One-Bit MUSIC Huang, Xiaodong; Liao, Bin
IEEE signal processing letters,
07/2019, Volume:
26, Issue:
7
Journal Article
Peer reviewed
In this letter, we consider the problem of direction-of-arrival (DOA) estimation with one-bit quantized array measurements. With analysis, it is shown that, under mild conditions the one-bit ...covariance matrix can be approximated by the sum of a scaled unquantized covariance matrix and a scaled identity matrix. Although the scaling parameters are unknown because of the extreme quantization, they do not affect the subspace-based DOA estimators. Specifically, the signal and noise subspaces can be straightforwardly determined through the eigendecomposition of the one-bit covariance matrix, without pre-processing such as unquantized covariance matrix reconstruction. With so-obtained subspaces, the most classical multiple signal classification (MUSIC) technique can be applied to determine the signal DOAs. The resulting method is thus termed as one-bit MUSIC. Thanks to the simplicity of this method, it can be very easily implemented in practical applications, whereas the DOA estimation performance is comparable to the case with unquantized covariance matrix reconstruction, as demonstrated by various simulations.
Green building development(GBD) plays an important role in improving carbon emission reduction efficiency of the construction industry(CEEOCI), and accelerating the construction industry to achieve ...carbon neutrality goals. In this paper, for the first time, the topic of “green building development promotes carbon neutrality in the construction industry” is included in the crossover research category of industrial economics and space economics. A framework for the analysis of the impact mechanism of GBD and CEEOCI under the dual perspective of “industry-space” is proposed. Based on China’s provincial panel data from 2008 to 2019, using the intermediary adjustment model and the spatial Dubin model to analyze and test the industrial mechanism, spatial mechanism, and spatial effect attenuation boundary of the GBD effect on CEEOCI. The results show GBD is found to promote CEEOCI, and both the GBD and CEEOCI have a clear “center-periphery” spatial pattern. Meanwhile, the impact of GBD on CEEOCI has a “industry-space” two-dimensional mechanism. From an industrial perspective, GBD can change the supply-demand relationship of the construction market by promoting the greening of supporting industries in the construction industry and stimulating green consumption in the market, and ultimately achieve the overall improvement of CEEOCI. From a spatial perspective, GBD can form a new sectoral growth pole and provide elemental support for the improvement of CEEOCI through the polarization effect, but the polarization effect is higher in the range of 1000 km, while attenuation occurs outside the range of 1000 km. This paper provides not only a scientific and effective medium and macro analysis framework for green building development emission reduction performance evaluation but also a new theoretical basis and policy direction for the construction industry to improve carbon reduction efficiency and achieve industrial carbon neutrality.
Green development of cities has been gaining attention worldwide, especially in urban agglomerations, where market integration is promoting. However, it is not clear whether the market integration in ...urban agglomerations is conducive to promote the green development of cities. Hence, this research aims to address this question. This research employed the data of 100 cities in China’s Yangtze River Economic Belt from 2006 to 2019 and a comprehensive analytic framework including a panel threshold model to explore the impact of urban agglomeration market integration on urban green development and the nonlinear adjustment mechanism. The main findings are shown below: (1) urban agglomerations market integration was found to be significant to promote green development of the city, but there are two dimensions: the horizontal dimension and the efficiency dimension, (2) the optimal dimensions for urban agglomeration market integration to promote green development of the city were found has regional and urban heterogeneity. Therefore, it is necessary for the city to formulate differentiated green development strategies, (3) when human capital advancement and knowledge sharing intervene, urban agglomeration market integration will have a “jumping” threshold impact on green development of the city through the level path; and under the adjustment of environmental regulations and the green transformation mechanism of the industrial structure, the influence of the urban agglomeration market integration on the efficiency of urban green development presents a “U-shaped” threshold characteristic, (4) lastly, the conclusions enlighten urban agglomeration market integration and heterogeneous green development model for approaching a better performance in urban green development.
