superconductor

Nontrivial topological superconductivity has received enormous research attentions due to its potential for diverse applications in topological quantum computing. The intrinsic issue concerning the correlation between a topological insulator and a superconductor is, however, still widely open. Here, we systemically report an emergent superconductivity in a cross-junction composed of a magnetic topological insulator MnBi2Te4 and a conventional superconductor NbSe2. Remarkably, the interface indicates existence of a reduced superconductivity at surface of NbSe2 and a proximity-effectinduced superconductivity at surface of MnBi2Te4. Furthermore, the in-plane angular-dependent magnetoresistance measurements reveal the fingerprints of the paring symmetry behaviors for these superconducting gaps as a unconventional nature. Our findings extend our views and ideas of topological superconductivity in the superconducting heterostructures with time-reversal symmetry breaking, offering an exciting opportunity to elucidate the cooperative effects on the surface state of a topological insulator aligning a superconductor.Comment: 6 pages, 4 figure

OP9-Lhx2 stromal cells facilitate derivation of hematopoietic progenitors both in vitro and in vivo

AbstractGenerating engraftable hematopoietic stem cells (HSCs) from pluripotent stem cells (PSCs) is an ideal approach for obtaining induced HSCs for cell therapy. However, the path from PSCs to robustly induced HSCs (iHSCs) in vitro remains elusive. We hypothesize that the modification of hematopoietic niche cells by transcription factors facilitates the derivation of induced HSCs from PSCs. The Lhx2 transcription factor is expressed in fetal liver stromal cells but not in fetal blood cells. Knocking out Lhx2 leads to a fetal hematopoietic defect in a cell non-autonomous role. In this study, we demonstrate that the ectopic expression of Lhx2 in OP9 cells (OP9-Lhx2) accelerates the hematopoietic differentiation of PSCs. OP9-Lhx2 significantly increased the yields of hematopoietic progenitor cells via co-culture with PSCs in vitro. Interestingly, the co-injection of OP9-Lhx2 and PSCs into immune deficient mice also increased the proportion of hematopoietic progenitors via the formation of teratomas. The transplantation of phenotypic HSCs from OP9-Lhx2 teratomas but not from the OP9 control supported a transient repopulating capability. The upregulation of Apln gene by Lhx2 is correlated to the hematopoietic commitment property of OP9-Lhx2. Furthermore, the enforced expression of Apln in OP9 cells significantly increased the hematopoietic differentiation of PSCs. These results indicate that OP9-Lhx2 is a good cell line for regeneration of hematopoietic progenitors both in vitro and in vivo

Effects of acidification on nitrification and associated nitrous oxide emission in estuarine and coastal waters

In the context of an increasing atmospheric carbon dioxide (CO2) level, acidification of estuarine and coastal waters is greatly exacerbated by land-derived nutrient inputs, coastal upwelling, and complex biogeochemical processes. A deeper understanding of how nitrifiers respond to intensifying acidification is thus crucial to predict the response of estuarine and coastal ecosystems and their contribution to global climate change. Here, we show that acidification can significantly decrease nitrification rate but stimulate generation of byproduct nitrous oxide (N2O) in estuarine and coastal waters. By varying CO2 concentration and pH independently, an expected beneficial effect of elevated CO2 on activity of nitrifiers (“CO2-fertilization” effect) is excluded under acidification. Metatranscriptome data further demonstrate that nitrifiers could significantly up-regulate gene expressions associated with intracellular pH homeostasis to cope with acidification stress. This study highlights the molecular underpinnings of acidification effects on nitrification and associated greenhouse gas N2O emission, and helps predict the response and evolution of estuarine and coastal ecosystems under climate change and human activities.publishedVersio