Covering: up to July 2023Terpene cyclases (TCs) catalyze some of the most complicated reactions in nature and are responsible for creating the skeletons of more than 95 000 terpenoid natural ...products. The canonical TCs are divided into two classes according to their structures, functions, and mechanisms. The class II TCs mediate acid-base-initiated cyclization reactions of isoprenoid diphosphates, terpenes without diphosphates (
, squalene or oxidosqualene), and prenyl moieties on meroterpenes. The past twenty years witnessed the emergence of many class II TCs, their reactions and their roles in biosynthesis. Class II TCs often act as one of the first steps in the biosynthesis of biologically active natural products including the gibberellin family of phytohormones and fungal meroterpenoids. Due to their mechanisms and biocatalytic potential, TCs elicit fervent attention in the biosynthetic and organic communities and provide great enthusiasm for enzyme engineering to construct novel and bioactive molecules. To engineer and expand the structural diversities of terpenoids, it is imperative to fully understand how these enzymes generate, precisely control, and quench the reactive carbocation intermediates. In this review, we summarize class II TCs from nature, including sesquiterpene, diterpene, triterpene, and meroterpenoid cyclases as well as noncanonical class II TCs and inspect their sequences, structures, mechanisms, and structure-guided engineering studies.
Abstract
Terpene cyclization, one of the most complex chemical reactions in nature, is generally catalyzed by two classes of terpene cyclases (TCs). Cytochrome P450s that act as unexpected TC‐like ...enzymes are known but are very rare. In this study, we genome‐mined a cryptic bacterial terpenoid gene cluster, named
ari
, from the thermophilic actinomycete strain
Amycolatopsis arida
. By employing a heterologous production system, we isolated and characterized three highly oxidized eunicellane derived diterpenoids, aridacins A−C (
1
–
3
), that possess a 6/7/5‐fused tricyclic scaffold. In vivo and in vitro experiments systematically established a noncanonical two‐step biosynthetic pathway for diterpene skeleton formation. First, a class I TC (AriE) cyclizes geranylgeranyl diphosphate (GGPP) into a 6/10‐fused bicyclic
cis
‐eunicellane skeleton. Next, a cytochrome P450 (AriF) catalyzes cyclization of the eunicellane skeleton into the 6/7/5‐fused tricyclic scaffold through C2−C6 bond formation. Based on the results of quantum chemical computations, hydrogen abstraction followed by electron transfer coupled to barrierless carbocation ring closure is shown to be a viable mechanism for AriF‐mediated cyclization. The biosynthetic logic of skeleton construction in the aridacins is unprecedented, expanding the catalytic capacity and diversity of P450s and setting the stage to investigate the inherent principles of carbocation generation by P450s in the biosynthesis of terpenoids.
Osimertinib is the current recommended treatment for EGFR T790M–positive NSCLC after EGFR tyrosine kinase inhibitor therapy. However, resistance to osimertinib therapy is inevitably acquired after a ...period of effective treatment. We had a patient with EGFR L858R/T790M–positive NSCLC who initially responded to osimertinib therapy but eventually experienced development of resistance. Plasma cell–free DNA analysis revealed the occurrence of exon 16–skipping HER2, which may have resulted in the erb-b2 receptor tyrosine kinase 2 gene (HER2) splice variant HER2D16. HER2D16 has never been reported in lung cancer, and HER2D16-driven signaling is known to be regulated by Src kinase in breast cancer. We investigated the role of HER2D16 as an osimertinib-resistant mechanism.
We constructed and established H1975 cells stably expressing HER2D16. The dimeric formation of HER2D16 was tested by using nonreducing polyacrylamide gel electrophoresis. The effects of the study drugs on signaling transduction were examined by using Western blot. Synergistic effect was assessed by using the Chou-Talalay method.
We found that HER2D16 can form a homodimer in NSCLC cells. HER2D16-expressing H1975 cells were resistant to osimertinib treatment. We also found that mutant EGFR and HER2D16 cooperated to activate downstream signaling for osimertinib resistance. In addition, cotreatment with osimertinib and an Src kinase inhibitor failed to reverse resistance, indicating that HER2D16-driven signaling in NSCLC did not occur through a canonical pathway. Finally, we revealed that the combination of osimertinib with the pan-HER small-molecule inhibitor afatinib could synergistically repress cell growth and signaling in H1975-HER2D16 cells.
HER2D16 can contribute to osimertinib resistance through an Src-independent pathway. HER2D16 should be included in the molecular diagnosis panel for lung cancer.
A new method for direction finding with partly calibrated uniform linear arrays (ULAs) is presented. It is based on the conventional estimation of signal parameters via rotational invariance ...techniques (ESPRIT) by modeling the imperfections of the ULAs as gain and phase uncertainties. For a fully calibrated array, it reduces to the conventional ESPRIT algorithm. Moreover, the direction-of-arrivals (DOAs), unknown gains, and phases of the uncalibrated sensors can be estimated in closed form without performing a spectral search. Hence, it is computationally very attractive. The Cramér-Rao bounds (CRBs) of the partly calibrated ULAs are also given. Simulation results show that the root mean squared error (RMSE) performance of the proposed algorithm is better than the conventional methods when the number of uncalibrated sensors is large. It also achieves satisfactory performance even at low signal-to-noise ratios (SNRs).
Altered expression of circEPHB4, miR‐637 or SOX10 was independently associated with overall survival of glioma patients. By sponging miR‐637, circEPHB4 up‐regulated SOX10 and its target Nestin to ...promote stemness and self‐proliferation of glioma cells, stimulating the malignant progression of gliomas. Consistently, silencing circEPHB4 or overexpressing miR‐637 inhibited xenograft growth of glioma cells in vivo and has therapeutic prospects.
Gliomas are the most common type of primary brain tumors. CircRNA ephrin type‐B receptor 4 (circEPHB4) is a circular RNA derived from the receptor tyrosine kinase EPHB4. However, the clinical significance and the specific roles of circEPHB4 in gliomas and glioma cancer stem cells (CSC) have not been studied. Here, we found that circEPHB4 (hsa_circ_0081519) and SOX10 were up‐regulated and microRNA (miR)‐637 was down‐regulated in glioma tissues and cell lines. Consistently, circEPHB4 was positively correlated with SOX10 but negatively correlated with miR‐637. The altered expressions of these molecules were independently associated with overall survival of patients. CircEPHB4 up‐regulated SOX10 and Nestin by directly sponging miR‐637, thereby stimulating stemness, proliferation and glycolysis of glioma cells. Functionally, silencing circEPHB4 or increasing miR‐637 levels in glioma cells was sufficient to inhibit xenograft growth in vivo. In conclusion, the circEPHB4/miR‐637/SOX10/Nestin axis plays a central role in controlling stem properties, self‐renewal and glycolysis of glioma cells and predicts the overall survival of glioma patients. Targeting this axis might provide a therapeutic strategy for malignant gliomas.
FOXM1 (forkhead box protein M1) is a critical proliferation-associated transcription factor that is widely spatiotemporally expressed during the cell cycle. It is closely involved with the processes ...of cell proliferation, self-renewal, and tumorigenesis. In most human cancers, FOXM1 is overexpressed, and this indicates a poor prognosis for cancer patients. FOXM1 maintains cancer hallmarks by regulating the expression of target genes at the transcriptional level. Due to its potential role as molecular target in cancer therapy, FOXM1 was named the Molecule of the Year in 2010. However, the mechanism of FOXM1 dysregulation remains indistinct. A comprehensive understanding of FOXM1 regulation will provide novel insight for cancer and other diseases in which FOXM1 plays a major role. Here, we summarize the transcriptional regulation, post-transcriptional regulation and post-translational modifications of FOXM1, which will provide extremely important implications for novel strategies targeting FOXM1.
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